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Track'ish Oriented 99 Build (The other kind of forced induction though)
Big thanks to all you guys posting helpful info on this forum. I found myself lurking here in search of information pretty often. There are some great build threads on here too which is what prompted me to finally create an account. I think a build thread would be helpful with tracking what's being done to the car, what the future plan is, and a good place to get some feedback from people who are knowledgeable about the platform. Anyway...
This is my 1999 NB (next to the POs S2000) when it was pretty much bone stock when I bought it in 2018 with 93,XXX miles on it. It did come with the Hard Dog roll bar which was nice. https://cimg9.ibsrv.net/gimg/www.mia...3432ccaa8f.jpg https://cimg0.ibsrv.net/gimg/www.mia...d6ede00f5b.jpg I bought the car with intention to go AutoXing - and that's what I did. Outside of regular maintenance all that I did over the past few years (until about a month ago) was change the 14" OEM wheels to the 15", replace the cast iron California spec headers for the tubular OEM headers, and install high flow cat and cat back exhaust. Also replaced the OEM springs for adjustable yellow Konis. Even though I had an intake and exhaust, I tried to keep the car as close to SCCA ES class as possible (I wasn't competitive enough for anyone to care about the intake and exhaust). https://cimg3.ibsrv.net/gimg/www.mia...4d0d8c8810.jpg https://cimg4.ibsrv.net/gimg/www.mia...529fd1b8c4.jpg https://cimg5.ibsrv.net/gimg/www.mia...277bc7771d.jpg https://cimg6.ibsrv.net/gimg/www.mia...60627a1625.jpg https://cimg8.ibsrv.net/gimg/www.mia...4e8c810738.jpg https://cimg9.ibsrv.net/gimg/www.mia...29a4e30c87.jpg The OEM heat shield was also sand blasted and got a few coats of the same ceramic exhaust paint. https://cimg1.ibsrv.net/gimg/www.mia...ae1984ddfd.jpg https://cimg3.ibsrv.net/gimg/www.mia...911e7ab4ef.jpg https://cimg4.ibsrv.net/gimg/www.mia...523675bf93.jpg https://cimg7.ibsrv.net/gimg/www.mia...9d8f1242d4.jpg https://cimg2.ibsrv.net/gimg/www.mia...f050f15d38.jpg https://cimg4.ibsrv.net/gimg/www.mia...ac66db8523.jpg https://cimg6.ibsrv.net/gimg/www.mia...ac4d6c7231.jpg Every AutoX event was a blast with this car. And although I wasn't competitive in my class, beating some of my friends in cars which shoild be much faster was a lot of fun. Here's when things start to get interesting though. After about 4 or 5 years or AutoX, a few of my buddies and I drove to Pocono Raceway for a track sprint event. A track sprint was a great idea because I wasn't comfortable to do any wheel to wheel racing yet. Because driving in a Miata on the street for longer than 15 minutes is uncomfortable, I decided to just go ahead and buy a car dolly so that I can tow the Miata from South Jersey to Pocono Raceway. https://cimg5.ibsrv.net/gimg/www.mia...c2857e632d.jpg https://cimg6.ibsrv.net/gimg/www.mia...8f4bcba49c.jpg https://cimg5.ibsrv.net/gimg/www.mia...a7c6ce2159.jpg https://cimg7.ibsrv.net/gimg/www.mia...8fbfbeb89c.jpg The event was an incredible experience. Instantly fell in love. This was only back in May and unfortunately have not been able to do another track sprint since. I had been apprehensive about going to events far from home because driving the Miata pretty much all day just doesn't seem like a fun time. Being able to now tow the car to an event completely changed that... With track events further from home now on the table for consideration, I started to consider stepping out of the stock class. In my opinion the car performed great in all aspects except one thing. You guys are all aware... It's why we're all here anyway, the car just lacked some balls. Coming out of a hairpin the car just felt bogged down and slow. The braking and momentum were great all things considered but the torque just wasn't there when I needed it. Granted a lot of the issue is my lack of experience, but still. My friends with faster cars who I used to be able to compete with in AutoX pretty much wiped the floor with me and there was no one else in my class to compare to. Plus it's fun to go fast. I always liked the idea of a supercharger on the Miata. The idea of more low end torque was really attractive to me. So I started searching for a supercharger kit. You guys probably know this but, but I didn't, pretty much no one makes new roots style kits anymore unless you want the clodside FFS. I honestly wouldn't mind the FFS, but I was priced out of if unfortunately. Plus I know eventually I would probably want an intercooler if the car were to ever make any serious power. I ended up finding a used M45 Jackson Racing supercharger kit for sale and bought it. I pretty much snagged it immediately because it was the only kit that came up for a while. I woild have preferred an MP62 kit but beggers can't be choosers, right? https://cimg9.ibsrv.net/gimg/www.mia...4ebf14cb89.jpg Well. I read a bunch of people's experience with the M45 (mostly on here) and you guys made it clear that the MP62 is the way to go if you have the option. So I kept my eye out for one for shits and giggles. Literally the day the M45 is shipped to me from the South, I find a local MP62 kit with the correct piggy back power card for my car... So I bought that one too. https://cimg3.ibsrv.net/gimg/www.mia...c017f75c92.jpg This kit allowed me to get up and running without having to immediately go with a standalone ECU which was a huge plus for me. The M45 kit would have probably have to wait until I found an ECU and a tuner to help... Well... Tune it. So I sold the M45 kit and installed the MP62. https://cimg8.ibsrv.net/gimg/www.mia...fe6f9d4f4b.jpg https://cimg9.ibsrv.net/gimg/www.mia...f8c2086877.jpg https://cimg0.ibsrv.net/gimg/www.mia...cea25c03d8.jpg Was determined to keep the OEM heat shield which technically isn't compatible with the BRP MP62 bracket. It actually worked out well after some modification to access the exhaust studs. https://cimg1.ibsrv.net/gimg/www.mia...2044bfee95.jpg https://cimg3.ibsrv.net/gimg/www.mia...5a4d21a7af.jpg https://cimg4.ibsrv.net/gimg/www.mia...b20e4e46fa.jpg https://cimg7.ibsrv.net/gimg/www.mia...a988d0f099.jpg https://cimg8.ibsrv.net/gimg/www.mia...b42fc661dc.jpg This is pretty much where the car stands now. It's a joy to drive. Have not had a chance to do any AutoX or track sprints since but there is an AutoX event coming up this weekend. I've been dailying the car just to work out some kinks if any, but luckily there hasn't been any. I'm a big fan of Beavis Motorsport (along with a bunch of serious builds on here). Although the original plan was to keep this car as stock as possible, now that it's supercharged... A track oriented car sounds incredibly fun. The impact modifying a car has on resale value makes me a little hesitant to really let loose and do what I want with it, but at the same time, I have no interest in selling the car to buy another car for the same purpose. I really can't think of a better car for the purpose within my budget... I even conserved looking for another NB in bad shape that I can buy for cheap, but prices have gone up so much that I woild be paying more than I paid for this car PLUS I woild have to deal with all the rust/mechanical issues that this car doesn't have. Experimenting with ducting, areo, weight reduction, engine and suspension modifications sounds like a dream to me. So that's pretty much where the car is at right now, along with the crossroad I'm currently at. Build dedicated track car or just enjoy a fun street car? My heart tells me to build what I want, my mind is telling me not to 'ruin' the car. I'm curious to know if any of you have struggled with the same dilemma. Superchargers are cool too btw. -Sherif |
Was able to get some work done on the car this past weekend. The shifter needed to be rebuilt and I was between a short shifter like the MiataRoadster, or just an OEM rebuild kit. A lot of people (especially on this forum from what I can tell) really like the OEM shifter. I can't disagree. So I went with an OEM kit from Treasure Coast Miata with the 5X Racing brass bushing.
