High Compression 2.3 Stroker.

[CPHunter]

Hey guys,

Just had a question about building a High Compression Stroker for E-85. My current 2.0 isn't cutting it for me. Takes longer then I want to stall my auto and a faster spool for the Hx-40 I think would be nice. Anybody know any disadvantages to high compression strokers. It's a drag car only. I'm looking at the following for my parts list

Piston : 10:5:1
Rods : Alumium Rods
Others : Kiggly Main Girdle , Jays Racing Main caps, ARP main studs, L19 head studs, ACL race Bearings Main and Rods.


Anybody think I'm missing anything? And any thoughts about going so high? And worth it?

 

[TofastForU_99]

I am running 9.6:1 stroker in my car. Its working well so far. Spooling a Hx40 in a 17cm^2 T4 to 30 psi around 5k. I rev it out to 8k. 10.61s@134 at 27 psi.

Sorry I am on the wrong account at the shop. I am talking about Johns Talon

 

[zedicus]

if i was going to have custom pistons made for an all out drag build they would be 12:1.

then on a stroker you could get a small turbo (16g) and build boost at like 2000rpm.

look, motorcycle and ATV engines (where i come from) are so similar to these I4s we have that its not even funny. and we build 13:1 and 14:1 engines then spray them. or all motor busa engines at 14:1 making 500hp. small efficient turbos that spool at nothing and carry peak boost to redline. this guy in our shop has a blown 500 single making well over 100hp.

12:1 then add boost. i could imagine going 14:1 at some point, i would want a meth injection kit to fend off knock while tuning though. better have a BUILT drivetrain to though.

ive seen perfect engines run 20:1 on 91 pump gas with no knock or detonation.

ultra high compression does have a downside though, after a point, peak hp will fall off as the massive force in the chamber will actually start fighting the piston from gaining more speed.

Honda spins the engine faster to gain HP. we dont have to.

 

[ViciousLord]

10.5, even 12.1 is fine running E85.

and no matter what anyone says compression ratio does not effect spool

 

[TSi Kid]

if i was going to have custom pistons made for an all out drag build they would be 12:1.

then on a stroker you could get a small turbo (16g) and build boost at like 2000rpm.

look, motorcycle and ATV engines (where i come from) are so similar to these I4s we have that its not even funny. and we build 13:1 and 14:1 engines then spray them. or all motor busa engines at 14:1 making 500hp. small efficient turbos that spool at nothing and carry peak boost to redline. this guy in our shop has a blown 500 single making well over 100hp.

12:1 then add boost. i could imagine going 14:1 at some point, i would want a meth injection kit to fend off knock while tuning though. better have a BUILT drivetrain to though.

ive seen perfect engines run 20:1 on 91 pump gas with no knock or detonation.

ultra high compression does have a downside though, after a point, peak hp will fall off as the massive force in the chamber will actually start fighting the piston from gaining more speed.

Honda spins the engine faster to gain HP. we dont have to.

 

[ViciousLord]

ive seen perfect engines run 20:1 on 91 pump gas with no knock or detonation.

Bull!

Honda spins the engine higher to gain HP.

Fixed.

 

[viperlp01]

You can think that compression ratio does not affect spool but personal experience along with the thermal dynamics of a high compression engine say differ. With that being said it isn't much but a more efficient engine that creates higher cylinder pressures faster will spool a turbo quicker

 

[LandSpeed-DSM]

Speaking of Thermodynamics..

From what I recall, higher compression doesn't help spool so much as it provides the torque to get you to your boost threshold faster. Because the higher comp motor is more thermally efficient less waste heat reaches the turbine, so if anything it would serve to hamper spool.

But the increase in torque and off boost response makes up for it. So it's a wash.

 

[zedicus]

my bet is 12:1 is doable on pump gas.

compression will gain toque. making your curve look more like an N/A motor. this is not exactly directly effecting spool itself. but efficiency of burn as mentioned, will effect spooling, plus heat and load... you will build boost going up a hill a lot faster then going down a hill, if everything else is equal. boost will build faster with high compression, not exactly do to the higher compression, get it?

i don't see how spinning the engine higher vs faster would be different things? and spinning (circle) faster is more descriptive then saying spinning higher.

static comptression of almost 300 psi on 91 pump gas. that is like 19ish : 1.
i have a friend with a 16:1 pump gas engine, i can take pics of the psi gauge hooked to it if you want.

