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Old 01-27-2010, 12:48 AM   #1
syoung0298
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Default Full Race Twin Scroll GT4088R > Cosworth High Compression; prelim. logs are up

I just wanted to post some initial impressions of my Full Race GT4088R twin scroll setup with a Cosworth longblock and higher compression pistons (9.2:1, rather than 8.2:1); I don't recall anyone posting results for a twin scroll manifold, large frame turbo, and high compression pistons with cams, so I figured I'd be the first to post some results (big Al's is probably the closest, Cossie motor with an HTA86.. hybrid 35R)...






..... For reference, my motor is still in break-in, but I do have some initial perspectives to share.

Partial mod list is as follows:

Drivetrain

Build and break-in tune performed by Element Tuning
Cosworth longblock inspected and re-assembled by Phil
Cosworth honed and prepped subaru block (stock bore)
Cosworth Billet 79mm crankshaft
Cosworth Forged Connecting Rods
Cosworth 9.2:1 compression pistons
Cosworth head studs
Cosworth CNC ported heads with dual valve springs
Cosworth 1mm oversize intake and exhaust valves
Cosworth S2 cams, 274 intake, 278 exhaust
Cosworth intake manifold
Element Tuning modded Cosworth high volume oil pump
JDM top Feed TGV deletes
Grimmspeed phenolic spacers
Aeromotive Top Feed Fuel Rails & Regulator with custom fuel system ( -8 AN feed and return.. stock hardlines)
Bosch 044 pump with 55 psi base pressure
Injector Dynamics ID2200 - 2200cc injectors
Full Race twin scroll turbo kit with custom downpipe and coated piping
Dual Tial 38mm wastegates with 14.7 PSI springs
Tial 50mm Q series BOV
Garrett GT4088R 1.06 A/R turbo
APS 3.5" exhaust
Element Tuning Hydra EMS v2.6
Element Tuning Hydramist v2
Aim Sports MXL Pro data acquisition system with MSI sensors
Koyo Radiator
Grimmspeed AOS
Turbosmart EBoost 2
Ultimate racing upper intercooler piping
ACT 6 puck spec'd by Phil, with stock flywheel (decided against a multi-disc due drivability compromises)

Suspension

Q-rack 11.5 ratio steering rack
Whiteline Solid steering mounts
RCE T2 coilovers .. re-valved 500/500 spring rates
MSI front and rear competition camber plates
Whiteline 27mm front and rear sways
Whiteline anti lift kit
Whiteline Roll center adjusters
Kartboy endlinks
JDM titanium front brace
Carlabs X-brace
Advan RS 19x9 +29 offset with 255/35/19's
MSI lateral links

Target objectives (from Altered Atmosphere's dyno; stock sti baseline at 230WHP)

550WHP on pump
600WHP on pump + meth
700WHP+ on race
full boost by 4000 RPM in 5th gear


Initial Impressions at 500 miles post build:

In the past, I've owned several rotated kits including a Godspeed 35R, Perrin 35R, Ultimate Racing 35R, APS twin scroll TSR70 and now a Full Race twin scroll 40R. All of my previous setups, with exception of the Full Race kit, were run on a stock block with stock compression and a stock STI intake manfold. Going into the final build, my biggest concern was sacrificing high end power for driveability.

Comparatively speaking, even with the high lift Cosworth cams which increase lag, the Full Race 40r kit is still extremely responsive reaching 12psi by 3500 RPM in 4th gear, 12 psi by 3300 in 5th and 12psi by 3000 RPM in 6th. For reference, 12 psi on a built motor with heads and cams feels like 20+ PSI on a stock turbo's sti.

...boost response is immediate at any RPM above 3500.. I assume this is attributed to the higher compression cooupled with the twin scroll config.