The shifter didn't feel terrible before the rebuild but regardless getting these boots replaced made it worthwhile. https://cimg4.ibsrv.net/gimg/www.mia...48a9b22056.jpg https://cimg5.ibsrv.net/gimg/www.mia...2238bcc004.jpg https://cimg2.ibsrv.net/gimg/www.mia...1354d5b796.jpg Nylon bushing wasn't even in terrible shape. Not sure when/if it's been replaced. https://cimg6.ibsrv.net/gimg/www.mia...e883eae418.jpg Tried to get as much of the old fluid out with a turkey baster... There was still a lot of gross fluid in the turret, so I just decided to take it off and give it a good cleaning/flush. I followed https://cimg0.ibsrv.net/gimg/www.mia...93f91004a5.jpg https://cimg1.ibsrv.net/gimg/www.mia...d7bd478dbf.jpg https://cimg2.ibsrv.net/gimg/www.mia...c4a1927841.jpg https://cimg5.ibsrv.net/gimg/www.mia...90e75061bd.jpg https://cimg6.ibsrv.net/gimg/www.mia...d9d0035e46.jpg https://cimg7.ibsrv.net/gimg/www.mia...bcd8775b05.jpg https://cimg8.ibsrv.net/gimg/www.mia...98493301d7.jpg https://cimg9.ibsrv.net/gimg/www.mia...3bc1c903bf.jpg https://cimg1.ibsrv.net/gimg/www.mia...eff85ffbc4.jpg https://cimg2.ibsrv.net/gimg/www.mia...67227f324f.jpg The shifter had some surface rust so I gave it a quick light sanding and re painted the white dot. https://cimg8.ibsrv.net/gimg/www.mia...f020604050.jpg https://cimg9.ibsrv.net/gimg/www.mia...9f6f8b3ddb.jpg Rebuild time https://cimg4.ibsrv.net/gimg/www.mia...084fd99b6f.jpg https://cimg5.ibsrv.net/gimg/www.mia...3963a75336.jpg https://cimg7.ibsrv.net/gimg/www.mia...1a4c65d762.jpg While waiting for the gasket maker to set I went ahead and replaced the broken glove box handle which has been in my glove box for at least 3 years haha. Super easy to do. I thought moving the key cylinder would be a pain but it wasn't at all. https://cimg7.ibsrv.net/gimg/www.mia...5213830847.jpg https://cimg8.ibsrv.net/gimg/www.mia...74b0978cbc.jpg Got everything back together and cleaned up. Feels great and the supervisor has approved. https://cimg3.ibsrv.net/gimg/www.mia...cefc960862.jpg https://cimg4.ibsrv.net/gimg/www.mia...82896c212c.jpg https://cimg5.ibsrv.net/gimg/www.mia...e413660014.jpg A couple easy things on the to-do list: I have the "turbo" PCV (E301-13-890A) that I can install, just need some new vacuum line. And I have to mount the IAC, right now it's just nestled on top of the intake. I'll probably mount it on the passenger side firewall. I do have a decision to make. The AC compressor appears to have died (self destructing). It's been a bit weak for the past year or so. I'm considering just deleting the AC. I have to look into what the power benefits are but the weight savings and engine bay space would be nice... I'd be curious to hear what other people think. |
First autocross event with the supercharger was a lot of fun. The car behaved great and was a pleasure to drive. Ended up 6th out of 37 cars in open class. I'm really happy with how well the RT660s have been performing!
I think it's time to seriously consider some suspension upgrades. Now that I'm not worried about deviating far out of the SCCA SE class, I can explore some aftermarket adjustable coilover options. Also doing some research into DIY Bilstein coilovers. It's either that or Xidas, but it would take me a while to get some Xidas... So, we'll see. Still plenty of other work the car needs in the meantime. This weekend I'll be taking the Miata to a local road course. Very excited! This will be my first time trying (non-competitive) w2w. |
Autocross - the most fun you can have sitting down!
Non-competitive w2w seems like a contradiction? |
Originally Posted by Gee Emm
(Post 1640404)
Autocross - the most fun you can have sitting down!
Non-competitive w2w seems like a contradiction? Not sure how else to describe it. It's going to be w2w with point by's. It's not sanctioned by a racing organization like SCCA or anything. Just an event at a local track. Ahh! I forgot to mention I picked up some goodies for racecar activities. I found someone local parting out an NB1 so I picked up the hood, front and rear bumpers, and both headlights. https://cimg4.ibsrv.net/gimg/www.mia...1cc569d22b.jpg Now I won't feel bad cutting into unmolested OEM body panels :dunno:. |
Originally Posted by HalalBuilt
(Post 1639913)
I do have a decision to make. The AC compressor appears to have died (self destructing). It's been a bit weak for the past year or so. I'm considering just deleting the AC.
