civicmark

OK, I know this is kinda a noob question, but here goes. Feel free to correct me anytime i go wrong.
The lower the compression ratio (8.5:1) the more lbs of boost you can run safely?
And if that's true, which makes more power: Lots of boost(22lbs) and low compression, or high compression 11:1 and above, and fewer lbs of boost?
sorry if this is a stupid question, but i hope u guys can help
thanks

reXem

Try these links

http://www.hondalife.com/articles/tu...ompression.htm

http://www.hondalife.com/effectivecompression.htm

civicmark

ok, i basically knew everything that was on those site, and i know that high compression is much better, however i still didnt get my questions answered!
thanks anyways


[Modified by civicmark, 4:48 PM 7/15/2002]

CovertFI

well the bottom line is more air+fuel = more power, but there is always a trade off from one thing to another. lower compression will give you more lag. higher compression will not allow you to boost as much. you just have to find what will suit your needs best.

b18cya

now that i've read those two articles, I have the same questions that he posted at first...

b18cya

Civicmark, have you ever been to http://www.highaltitudeimports.com ? there is a good forum there to

reXem

Dunno how you guys missed it.....

You just have to have the best tuning......

boosted hybrid

I was running a built 11:1 b16a turbo, just sold that long block to build my next project. 2.0L gsr block, b16a head and 11.5:1 compression...turbo, daily driven. Ever since i switched from 9:1 to 11:1 I will never go underneath 11:1 compression. The entire rpm band is filled with power, transition into boost is awesome and its allows me to run larger turbos and have the same spool up time as smaller ones.

apexii

I think heat becomes one of the most relevant factors. Efficiency also comes to mind.

b18cya

so, how much boost did you run on the b16a turbo? & what hp/tq did it produce?

a smaller turbo would suffice on a higher compression setup...allowing a lower boost threshold, quicker spool-up time, etc.

flow restriction causing heat at high rpm is the only problem i'd see with that setup.

a larger turbo could still be used because the high compression give you plenty of power before the turbo spools up

i'm just thinking out loud, so please correct me

on a high compression/lower boost setup there is actually less air volume going into the combustion chamber, correct?

this idea just threw a wrench into my turbo plans

so this goes back to the original question
"Which is better, high compression/low boost or low compression/high boost?"

reXem

I believe in the articles above the answer to that question is that there is no one that is truely better.....a low comp/high boost in the end will cost you less, be more reliable, and less risky.... high comp/low boost will cost more (due to tuning), make more power and overall perform better....they gave an example as to how much is needed to make up the lower compression....

b18cya

what is the highest effective CR that can be run on pump gas?

bretx0r

high compression is better in any case, but you are more likely to blow up your motor running 13psi stock internals B18C vs B18B, and not all of us can afford to have a full blown drag car every day of the week.


[Modified by bretx0r, 9:55 PM 7/15/2002]

b18cya

however, at stock compression, the b18c1 will produce a lot more power at the same amount of boost. so we can turn the boost down until the power level evens out. now the boost isnt as likely to blow up the engine, and less fuel is required because the mass of air is less. higher octane fuel is needed tho, because of the CR

civicmark

I dont know how i missed that, but thanks

pub

Yeah at a high C/R with a fully built engine I could only imagine your weakest link would be when the combustion starts to detonate. Race gas would most likely have to be used. I would love to have a high C/R and get the whole powerband, but for a daily driver, I sadly don't think it'll be my cup of tea for right now. Maybe a project auto-xer after I get out of college?!

boosted hybrid

I ran 8lbs on pump gas, 14lbs on race gas. I also use methanol injection as well to cool the combustion chamber down, as well as a huge spearco core.

I tuned the car myself on haltech, tuning is free for me. It doesnt take that much to tune a car, just general knowledge, a egt and wideband...and some dyno time.

I never got the car to the dyno. I just street wideband'd it, probably like 30-40hr of tuning. I would say over 300whp on 8lbs, and a bit over 400whp on 14lbs.

Heat is a good thing when it comes to spooling up turbo's. The more heat in the burnt gas, the faster the turbo will spool up.

As long as you run the high compression engine rich, and take out timing when its needed there is no reason its not as reliable as low compression engine.

I will never go back to low compression again.

SimonsTeg

this information is good to know, but on 91 octane pump gas, boosting 10 psi, how high of a compression can be run???

Charlie Moua

iTrader: (3)

so what would be a medium #(cr) to go by? 9.1:1 or 10.5:1 in a B series motor daily driven?

CheezeFrog

So how many gallons per mile did you get? :D