Oh and double check your injector dead times & fuel pressure are correct.

 

Hey, thanks again for all of the information in the PMs! I'll do back to back VD pulls and target a slightly leaner AFR in boost to check if I gain anything.

I finally have access to my VD plots you were asking about. I'll also toss in the data log of the VD pull showing the 90% duty cycle.

In an attempt to bring my mass following (ha!) in here up to date. The car is currently running 10 psi tapering to just a hair over 11 psi at redline. When looking through the VD datalogs, I noticed my FF640s are touching 90% duty cycle. According to others on here, that should put me close to 300hp. The car feels great but not that great. VD puts me at a somewhat puny 225hp. Somethings funky here.

I've checked the Barometric correction and it's not affecting it. I also don't believe the problem to be fuel pump related. If I command more fuel in the top end my AFRs change accordingly. Allofit suggested I check that my fuel pressure and injector dead times are input correctly in TS. I'm using the stock NA6 FPR so it should be 43.5 psi. TS is showing 42.9. I can't see that small difference making a huge impact. The injector dead times were input with data straight from Flowforce. So I'm still at a loss here. I'll try changing the fuel pressure from 42.9 to 43.5 to see if there's a difference and report back.

In the meantime, here's an updated 3rd gear VD pull and the associated datalog. I'll get off my *** and install the knock sensor real soon I promise!




Edit - Before anyone comments, I fixed that 11psi spike on the initial spool-up. The VD plot shows me hitting 11.8 AFR towards the top end at 10 psi. Nowadays I'm consistently hitting 11.5 AFR.

 

I've had a look through your log and tune again.





Your VE table makes a pretty big jump in the 180kpa row as you move from the 6100rpm cell to the 7000rpm cell. That's where your injector duty cycle shifts from 80% to 92% in the transition between those cells.

Expect the general shape of your VE table to be similar to the shape of the engine's torque curve. By which I mean it will start low, increase and peak, and then begin dropping as rpm increases.

My VVT motor and tune has the VE table numbers level off around 6000-6500rpm and then start falling beyond that. Your VE table numbers are rising exponentially well beyond your engine's torque peak as shown in the Virtual Dyno plot.

And I still think a target AFR of 11.5 is too rich for just 180kpa!

 

I apologize, I should have uploaded an updated version of my tune with that datalog earlier. The tune and subsequent VE table you are referring to are pretty out of date. I think I was only on wastegate at the time.

Last night after work I took the car out for back to back VD pulls. The first pull was with my current target of 11.5 AFR in boost and the 2nd pull was targeting 11.8. As you can see, there is a noticeable gain however the 2nd pull peaked at 12 psi vs 11.5psi from the first run. /shrug

I also adjusted the fuel pump pressure in TS from 42.9 to 43.5 but no noticeable difference was made. The duty cycle on the FF640s is still in the 90s at redline at only ~225 hp. I'm still stumped on this one.



Both pulls were taken within 10 minutes of each other on the same stretch of road in the same direction. Side note, I'm not concerned with the hp/tq numbers. I had my girlfriend in the car with me and I wasn't about to ask what her weight was.

Current tune and datalogs of both pulls are below.

 

Since NB2 has a higher pressure system (60psi vs 43), your input of injector flow at the req fuel table is wrong. Should be in the 720's if I'm not mistaken.
But that still doesn't account for such high injector duty. It should be in the 30s or 40s in your case.
Also I noticed your alternator control is set to "off", while MS should control it to the best of my knowledge.

 

Your fuel pressure is probably tanking at higher RPM. Hook up a fuel pressure gauge and go for a drive.

 

Can we have some more details about your '91 FPR setup? Are you using a 1999-2000 fuel rail with it?

Yes this.

 

I'm using an NA8 alternator so voltage regulation is handled by the alternator.

That's a very good thought, I'll see if I can find a pressure gauge locally. I'm assuming If I'm losing fuel pressure this would point to a bad pump, correct?

Absolutely. Since I'm NA VVT I'm using a 99'-00' fuel rail with the stock NA6 FPR flipped upside down. Exactly how It's outlined in the VVT megathread.

On the topic of fuel pumps, I hear DW100 pumps are fine but DW200 may overwhelm the FPR. The 200 seems to be more common than the 100, however. I'm wanting to push the car towards the 300hp number in the future. Would the DW100 still handle that power level? The current fuel pump in the car may be the same one that rolled off the showroom floor. I may order up a new one anyway. I'm just trying to decide which of these two would be best for my long-term goals.

 

30 year old OEM fuel pump with 150k miles wear and tear? Yeah that might be your problem.

