High compression SR20det

[D1S13]

I was thinking about my next build and I'm not one to run the turbo to the max, so in order to get the most power out of my turbo while keeping it efficient; I have been contemplating increasing the compression on my sr20det.

what do you think stock compression is 8.5:1 and I was thinking about increasing it to 10.0:1 if not 11.0:1

my current set up consists of stock bottom end, hks 264 cams, 850 sards, Apfc, Tomei manifold and 2871.

I currently dont boost over 14lbs, i stay at 10 during the week and 1 bar when necessary.

and yes we have plenty E85 for tuning, this will be more of a weekend car anyway

feed back welcomed

[HYPNOTIK]

I think that is a horrible idea. You're not going to make anymore power. With higher compression your just going to have to pull timing to keep it from knocking. That's why most people replace there stock head gasket with a thicker one to lower the compression ratio. Compression has nothing to do with how much power a turbo can make anyway. A particular turbo will only support a certain amount of power no matter what motor you put it on or what the compression ratio of said motor is. Stock SR turbine will still only support ~300hp even if you put it on a V8. I think you need to read up on turbines and compressor maps.

[fliprayzin240sx]

9:1 is that most I'd bump it up to on an SR20DET. Anything more than that, you might as well keep the KA and slap a turbo kit on it.

[S14DB]

Originally Posted by HYPNOTIK

I think that is a horrible idea. You're not going to make anymore power. With higher compression your just going to have to pull timing to keep it from knocking. That's why most people replace there stock head gasket with a thicker one to lower the compression ratio. Compression has nothing to do with how much power a turbo can make anyway. A particular turbo will only support a certain amount of power no matter what motor you put it on or what the compression ratio of said motor is. Stock SR turbine will still only support ~300hp even if you put it on a V8. I think you need to read up on turbines and compressor maps.

Huh?


Forced induction raises your effective compression ratio. I don't know the PLAN numbers on the SR. But an cylinder can only hold so much pressure. You can increase cylinder pressure with a change in C:R, Cam Timing or adding forced induction.

The engine is going to produce the same power at the same effective C:R. Whether it is a high C:R engine and low CFM turbo or a Low C:R engine, high CFM turbo.

The advantage to running a high C:R is that it is always a high C:R. You don't have to wait on a turbo to spool up to raise the cylinder pressure. The exhaust velocity's will be faster and the turbo will spool faster.

The benefit is also the problem. With a high C:R it is harder to tune cause your margins are much closer and the effective C:R raises faster with boost. It is a lot easier and safer to run low C:R, high boost.


If you are going to build a high C:R motor for boost. Make sure you are getting bottom end parts designed for forced induction. Some of the high C:R stuff is designed for NA. Light weight to reduce rotating mass not hold increased cylinder load. I know a guy that got some nice 11:1 pistons that were designed for NA and he blew the ring lands out on them cause they were high on the skirt for ring seal. Didn't shroud them from the pressure. I'm sure the dome top vs a dish didn't help ether.

[D1S13]

thank you for the information

[SoguRacing]

Go with a longer stroke. more torque

[D1S13]

Originally Posted by SoguRacing

Go with a longer stroke. more torque

so pretty much for my idea to be the most useful, i should change my power plant to my KA,

increase the compression and run a small quick spooling turbo like t28-s15.

[4x4le]

If you were going to ever consider running this setup on gas (even race gas) I would say horrible idea. I think allot of the guys in this thread might not have much experience with actually tuning an e85 vehicle however, and I do and I have spoke with many other e85 tuners as well and we all agree on 1 thing, its very odd to us how detenation is NEVER present even after we go past the threshold where timing no longer benefits the hp/tq.

That alone has really made me want to do a high compression turbo vehicle. The reason you dont see it much is because its not worth it (on a gas motor, maybe e85 as well but time will tell when someone does it) because it just makes for a tuning nightmare. Everyone that has tried the high compression turbo setups has ended up with the realization that more boost would have been easier and safer and smarter.

