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Long-rod BP build underway
2 Attachment(s)
https://www.miataturbo.net/attachmen...ine=1330030904
Long connecting rod 1.9-ish-liter built VVT BP is being done on Edmunds' green hoopty '97 whine and cheese edition. It'll be a little while before all the bits are in place but it's coming together... http://blogs.insideline.com/roadtest...d-nerdery.html |
You appear to have the best job evar.
Keeping the Rotrex? |
compression ratio?
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Getting the longest rod to stroke ratio is a design mantra seriously, though, very cool read. love ---- like this, as it feeds my inner nerd with the stuff that i love understanding but will likely never implement. |
in for cool new stuff
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OO ooo OOOOHHHH. I. LIKE.
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Tasty.
One day. One day I will have a bit of time and money to mildly build a short block. |
EO2K- am ginning up a turbah
y8s- 9:1 |
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Nice job Jason. Ben trying to research this myself. Talked to J&E, they seemed very willing to work with the customer. So, did Mil-spec end up being a custom rod? What kind of pricing did it work out? What bore did you go out to?
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How do you get to 1.9 from 1.8 without changing the crank and without lowering the compression ratio?
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Originally Posted by JKav
(Post 839479)
EO2K- am ginning up a turbah
y8s- 9:1 what order of magnitude for such precious internals kit? Most of us are thinking "supertech and those chinese guys can supply rods and pistons for like 700 for all of it" |
Originally Posted by triple88a
(Post 839520)
How do you get to 1.9 from 1.8 without changing the crank and without lowering the compression ratio?
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http://www.motoiq.com/magazine_artic...th-matter.aspx
What does a rod like that cost? I have a buddy who just popped an engine, it might be cool to get some of these if the price is right. |
What are Honda rod ratios compares to our BP "slugger"? Is the higher rod ratio of the F20 the reason the S2k feels a bit sluggish below 5000rpm?
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Originally Posted by hustler
(Post 839561)
What are Honda rod ratios compares to our BP "slugger"? Is the higher rod ratio of the F20 the reason the S2k feels a bit sluggish below 5000rpm?
BP: 1.56:1 S2000: 1.82:1 Chevy 350: 1.64:1 Ford 4.6L: 1.67:1 Nissan SR20: 1.58:1 |
Originally Posted by hustler
(Post 839561)
What are Honda rod ratios compares to our BP "slugger"? Is the higher rod ratio of the F20 the reason the S2k feels a bit sluggish below 5000rpm?
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Originally Posted by Bryce
(Post 839572)
According to Google...
BP: 1.56:1 S2000: 1.82:1 Chevy 350: 1.64:1 Ford 4.6L: 1.67:1 Nissan SR20: 1.58:1 |
Originally Posted by hustler
(Post 839599)
Thanks. It again appears that we have the worst engine on Earth. Is there an engine from the same era that does worse in than the BP in terms of vibration, rod ratio, head flow, fuel economy, and output?
Forgive my ignorance, but are we talking about "stroking" the BP? If so, then why not see if there is another crank that will work in this engine? In the mopar world for instance, you can drop a 440 crank into a 383 and net a 400CI engine. With a new crank and rods you can get 500+ ci from a 440 (this takes grinding inside the block though) Custom cranks are probably expensive, but if Emelio is approaching 200HP on an NA, then I assume "there is no replacement for displacement" holds true. |
Originally Posted by djp0623
(Post 839608)
Forgive my ignorance, but are we talking about "stroking" the BP?
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Originally Posted by emilio700
(Post 839594)
The F20C is actually pretty strong below 5000. it is just that when Vtec kicks in (yo) its bipolar welterweight cage fighter side makes the other side feel like a libertarian vegan.
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Still no word on the specifics of this unit, no word on cost, no word what it's suppose to do as to is it increases low end and mid range torque. So why should we interested if the seller offers up no info?
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JKav (Jason Kavanaugh) works for Inside Line (Edmunds) and he's not selling anything. I'm sure all the gory details for the build will be included in the continuing "1997 Mazda MX-5 Miata: Long Term Road Tests" series found here. You can read about the details as soon as they publish them, just like everyone else. As to the benefits, look at the link hussy posted or read the damn article linked w/comments and it should be somewhat obvious.
Ungh, why do I bother? :facepalm: |
lol
this is not an advertisement. its a show off of badassery |
EO2K...Haha, you were nicer than most would have been.
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BP rod length and piston height
5.228 + 1.20 =6.428 Honda rod and custom piston length 5.392 + 1.020 = 6.414 (.014 diff) Rod ratio increases to 1.611 The BMW rod is 5.510. This means that the piston height must be .919 (23.342mm)to make the stock height of 6.428. Rod ratio works out to 1.64. I didn't think J&E or Wisco could do that short. JKav, what did you say the piston height was for these? |
Originally Posted by Track
(Post 839779)
EO2K...Haha, you were nicer than most would have been.