From: https://www.miataturbo.net/engine-pe...er-logs-91349/

 

Thanks for the link, I actually happened upon this when I first researched my issue. I figured since my AFRs in boost reacted accordingly to a change in commanded fuel, I could rule this out. On the same coin, a drop in fuel pressure in the top end resulting in an increase in injector duty cycle to compensate makes perfect sense to me. A DW200 will be here sometime next week!

I'm hoping to get out to the garage tomorrow to install my 2nd catch can and finally wire up the OEM knock sensor.

 

On paper, the oem pump is just about sufficient, but after 30 years of wear and tear, they often don't flow quite enough and it's better to upgrade. DW200 is a good choice.

If you look at your logs, you go from ~70% injector duty cycle at peak torque of ~5700rpm to over 90% injector duty cycle by ~6700rpm. That's a clue.

After the new fuel pump is installed, spend some time working on your VE table. Those fuelling numbers should be flattening off around 6000rpm with a square top and VVT head. I'll upload my VE table later for reference.

Btw, your 'VD1 rich' log AFR's are getting down into the 10s at 170-180kpa.

 

Shew, it's been awhile and, oh boy, a ton has changed around here. I'm running into some issues that I've been trying to trouble shoot in another recent thread, but It may be better to bring it into here. The other thread and issues I'm referring to are in here.

I've got some time and the motivation to try to bring everything more up to date around here. Here goes. I'll try to keep it brief.

So, the car was running great for a good 10k miles at ~230hp. One day on the way home from my local Cars & Coffee I decided to show off with my dad in the car and launched it off of 2 step. I've done this too many plenty of times, but that time it developed very loud ticking/tapping sound after immediately after. Crap. The sound was very high up in the head so I figured maybe it spat a shim as it sounded like very loud lifter tick.

Nope. No shims were spat and valve lash was all in good shape. I had another vvt head and got it completely rebuilt. I upgraded with the stiffer VS855 springs while it was at the machine shop. Got the fresh head back on and fired it up. The tapping was still there. lovely... I went back to the drawing board and did a ton of reading to find anyone else with this noise. It wasn't a rod knock type of sound. Well, I found out what it was. I'll let this next pic speak for me:



See anything wrong here? Turns out rod #4 wanted to start transitioning to be a banana. I suppose the launch off of 2step with the combined weight of me and my dad in the car had just the right amount of shock to the rod to bend it. That, and it being a little tired of the 230hp I was commanding from it played a part as well.

It was bitter sweet, I was admittidly used to that power level for awhile and was ready to step it up a notch or three. This is when the process of burning my wallet officially started.

• Supertech 84mm 8.7:1 pistons
• Weisco x Rings - top ring gapped at .017, bottom at .020 if I remember correctly
• Manley Rods
• BE Stage 2 Oil Pump
• SM coolant reroute
• ACL race bearings
• Circuit Sport Oilpan baffle (I lost OEM one)
• Cometic 99-00 Headgasket
• OEM gaskets/seals etc

I think that's all of the key points for the rebuild items. I decided to spare my wallet and went without a ATI/Fluidampr for now. I figured the BE pump would be enough insurance for the time being - famous last words. This was my first ever dive into engine building so I took it slow and worked on it over winter and spring of this year. I'll dump some of the rebuild pics I could scrounge up next.







Fresh head rebuilt and block back from the machine shop. I was pleasantly surprised with what my local shop charged for this. For the full head rebuild I think I paid 180? For the block hot tanked, and bored I think I paid 250. No complaints from me except I wasn't the biggest fan of the assembly lube the used on the head. It was like a foamy aresol type. Oh well, probably isn't a big deal.



Like I mentioned, I tried to really take my time with this. I tried to be as methodical and clean as possible. I'm an electrical engineer by trade, so I really appreciated paying attention to the small details through this whole process. It was a lot of work, of course, but I enjoyed it. Both main and rod bearings were plastigauged for oil clearance. The rod bearings came out to be on the tighter end of the acceptable range. I read that you can mix and match the standard and +1 bearings to get .5 more oil clearance. I decided to go with it. This now put the rod bearings on the looser end of the acceptable range where I wanted to be.



I didn't get a good before/after pic of the block after painting it. I need to do better with progress pics. Anyway, head on and torqued. Don't mind the little stuffed bear, I won it for my wife at the fair. Cool, but what the heck are you supposed to do with it? We don't have kids. So, it lives on top of my car for some reason. He's basically a garage mascot at this point.



Timing belt installed and set! Getting close.




And it's in! My goodness, me and my friend a DEVIL of a time getting it to sit in the motor mounting holes. I think we spent over and hour wrangling and prying that thing to get it to finally sit correctly.