The info on a turbo can only make X amount of horse power on any engine is very untrue. Take a holset turbo for example. It spools fast on the cummings and makes great tq but not a lot of hp due to the fast spool and the low rpms of the engine. Now put that turbo on a rotary motor. It will not make much tq and will make decent power. Rotarys that make good hp #s are usually ported like crazy and high revving with a good flowing turbo. They almost always however make less power than a piston engine with the same turbo (due to their exreamly low compression) which brings me to my next point: put that same holset turbo on a ka and see that it makes good tq (but still less than the cummings) but better hp than the rotary.

So in my eyes, just reading compressor maps alone means nothing because all engines are not =
Compression ratios and displacement to start with are one of the major things that cause a turbo to react differently on each engine, followed by cams. Some cams will just plain not allow enough air to enter the engine causing higher manifold pressure while the hp output does not actually increase, while some very extream cams can actually bring small turbos out of their effency range on no more boost than stock wastegate springs.

Anyways, I like youre idea if your willing to run nothing but e85 in the beast. You will have very good tq numbers due to the turbo being able to spool like never before (did you know that e85 creates more exhaust gasses than gas does too?) with high compression and e85. Also when the turbo is spooling up untill a little past the peak tq rpm its smart to run it a little richer and this will allow for even more timing which will spool the turbo even faster and create gobs of tq.

You cant just be unsmart with the timing, if your not making more power dont throw more timing at it, but your not really going to have to worry about detenation as much as a gas tuner is. You will probably be supprised at how much timing your actually going to be able to throw at the engine though! That part just isnt going to make sence to you, at first at least!

Go ahead and do it, then show the haters the results.

[S13 curtis]

the enjuku racing drift car ran SR20 11:5:1 compression with C16 fuel and a GT2871r on 22lbs and made 480whp on an AEM standalone.

[4x4le]

and you could never dream of that kind of power with that turbo and low compression. Them pistons easially added around 80hp.

I know 1 thing, If i ever have to rebuild my engine Im going with a way higher compression ratio.

[D1S13]

Originally Posted by 4x4le

If you were going to ever consider running this setup on gas (even race gas) I would say horrible idea. I think allot of the guys in this thread might not have much experience with actually tuning an e85 vehicle however, and I do and I have spoke with many other e85 tuners as well and we all agree on 1 thing, its very odd to us how detenation is NEVER present even after we go past the threshold where timing no longer benefits the hp/tq.

That alone has really made me want to do a high compression turbo vehicle. The reason you dont see it much is because its not worth it (on a gas motor, maybe e85 as well but time will tell when someone does it) because it just makes for a tuning nightmare. Everyone that has tried the high compression turbo setups has ended up with the realization that more boost would have been easier and safer and smarter.

The info on a turbo can only make X amount of horse power on any engine is very untrue. Take a holset turbo for example. It spools fast on the cummings and makes great tq but not a lot of hp due to the fast spool and the low rpms of the engine. Now put that turbo on a rotary motor. It will not make much tq and will make decent power. Rotarys that make good hp #s are usually ported like crazy and high revving with a good flowing turbo. They almost always however make less power than a piston engine with the same turbo (due to their exreamly low compression) which brings me to my next point: put that same holset turbo on a ka and see that it makes good tq (but still less than the cummings) but better hp than the rotary.

So in my eyes, just reading compressor maps alone means nothing because all engines are not =
Compression ratios and displacement to start with are one of the major things that cause a turbo to react differently on each engine, followed by cams. Some cams will just plain not allow enough air to enter the engine causing higher manifold pressure while the hp output does not actually increase, while some very extream cams can actually bring small turbos out of their effency range on no more boost than stock wastegate springs.

Anyways, I like youre idea if your willing to run nothing but e85 in the beast. You will have very good tq numbers due to the turbo being able to spool like never before (did you know that e85 creates more exhaust gasses than gas does too?) with high compression and e85. Also when the turbo is spooling up untill a little past the peak tq rpm its smart to run it a little richer and this will allow for even more timing which will spool the turbo even faster and create gobs of tq.

