How Much Comp Is Too High

[nedic]

gday guys, I'm about to put my motor back into my ke30 after having it sprayed and recently found that ive got somewhat of a rare s15 na motor called an autech which produces 150kw. i have already had the oil and water lines made up and tpped into the block. I got a custom manifold and all the works bigger injectors and everything else to go with a turbo conversion. However this particular motor has 11.8:1 comp. A few places tell me don't bother where as ricol performance is telling me that it should not be a problem to run 10psi which i did not plan on runnning more then that anyway. They said with a very safe tune and alot of fuel it should be fine.

 

I would like your opinon and although its a nissan motor it is in a ke30 lol cheers guys

[KE ping it real]

6 psi maybe but i reckon even that would be pushing it, Thats a pretty high comp motor you have there by the sounds of it

[love ke70]

that is high comp

it all comes down to dynamic compression though.

which depends on cams and overlap etc etc.

 

plenty of high comp bike motors getting around with turbos sticking out the side :P

 

what sort of power are they expecting with the turbo on it?

[oh what a nissan feeling!]

11.8, that is pushing it i recon, but anything is possible under the right tune.

 

The power gains would be limited due to the lack of timing you would have to run.

 

Sr20dets are so cheap these days, I'm surprised people still bother with srde+t.

[SLO-030]

Just keep them head bolts/ studs torqued right down :P

[twitchy]

Any decent turbo motor will be on low compression. 11:1 is a bit much without spending a fair bit of money to keep it in one piece.

[Jono]

the new(ish) bmw 3.0 twin turbo is 10.2:1 but only runs 8.5psi.

 

my smallport had 10.3:1 and 10psi.

 

11.8:1 is very high though. could you swap the motor with someone on their 'p' license, doing a similar conversion?

[nedic]

hey guys i wouldnt wanna run more the say 6 psi. i can rid of the motor no stress as they are in high demand, i was just lucky that i got it so cheap, but I'm curious what sort of power i would be getting out of it, since it already has 150 kw. and the only reason i went down the de+t route was because of how cheap i was able to pick the motor up.

Edited May 8, 2009 by nedic

[love ke70]

id sell that motor and get a lower comp one mate.

your not gonna unlock all that much more power from that motor with 6psi, theres gonna so much fuel (less power) and so much timing pulled out of it (less power) i wouldnt think it would be worth the cost.

especially if its a sort after motor, make some money on it and buy a better suited donk.

my diesel ran 22:1 compression and then i added 13 psi, but thats a different ball game :P

[philbey]

Yeh it is a different ball game, its a diesel haha!

 

I think CA18 were running over 9:1 comp with about 8psi factory and that's a twenty year old motor. If you got the motor so cheap, just boost it to ten and see what happens, it'll be a barrel of laughs, even if it does go pop.

 

Oh, I'd be using 98 RON though.

[Greene]

it'll be a barrel of laughs, even if it does go pop.

 

 

Haha yehhh... Untill you have to rebuild it anyway

[curly]

that there is to much comp, be a shame to blow it when you know it wont work

[oh what a nissan feeling!]

Are you in bris?

 

Interested in a swap?

 

I have an s13 sr20det here if you're interested.

 

I can't legally put a det in my ke25....

Edited May 20, 2009 by oh what a nissan feeling!

[beerhead]

On methanol that'd be fine for boost :y: I really wouldn't be boosting such a hi performance atmo motor. It'll go like all hell without boost hey. I'd be researching if factory SR20DET pistons will work in your block if you have the boost bug.

[furryfrog]

swap it for a det motor.

The comp is too high and no decent turbo is going to be running in its efficiency at 6psi or 10psi, unless you plan on using a t25