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Originally Posted by my97miata
(Post 839770)
Still no word on the specifics of this unit, no word on cost, no word what it's suppose to do as to is it increases low end and mid range torque. So why should we interested if the seller offers up no info?
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I'd like to see how changing the rod ratio changes the harmonics of the motor (make it run smoother/vibrate less, hopefully). I read that article from MotoIQ when it came out, and they noted that their SR20 seemed to have run quieter(?).
In for results. |
Originally Posted by hustler
(Post 839817)
You know those "most interesting man in the world" commercials for Dos Equis? Thoese were originally written for Jkav in a previous life by Billy Shakespeare.
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Originally Posted by vintagerust
(Post 840751)
I'd like to see how changing the rod ratio changes the harmonics of the motor (make it run smoother/vibrate less, hopefully). I read that article from MotoIQ when it came out, and they noted that their SR20 seemed to have run quieter(?).
In for results. |
So, who is going to call Mil.Spec and get a group buy worked up?
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Originally Posted by vehicular
(Post 840787)
So, who is going to call Mil.Spec and get a group buy worked up?
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I spent many an hour pouring over con-rod specs to try to find an off the shelf rod for a long rod for my non-vtec b18 motor. MotoIQ is building a long rod vtec B18 motor using Nissan rods but suprisingly the non-vtec and vtec crankshafts are quite different, so the Nissan rods won't fit my crank (non-vtec rod journals are wider).
My question was always this: What change in rod/ratio makes this all worthwhile? Of the long rod builds I've heard about, everyone seems to be getting around a 0.08 increase in rod ratio. That's about what motoiq got with their SR20 motor and it seemed to have an appreciable affect. To get a +0.08 rod/ratio for my non-vtec B18 it looked like I was going to have to get cutom pistons and rods, the dollars and cents just wasn't adding up for me. |
Originally Posted by emilio700
(Post 840756)
A friends long rod 1.9 is the smoothest revving BP I have ever driven. No science there but my SOTP impression.
If I ever do build a block, N/A or turbo, I would definitely cough up the coin to do this. |
Originally Posted by vintagerust
(Post 841135)
I figured as much.
If I ever do build a block, N/A or turbo, I would definitely cough up the coin to do this. |
^lol. While smoothness is one of the noticeable effects, I assure you that is not my reasoning for why I would choose to build a long-rod motor.
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2 Attachment(s)
https://www.miataturbo.net/attachmen...ine=1330479554
More geeky deets, this time on the JE pistons. FSR, yo. http://blogs.insideline.com/roadtest...the-house.html |
Originally Posted by vehicular
(Post 840787)
So, who is going to call Mil.Spec and get a group buy worked up?
Originally Posted by y8s
(Post 840905)
the same guy who calls JE for the piston group buy?
Originally Posted by JKav
(Post 841200)
More geeky deets, this time on the JE pistons. FSR, yo.
http://blogs.insideline.com/roadtest...the-house.html |
Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles. |
Originally Posted by Reverant
(Post 841358)
Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles. maybe a block heater is your best option... :bowrofl: |
Originally Posted by Reverant
(Post 841358)
Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles. The 2.0L race motor we just built with Supertechs is silent. |
Emilio and Sav, I understand you both have done extensive sonic measuring of the BP blocks. I would like to know if boring to 85mm would be acceptable in a turbo build if boost pressures were kept to about 18-20 psi. How thin were the readings at 85 mm? Did they vary much block to block? Did one year of engine block happen to be better than another?
Thanks |
Originally Posted by JKav
(Post 841200)
More geeky deets, this time on the JE pistons. FSR, yo.
http://blogs.insideline.com/roadtest...the-house.html |
Originally Posted by 2manyhobyz
(Post 841412)
Emilio and Sav, I understand you both have done extensive sonic measuring of the BP blocks. I would like to know if boring to 85mm would be acceptable in a turbo build if boost pressures were kept to about 18-20 psi. How thin were the readings at 85 mm? Did they vary much block to block? Did one year of engine block happen to be better than another?
Thanks |
Originally Posted by emilio700
(Post 841403)
The 2.0L race motor we just built with Supertechs is silent.
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Originally Posted by Reverant
(Post 841358)
Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles. Cast pistons are probably not a bad idea for a long term DD :). |
My Wesico's are silent.
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Originally Posted by Reverant
(Post 841358)
Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles. Are rings really that much harder than the cylinder walls?
Originally Posted by hustler
(Post 841503)
My Supertech 8.6:1 is silent too.
Originally Posted by jtothawhat
(Post 841572)
My Wesico's are silent.
My Weisco's squeak when hot. Or kinda moan. |
The biggest thing is you lose oil control when the gudgeon pin intersects the oil control groove like that. Thats why FM has everyone delete their oil squirters on their stroker kits. :facepalm: I don't really feel like checking the difference in g-loading, but a longer rod should theoretically only reduce piston G's by maybe 1 to 2 percent by increasing the amount of dpistondisplacement/dtheta around TDC. This also theoretically increases engine breathing by a small amount by allowing more time for intake valves to open before the piston begins traveling down the bore.