https://cimg1.ibsrv.net/gimg/www.mia...ba5e22ec66.jpg https://cimg3.ibsrv.net/gimg/www.mia...c5d3990991.jpg https://cimg4.ibsrv.net/gimg/www.mia...af38c530a4.jpg https://cimg3.ibsrv.net/gimg/www.mia...e6c3b9b18a.jpg https://cimg1.ibsrv.net/gimg/www.mia...9250bfb06b.jpg I saved all the parts in container incase I ever want to reinstall... https://cimg3.ibsrv.net/gimg/www.mia...d65513ce94.jpg While the fender liners were off I cleaned up this embarrassing mess. https://cimg7.ibsrv.net/gimg/www.mia...1b0122bb1a.jpg https://cimg8.ibsrv.net/gimg/www.mia...b864931724.jpg https://cimg9.ibsrv.net/gimg/www.mia...2b4f8ad0f5.jpg https://cimg1.ibsrv.net/gimg/www.mia...4467b43a85.jpg In preparation for the track day I did a complete brake fluid flush. The existing fluid was pretty bad. I've always been a bit apprehensive about opening up the braking system... But it want difficult at all. I'm used to working on my old Silverado on which everything was rusty and seized. https://cimg6.ibsrv.net/gimg/www.mia...a90f80cf58.jpg https://cimg7.ibsrv.net/gimg/www.mia...e5536746ac.jpg Documenting treadwear for future reference and also rotated tires. https://cimg2.ibsrv.net/gimg/www.mia...ff1e68b138.jpg https://cimg3.ibsrv.net/gimg/www.mia...575a5799c5.jpg https://cimg4.ibsrv.net/gimg/www.mia...43be46fbc9.jpg Replaced the clutch and brake pedal pads with OEM replacements. https://cimg2.ibsrv.net/gimg/www.mia...f8cc666bcc.jpg https://cimg4.ibsrv.net/gimg/www.mia...30c0337fa0.jpg Ready for Englishtown! https://cimg7.ibsrv.net/gimg/www.mia...34a9335c92.jpg |
First time on a road course with other cars was very fun. I'm hooked for sure. The day started out with the road course school with a couple of parade lap sessions then by mid day we were able to push as hard as we're comfortable with, with point bys in designated areas. Coming from AutoX, I'm used to the occasional spin and miscalculation - so I was nervous about doing any wheel to wheel. But it ended up being totally different and easier than expected.
https://cimg2.ibsrv.net/gimg/www.mia...1277b5c94d.jpg https://cimg6.ibsrv.net/gimg/www.mia...9cec15249f.jpg Only trouble experienced with the car was the power steering belt getting thrown which, I believe, in turn threw the supercharger belt. Both of them came off at the end of the second session of the day, so I popped the supercharger belt back on and ran the rest of the day without power steering. Otherwise the car ran great! Here's a short clip of a mid-day session without power steering. Chasing a new Corolla GR. Looking for suggestions for a lap timer. In this video I was borrowing my buddies RaceBox. Worked well and I liked it but would like to know what others use before purchasing one. Just sourced a pre-owned QMAX reroute kit that I'll be installing. The cars not experiencing any overheating issues or anything, but I do want to make some space in the front of the engine for proper radiator ducting (singular hood vents on the list to be ordered and installed eventually). Plus as it stands right now, the OEM radiator tube is in contact with & and running under the crossover tube from the supercharger to the intake manifold. So this should help a bit with heat transfer into that crossover maybe? Not sure if it really matters but regardless, a reroute is always a good idea. Planning to go back to Raceway Park in a couple weeks! |
Originally Posted by HalalBuilt
(Post 1640787)
Only trouble experienced with the car was the power steering belt getting thrown which, I believe, in turn threw the supercharger belt. Both of them came off at the end of the second session of the day, so I popped the supercharger belt back on and ran the rest of the day without power steering.
A potential solution is the 5xRacing CPS bracket to protect pivoting with a second bolt. During the pandemic, they were out of stock, so I rigged up my own, a simple metal bracket shaped like an upside down "V"/C-shape using the 10mm bolt just above it. Not nearly as nice, nor close tolerance with my sausage fingers. But at least the CPS is protected from the timing wheel. |
Originally Posted by RunninOnEmpty
(Post 1641106)
Keep a backup crank position sensor too. Since the CPS is only held by a 10mm bolt that can pivot, a wayward belt can knock the sensor into the timing wheel like a circular saw.
Small update: I was prepping for another local event that was supposed to be this past Sunday but it got rained out unfortunately. But anyway... Replaced the original PCV with the "turbo" PCV (E301-13-890A). Still need to install some catch cans but I already have this part on hand. https://cimg5.ibsrv.net/gimg/www.mia...45791538db.jpg Also wrapped the cross over tube from the supercharger to the intake manifold with gold bling bling racecar tape. To be fair I'm not exactly sure if it'll help with heat management. Maybe it'll help avoid heatsoak from the radiator while the car is stopped? Not sure. Eventually the plan is to install a water to air intercooler with a water reservoir in the trunk. https://cimg2.ibsrv.net/gimg/www.mia...caaa2ef719.jpg https://cimg0.ibsrv.net/gimg/www.mia...7dcccba3a2.jpg https://cimg9.ibsrv.net/gimg/www.mia...659b228863.jpg Replaced the front pads with Hawk Blue HPS (HB149F.505). The rear already has Hawk Black HP Plus pads (HB159N.492). https://cimg3.ibsrv.net/gimg/www.mia...b9d3a4a4e9.jpg Old OE replacement pads after much abuse, about two years of autox and HPDE. Is this typical ware or did these glaze over? https://cimg5.ibsrv.net/gimg/www.mia...f409c30f78.jpg Then I noticed this gash in one of the front tiers... Sheesh https://cimg8.ibsrv.net/gimg/www.mia...f644af7940.jpg I was unsuccessful in trying to source a used Rt660 before the planned event, so that I wouldn't have to buy 2 or 4 new tires. But I did find someone with a pair of barely used NT01s locally. So I grabbed those for the fronts and got them mounted and balanced. https://cimg3.ibsrv.net/gimg/www.mia...1e1cfd0652.jpg https://cimg4.ibsrv.net/gimg/www.mia...40622b434e.jpg Also finally lubed up area where the slave cylinder touches the clutch fork because that's been making an awful squeaking noise. I used white lithium grease which worked great. But the boot on the slave cylinder is torn so I suppose that needs to get replaced? Not sure how critical that is. I'm assuming it's pretty important. https://cimg0.ibsrv.net/gimg/www.mia...0b565f6b0a.jpg Photo of sad Miata because it didn't get to go have fun. https://cimg1.ibsrv.net/gimg/www.mia...9fc4b9a581.jpg Maybe next time. |
Well...... The plan was to wait patiently, set asside some shekels, and order a set of Xidas... But then a barely used set popped up for sale... And well... Here we are.
https://cimg8.ibsrv.net/gimg/www.mia...a87c078659.jpg Spring rates are 850/500 which I think might be too stiff for my current setup, but I'm not sure. Car currently has OEM 15x6. I'm between 15x8 or 15x9. We shall see! https://cimg3.ibsrv.net/gimg/www.mia...31a8dbc7a5.jpg Was supposed to go to Pocono Raceway yesterday but we had rain all weekend... Another event missed due to rain. Big sad. |
Watching your car zoom through the cones made me wish I had kept working to install the MP62 kit I sold years ago. I really need more power.
I did a lot of track days on MSM takeoff shocks and springs and fat swaybars. The time sheet doesn't show how much nicer the car is to drive over the curbs and bumps. |
Those rate are appropriate for your project. Run it!
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Originally Posted by OptionXIII
(Post 1641557)
Watching your car zoom through the cones made me wish I had kept working to install the MP62 kit I sold years ago. I really need more power.
