GEN2 LS

iTrader: (3)

With that much compression would you need to run larger cams like Skunk2 Pro Series cams to run well? Or will ITR's or GSR's suffice?

fuel being used is E85 so no worries. setup is a 81mm b16, 30R, peakboost ramhorn, built head blah blah blah

BoosterB16

14:1 compression on boost??? Goodluck

CanadianEF9

maybe you should just switch from e85 to deisel and from a b16 to a 5.9 cummins

the171

cummins civic ftw

crispchris

main question I have is why do you feel the need to run that high of compression?

96 GSR-T

I know E85 is good stuff and I have used it in the past, and I am using it in my new motor at 11:1, but I dont think your going to find one person that is going to be able to really answer your question, that is a tremendous amount of compression... I hope your not using pump E85.

Anyway, I would still go no larger than a Pro-1 if you do decide to go ahead with your plans lol.

GoSickemRobert

14:1 with boost? boom

CanadianEF9

anything is possible

DDTECH

So much misinformation..unreal..

Miller had a motor on 14.1 cr on 10psi.. made upper 600's.. gave it to a friend of his..

this isn't 1992.. there are tuning and engine advancements out there.

Uncle Dave

Well guys WRC rallycars run compression ratio's like that but they also run restrictors in front of the turbo.So if you dont want to rev your engine go ahead run the compression but fit a restrictor it will make insane torque down low but 36mm or smaller restrictor will limit peak power to 5000 to 6000rpm.

fcluddington

I am not sure why so much against the high compression and boost. I have not heard of buying E85 that wasent from the pump. I think you will need adjustable cam gears and read up on valve overlap. Might want to invest in a egt gauge.

96 GSR-T

And one funky tank of corn or anything else can cause undesireable results, sure it can be done its just pushing the limits. I wouldnt even think about doing it without knowing in real time what the Ethanol Content in my tank was. I saw alot of difference in the stuff from my local station from batch to batch.

2k.civic.si

people were running high boost on high compression long ago using alcohol.
this isnt anything new and has been done long before some of us were even alive.

Spawne32

iTrader: (3)

well the tradeoff there is how much boost...or i should say cfm you can push before you have a problem, you get more power out of the compression but your effective compression ratio on 10psi is probably that of say a car running 35psi on low compression pistons, with less airflow overall

GEN2 LS

iTrader: (3)

I doubt the compression will be exactly 14:1, but I know it will be right around the 13:1 range. Everyone is asking why... why not is the question! The pickup and throttle response would be crazy for a lil street car IMO! The car is at 11:1 right now and on 9psi its got a pretty stout powerband! I know some big name guys have done it before, just wanted sum feedback and tech info. 96 GSR-T I was thinking about the blends changing too. A local tuner in my area is able to get ahold on E98 so I may look into it.

vtechjunkie

iTrader: (2)

I was thinking about running a little higher compression as well. Although, I live @5300 feet, and the elevation effectively reduces my compression approx. 1 point. so I was going to get some 11-1's and see how they respond.

Tony the Tiger

The compression ratio isn't really the biggest problem... It's the design of the piston, and a 14:1 CR piston will have a pretty high dome on it. This completely ruins the burn characteristics, and technically trading off efficiency with just "brute" squish.

Milled head, decked block, flat faced valves, smaller valve reliefs and such are the best ways to bump up the compression effectively.

96 GSR-T

Can you even hit 13:1 with just those mods on a flat top piston? My new motor is at 10.8:1-B16 head with the pistons .010 in the hole and .020 taken off the head and deck with flat tops, even if I used a GSR head with .050 taken off total that doesnt get the CR up to 12:1.

Natural Aspirations

Probably possible on a 2l

My 1.8 (still estimated) is at ~11:1 with -1cc pistons, minimal deck milling and 40cc chamber GSR head.

Add a few cc's to the pistons, zero deck the block and mill the head and you would get quite close.

LightningTeg

E85 analyzer

EG1834

Back when F1 cars had turbos, weren't they runing like under 7:1 CR?

The 14:1 CR is going to limit how much air you can cram into the cylinder without detonating, and last time I checked, more air makes more power than more compression. Why would you want the engine compressing the air when the turbo can do it?

96 GSR-T

My motor is a 1.97 (84x89) with -3cc Arias. I am assuming your All Motor? Why would you want a chamber that small? I did some more playing around and with an 84x89 0cc dome with a 40cc chamber gsr head, pistons set at 0 and .030 off the head got me to 13.5 so I guess its not too hard, but hacking a motor that bad really limits its service life if it needs to be decked again IMO.

Tootsie7944

If your main thing is a "nasty street car" to terrorize around town in, I'm telling you right now you don't need that compression. I'm running 9:1 CR w/ 600 whp on pump gas and I can take 600 whp Mustangs from 2nd gear, once you hit 3-4 it's over for them.

It's all about the QUALITY of your build and the parts used, and most importantly the TUNE. The compression will only help you if you're in low rpms, and who ever races someone out of their power band?

96 GSR-T

The compression decreases the time it takes to get the turbo up to speed, I agree he doesnt need near that much but I bet you would be suprised with a 2 point increase in comp with your motor rolling into boost on the street and between shifts...

0c00l

Great point! I just purchased 9.1cp 85mm pistons for a sleeved b18a not installed yet but this gives me hope!