You cant just be unsmart with the timing, if your not making more power dont throw more timing at it, but your not really going to have to worry about detenation as much as a gas tuner is. You will probably be supprised at how much timing your actually going to be able to throw at the engine though! That part just isnt going to make sence to you, at first at least!

Go ahead and do it, then show the haters the results.

thx for the Much needed Info, i figured since i don't boost crazy numbers now if i can increase the compression of my motor I will create better response because i am keep the turbo in its most efficient range.

to me; NOT All but most high horse power 240's I see locally have alot of useless power. Boosting 20lbs plus, every time we run I've won so far because my set up is efficient and the hp I do have is mostly transfered to the grown, Not just spinning tires through 5 gear...

So, with your understanding in depth the high compression theory would you suggest staying with the SR20, or should I use my KADE power plant as they are both available

and the ka obviously offers more displacement + high compression + smaller fast spooling turbo= fun

or stay with the SR set up?

and yes this will be a E85 only car.

[4x4le]

The reason I like the sr is because its lighter and I feel that it makes for a better handling car. If thats not your reason for having it go ahead and go back to the ka.

The ka is a good engine. I honestly cant remember the hp # off the top of my head but it was like 430whp but the tq # is what sticks with me. And it was 455wtq on a s14 ka24det we made the other day on a tuned stock ecu in the shop owners car. All the engine build is 740cc injectors, z32 maf, forged pistons and stock rods.... Its a pretty strong engine........

[rex2sx]

Originally Posted by 4x4le

The reason I like the sr is because its lighter and I feel that it makes for a better handling car. If thats not your reason for having it go ahead and go back to the ka.

The ka is a good engine. I honestly cant remember the hp # off the top of my head but it was like 430whp but the tq # is what sticks with me. And it was 455wtq on a s14 ka24det we made the other day on a tuned stock ecu in the shop owners car. All the engine build is 740cc injectors, z32 maf, forged pistons and stock rods.... Its a pretty strong engine........

What turbo?

If your going to raise compression, dont stroke it. If you get a bigger stroke then youll get small length rods. So your CR could possibly stay the same. I was thinking about this kind of build to but your really going to have to watch AFRs and tuning will be more critical. Im not sure about Srs but theres a few vehicles i have searched running high compresion + Turbo (I fogot the name of the Japanese NSX..SCCs Focus and other..)

But i agree your effective CR has to be different/higher to make more power, but cylinder pressure also come in to play.

Becuase of Holsets i think using compressor maps has lesss of an importance but you stil should use them. Just to make sure your out of the surge line and close the highest efficiency as possible.

But i also agree, as to its retarded where they say turbo "X" makes this amount, though you MIGHT be able to figure out a max for a specific engine.

Basically all this can be summed up into 2 charqcters

X2!

[rex2sx]

Oh 4x4le can you post up more of that KA build..Maybe a dyno sheet and engine specs?

[4x4le]

Wiseco 90.5 9.1
stock rods
ARP Head Studs
OE Head Gasket
248/248 cams
T3/T04E .57 trim .63 A/R
JGS Log
Tial 38mm wastegate with 2" dump tube (nice and loud)
HKS SSQV bov
Nismo Adjustable FPR w/ seperate silicone filled gauge
Walbro 255lph Fuel Pump
FMIC 28x8x2.75
740cc Deatchworks
Z32 MAF
Custom 3" downpipe
Custom 3" exhaust
Custom Intercooler piping

and I he had the dyno graph uploaded but it dont seem to be there anymore. I just got to see it once on my Ipod,... I hope he posts it back up!


One thing that you really need to remember about the op's possible build is that he is going to be tuning with one of the most forgiving fuels that are easily available, e-85.
The main reason people dont go high compression/turbo is because the initial tuning can easially blow the engine. Well, with e-85 he will be able to get the tuning right without detenation and should have a long lasting engine for long afterwords.
If I ever blow my engine and it ends up needing a bore, Im so going high compression on it as I never run anything other than e85 in my car.