Aright that gets us caught up to about May of this year. I've got some more updating but I'll get to it maybe tomorrow. Thanks for reading, more to come soon!

 

Tell me about bent rods ...


The really nasty one is No4 too, bent and twisted at the wrist.

!40rwkw, and a bit of this will do it, so it seems. No hard starts or the like, at least not in my ownwership. Full story in my build thread (see sig)

 

I took a quick look at your build thread and, DANG! That rod no 4 is all sorts of mangled. I would almost be proud of that in a sort of a sadistic way. lol How much power/tq do you estimate you were making at that time?

When I was trying to figure out what my problem was, I was really convinced it was head related due to the noise sounding so loud up at the top of the head. After swapping a rebuilt head on and the sound persisting, I accepted the answer was a full overhaul and went to town ripping it all apart without much thought. It turned out that noise I was hearing was the crankshaft counterweight contacting the bottom of the piston skirt. The machine shop said my crank measured in spec - just with a little bit of blueing on the coutnerweight due to the heat build up.

 

Well. we all know these rods are weak. I have seen more than one set of bent rods, and the result of someone ignoring the ticking - rod out the side, and crank destroyed. In my case as soon as I heard the ticking I pulled out of the track day (only did one session) and nursed the car home, and pulled the engine after my 'dipstick' (pat pending) confirmed at least one seriously bent rod. That was the stock MSM turbo, Autronic ecu tuned to 140rwkw with zorst and intake, reline at 7k rpm.

Yes that one is going on the wall, with all my other memorabilia!!

 

I was also careful with it as soon as I heard the ticking sound. I limped it the rest of the way home and parked it while I looked into it and only started it for diagnosing purposes.

Time for more updates!

After a lot of choice words and a beer or three later, we got the engine mounted up and all the remaining ecoutremounts bolted/plugged in. I was surprised at how long it took to build oil pressure when cranking (with the injectors unplugged). At first, I tried cranking for a few seconds while watching the OP gauge. Nothing. I did some reading and someone on here mentioned to set a timer for 2 minutes, crank nonstop until the time was up or you get OP. I was quite nervous for this hoping I used enough assembly lube. Sure enough, after about a minute or so of continuous cranking, we got OP. Oh, and I pulled the spark plugs to give me poor little starter a break.

Once I got it to fire up I ran into a pretty strange issue that I'll try my best to recall incase anyone else reading runs into similar issues. Most of the context is in the thread I made on the problem found here. The short of it is this: I was using something like a trigger angle offset -30° in the trigger wizard to get base timing as close as I could to the 10° I was commanding. Long story short, it ended up being this little setting needing to be switched to "inverted"


Prior to the rebuild, this had been set to "normal" for many miles with no issues. Maybe with the addition of the 36-2 wheel things are different? It's beyond me. I'm not certain what this setting does, anyway. With this setting flipped to inverted, I was able to get the trigger angle offset dialed in to 10° with a more typical value. Heck yeah, time to drive it. Stay tuned.

 

From here, I started the break-in procedure most around here employ. drive it 2 miles/20 minutes with a bunch of vacuum and slowly raise the rpm limit working your way up. Oil change after. During this first oil change I was fooling with the turbo to reconnect the wastegate actuator and noticed this...



That's not good. Further inspection revealed the the compressor housing bolts backed out enough to cause the blades to contact the housing. Honestly, I probably deserved it. During the, idk, 15k miles boosted I never once bolt checked the housing bolts. Flange bolts? Yes. Housing bolts? Nah, they could never come loose on their own. Right?

After a couple of emails to Lars, $150 and 4 days later, a new T3 Churbo was at my doorstep. It's insane how cheap these are for what they are. The replacement is a little larger on the compressor side. My old turbo was .48 A/R on both turbine and compressor. The replacement was .48 turbine and .64 A/R compressor. This actually turned out well in my favor. Before the rebuild, the old turbo was at about 85% duty cycle at redline to hold 11psi and 230 hp. So, not much more gas (air) in the tank. It spooled great though, so I kinda miss the response - 10 psi at 3400. I'll have my boost response back real soon though. Foreshadowing....


This wouldn't boost creep right? Nah, never. I thought I did a pretty good job enlarging the hole and grinding a decent channel to help it bypass exhaust flow. But, it would still hit my 13 psi boost cut before redline. I eventually had to yank it back off and port more aggresively. It still creeps some but I'm okay with it.

