well im planning on my second car being an integra, ls or rs most likely. i'd like to go with an all motor set up, because i just wont be able to put out 3 grand at 1 time for a turbo, so i wanna build the motor up slowly, piece my piece. the first thing i want to do is raise the compression. if i remember right, the b18b has a 9.1:1 compression ratio, if i raised that to 11.1:1, about how much power would i gain, and would i still be able to run pump gas (92 octane). whats the highest compression ratio i could go up to and still be able to use pump gas? btw im sure someone will tell me to search, since i see that in about every thread, but i did search and didnt find anything. thanx

 

i'm sure you can run 11.1:1 on 92 pump gas. Many people are running higher compression set ups and are using pump gas. its all in the tuning.

 

youd be fine running 11:1, my buddy runs 13:1 on pump gas and hes fine, had to put a little bit of fuel in and take some timing out but its fine, an all motor high compression ls motor or are you planning on having a vtec motor swap, i would suggest getting ahold of a vtec head or motor cause vtec feeds off of high compression and you will get alot better results than with your non vtec setup, but i like the idea of a 200 hp all motor ls, but that would be a tough one to achieve for a street car but it would be hot business if you did........good luck dude.....

 

well i'd like to go for ls vtec but incase you cant tell, i dont know the most about engines and ****. if i went for lsvtec i'd probably be looking to buy a new motor in a month. i havent really thought about getting a gsr motor, but i'd rather just turbo the ls instead of swapping in a gsr. i guess i'll stick with an all motor ls set up, until i learn more about ls vtec. thanks for the input.

o btw im still wonderin, about how much of a power difference would i notice if i b
bumped the compression up to about 11.1:1?


Modified by shibby at 10:29 PM 10/14/2003

 

um just off the top off my head i would say at most maybe a 10hp increase wich isnt bad but throw some cams on top of that and you got youreself a rockin motor, but dont plan on having a 200hp all motor ls its just not going to happen, i have never seen a ls go over 175 hp.....

 

I dont think the B18B motor is that low of a CR. I think it's more around 9.8:1 or low 10s. 9.1 :1 CR is ******* horrible CR to drive on without boost. That is the magic number if you want to boost your motor, but if you run N/A man I bet single slam civics could walk on you.

On 93 Octane, the theoretical max is 11.5:1 however 12:1 Seems to run fine. Just remember the higher the CR the more you have to retard the timing to compensate knock.

Lets say you are increasing the CR from 9.8:1 to 11.1:1. That is 1.2 points of increase. For every tenth of a point you gain roughly 2whp (give or take some).

Do the math, it's a significant increase in power.

 

i just checked hmotors and they say a usdm b18b has a compression ratio of 9.2:1. so if i increased that to 11.2:1, that would be an increase of 2 points. if i understand you correctly, that would be a 40hp increase? that seems like an awful lot. did i miss somethin?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by shibby &raquo;</TD></TR><TR><TD CLASS="quote">i just checked hmotors and they say a usdm b18b has a compression ratio of 9.2:1. so if i increased that to 11.2:1, that would be an increase of 2 points. if i understand you correctly, that would be a 40hp increase? that seems like an awful lot. did i miss somethin?</TD></TR></TABLE>

40hp increase? no way...more like 4-8 hp increase.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J337_UNIT &raquo;</TD></TR><TR><TD CLASS="quote">

40hp increase? no way...more like 4-8 hp increase.</TD></TR></TABLE>

you must not know anything about raising the CR in a car. It is a very dramatic affect.

I wouldn't expect 40hp out of it, maybe like 30 at the most. But yes, It will be very very noticable. Slapping CTR pistons in a i/h/e GSR basically adds around 25whp. It's quite more than a 4-8 hp increase

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by shibby &raquo;</TD></TR><TR><TD CLASS="quote">i just checked hmotors and they say a usdm b18b has a compression ratio of 9.2:1</TD></TR></TABLE>

correct.

 

http://www.rosspistons.com/CR%20Calculator.htm

try that out

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Slain &raquo;</TD></TR><TR><TD CLASS="quote">its all in the tuning.</TD></TR></TABLE>

 

well damn. My 4-8hp seems to be good enough to romp all over Hype Arrs and WRXs (moderatly stock).

Gotta love this useless 12:1 CR.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by P1mpSlap &raquo;</TD></TR><TR><TD CLASS="quote">well damn. My 4-8hp seems to be good enough to romp all over Hype Arrs and WRXs (moderatly stock).

Gotta love this useless 12:1 CR. </TD></TR></TABLE>

look, dont get me wrong..every motor is different..but i believe he was talking about the b18b motor and raising the compression ratio on that motor doesnt increase power very much...4-8hp may have been a low figure..it may be more like 12-16 ..it is all about tuning and what not. From what ive HEARD , b18c1 and c5 and b16's respond better to raising compression ratios as opposed to the lower revving b18b motors.