I did a lot of track days on MSM takeoff shocks and springs and fat swaybars. The time sheet doesn't show how much nicer the car is to drive over the curbs and bumps. Haven't been able to drive the car much since installing due to weather but looking forward to the ride improvement!
Originally Posted by emilio700
(Post 1641664)
Those rate are appropriate for your project. Run it!
My next step was to go through your wheel size threads to see if I should run a 15x8 or 15x9. I think the car is right on the threshold of the two but I'm not sure which would be faster. Leaning towards 15x9... |
Hmm. In a bit of a self inflected predicament here. I installed the Xidas and lowered the car about an 1" for a total ride height of 5" to the pinch weld but haven't gotten it re-aligned yet. I have a track day scheduled for Monday (a few days from now) at NJMP. I was planning to take the car in for an alignment (Supermiata dual duty) but I couldn't find a shop that A) was willing to do a non factory spec alignment or B) had availability this weekend. I was going to learn how to do a DIY alignment so I can make adjustments when needed without having this same issue in the future, but I'm a bit nervous about messing it up/not having enough time.
Does anyone do their own alignments? Is it hard to do? Videos seem pretty easy and I'm not full blown stupid. Only a little. The other options are to run it the way it is, and by the way, it drives great honestly. Or raise it back to stock height to hopefully get close to the original alignment (maybe?). What would you guys do? |
At the very minimum verify what your toe is. That will eat up tires more than anything else. You'll be able to DIY it so that it is good enough to do an event and then preferably have it corner balanced and set up by a reputable shop. It's not super difficult it is just tedious and you need to take accurate measurements.
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Originally Posted by Arca_ex
(Post 1642043)
At the very minimum verify what your toe is. That will eat up tires more than anything else. You'll be able to DIY it so that it is good enough to do an event and then preferably have it corner balanced and set up by a reputable shop. It's not super difficult it is just tedious and you need to take accurate measurements.
Originally Posted by HalalBuilt
(Post 1642041)
The other options are to run it the way it is, and by the way, it drives great honestly.
There were a few things working against me that day. First and foremost was my driving skill and unfamiliarity with NJMP Lightning. My instructor is actually a spec Miata guy which was great. But in addition to driver incompetency and a alignment mess, I had NT01s in front and some pretty well used RT660s in the back. The car was very tail happy as I guess should have been expected. But since that event, I got the car aligned (tired to follow SuperMiata Race Alignment as close as possible) and went to another event at Old Bridge Raceway Park. The alignment made an incredible difference. Video from Raceway Park post alignment to come. Throwing around the idea of picking up some Advanti Storm S1s but I can't decide on 15x8 or 15x9. Is 15x9 always better, even for a relatively low power (about 200 WHP) car? |
GoPro hint: center frame on center of windshield. Aim too low at dash and it overexposes. Most gopros allow center spot metering, some don't.
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First time doing a compression test so I definitely may have done this wrong. I performed the test while the car was cold and I didn't run the test at WOT either. I'm now reading that would be the correct way to run the test. Results are in order of cylinders from front of the car to back.
https://cimg7.ibsrv.net/gimg/www.mia...ff287c6b04.jpg https://cimg8.ibsrv.net/gimg/www.mia...421965b73e.jpg https://cimg9.ibsrv.net/gimg/www.mia...32c6230720.jpg https://cimg0.ibsrv.net/gimg/www.mia...6d37eb182b.jpg Cylinder 1: 184PSI Cylinder 2: 166PSI Cylinder 3: 195PSI Cylinder 4: 150PSI Seems kind of all over the place. I'll try re running the test warm at WOT. Should I be concerned about these results? Spark plugs didn't look so great. Can't remember if I've ever changed them in my ownership. If I did, it was probably about 8k miles ago. https://cimg5.ibsrv.net/gimg/www.mia...67293dce33.jpg In order from left to right (Cylinder 1 to 4) https://cimg6.ibsrv.net/gimg/www.mia...c0b3c7de78.jpg https://cimg7.ibsrv.net/gimg/www.mia...e113b207c1.jpg https://cimg9.ibsrv.net/gimg/www.mia...4b5af74867.jpg https://cimg0.ibsrv.net/gimg/www.mia...46ce0fbdec.jpg https://cimg3.ibsrv.net/gimg/www.mia...9fd54391aa.jpg https://cimg7.ibsrv.net/gimg/www.mia...522a3d8fda.jpg I cleaned them up the best I could with a brass wire brush and put them back in. I'll be replacing them with NGK BRK7E. Is there anything we can tell of the motors health from the condition of these plugs and compression test? I guess my main concern is if I should plan to rebuild the engine before anything else. |
Plugs are indeed toast. Standard copper plugs last about weekend of abuse before the center electrodes are rounded. It need to have nice sharp edge on it like new. Iridium plugs hold there edge basically forever. Well worth the coin.
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Originally Posted by emilio700
(Post 1643385)
Plugs are indeed toast. Standard copper plugs last about weekend of abuse before the center electrodes are rounded. It need to have nice sharp edge on it like new. Iridium plugs hold there edge basically forever. Well worth the coin.
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Not familiar with those. In the B series engine we like the NGK BKREIX
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Originally Posted by HalalBuilt
(Post 1643383)
First time doing a compression test so I definitely may have done this wrong. I performed the test while the car was cold and I didn't run the test at WOT either. I'm now reading that would be the correct way to run the test. Results are in order of cylinders from front of the car to back.
Cylinder 1: 184PSI Cylinder 2: 166PSI Cylinder 3: 195PSI Cylinder 4: 150PSI Seems kind of all over the place. I'll try re running the test warm at WOT. Should I be concerned about these results? Nice build thread. This probably isn't a bad idea for me to do as well as a baseline for my 120k mile engine. The list of stuff keeps growing. :p |
Originally Posted by SlowTeg
(Post 1643424)
Ultimately looks like the results aren't great but not horrible.. you could also rerun the results with a warm engine (unless this was warm) and see if the results improve. Ultimately not something to probably worry too much about if the car feels fine. Other things to keep in mind have you done a valve adjustment in a while? Definitely something to do if some are out of spec that will affect a compression test.
Nice build thread. This probably isn't a bad idea for me to do as well as a baseline for my 120k mile engine. The list of stuff keeps growing. :p Thanks!