Maximum gain? 1% higher RPM limit? 2-3% in output, but not exceeding previous knock limits? Innovation is good, but value is calling. Then again I could be missing something. Who knows? 4032
2618
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The significant advantage is the 5.2% decrease in cylinder wall side loading. That's going to reduce wear and egg-ing due to skirt to wall force, and thus increase cylinder sealing and power. Some.
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Originally Posted by Reverant
(Post 841358)
Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles. Historically, the slap noise really has been the biggest driving factor on whether to use 2618 or not, and that's why they designed the FSR forging to accomodate pin offset if so desired. Pin offset essentially preloads the major thrust side skirt so that it doesn't rock over and slap. The tradeoff to pin offset is a bit more side loading.
Originally Posted by JasonC SBB
(Post 841454)
What design considerations were made wrt oil control with the factory oil squirters?
Originally Posted by TravisR
(Post 841774)
The biggest thing is you lose oil control when the gudgeon pin intersects the oil control groove like that.
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The only reason I said that I said is because of my experience with 347 V8 Ford strokers. Every kit that intersected the oiling groove burnt oil. Every kit that didn't controlled the oil. This is the actual reason FM has you delete the oil squirters. The additional oil is not able to be controlled by a compromised oil groove.
The belief that every stroker engine uses oil is a myth. There are several factors to consider when building an engine in order to have proper oil control. But it's especially critical with stroker engines where the lower oil ring is in the wristpin hole. Read more: http://www.mustang50magazine.com/tec...#ixzz1nuqA0HSN And consequently the deletion of the oil squirters increase piston temperature and decrease piston life. The same 2618 alloy at 600*F has just 2030 psi of yield strength. While that same piston at 300*F has 49000 psi of yield strength (a 96% reduction in strength in just 300*F of change). Now considering combustion temperatures can easily exceed 1500F in these high output combos you need every bit of help you can get to maintain the strength of the aluminum in the pistons. |
So if I recall from back in the day in sport compact car, they did a big shtick on Swain coatings--particularly ceramic piston top coatings.
The intent was to keep heat out of the piston if I recall. I guess both to reduce thermal expansion and help maintain tensile strength. I think they even said they ran slightly tighter clearances too. I didnt re-read this since I read it originally in print but here's the article: http://www.modified.com/projectcars/...vii/index.html edit: I have a minor issue with Swain using a "Jesus Fish" in their magazine ads but there are quite a few other coating companies out there now so it is mostly moot. |
Originally Posted by TravisR
(Post 842114)
The only reason I said that I said is because of my experience with 347 V8 Ford strokers. Every kit that intersected the oiling groove burnt oil. Every kit that didn't controlled the oil. This is the actual reason FM has you delete the oil squirters. The additional oil is not able to be controlled by a compromised oil groove.
Its well known within the V8 community that compromising that ring groove makes life hard. And consequently the deletion of the oil squirters increase piston temperature and decrease piston life. The same 2618 alloy at 600*F has just 2030 psi of yield strength. While that same piston at 300*F has 49000 psi of yield strength (a 96% reduction in strength in just 300*F of change). Now considering combustion temperatures can easily exceed 1500F in these high output combos you need every bit of help you can get to maintain the strength of the aluminum in the pistons. Something else is going on if consumption increases. With a proper support rail for the oil control ring, there's no difference compared to ordinary pistons. Agreed 100% that deleting the squirters is a horrible idea.
Originally Posted by y8s
(Post 842160)
So if I recall from back in the day in sport compact car, they did a big shtick on Swain coatings--particularly ceramic piston top coatings.
The intent was to keep heat out of the piston if I recall. I guess both to reduce thermal expansion and help maintain tensile strength. I think they even said they ran slightly tighter clearances too. I didnt re-read this since I read it originally in print but here's the article: http://www.modified.com/projectcars/...vii/index.html edit: I have a minor issue with Swain using a "Jesus Fish" in their magazine ads but there are quite a few other coating companies out there now so it is mostly moot. That said, I do like dlc coating esp on valve buckets. Nice on wrist pins too, since you can then delete the bushing and save some more rod mass. Spendy, though. |
Originally Posted by y8s
(Post 842160)
edit: I have a minor issue with Swain using a "Jesus Fish" in their magazine ads but there are quite a few other coating companies out there now so it is mostly moot. |
Originally Posted by y8s
(Post 842160)
edit: I have a minor issue with Swain using a "Jesus Fish" in their magazine ads but there are quite a few other coating companies out there now so it is mostly moot.
I saw that fish on cars for 20 years before I learned what it meant. By that time though, I was already a Satinist.
Originally Posted by JKav
(Post 842214)
Ceramic crowns may reduce piston temp but the heat that doesn't go into the piston is in the chamber on the next intake stroke.
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That's why you can't open an oven when you are baking, all the heat is lost and you have to start over again.
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Originally Posted by Braineack
(Post 842277)
That's why you can't open an oven when you are baking, all the heat is lost and you have to start over again.
Not sure if you are serious :| |
im not.
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