JrCRXHF

I want to know what you guys think the benfits for both 9:1 or 10.2:1 with a turbo i have a 88 CRX HF with a B16 stock with hondata and intercooler with t3/t4 big shaft stage 5. how thick of a head gasket should i go for. For the most part i do daily driven with some autocross comeing next summer. and how much boost can i run stock 9:1

T-sohctec

Turbo=low comp.

you're not gonna see a real big performance gain with 1 point of C:R IMO. It's also gonna be that much harder to tune and your gonna have to worry about what octane gas you use all the time. Just a couple things for you to think about.

9:1 on stock internals on a B16 can see 1BAR plus pretty easily.

Boltz

mos def 9:1.... just not worth it, on a turbo you want as low of compression as you can run and still spool the turbo quickly

TurboJesse

im running ~9:4 on a stock jdm b16 with inline pro headgasket...307whp 212 tq

boosted92

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mpir3 &raquo;</TD></TR><TR><TD CLASS="quote">im running ~9:4 on a stock jdm b16 with inline pro headgasket...307whp 212 tq</TD></TR></TABLE>

IT'S NOT 9:4!!!! 9:4 IS THE SAME RATIO AS 2.25:1, WHICH YOU ARN'T RUNNING IN YOUR CAR!!! ARRRGH!!!

Ok now that I got that out of my system, it really bugs me when people say that incorrectly

I'd go with 9:1, but don't do it with a thicker gasket. A thicker gasket increases your quench area, which increases the chances of detonation vs. a motor with less quench area and the same compression ratio.

TurboJesse

Sorry i don't feel like typing everythign out for you. And tons of people have made power with thicker headgaskets, i wish i could afford a build block but can't at the time

JrCRXHF

i have a turbo on the car now with stock ratio which is either 10.5:1 or 10.2:1 i really like haven the turbo on the car because i don't have to boost all the time but when i want power i can get power but yet i am worried about the gas sometimes i can get 93 somtimes only 91. so i was thinking about lowering the comp but i don't want to have to build the whole motor because if i do that i might as well put 380+ hp out of the motor and then i have to upgrade all kinds of things. so that is why i did the pole

Doug

Soon_2b_evil

if its for AutoCross then go high compression with low boost. you'll be fine.
Im going 10.5:1 with my turbo setup.

ahobbs

can't ask a question like that in here.......were racist MOOOOOOOOOOre BOOOOST

Ricey McRicerton

Higer compression with lower boost. That way you're off boost performace is better and your powerband will be more linear. I always vote for lower boost on higher compression.

EDIT: And if you have higher compression, you don't have to run more boost to make the same amount of power. I had to give the Corky Bell book back, but they said every psi of boost was like raising the CR 1 point (don't quote me on that exact no.) so having a 9.1 motor with 7 psi would be similar to a 10.1 motor with 6 psi.

Kataku2K3

10.0:1

JrCRXHF

so how much are most people getting out of a stock tranny and drive shafts lets say i do want to put 300whp down will everything last i have a clutch masters clucth but that is about it to the drive line.

T4eg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kataku2K3 &raquo;</TD></TR><TR><TD CLASS="quote">10.0:1 </TD></TR></TABLE>

MRSI00

9.8:1 is good on my b16

mskibbz-T

You want higher compression, especially since you are doing AutoX... Low compression, high boost for drag... High compression, lower boost for autoX, street, etc.. Why make a laggy setup for street and AutoX?

JrCRXHF

i know i can make about 280whp if i leave it all stock how far would i have to drop the comp. to make 300whp on pump gas.

highmilehatch

In a street car that primarily runs pump gas, I'll take lower compression and more boost any day. However, since you will be autocrossing, I doubt you'll be running enough boost to warrant running lower compression in order to run more boost. So in your case I say stick with the higher compression.