Originally Posted by emilio700
(Post 1643390)
Not familiar with those. In the B series engine we like the NGK BKREIX
Compression test done while motor was hot and at WOT. https://cimg5.ibsrv.net/gimg/www.mia...26fee2fc37.jpg https://cimg6.ibsrv.net/gimg/www.mia...aa3948e041.jpg https://cimg8.ibsrv.net/gimg/www.mia...f9fb17ec0b.jpg https://cimg9.ibsrv.net/gimg/www.mia...bf1521bc77.jpg Cylinder 1: 195 PSI Cylinder 2: 170 PSI Cylinder 3: 200 PSI Cylinder 4: 155 PSI https://cimg2.ibsrv.net/gimg/www.mia...c6778a1f21.jpg I noticed the tester came out wet after testing the fourth cylinder. Looking at the spark plug from the same cylinder you can see that the threads are wet. I'm not sure what this means. Will have to look into it. https://cimg4.ibsrv.net/gimg/www.mia...1f958462cd.jpg 4th cylinder spark plug shown on the right. The threads are wet. Seems to be oil. Couldn't be anything else, right? Didn't smell like fuel. https://cimg5.ibsrv.net/gimg/www.mia...0ddd119678.jpg https://cimg6.ibsrv.net/gimg/www.mia...8fe3cb1517.jpg New plugs gapped to 0.044 per Treasure Coast Miata suggestion. https://cimg8.ibsrv.net/gimg/www.mia...8b76f08d8d.jpg Out with the old in with the new at 102,105 miles. |
You've got something going on in cylinder 4. Plug and compression test shows it. Whatever it is, it might be happening in 2 as well, plug isn't showing it yet though.
Next do a warm leak down test to see if its rings or valves. Intake valves will leak out the throttle body, exhaust out the tail pipe, and rings can be heard/felt through the oil cap. Just looked through your thread to see if you have a reroute, I noticed you didn't. IMO, hot side superchargers are the reason miata's got the reputation for melting #4 pistons. If you have an aftermarket ECU that's capable of it, you can enable individual cylinder correction, and add a percent or two of fuel to #4 to help it out. But if you were to ask me, I'd be taking the winter to pull the engine, re-ring it, add a Supermiata reroute, send your ID1050x injectors out for cleaning, or buy them if you don't have them, and pull the supercharger for a turbo. |
A few things. The -11 on the end of the plug part number is the gap. They are pre-gapped to 1.1mm, which is .043.
Stock NB1 coils aren't strong and may have trouble jumping that gap at 7,000rpm and 10psi. If, after rebuilding the engine and adding a reroute as Josh suggested, you get an intermittent misfire from spark blowout, don't reduce the gap. Do a Toyota or better yet, Audi R8 COP conversion and open the gap to like .05 or .06. Much better combustion with a fat consistent spark. |
Originally Posted by curly
(Post 1643539)
You've got something going on in cylinder 4. Plug and compression test shows it. Whatever it is, it might be happening in 2 as well, plug isn't showing it yet though.
Next do a warm leak down test to see if its rings or valves. Intake valves will leak out the throttle body, exhaust out the tail pipe, and rings can be heard/felt through the oil cap. Just looked through your thread to see if you have a reroute, I noticed you didn't. IMO, hot side superchargers are the reason miata's got the reputation for melting #4 pistons. If you have an aftermarket ECU that's capable of it, you can enable individual cylinder correction, and add a percent or two of fuel to #4 to help it out. But if you were to ask me, I'd be taking the winter to pull the engine, re-ring it, add a Supermiata reroute, send your ID1050x injectors out for cleaning, or buy them if you don't have them, and pull the supercharger for a turbo. I can see a turbo in this cars future at some point but I don't think I'm ready for that. There's so much information to consider for a good reliable turbo build. I don't want to rush into that yet.
Originally Posted by emilio700
(Post 1643540)
A few things. The -11 on the end of the plug part number is the gap. They are pre-gapped to 1.1mm, which is .043.
Stock NB1 coils aren't strong and may have trouble jumping that gap at 7,000rpm and 10psi. If, after rebuilding the engine and adding a reroute as Josh suggested, you get an intermittent misfire from spark blowout, don't reduce the gap. Do a Toyota or better yet, Audi R8 COP conversion and open the gap to like .05 or .06. Much better combustion with a fat consistent spark. |
I would rebuild to OE spec, yes. more than likely you have an eroded piston you can see on a really good borescope, or the rings just got too hot and lost tension. You typically build for torque, not hp, but whatever you do I'd suggest forged rods, and if you want to go over 280-300ft/lbs, I'd suggest doing forged pistons as well, personally I like Wisecos.
If you want a really good, cost effective, yet capable engine, buy a ball hone. Dump ATF on it, put it in a drill on speed 1, 1/2 to full throttle, and go up and down 12 times, fairly quickly. That'll give you a decent cross hatch for new rings. Buy OE, STD rings, OE STD rod bearings, and OE STD main bearings. One of those bearing sets is expensive, like $125, I think it's the mains, rods are around $60. I've rain the Mahle mains, they're like $25/set on Rockauto. Throw this all together with some forged rods from Eagle, K1, Manley, etc. If you want to be extra careful, take the rods to a reputable machine shop and have them check the big end for roundness. Boom, 300+ capable engine for about $1000. |
Originally Posted by curly
(Post 1643581)
I would rebuild to OE spec, yes. more than likely you have an eroded piston you can see on a really good borescope, or the rings just got too hot and lost tension. You typically build for torque, not hp, but whatever you do I'd suggest forged rods, and if you want to go over 280-300ft/lbs, I'd suggest doing forged pistons as well, personally I like Wisecos.
If you want a really good, cost effective, yet capable engine, buy a ball hone. Dump ATF on it, put it in a drill on speed 1, 1/2 to full throttle, and go up and down 12 times, fairly quickly. That'll give you a decent cross hatch for new rings. Buy OE, STD rings, OE STD rod bearings, and OE STD main bearings. One of those bearing sets is expensive, like $125, I think it's the mains, rods are around $60. I've rain the Mahle mains, they're like $25/set on Rockauto. Throw this all together with some forged rods from Eagle, K1, Manley, etc. If you want to be extra careful, take the rods to a reputable machine shop and have them check the big end for roundness. Boom, 300+ capable engine for about $1000. |
Originally Posted by curly
(Post 1643581)
Boom, 300+ capable engine for about $1000.
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Originally Posted by SlowTeg
(Post 1643585)
Thanks that's some really good info. Do the 5 speeds survive on track with low 200whp or do they not last?
Since you are SC’d the overall torque at ~200whp and the torque delivery should be more liveable for a 5-spd. That said, it’s a bit of a dice roll. I had a 5-spd survive thousands of track miles turbo’d at ~190-200hp (~200wtq in the mid range). I’ve seen other people lose the trans first time out with 150wtq. If you plan on tracking your car with forced induction, you probably want a spare 5-spd around for the inevitable. |
Definitely a spare transmission, 5-speed if replacing gearboxes is one of your more enjoyable pastimes, otherwise 6-speed. If you break it once, take the hint.