For those interested in comparisons; the APS twin scroll reached 12psi 300 RPM earlier than the Full Race 40r ... and the single scroll 35R kits about 400 RPM later than the 40R.. I expect to reach target boost in higher gears around 4000 RPM

When I have an opportunity, I'll post logs to substantiate my claims. For now, I have 800 miles to go before I return for my final tune. So far, I'm happy with the results, less the horrible drone from the 3.5" exhaust. I'l post final results in a few weeks post break-in; for now I have to lug along under 5K RPM and 12 psi.
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Last edited by syoung0298; 09-21-2010 at 02:39 PM. Reason: Better readability
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Old 01-27-2010, 12:50 AM   #2
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very nice
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Old 01-27-2010, 02:24 AM   #3
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Which 40r is it? 88 or 94?
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Old 01-27-2010, 03:06 AM   #4
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Stout build by the sounds.
19's seem like a big wheel unless you're running massive 6 pot AP's/Brembo's or Alcons with huge rotors.
Also have you ever run softer sway bars? They seem very strong with the firm coilovers.
How does the car handle?

Last edited by Bbee 4; 01-27-2010 at 05:31 AM.
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Old 01-27-2010, 04:26 AM   #5
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Quote:
Originally Posted by syoung0298 View Post
This is undoubtably due to the high compression motor.

lol at 9.2 being considered high compression, try 11:1, i built 2 honda motors, 1 high compression turbo, one low compression turbo, they spooled the same, this high CR = faster spool thing is really a myth. Full-Race has been playing with twinscoll setups and the 40R for some time now, i'm just willing to bet they have found a combination that works ande is damn near perfected, i am completely against nutswinging but i really do think they deserve the credit at this point...

Consider lower CR engines can run more timing to make up for the loss of response down low, this helps with spool up, neither higher compression or lower compression is superior, it's just what you want and its a personal choice.
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Old 01-27-2010, 08:07 AM   #6
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but it doesn't break

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higher compression......justs gives you better off boost driveability..

Which can be useful in city driving.
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Old 01-27-2010, 09:28 AM   #7
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Quote:
Originally Posted by GundamFan View Post
lol at 9.2 being considered high compression, try 11:1, i built 2 honda motors, 1 high compression turbo, one low compression turbo, they spooled the same, this high CR = faster spool thing is really a myth...
How many psi can you run on the 11:1 motor on pump gas? Just curious.
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Old 01-27-2010, 09:32 AM   #8
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yummy
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Old 01-27-2010, 11:01 AM   #9
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Subscribed!
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Old 01-27-2010, 11:09 AM   #10
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Quote:
Originally Posted by dankster View Post
How many psi can you run on the 11:1 motor on pump gas? Just curious.
Even the 9.2:1 Cosworth Pistons are pushing the limits of 93 octane. Without injection? forget about it. You wouldnt be able to run much boost at all.
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Old 01-27-2010, 11:28 AM   #11
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GundamFan is right. I wouldn't consider that high compression. Last Honda s2000 I tuned made 520whp on a bone stock 11:1 compression F20 engine. It was running on 93 octane with water/meth injection. Low 400's would have been easily possible without the meth.
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Old 01-27-2010, 11:35 AM   #12
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So how did this turn into a Honda vs. Subaru thread?

Back on topic. I can't wait to see the final numbers. That is an absolutely amazing build. Any reason Phil took the cosworth motor apart? Just curious, that's all.
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Old 01-27-2010, 11:56 AM   #13
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post some pics of this beast. i want to see it and i am sure everyone else does too
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Old 01-27-2010, 11:56 AM   #14
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have you seen the s2000 from hell on youtube tuned by t1? 700whp on stock motor.
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Old 01-27-2010, 12:20 PM   #15
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Quote:
Originally Posted by ownnij View Post
have you seen the s2000 from hell on youtube tuned by t1? 700whp on stock motor.
Yes these big power stock engines are becoming common now
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Old 01-27-2010, 12:24 PM   #16
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This is gonna be a monster.
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Old 01-27-2010, 03:06 PM   #17
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Quote:
Originally Posted by GundamFan View Post
lol at 9.2 being considered high compression, try 11:1, i built 2 honda motors, 1 high compression turbo, one low compression turbo, they spooled the same, this high CR = faster spool thing is really a myth. Full-Race has been playing with twinscoll setups and the 40R for some time now, i'm just willing to bet they have found a combination that works ande is damn near perfected, i am completely against nutswinging but i really do think they deserve the credit at this point...

Consider lower CR engines can run more timing to make up for the loss of response down low, this helps with spool up, neither higher compression or lower compression is superior, it's just what you want and its a personal choice.
I'm right there with you...in every aspect. Just toss in some 4G63 build experience as well. My personal subie is only 9.5:1 and I don't consider it a high CR build by any means.

