dambikeracer

iTrader: (6)

I had plans of doing a motor build for a 3586 or bigger but have had a change of heart. I now want to build a high compression engine with a FP Red or Black. What is the hightest compression that an Evo have been built to? I have heard of 10.5 to 1 on a stock turbo.

Currently I am putting down 470WHP at 29.5 PSI on E-85 with my Red on the stock bottom end, head and ECU. I want 600-650WHP with a high compression build. Any info would help.

I have followed the Project White build, Most-Wanted, and 9sec9 with their builds and I want to get into the 9's with the stock ECU on a stock appearing turbo.

JohnBradley

iTrader: (30)

We have done numerous 11:1 motors but this is where the octane limit on smaller turbos (stock specifically) seems to rear its head. Our most common is just a 10:1 build for E85. My current build is a 10:1, Lucas has a couple 11:1 motors and one of our drag cars might be going higher than that this winter. There is a thread I started awhile ago that discusses the pros and cons of high compression engines. I think its the "piston comparison thread"

SeanC

iTrader: (7)

JE just came out with off-the-shelf 10.0:1 pistons for E85 engines...

Aby@MIL.SPEC

iTrader: (161)

^ Figures.....

MOREPSiTEHBETT4

in your builders opinions, do the high compression motors stay together as well compared to the normal 9:1 or 8.8:1 or so motors?

project_skyline

iTrader: (30)

You could probably do 11:1 with E98 but i doubt you could hit 9's up here on a stock frame turbo. Hell nobody has done it with any turbo for that matter. I had the same goal but up here it just wont happen i think. Either way, GL to ya bro.

Migsubishi

iTrader: (38)

I'm very interested in this, I know English racing has something up their sleeve for a future build of theirs. At that type of compression I'm sure peak power can be achieved by 27psi of boost. I for one am interested in 12.1 as it seems max power may be achievable by 30-31psi. Less pressure on couplers, easier on pumps and vacc lines, cooler intake charge etc. I plan to do this with E98 though, and the more efficient the engine, the less turbo you need.

Lucas English

iTrader: (12)

10:1 gas motors have been around for quite awhile. 11.5:1 and boost on 92 has been done (albeit at low boost) for years at this point. In the Evo world though, the 10:1 and 92 is good for about 20psi tops.

11:1 on E85-E98
10:1 all day long
9.5:1 all day long
8.8/9.0 obviously

The 12:1+ motors and the 13:1 E98 motor are still in the wings pending a few other choices (displacement, rod length, etc.) before I admit we are doing an ultra high compression 2.0l.

tkklemann

iTrader: (6)

As for someone who built their motor to 9.8:1 (Started with 9.5:1, shaved bown block), I can honestly say I really want more N/A power. It is a pretty sizeable difference for day to day driving, having the higher compression. The only problem now is that I want more, and am thinking of going up to 10.5:1. The "more quickness" (For lack of better terms) the car has pre-boost makes it much more addicting.

If I had to do it all over again, I would be doing 10.5:1. I switch back and forth between E85 and 93, so map switching would be a huge plus if you are looking to do that. With 10.5:1 and a stock(ish) turbo your pump gas tune should be spot on whereas E85 is more forgiving.

Migsubishi

iTrader: (38)

dambikeracer

iTrader: (6)

What about a 2.1 or 2.2L with a 12:1, 12.5:1, or 13:1 compression? I want to be able to rev to 9000+ RPM no problems. What draw backs if any come from a higher compression? I know the Red can handle up to 40 PSI. From what I read, it looks like high compression and high boost are not a good combo? Why not? If the engine is built?

Anyone know the compression on Most-Wanted's or 9sec9 Buschur motors?

cij911

iTrader: (14)

If you run a 12.5:1 compression ratio with serious boost, you'll definitely need a great fuel (race or e85 + )....High boost and high compression are great if you have the proper fuel, head, and ignition ... If you are not going to go nuts and this is a street car, just stick with 10:1 CR and your Red or a 35R variant and you should be capable of 550+ whp...

Migsubishi

iTrader: (38)

You can usually only fill the cylinder with so much pressure before it starts pushing up on the head and blowing gaskets. Thats the reason why your limited on the amount of boost you can run. You ever see how top fuel cars have their blowers ratchet strapped to the block lol.... yea that....

The object of running high compression is to make the engine more efficient therefore not needing high quantities of boost and yet still achieving the same hp goals.

example

9.1~~~ will make max power at 47-50psi
10.1~~ will make max power at 38-42psi
11.1~~ will make max power at 32-35psi
12.1~~ will make max power at 29-32psi
13.1~~ will make max power at 26-28psi

Not exact but close.... This will also vary from engine to engine depending on bore,stroke,rod length etc..... Oh and you better have a damn good tuner and a fuel with enough octane to support the compression. E98 - E100 is my choice...

CO_VR4

iTrader: (83)

Higher compression is the #1 choice for higher power, from a basic physics standpoint. It gives much better efficiency and high cylinder pressures just after combustion, which translates to high torque increases. However, like high boost, if your tune and fuel are not well matched, you can get earlier detonation or pre-ignition.

Magnus Motorsports has been building high compression 4g63s for a long time and offers piston combinations that are taylored to high compression engines. Might be useful to have a talk with Marco, as well as the guys at Lucas English Racing, who are doing similar stuff with high compression motors.

dubbleugly01

iTrader: (24)

thinking in general terms, why would you not want to get the equivelant compression from a higher turbo boost pressure vs. a high compression motor? With a turbo, your intercooler can remove a good portion of the "heat of compression". If you do it with the motor, you don't have that chance. Wouldn't this help lower the octane needed for equivelant cylinder pressures? Obviously the higher compression motor will most definitely help the low end torque while the turbo is still spooling up to full boost, but once full boost is reached?