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Originally Posted by Gee Emm
(Post 1643605)
Definitely a spare transmission, 5-speed if replacing gearboxes is one of your more enjoyable pastimes, otherwise 6-speed. If you break it once, take the hint.
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Lets say most will hold up to 250 tq. If you want more, think about a transmission oil cooler
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Leak Down Test Results
Thanks for the advice guys. Was able to perform the leak down test today. The results are unfortunate but expected I suppose.
Cylinder 4: https://cimg1.ibsrv.net/gimg/www.mia...db7adab366.jpg Cylinder 1: https://cimg5.ibsrv.net/gimg/www.mia...0bd397edbb.jpg Cylinder 2: https://cimg7.ibsrv.net/gimg/www.mia...d04a90dab7.jpg Cylinder 3: https://cimg9.ibsrv.net/gimg/www.mia...6e28279f0e.jpg Cylinder 4 was the one with low compression. From my very limited understanding, the pressure drop isn't actually all that bad. About 15%. But it's definitely the rings because all the air was coming out of the oil fill cap. Spark plug condition after about 60 miles for documentation: 1,2,3,4 https://cimg9.ibsrv.net/gimg/www.mia...b9de5425f2.jpg 4,3,2,1 https://cimg0.ibsrv.net/gimg/www.mia...16507bf67d.jpg I guess it's time to plan a rebuild. Is there a good guide out there? Video or written are fine. I found this video from Napp which looks to be detailed enough: |
Yep between the air coming out of the oil cap and the condition of that spark plug, either rings are toast or cylinder wall is damaged, or a combination of the two. Good time to rebuild before catastrophic failure.
Also not sure if someone else mentioned it already but oil on the spark plug threads when you remove them but not on the tip is most likely a valve cover gasket leak. |
Originally Posted by Arca_ex
(Post 1643755)
Yep between the air coming out of the oil cap and the condition of that spark plug, either rings are toast or cylinder wall is damaged, or a combination of the two. Good time to rebuild before catastrophic failure.
https://cimg9.ibsrv.net/gimg/www.mia...3c14128096.jpg https://cimg0.ibsrv.net/gimg/www.mia...ac60c181b8.jpg https://cimg1.ibsrv.net/gimg/www.mia...dccbfe3806.jpg |
I started putting together a couple of lists for parts and materials/tools needed for a rebuild. I leaned heavily on 929 Racings article called Planning Your BP Engine Build and Napp Motorsports video called Building a High HP Turbo Miata Engine - Full Build! (linked in post #34). Also the information given here by members like @curly above. Thanks guys.
The goal is to build a track reliable motor that can handle moderate boost from either a supercharger or turbo below 8K RPM (using that benchmark to match 929's guide). Hierarchy of objectives is: reliability, cost effective, best performance. I want to take advantage of “free mods” like porting and polishing that just require time. Screengrabs of the lists below. Link to the Google Sheet can be found here for easier reference as well. Disclaimer for anyone who might come across these lists in the future. I have ZERO experience building motors. I'm just trying to learn. This is only based on some research in preparation. It's more of a public journal than anything else. https://cimg9.ibsrv.net/gimg/www.mia...c90f8b53fa.png https://cimg0.ibsrv.net/gimg/www.mia...31208c828e.png Am I on the right track? Am I missing anything or going overkill on anything? Getting the total for parts down below $2,500 would be really nice but I also don't want to save a penny to lose a dollar. Feedback is appreciated, thanks guys. |
Pulled the engine and trans this weekend. First time to do this on any car so I'm happy it went smooth. I would say the most difficult part was removing the two bolts at the top of the bell housing that holds the slave cylinder line and wiring harness.
Before starting https://cimg0.ibsrv.net/gimg/www.mia...6ead418e0a.jpg End of first day https://cimg1.ibsrv.net/gimg/www.mia...3399424567.jpg End of second day (PPF, driveshaft, and exhaust removed under the car) https://cimg1.ibsrv.net/gimg/www.mia...344ade4936.jpg Third day https://cimg8.ibsrv.net/gimg/www.mia...0ca651cc58.jpg https://cimg0.ibsrv.net/gimg/www.mia...32f801a1e1.jpg Separated the trans https://cimg4.ibsrv.net/gimg/www.mia...11763b7548.jpg https://cimg5.ibsrv.net/gimg/www.mia...7e6e98232b.jpg And just some overall shots for those of you with a keen and experienced eye. If you see anything of concern, please let me know ✌️ https://cimg1.ibsrv.net/gimg/www.mia...ac33dd776c.jpg https://cimg3.ibsrv.net/gimg/www.mia...dc5796ee03.jpg https://cimg5.ibsrv.net/gimg/www.mia...91288276ba.jpg https://cimg6.ibsrv.net/gimg/www.mia...5a0f491ba4.jpg https://cimg7.ibsrv.net/gimg/www.mia...a6c2269a99.jpg I didn't realize I needed to source bolts long enough to mount the engine on the stand and all the stores were closed. So this was as far as I could get. I was anticipating to just use some of the bolts from the bell housing but they're too short... Need to find some M12 x 1.5 x 110mm (or 100mm) along with some washers. |
Crud normal. Hot tank everything.
Wear pattern on cams, normal. |
Ya, crud is definitely normal especially if your motor was on its way out. You start having more blow by with oily crankcase vapors that make it into the intake path which end up gumming up the intake side a bit.
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Awesome. Thanks guys. I'm glad the buildup isn't a terrible sign. Also very happy the cam lobes are normal as well.
