Would high compression with a turbo be a good way to produce some power? how can i go about making it reliable? Sleeves? would 11:1 be too high? (on a LS motor) how much boost can i push with that compression, need help on this im tryin to build a good drag motor Thanks

 

NO....High compression and turbo do not mix!!!!!!!!

 

gyeah it wouldnt spool

 

how would it not spool? that doesnt make sense if theres exhaust gasses theres spooling . . . .

 

it will spool..... and it makes awsome power. But unless you know what your doing.... that engine could blow up on the test run. FI and high comp dont mix. But if you can do it..... you get crazy power.

 

https://honda-tech.com/zerothread?id=64615

for an all out drag car? hmmm... imo? hmmm... 12.xxx:1 comp... something along the lines of a t-72 turbo... 50mm wg, 75mm tb, BIG BORE! and i mean big... but i cant say how big u can go... vtec head obviously, some HIGH lift cams, oh... and the block... woops... cant tell ya about that... just thinking about it... the thing about building race motors is... no one tells u what they really have... because its takes time a research into making a fast car... i have my own concepts, and i know shops that have some crazy idea's... but if everyone gave out their secrets... it'd be no fun...

your best bet is to fiund a shop who really knows their stuff and see what they think

 

Ugh. High compression and turbos don't have anything directly to do with eachother.

High compression = more air in the combustion chamber
More air = the requirement of more fuel to avoid detonation

high compression + poor fuel management = detonation

Some of the big dogs are running 10.5+:1 and are making plenty of power under lots of boost. Don't let the keyboard mechanics tell you that you can't run 11:1.

Rich

 

Compression that high w/ boost would be a nightmare to tune... tune it to "perfection" on the dyno one day, wait 24 hours, hit the dyno again and you'll be down 40 hp because the fuel pump isn't warmed up or maybe the ignition curve is too aggressive for the given humidity that day. If a street setup is what you're after, look into the 9:1 compression range. It gives you a good compromise between top power, tuneability, and off-boost response. A 1.8L LS motor revving to 7,200 RPM with 10 psi of boost (intercooled) will be getting some good power and response with a Garrett T3/T4 turbo with 40 compressor trim and 0.49 turbine housing A/R. That'll clear 250 to the wheel EASY.

 

Not only would it be tough to tune, but do you realize how much fuel you would have to run through that engine to keep from melting it? High compression really helps keep the power band smooth, but if you are wanting to run a big turbo and big boost (and thus get great timing advance and make awesome power) then keep the compression a little lower. I would say 9:1 IMHO.

All in all though, cool idea if you are able to support 11:1 with big boost.

 

You could always run methanol if big boost with 11.0:1 compression is what you're after!

 

first of all this is incorrect... cr has a direct effect on how large a turbo it can spool... a lower comp will NOT spool a big turbo... and dont forget... he's talking about a drag car here... NOT a street car...

and i personally know people running 11.5 comp turboed b18's on the streets... and they turn up the boost for track days... 9:1 is too low for the street nowadays... there is no need or reason for it... IF anything... go with at least a 10:1...

 

would'nt run more then 6 pounds and have proper fuel levels .

 

huh?

 

yeah 9:1 is way to low for the street now a days. im running 10:1 in my motor. but it really comes down to tuning. im running about a 11.8 a/f so its pretty safe

 

for a full drag car, I wouldn't go any less than 12:1 and a turbo with high boost. I have read numerous Japanese car magazines, and they all say the same thing.

Regardless of amount of boost or how high your CR is, you only need two things to make it work

1.) Plenty of fuel

2.) Plenty of air for the intercooler.

You should actually have an incredibly strong valvetrain to handle the speeds that the engine will be running, the rods and pistons have to be not just bulletproof, but NUKE proof, and you can expect to run through transmissions like water.

If its gonna be a full drag car, expect to rebuild the motor frequently. When I say frequently, I mean like every month or so. It takes alot of money to do this, so I hope your well sponsored or very wealthy.

Good luck!

 

my problem with this set-up is the cams and the timing. turbo motors like short duration cams and all motor loves long duration. So wich one would you pick there is to many varibles. It would be the hardest to tune....

 

High compression Turbo is cool if the setup is rightm look at Lisa Kubo's motor the compression is 13:1...you ask how do i know? I was talking to Gary Kubo at Summit National drags in Sacramento raceway....

 

Actually, high compression does not equal more air in the combustion chamber. If you're looking at potential, then low compression will allow more force inducted air into the cylinder since you'll have more room. High compression only allows for more potential energy at TDC since the mixture is packed tighter. Moreover, air does require more fuel, you are correct on that, however, the main cause of detonation on high compression(especially with turbos) is heat. Anytime you compress anything, you create heat. Therefore, with a higher compression ratio, you will have more heat. On top of that, you are compressing air with the turbo, which creates more heat(given that the intercooler is a standard FMIC at 70% efficiency.) Anyway, just thought I'd clear some things up. However, it is still "all about tuning".
good luck,
Jared


[Modified by Jared, 12:21 AM 9/14/2001]

 

high compression can be done with proper aftermarket engine management such as speed pro, haltech, motec, hondata , etc.

That comment was funny about the "keyboard mechanics" LOL