[rex2sx]

Wow..seems like he put some $ into that build.

Yeah i forgot about the E-85 part.

[D1S13]

i've registered for ka-t.org and see the build you are referring to. thx

[4x4le]

Na, it was pretty budget oriented actually. Were a business specializing in these cars so we have accounts with many manufactures, plus allot of the odds and ends were just laying around. Andy did all the work himself, Andy and a friend of ours did all the dyno tuning, me and Andy did the street tuning (I couldnt make it to the dyno day).

I have allot more money in my sr than he has in his ka and his is allot more powerfull than mine. Most of my parts were already purchased however before me and Andy ever hooked up. I brought my engine to him when I wanted it built and we have been doing business ever since!

Here is Andys engine (the ka were talking about) and its an old pic and some things are different now.


and here is a older pic of mine, there are things different with it too.


Haha, we cant take pics every time we change our setup. That would take forever lol.

[4x4le]

Originally Posted by rex2sx

Oh 4x4le can you post up more of that KA build..Maybe a dyno sheet and engine specs?

[D1S13]

being i already have a sr power'd car... i may have to dab into the ka..

[rex2sx]

Originally Posted by 4x4le

Very nice. Thats a smooth curve. Max torque at 4.5k. Im really thinking about a KA buid now.

[S13 curtis]

Originally Posted by 4x4le

Na, it was pretty budget oriented actually. Were a business specializing in these cars so we have accounts with many manufactures, plus allot of the odds and ends were just laying around. Andy did all the work himself, Andy and a friend of ours did all the dyno tuning, me and Andy did the street tuning (I couldnt make it to the dyno day).

I have allot more money in my sr than he has in his ka and his is allot more powerfull than mine. Most of my parts were already purchased however before me and Andy ever hooked up. I brought my engine to him when I wanted it built and we have been doing business ever since!

Here is Andys engine (the ka were talking about) and its an old pic and some things are different now.


and here is a older pic of mine, there are things different with it too.


Haha, we cant take pics every time we change our setup. That would take forever lol.

well look how small of a turbo you have. and on top of that your using a T2 turbo. if you had a 3071r or a 50 trim you would kick his ass.

i would hope he can beat you with that bigger turbo.

[4x4le]

I have a 2871r.

I know that his turbo is bigger and his engine is bigger. I wasnt complaining or acting like I dont know why his is faster. I was just pointing out that it dont take large amounts of money to make an engine fast. I was just saying that mine is over built (although I would still love to add to all of that) because its rare that mine ever sees a leiserly drive. Most of its miles are spinning the tires wide open throttle near the red line. You do need to sink some cash into a setup for that.

[smelly240]

So - who is gonna break it to mazworx that their 11:1 is bad?

[D1S13]

Originally Posted by smelly240

So - who is gonna break it to mazworx that their 11:1 is bad?

not that one way is bad and one is good, as we all know mazworx is proven, more directed for drag but still proven non the less.

[GroundPerformance]

Originally Posted by 4x4le

If you were going to ever consider running this setup on gas (even race gas) I would say horrible idea. I think allot of the guys in this thread might not have much experience with actually tuning an e85 vehicle however, and I do and I have spoke with many other e85 tuners as well and we all agree on 1 thing, its very odd to us how detenation is NEVER present even after we go past the threshold where timing no longer benefits the hp/tq.

That alone has really made me want to do a high compression turbo vehicle. The reason you dont see it much is because its not worth it (on a gas motor, maybe e85 as well but time will tell when someone does it) because it just makes for a tuning nightmare. Everyone that has tried the high compression turbo setups has ended up with the realization that more boost would have been easier and safer and smarter.

The info on a turbo can only make X amount of horse power on any engine is very untrue. Take a holset turbo for example. It spools fast on the cummings and makes great tq but not a lot of hp due to the fast spool and the low rpms of the engine. Now put that turbo on a rotary motor. It will not make much tq and will make decent power. Rotarys that make good hp #s are usually ported like crazy and high revving with a good flowing turbo. They almost always however make less power than a piston engine with the same turbo (due to their exreamly low compression) which brings me to my next point: put that same holset turbo on a ka and see that it makes good tq (but still less than the cummings) but better hp than the rotary.