Some more progress yesterday. Before taking the head apart I checked all the valve lashes. I believe the specs are the following (thanks Car Passion Channel) Intake = .008 - .009 Exhaust = .011 -.013 https://cimg0.ibsrv.net/gimg/www.mia...9fb2b00095.jpg And just for informational purposes I checked the roundness of one of the cam lobes on cylinder 4. In retrospect I should have check the exhaust side because those were out of spec. But the test setup wasn't ideal anyway and the values aren't really that accurate (I had to mount the dial indicator on the engine stand, not the engine itself). https://cimg8.ibsrv.net/gimg/www.mia...4ed5b6cf36.jpg https://cimg9.ibsrv.net/gimg/www.mia...e97ac6ecd7.jpg Then I started removing the cam caps. Very thankful all the journals look healthy. No signs of damage. https://cimg6.ibsrv.net/gimg/www.mia...014d0a1e98.jpg https://cimg9.ibsrv.net/gimg/www.mia...577100addd.jpg Removed the head. Cylinder 4 is toasty. https://cimg5.ibsrv.net/gimg/www.mia...92ec77afe1.jpg https://cimg6.ibsrv.net/gimg/www.mia...29accc8a63.jpg Cylinder 2 isn't great either. Which is cool to me, because the compression tests showed 4 and 2 as the weakest. https://cimg9.ibsrv.net/gimg/www.mia...478db33333.jpg Cylinder 1 wall condition: still see some cross hatching. No scratchs felt with the nail. https://cimg0.ibsrv.net/gimg/www.mia...de75e8d022.jpg Cylinder 2 wall condition: no cross hatching. Very shallow scratches felt. https://cimg3.ibsrv.net/gimg/www.mia...48b2536b17.jpg Cylinder 3 wall condition: Some cross hatching, no scratches felt https://cimg2.ibsrv.net/gimg/www.mia...31efe1a078.jpg Cylinder 4 wall condition: No cross hatching, lots of shallow grooves felt with nail https://cimg0.ibsrv.net/gimg/www.mia...ae6e274ef4.jpg Cleaned the deck and checked for flatness with a straight edge. Couldn't get a 0.0015 feeler under anywhere. So I'm thinking a decking isn't needed. https://cimg4.ibsrv.net/gimg/www.mia...b68d8d2804.jpg https://cimg5.ibsrv.net/gimg/www.mia...d365fa67c6.jpg This scared the absolute shit out of me. I thought the block was broken. https://cimg0.ibsrv.net/gimg/www.mia...86c933a8f8.jpg Checked crank walk (my first car was a DSM btw). I measured 0.19-0.20mm which is about 0.0075". Max is 0.012 so I think we're good there. https://cimg5.ibsrv.net/gimg/www.mia...f6bfb1499d.jpg https://cimg7.ibsrv.net/gimg/www.mia...7ecd6f8ccc.jpg https://cimg9.ibsrv.net/gimg/www.mia...21e8528a67.jpg Checked connection rod gaps. All within spec (0.0044-0.0103) https://cimg8.ibsrv.net/gimg/www.mia...c19115bcd3.jpg Removed pistons and caps to inspect journals. All the journals were good. https://cimg2.ibsrv.net/gimg/www.mia...e5a2b8aa68.jpg https://cimg4.ibsrv.net/gimg/www.mia...ebdd14a0c9.jpg https://cimg8.ibsrv.net/gimg/www.mia...cb545547f0.jpg https://cimg4.ibsrv.net/gimg/www.mia...41bd9ac9e4.jpg But a couple of main bearings showed signs of wear. https://cimg0.ibsrv.net/gimg/www.mia...7d5ce221e8.jpg Between cylinder 1 and 2: no groves felt https://cimg0.ibsrv.net/gimg/www.mia...41c53b3105.jpg Between cylinder 2 and 3: no groves felt https://cimg5.ibsrv.net/gimg/www.mia...50db0ddb45.jpg Between cylinder 3 and 4: groves felt https://cimg1.ibsrv.net/gimg/www.mia...474105de33.jpg https://cimg2.ibsrv.net/gimg/www.mia...c7fa8cfdb6.jpg https://cimg3.ibsrv.net/gimg/www.mia...7e4644bb46.jpg Last bearing: no groves felt https://cimg9.ibsrv.net/gimg/www.mia...8928b10faf.jpg I'll be taking a closer look at the crank journal that had a scratched bearing. But it looks like a particle was introduced and ejected in a few rotations. Maybe. Im not sure. Otherwise I don't have any concern about the crank. https://cimg0.ibsrv.net/gimg/www.mia...5eb7daa3f9.jpg https://cimg5.ibsrv.net/gimg/www.mia...ddb3469bcd.jpg I just have to figure out if I should get the cylinders bored or just do a rehone myself. What's the qualifications for a required bore? Is it just any physical groves in the walls? If that's the case then it definitely needs to be bored... Also, I was expecting to see some broken rings or some obvious signs of what caused the damage in cylinder 4 (and maybe 2). I couldn't find anything that stood out to me. Am I missing something? Is it possible I won't actually see anything out of the ordinary? |
You could have just ran 4 too hot, ring gaps from factory are much smaller than a typical forced induction build. That’s only a guess though.
If you have access to a correctly sized ball hone, soak it in ATF and go up/down fairly quickly at a slow drill speed. If the grooves aren’t gone, it needs a proper bore and oversized pistons. |
It sounds like you don't have an FSM (factory service manual). If so, please get one stat.
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Originally Posted by curly
(Post 1644491)
You could have just ran 4 too hot, ring gaps from factory are much smaller than a typical forced induction build. That’s only a guess though.
If you have access to a correctly sized ball hone, soak it in ATF and go up/down fairly quickly at a slow drill speed. If the grooves aren’t gone, it needs a proper bore and oversized pistons. I'll get my hands on a ball hone and try it out. Thank you.
Originally Posted by emilio700
(Post 1644501)
It sounds like you don't have an FSM (factory service manual). If so, please get one stat.
https://cimg6.ibsrv.net/gimg/www.mia...4f85cf72bb.jpg https://cimg7.ibsrv.net/gimg/www.mia...b0c09dd9ae.jpg |
Some further investigating. Used a dial bore gauge to check the cylinder diameters at the top middle and bottoms (all within piston travel range). X1 is parallel to the crank, X2 is perpendicular (I guess this would be called the trust axis). OOR is the out-of-round measurement - all within spec. All unites are in mm.
After taking all the measurements I went back and did some spot checking to make sure 1) the tool hadn't lost calibration and 2) I didn't mess up with taking the measurements. I could not for the life of me get consistent readings on cylinder 2. Is it possible that cylinder wall is warped or wavy or something? https://cimg6.ibsrv.net/gimg/www.mia...1ecffd7222.jpg https://cimg2.ibsrv.net/gimg/www.mia...3e2eccf7cc.jpg Anyway, do you guys make sure the machine shops that work on your blocks use a torque plate? Overkill? I did a quick search and it doesn't seem to be too big of a concern but it's possible people just don't mention it. I also just (embarrassingly) realized all the recommended forged pistons (supertech/wiseco) are for oversize bore sizes. I've been trying to figure out if the block actually needs to be bored but in reality, if I want to use forged pistons as planned, an overbore is necessary. If I understand correctly the minimum target bore size is 83.5 to fit the smallest commonly available forged piston. Good idea? Worth it? I have no idea. What would you guys do for a HDPE track car that will probably get a turbo eventually? |
Smallest pistons the block will take for F/I. Thicker walls. Early blocks have thinner walls and more core shift. NB2 blocks tend to have thickest walls. For anything above about 15psi, we suggest sonic testing the block to ensure at least .120 wall. .150 more bester
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Originally Posted by emilio700
(Post 1644573)
Smallest pistons the block will take for F/I. Thicker walls. Early blocks have thinner walls and more core shift. NB2 blocks tend to have thickest walls. For anything above about 15psi, we suggest sonic testing the block to ensure at least .120 wall. .150 more bester
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Originally Posted by HalalBuilt
(Post 1644597)
You're saying I should run standard/oversized (0.010" or 0.020" over) OE pistons? Or smallest forged pistons the block will take (83.5mm is what I'm seeing)?