Anway, new turbo slapped on and I continued the break in. I kept up with the frequent "vacuum pulls" for the first 100 miles or so. I (painfully) avoided boost for the first 20ish miles before starting to work boost and more revs in. By 100 miles I was on 8psi wastegate. Oil change intervals were: 2 miles/20 minutes, 50, 250, 500 and soon to be 1000. Is it more oil changes than neccesary? Probably.

That puts us almost up to date with where I'm at currently. I hope my rambling diary entries are interesting for at least a couple of you guys! I'll give some more updates again tomorrow.

Also, I have no idea how to resize these photos. I apologize for the massive pictures. Cheers!

 

Time for another update! hopefully I can get this one caught all the way up to present day. I have both exciting and not exciting things coming up real soon, so I really want to fly through these updates without skipping too much. Here goes.

With the new turbo and some miles on the rebuild, it was time to start adding in some boost. I was running 8psi from 100-250 miles and I was itching for more. I had a devil of a time tuning my open loop EBC control around the boost creep from this wastegate. Even with my port job it would creep from ~7psi to 11 by redline. I settled at around 12 psi for now until I can get proper electronic detcans built/setup. The car felt great at this power and I was enjoying it. A few rough VDs put me in the 250s - about 20hp more than before my rebuild. While adding in more boost i did notice my IATs were creeping up pretty bad with each pull. I had this problem before the rebuild, but now it seemed to be worse. The IC setup Lars ships with his kit is truly great for stock rod power, but the IC and the piping diameter is tiny. Mind you, this was in the dead heat of summer, but even on cold mornings at ~75° F out I would see IATs from one 3rd gear pull rise from ~80 alllllll the way up to 120-130 (!). It's no bueno hitting MAT retard every pull.




Yeah,... it's time for a new intercooler. Luckily, someone on here was seeling a new Vibrant 12800 intercooler a couple weeks prior to getting the car running. I scooped it up for a great deal but wanted to wait to install it until after I got the car running and somewhat dialed. The new IC didn't have the miata specific welded tabs for easy mounting so I did some digging on how best to mount it and found this thread.



Sadly, this is pretty much all I have for pictures of the intercooler install. I promise I'll be better with progress pictures in the future. Just know that I followed the thread I linked almost to a T. A trip to HDR to purchase some 1/8 in sheet steel and a bunch of whacks of a BFH later, I fabbed up the mounting brackets. The downside is that the IC only has 2 bolts mounting it in place. I don't love it, but I used higher grade bolts with lock washers to combat any vibration fatigue causing them to shear. I also plan to add some sort of rubber isolater between the bracket and the chassis mounting point. It currently buzzes like crazy at certain resonate idle rpms.

As mentioned earlier, the MKTurbo IC piping is TINY. 1.75" hotside and 2" cold side. I took this chance to completely redo the piping. I really disliked how the kit has the turbo exit pointing straight up. I know this is for easy routing around AC/PS, but I don't have AC. I clocked the turbo where it is pointing down at the 6 o'clock position and ran 2" piping to the IC. I used a 45 coupler -> 90 pipe -> straight coupler -> 90 pipe to the IC. This is wayyy more simple and condusive to overall flow to the IC. The hotside is all 2.5" and was able to run from the IC to TB: 90 pipe -> short 6" straight pipe -> 90 pipe -> another 90 pipe up towards TB, short straight with a Type S BOV adapter - 90 coupler into the TB. Overall, I'm very pleased with how this new piping turned out. It is so much more simple than the old skinny piping. I'm sure the small diameter was encouraging my IATs to skyrocket since the charge velocity was much higher through the IC. I also was deep into the rabbit hole while researching and read about airflow becoming turbulant as it exceeds .4 Mach. The calculations I was reading aluded to my old piping causing charge turbulance with a guesstimated churbo flow rate and my skinny piping. I'm pretty sure the calculations were in a straight pipe for each given diameter, but whatever. It was an intriguing rabbit hole none-the-less.




This isn't the best picture, but this is almost what my setup is looking like currently. This is taken right after getting everything buttoned back up after the new IC and piping. You may notice my valve cover changed colors. The purple powder coated VC was terrible and I hated it. It was originally supposed to color match my black cherry mica NB, but it is so not even close it's funny.

Now, this is slightly out of order, but right before the IC install I noticed my VC gasket leaking on the drivers side. I thought, at first, it was just a small leak. but I smelled a little oil burning after a pull, poppped the hood, and noticed crankcase pressure had blew aereated oil onto my downpipe from the VC where it had been leaking. BIG YIKES. I immediately ordered a fire extinguisher and a new VC gasket. I know, shame on me, I should've had one to begin with. Thinking about the crankcase pressure being high enough to squirt oil through the VC gasket didn't sit well with me. So I drilled out the exhast side PCV ports inside the VC, added some copper scrubbies, and drilled and tapped for -10AN lines and fittings to my breather catch can.