 

[TSimage]

12: on pump???

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[zedicus]

1.4l i4 motorcycles run 14:1 on pump and my cheap ass friends run 87 octane in them. my water cooled v-twin ran 12:1 on 91 octane no prob.

12:1 on 91 oct. doable. easily with a good tune. especially with forged pistons.

im gunna be 10:1 stroked and bored to 2.4l with a 16g on pump gas. 91oct is all we can get here. woulda went higher but high comp pistons are hard to find on this platform. especially in 86.5mm or bigger pistons. but then the lil 4g63 block couldnt take much more any way.

technically i will be 2350.6cc the same exact volume as a 4g64 stock.

 

[dsm's can fly]

my bet is 12:1 is doable on pump gas.

compression will gain toque. making your curve look more like an N/A motor. this is not exactly directly effecting spool itself. but efficiency of burn as mentioned, will effect spooling, plus heat and load... you will build boost going up a hill a lot faster then going down a hill, if everything else is equal. boost will build faster with high compression, not exactly do to the higher compression, get it?

i don't see how spinning the engine higher vs faster would be different things? and spinning (circle) faster is more descriptive then saying spinning higher.

static compression of almost 300 psi on 91 pump gas. that is like 19ish : 1.
i have a friend with a 16:1 pump gas engine, i can take pics of the psi gauge hooked to it if you want.

I do not know about 300 PSI at 16:1 my 2.4 is running high compression it has a compression test of 245 PSI. it is only 13:1 max. as for spool it is hard to say i have a gt4088r but due to the compression i currently only have it at 17 PSI making 630 hp. all that said i hit full boost at about 5000 rpm's. cars running more boost will spool faster due to the waste gate being closed longer. if i get a chance to turn it up to 30 psi i would imagine it would spool about the same.

 

[mrfister11]

how can you relate compression ratio to cylinder pressure directly?? i could have a c/r of 20:1 with bad valve seats and only have c/r of 150... ive seen a fresh engine, rebuilt stock that was sealed good have about 215.. i think it should have been around 8 something for the c/r.. just saying...

but anyways if you car really has 13:1 and you run 17 psi and make 630 hp thats awesome.. highest c/r on boost ive seen yet.. would like to know more

 

[WES_393]

ive seen perfect engines run 20:1 on 91 pump gas with no knock or detonation.

that is like 19ish : 1.

i have a friend with a 16:1 pump gas engine

12:1 on 91 oct. doable.

So which one is it.... 20:1, 19:1, 16:1, or 12:1?

 

[1990AWD]

Let's try to get back on topic here. If I gave a shit what bikes ran for compression I'd be on a different forum.

OP, your build list looks great, not sure you'll need aluminum rods though. On E85, 10.5:1 is safe and with a stroker that HX-40 in twin scroll will spool very nicely.

 

[dsm's can fly]

how can you relate compression ratio to cylinder pressure directly?? i could have a c/r of 20:1 with bad valve seats and only have c/r of 150... ive seen a fresh engine, rebuilt stock that was sealed good have about 215.. i think it should have been around 8 something for the c/r.. just saying...

but anyways if you car really has 13:1 and you run 17 psi and make 630 hp thats awesome.. highest c/r on boost ive seen yet.. would like to know more

I know what you are saying about compression ratio and actual compression numbers. cars bleed off compression from cams, valve's sealing and rings. that is why you cannot say 8.5:1 compresion equals "X" amount of PSI on a gauge. All i can say is on the engineering side when ordered from weisco they 13:1 and produce 245 PSI on a compression tester.

here is a link to the tread when i first cranked it up.
http://www.dsmtuners.com/forums/dyno-talk/421755-my-new-2-4-gt4088r-build-dyno-sheet.html

To keep this thread on topic though post any other questions in there.

Sorry to the OP for the slight thread jack. I think you have all you need to run a great set up. the tune will matter more than any part on your build. Good luck

 

[rhamlinii]

I do not know about 300 PSI at 16:1 my 2.4 is running high compression it has a compression test of 245 PSI. it is only 13:1 max. as for spool it is hard to say i have a gt4088r but due to the compression i currently only have it at 17 PSI making 630 hp. all that said i hit full boost at about 5000 rpm's. cars running more boost will spool faster due to the waste gate being closed longer. if i get a chance to turn it up to 30 psi i would imagine it would spool about the same.

Cams and overall valve overlap will change the effective compression ratio with any motor.