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I've been tearing my motor apart this winter as well. Mazda must've had a good laugh putting that oil drain (or whatever it is) in the block. I freaked out as well, I thought my engine was toast.
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Originally Posted by SimBa
(Post 1644689)
I've been tearing my motor apart this winter as well. Mazda must've had a good laugh putting that oil drain (or whatever it is) in the block. I freaked out as well, I thought my engine was toast.
Heeding Emilio's (and others) advice I'll forego the forged oversized pistons for either standard or +0.01" oversized OEM pistons. This'll leave more meat on the bone for future rebuilds which is nice. Called a few machine shops today to try to narrow down where to get this honing work done. I think I found a good option so I'm excited about that. Only downside is he doesn't have a torque plate but no one I called today did... so, ohh well. Maybe for the next build. Anyway, I ordered the ARP head & main studs from 949 so as soon as they come in, I'll go ahead and drop off the block with the main caps installed. In the meantime I'll clean the block/head as best I can. Machine shop will let me know which bearings and pistons will be appropriate. I also got what I need to do some porting on the head, but a bit more research to be done before I start that... |
Well. I had my friend (the one I borrowed the bore gauge and micrometer set from) over to double check my measurements. Looks like my zero wasn't perfect, so all the bores are actually within (or even smaller) than spec. So I'm hopeful a bore/hone to the first oversize will be sufficient to get a fresh cylinder walls.
ARP hardware came in last week! https://cimg2.ibsrv.net/gimg/www.mia...92df1bd048.jpg Over the weekend I got the block and head cleaned up and ready for the machine shop. https://cimg3.ibsrv.net/gimg/www.mia...d1e3a83ab9.jpg https://cimg9.ibsrv.net/gimg/www.mia...80c6170cb4.jpg https://cimg5.ibsrv.net/gimg/www.mia...d78f2f9683.jpg https://cimg1.ibsrv.net/gimg/www.mia...d976318ab4.jpg I'll be dropping both off at the machine shop today. I don't think the head needs to be decked (I put a straight edge on it and no light passes through), but I figured I might as well have them take a look at it to make sure I'm not missing anything. Some mistakes were made, though. While removing the valves I accidentally nicked two of the cam supports (cam journals? cam bearings? not sure what they would be called). If I knock down the edges can I still use this head or is it no good? I tried running my finger and cloth on it to see if it would catch an edge but the material is not protruding towards the cam. https://cimg3.ibsrv.net/gimg/www.mia...6243d320a9.jpg https://cimg8.ibsrv.net/gimg/www.mia...4f13cd5b8f.jpg |
Dropped the block and head off at the machine shop last week. He was confident we could get clean cylinder walls without an aggressive overbore. So I went ahead and ordered 0.010" oversized OEM pistons and the applicable OEM rings. Also ordered Manley forged rods along with all the ACL race bearings and an OE gasket set.
https://cimg8.ibsrv.net/gimg/www.mia...9e39e62b08.jpg https://cimg2.ibsrv.net/gimg/www.mia...ac7ebf8fbe.jpg Got the last of the packages last night! 949 packages not pictured. So I'm dropping the crank, pistons, and bearings off today. Not sure if he'll need the rods, but I brought them with me. While waiting for parts I asked him to check the head so I can pick it up when I came to drop this stuff off. He said it was a bit twisted and he had the take 0.0035" off to get it flat. That's not enough to be worried about volume change, right? Or should I check it? https://cimg6.ibsrv.net/gimg/www.mia...3a5d7ed51b.jpg https://cimg9.ibsrv.net/gimg/www.mia...ed2a466e41.jpg https://cimg0.ibsrv.net/gimg/www.mia...1fcfdf16df.jpg Beefy boi rod. I'm actually shocked at how light the OEM pistons are. I guess I was expecting them to be heavier. If all goes well I might be able to start rebuilding in a week or two! :likecat: |
Looking good! What is the cost difference between forged vs cast pistons? I would've thought it'd make sense to just get forged pistons if you're getting new pistons anyway but I also see plenty of "rod only" builds on here.
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Originally Posted by SlowTeg
(Post 1645472)
Looking good! What is the cost difference between forged vs cast pistons? I would've thought it'd make sense to just get forged pistons if you're getting new pistons anyway but I also see plenty of "rod only" builds on here.
Oversized OEM cast pistons: $312 Oversized OEM rings: $166. OEM total: $478 Forged oversized pistons (Supertech): $570 Rings (Wiseco): $134 Forged total: $704 $225 difference between the two. But to go with forged pistons I would need to skip over to at least a 0.5mm overbore. Not worth it IMO. The cylinder walls were still in good shape anyway. |
Originally Posted by HalalBuilt
(Post 1645477)
Thanks! Didn't make the decision to go cast for cost savings. It's actually not as crazy of a difference all things considered.
Oversized OEM cast pistons: $312 Oversized OEM rings: $166. OEM total: $478 Forged oversized pistons (Supertech): $570 Rings (Wiseco): $134 Forged total: $704 $225 difference between the two. But to go with forged pistons I would need to skip over to at least a 0.5mm overbore. Not worth it IMO. The cylinder walls were still in good shape anyway. |
Your head on its way to the hot tank looks better than when I got mine back. If only PO's knew how/when to change oil...
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If you're using stock cast pistons you're not going to get to the power levels where cylinder wall integrity becomes a problem anyways. You opted for a much weaker piston to get 83.225mm bore size if I'm reading the specs correctly, when you could have done 83.5mm with forged? The difference of 0.275mm bore size is not going to suddenly make it way more resilient, but using forged instead of the cast pistons definitely makes a difference in the 300whp+ range. Plenty of people running 83.5mm or 84mm bore sizes are at 400+whp, but stock cast pistons would be the weak link at that point.
Straight from a rough engine building guide from Emilio: Bore size - OEM is 83.0mm. The max for N/A is 85.5mm which requires a custom head gasket as the OEM just barely clears a 85.0. Low boost F/I ok up to 85.0mm. F/I high boost, we like to stick to 84.0mm to retain maximum cylinder wall thickness for bore stability. Anything 85.00 or bigger should get the block sonic tested. It is up to your pro engine builder to decide how much is enough. Power from bore increase is (generally) linearly proportional to bore delta. IOW, 83.00 to 85.00 is about 2.4% so a 150whp build becomes a 153.6whp build, or thereabouts. Personally, I love a 10.3:1 85.5 BP6D N/A build with a good flowing head for a 2100# HPDE build. Kinda of a sweet spot. |
Originally Posted by Arca_ex
(Post 1645506)
..., but using forged instead of the cast pistons definitely makes a difference in the 300whp+ range. ...
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Originally Posted by oreo
(Post 1645533)
For street use
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