Quote:
Originally Posted by foolio View Post
Even the 9.2:1 Cosworth Pistons are pushing the limits of 93 octane. Without injection? forget about it. You wouldnt be able to run much boost at all.
You must not remember the good old days before the bugeye was stateside. It wasn't uncommon for people to run 10-12 psi on a 10:1 CR stock 2.5RS motor
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Old 01-27-2010, 03:37 PM   #18
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Very interested in final results...good luck!
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Old 01-27-2010, 03:37 PM   #19
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Quote:
Originally Posted by Homemade WRX View Post
You must not remember the good old days before the bugeye was stateside. It wasn't uncommon for people to run 10-12 psi on a 10:1 CR stock 2.5RS motor
And back then we were using J&S voltage clamps with no real ignition control!
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Old 01-27-2010, 03:47 PM   #20
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^^^ and blowing up motors left and right (even more than in PPB now days )
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Old 01-27-2010, 04:27 PM   #21
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OP, sometime between now and getting the car broken in and tuned please update your 1st post to reflect the required format. You can find it here http://forums.nasioc.com/forums/show....php?t=1858764. Thanks.
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Old 01-27-2010, 05:27 PM   #22
syoung0298
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Quote:
Originally Posted by GundamFan View Post
lol at 9.2 being considered high compression, try 11:1, i built 2 honda motors, 1 high compression turbo, one low compression turbo, they spooled the same, this high CR = faster spool thing is really a myth. Full-Race has been playing with twinscoll setups and the 40R for some time now, i'm just willing to bet they have found a combination that works ande is damn near perfected, i am completely against nutswinging but i really do think they deserve the credit at this point...

Consider lower CR engines can run more timing to make up for the loss of response down low, this helps with spool up, neither higher compression or lower compression is superior, it's just what you want and its a personal choice.
agreed.. the term high compression is relative.. I can only assume that the higher pressure pulses from the higher copression also contribute to the lively feel of the motor and the ability to trnasfer energy to the turbine wheel resulting in better boost response; but being a novice defer to the experts on this.

Regarding the full race kit.. excellent fitment and engineering> compromise of responsiveness and high flow.. I am confident that this made a siginificant contribution to spool.. perhaps the most significant as you eluded.
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Old 01-27-2010, 05:35 PM   #23
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Quote:
Originally Posted by Bbee 4 View Post
Stout build by the sounds.
19's seem like a big wheel unless you're running massive 6 pot AP's/Brembo's or Alcons with huge rotors.
Also have you ever run softer sway bars? They seem very strong with the firm coilovers.
How does the car handle?

initially the 19's, Phil calls them wagon wheels , were for cosmetics, but I do plan on installing a pair of Brembo or Stoptech 6 piston's with 355mm rotors up front.. The 19s are my winter setup and have all season tires.. not sure what to do, relative to summer wheels and tires. I was considering a set of Enkei NT03's 18x9.5, with 265/35/18. We'll see. One of the decision points is whether or not to go with a widebody kit, which can change the dynamic altogether.

Regarding the sways, initially I wan't sure which coilovers I was going to end up with, and already had the 27mm bars. So I decided to use them. In the future I may soften the bars, and go with a set of JRZ's, but will have to do some more driving first. With the current set-up, the ride is tolerable and handling is very neutral ( coilovers set to 6 clicks from full stiff up front, and slightly softer in the rear, 8 clicks from full stiff)..

thanks for the input..

Last edited by syoung0298; 01-27-2010 at 05:49 PM.
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Old 01-27-2010, 05:48 PM   #24
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Quote:
Originally Posted by Scooby921 View Post
OP, sometime between now and getting the car broken in and tuned please update your 1st post to reflect the required format. You can find it here http://forums.nasioc.com/forums/show....php?t=1858764. Thanks.
will do.. thanks.
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Old 01-27-2010, 06:18 PM   #25
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when turboing NA cars it seems most people run 6-8 psi on stock compression....

when people turn the boost up i think the head gaskets and/or head studs are the failure point and not necessarily from high comp + boost and breaking pistons/rods.

i just going of pure heresay and a little honda forum reading so dont quote me on that.
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