So in my eyes, just reading compressor maps alone means nothing because all engines are not =
Compression ratios and displacement to start with are one of the major things that cause a turbo to react differently on each engine, followed by cams. Some cams will just plain not allow enough air to enter the engine causing higher manifold pressure while the hp output does not actually increase, while some very extream cams can actually bring small turbos out of their effency range on no more boost than stock wastegate springs.

Anyways, I like youre idea if your willing to run nothing but e85 in the beast. You will have very good tq numbers due to the turbo being able to spool like never before (did you know that e85 creates more exhaust gasses than gas does too?) with high compression and e85. Also when the turbo is spooling up untill a little past the peak tq rpm its smart to run it a little richer and this will allow for even more timing which will spool the turbo even faster and create gobs of tq.

You cant just be unsmart with the timing, if your not making more power dont throw more timing at it, but your not really going to have to worry about detenation as much as a gas tuner is. You will probably be supprised at how much timing your actually going to be able to throw at the engine though! That part just isnt going to make sence to you, at first at least!

Go ahead and do it, then show the haters the results.

I've spent days researhing regarding my current setup High Compression Turbo and Google lead me back to Zilvia.. What you have mentioned here is similar to my current project and can't wait to get it running soon. FYI I orded Type 3 Nistune board from you guys not too long ago for my Built S14 SR and will need another one. Any advice will be appreciated. Thanks!

For those curious below is a summary of my setup;
- Built KA24DE High Comp 11:1
- E85 Gas Only ( Weekend/Fun Car )
- 1600cc Bosch Alcohol Compatible
- FJO Injector Driver.
- Dual Intank 255lph FP.
- Holset H1E /w 22cm^2
- Nistune
- Cobra Maf
- Twin-Scroll T4 Turbo Manifold.
- etc....

[4x4le]

I would think you should possibly use a lightning maf instead of the cobra. Im assuming your going blow through though since your using a ford maf. I would also like to see if your ecu would be happy without the injector driver. Those injectors are very nice injectors with minimal lag for their size. Im running msd 756cc injectors but at 4bar fuel pressure and it seems as if my ecu would still be happy with much larger injectors. If your running 3bar fuel pressure (which I would assume with such a large injector) and the fact that your running e85 (which will make your injectors seem tunably 30% smaller) I wouldnt think you should need the driver.

I would be really interested in what your results are with that if you wouldnt mind........ I have thought if I ever needed injectors again I would go with the 1000cc equivalent to what you have and I would run them at 4 bar if needed.

[jr_ss]

If you chose to do the high C:R "lower" boost route. plan on investing in cylinder sleeves. I don't believe the factory SR sleeves will hold the amount of pressure we're talking about.

[4x4le]

^ the most recent fellow on here is doing it on a ka, which I think the block will not be his worries.

I do believe that enjuku did not use sleeves on their high compression turbo sr, but there is no telling how few miles that engine actually seen. I know I still plan on doing one (and Im not going to re read how I said Im going to do mine over a year ago) but I do plan on a sleeved engine and many other things. Im sure my ideal build up of the engine has changed quite a bit.

[jr_ss]

Originally Posted by 4x4le

^ the most recent fellow on here is doing it on a ka, which I think the block will not be his worries.

I do believe that enjuku did not use sleeves on their high compression turbo sr, but there is no telling how few miles that engine actually seen. I know I still plan on doing one (and Im not going to re read how I said Im going to do mine over a year ago) but I do plan on a sleeved engine and many other things. Im sure my ideal build up of the engine has changed quite a bit.

Yes, but he already has a cast iron block which is significantly more robust than that of the SR. The SR engine is known to flex under machining procedures, that's why it's best to have a deck plate and the bellhousing bolted to the motor when machining it.