Johnyquest

the thing is that you are boosting to MAKE UP for a lack of compression ratio. there is NO reason not to go 10:1 and use less boost. It will spool your turbo faster, making more power down lower, and will make more power on less boost. Everybody here neglects to mention this fact: there are two types of 'compression ratio.' There is static compression ratio (i.e. 9:1, 10:1) and then there is EFFECTIVE compression ratio, which is determined by how much boost your putting through it. When you get a 9:1 car to make the same hp as a 10:1 car (different boost levels) all you will have accomplished is to equal the EFFECTIVE compression ratio's of the two motors, making up for the 9:1's lack thereof with boost. In the end, at full boost, and max power, if both motors are making teh same #'s at a given RPM, the EFFECTIVE compression ratio is the same.

For these reasons, Run all the compression you can get away with. You won't regret it if you can tune (or find someone who can!)

EDIT:

Just came across this thread-- Another person who isn't all too happy with thier low compresson (though not as low as some have gone):
https://honda-tech.com/zerothread?id=648207

fredtoast

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mskibbz-T &raquo;</TD></TR><TR><TD CLASS="quote">Low compression, high boost for drag... High compression, lower boost for autoX, street, etc.. Why make a laggy setup for street and AutoX?</TD></TR></TABLE>

mskibbz-T

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Johnyquest &raquo;</TD></TR><TR><TD CLASS="quote">the thing is that you are boosting to MAKE UP for a lack of compression ratio. there is NO reason not to go 10:1 and use less boost. It will spool your turbo faster, making more power down lower, and will make more power on less boost. Everybody here neglects to mention this fact: there are two types of 'compression ratio.' There is static compression ratio (i.e. 9:1, 10:1) and then there is EFFECTIVE compression ratio, which is determined by how much boost your putting through it. When you get a 9:1 car to make the same hp as a 10:1 car (different boost levels) all you will have accomplished is to equal the EFFECTIVE compression ratio's of the two motors, making up for the 9:1's lack thereof with boost. In the end, at full boost, and max power, if both motors are making teh same #'s at a given RPM, the EFFECTIVE compression ratio is the same.

For these reasons, Run all the compression you can get away with. You won't regret it if you can tune (or find someone who can!)

EDIT:

Just came across this thread-- Another person who isn't all too happy with thier low compresson (though not as low as some have gone):
https://honda-tech.com/zerothread?id=648207</TD></TR></TABLE>

Well said... Lower compression and higher boost only equals less usable power

JrCRXHF

thanks alot guys for all the help

Jefnes

Topic: High boost.

Its not like we're talking going to 7.5:1 here....

off boost, I bet most can't feel the difference between a 9:1 and 10:1 motor.

Basically it all comes down to how you plan to use this engine: street car or
race car (i.e. NO STREET AT ALL).

For street aim for 9:1, after a fresh rebuild, decked head and block you'll
be ~9.2 - 9.3:1. Easy to tune on pump gas, more useable power
than you can use, and can tolerate a low octane tankful if you're stuck.

Again think about where/how you plan to use this engine.

Why not try to build an engine around 'regular' 87 octane pump gas?

Overbuild and under-stress the engine, you be happy for MANY miles.

Jeffrey Atwood

shermanyang

iTrader: (1)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by highmilehatch &raquo;</TD></TR><TR><TD CLASS="quote">In a street car that primarily runs pump gas, I'll take lower compression and more boost any day. . </TD></TR></TABLE>

^ yup...what he said. i don't want to risk blowing my motor in the middle of nowhere just because they don't have high octane fuel.

intekragsr

there really is only 1 factor.

How much power do you want on pump gas...........

low comp=mad power on pump gas
high comp= not going very far with pump gas

When raising comp, you are retarding a lot of timing. Just dont go so high, that when you retard, you are getting negative returns (like making 3hp per pound)

I was going with 10:1, but then it just struck me that in Cali, we are only limited to 91 octane, and I didnt see making over 300 to the wheels on pump with 10:1. My goal was higher (350-400)