AN lines = race car, right?

I wish the lines hugged tighter to the VC but, oh well. With the new VC gasket and upgraded exhast side PCV system, no more fire hazards!

I was eager to take the car out and get some data with the new IC setup. I was pleasantly surprised that IATs dropped significantly as well as overall boost dropped by about 2 psi. I'm seeing a ~5-10° delta from one pull as opposed to the 50°+ I was seeing before. The butt dyno also says the car is making about the same power as it was with 2psi less of boost. Huge win. Here's a screenshot of a 2nd gear pull (I think) with the new IC.



I'm very pleased with it. I don't have to worry about IATs in the heat nearly as much anymore. You can also see that this new churbo is a bit more laggy than I'd like. It hits 10psi around 3900-4000 rpm. @Fireindc 's recent build thread conviced me to pull the trigger on a certain something that will fix this issue. More on this soon!

Alright, this puts us to pretty much present day. I've got a couple other things I'll touch on in the next update. I've ran into some strange issues with some crazy VVT angles after 4k rpm and lowish oil pressure at higher rpms. I've explained all of this in another recent thread found here:

https://www.miataturbo.net/engine-pe...er-rpm-110663/

some of the later discussion is probably better suited in here as it's more oil pressure diagnosis than the original VVT angle issue I started the thread for. If anyone has anything that they'd like to add I'm all ears (eyes?}!



I really appreciate anyone tuning in to these diary entries. More to come soon!

 

Oh man, thanks for the tag and reminder. Your post just put checking CHRA bolts on my short list before the next track-day. So thanks!

And glad I could inspire you on some nice chinesium. Mines still been great to me, no complaints at all. At sea level it should spool even harder than mine so excited to see some results!

 

Oh yeah, I will definitely be checking those more often now. I'm just glad it was a cheap ebay turbo and not something nice.

I already had my sights on the real garrett version, I was waiting to see your updates once you got it installed and running. It was an easy decision once I saw you hitting wastegate by 3200 rpm. My 5spd will not be happy, but I will be. I'm sure that response and spool is ludicrous to drive.

I've kept it under wraps in here until I got the thread up to date (finally), but here it is:



The turbo came in the mail a few weeks ago. PSR GTX2860 Gen 2 .64 A/R. I heard there were tarrifs on these, and there were if you bought straight from PSR. I was able to find some US stock from FAB9 so I was able to save almost $300 in tarrifs. It was a "buy now so I don't have to pay tarrifs later" sort of thing.



Full Kraken top mount T25 + exhaust setup. Initially, I was planning to switch setups to the Kraken later this year around black friday. I get a bonus that time of year and was hoping to offset some costs with it. However, I caught wind that Kraken will no longer be offering the downpipe and exhausts with his kit starting Aug 15th. This may only apply to the top mounts but I'm not sure. I found this out just days before the Aug 15th cut off. I promptly took my wife out for a nice dinner and placed my order. It was delivered last week. I've never been so excited for something car related. I've been wanting this kit for ages and I've finally got it.

It's taking everything in me not to rip the old MKTurbo kit out and slap this stuff on. I'm really trying to be a good boy and wait until I figure out this VVT/Oil pressure issue first.

I linked the thread that discusses my issue in good length above, but I'll try to summarize it in here. Basically, I noticed I'm getting crazy and erratic VVT angles after 4k rpm. it'll swing from 0-40° multiple times in one pull. I also noticed that my oil pressure doesn't go higher than 45 psi hot. It'll quickly rise to 40-45 psi by 4000 rpm and just stays there through redline. This happens regardless with or without VVT enabled. Idle and cruise pressures are fine. 18 hot idle, 35-40 hot cruise. I think it is BES2 pump relief valve related. Perhaps the relief valve is opening at 40-45 psi (0 shims). Since this all started with weird VVT behavior, I'm going to replace everything VVT related I can from an extra BP6D head I have sitting around just to rule that out. I'm hoping to start tearing into it tomorrow.

I scoured through countless threads on here and miata.net (ew) about oil pressure in the mid 40s at redline and I'm starting to ask the question is this really too low? I found some conflicting threads where some say it's a little low but "should be fine," It's fine with the higher volume oil pump, and no it's too low. I have the higher volume BE pump and get 45-47 psi north of 6k with hot 15w40 oil. Pulling the oil pan to inspect/add shims to the relief valve will be a ton of work, and I know pulling the motor to rebuild after spinning a bearing is more work but ughh...