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Discussion Starter · #1 ·
Ok, heres the deal. My integra is in the shop due to a warped head and I was told at the honda dealership to go ahead and replace the rings because with a fixed head it could cause my rings to blow. Anyways, this is my daily driver, my other car 95 Talon TSi is also down cause I am working on the motor. The question is since I have to get into the bottom end I am thinking about going ahead and sleeving the cylinders and lowering the compression for turbo. If I do this it will be a few months before I can afford to add a turbo. Will the car run decent if I lower the compression or will it mess something up? I am not going to lower the compression much just enough to compesate for a t3/t04e. What do you all think?
 

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how far are you looking at lowering the compression? Since the LS's have a 9.x compression I dont know how well it will drive if it goes even lower. But of course I am not turboed or anything like that. If it was me I would just keep the Compression the same and go turbo. Everything else sounds good but the lower compression. BTW what PSI are you looking to run?
 

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Hakamoto on Feb/19/04 said:
That or bumping it up a little. I'd say if you're going all out you might as well bump it up, at least that way you're car won't be a dog out of boost.
I don't want to build it too much. It's my daily driver.. and my awd is what I am building for strip. I just don't want to keep the teg sheltered from any of its potential so I must do some stuff to it.
 

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higher compression + boost will have better throttle response and better acceleration out of boost. But, throughout my research i discovered that at the maximum threshold where you are teetering on detonation with whatever gas you are running (be it pump or race gas), the amount of power you can make is limited.

lower compression + boost will not have as good either acceleration or throttle response out of boost, but you will be safe to run much more boost and it ultimately would make noticably more power

its basically whether you want better acceleration out of boost (good for driving on the street and if you fall out of boost on a autox or road course) or if you want your car to be quicker while in boost, which you will see the most significant difference in a straight line as in a 1/4 mile track.

if you are going to run 20 psi on 10:1 or higher static compression, you arent gonna be running pump gas...

edit: i compared 9:1 boosted vs. 11:1 boosted. i dont remember all the other variables i used because this was almost a year ago but feel free to do your own...there should be plenty of threads on high compression + boost...and definitely low compression + boost..just do some searchin
 

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racinGSRstyle on Feb/19/04 said:
lower compression + boost will not have as good either acceleration or throttle response out of boost, but you will be safe to run much more boost and it ultimately would make noticably more power
Noticably more power. I want you to explain that, since common sense tells us this is BS. He already stated that this is a daily driver and he could get by w/93 octane w/11:1 and 10lbs of boost, if he even needs it. A car w/lower compression and 8lbs of boost is not going to make any more power than a higher CR w/8lbs of boost, plus his car won't suck out of boost. I'd like you to back up that statement. Even in the teens(boost) and a high static CR he could get away with pump gas. How much boost does it actually take to require a lower compression? Where's DaBoyNBlu when you need him? I'm not trying to be a dick racinGSR I'm just sick of this whole lower compression for boost myth.
 

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lol, i'm here.

first, decide how much boost you want to run with that t3/t4 turbo.

if it's less than 20psi (which i would assume, considering it's your daily driver, and you want the talon to be the fast car), then stock compression is easily do-able. 10:1 would be even better, for daily drivability.

i'm running 6psi on 11:1, with 9psi in the works. me and my tuner agree that i'll run out of JRSC oomph before i run out of pump gas tunability... so around 12psi, but i'm planning on staying at 9psi.

given an approximate 3psi of boost is worth 1 CR point, 10:1 could easily run 15psi. and more if your tuner is good.
 

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i will go back and look for the threads and such that i had accumulated and post up more clearly what i was trying to say..

i never said anything even resembling that a car with the same amount of boost would be better at 9:1 or worse at 11:1 static ratios...that would be rediculous to say.

by noticably more power i meant more boost, i just didnt say it in so many words. dont get me wrong, i am an advocate against people who say "you cant run high compression and boost." but unless i was on crack at the time (fairly unlikely) , my info suggested that the larger amount of boost you could run would significantly outweight the gains from the higher compression

like i said, when i get home i will look up the info i used to have and post up what i find.
 

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I'm just saying that even on stock compression you could pull 20lbs of boost on pump gas. I don't want to turn this into a low vs high cr for boost thread. I just think for a daily driven setup that will probably only be running moderate levels of boost, anything less than 10:1 is a waste of money. Why build your motor to be slower before adding boost? I have yet to come across a high cr turbo dyno graph but if anyone could post one I'd appreciate it.
 

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i dunno. you'll have to forgive me if im ignorant (as i have no experience in actually tuning anything myself) but on pump gas (premium is 93 here) i think it'd be difficult to have 10:1 and 20 lbs, perhaps depending on how effiecient the turbo is flowing, but i just think thats a little much.

but hey, feel free to prove me wrong here
 

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meh... 20psi on 10:1 might be pushing it, but i don't see why not.

look at other people... run 30+psi on 8:1 compression. taking 3psi/lb of boost, that's somewhere around 20psi on 10:1.

also again... i doubt 20psi is even part of the equation. when he said he wanted extra reliability and stuff, i automatically assume he means something more like 15psi or less. and that's easily do-able on 10:1. or even 11:1
 

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i have seen one sucessfull dyno with 10:1 compression with 21psi without detonation on a honda with pump gas. it is pushing it very hard. i ahve also seen several other dynos at around 1.2 bar on pump gas detonating like crazy.
low compression motor is very impracticle for the street, and really anything other than strip use. when focused more on auto cross and road course you still want out of boost throttle response. and in order to take advantage of a low compression boosted honda you would need a whole hell of alot more boost than anyone on here is running.
 
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