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High compression ???

AR

Experienced Member
Joined
15 August 2005
Messages
879
Location
UK
Any idea how much extra HP can be attained by increasing the ratio to 11.5 to one and addding cams, ems, injectors, etc.

Cheers,

AR
 
what about with 11.5 on a 3.0?
i was thinking about going the NA route, but it doesn't seem like many go that direction without boring/stroking the engine.
i'd be interested in keeping the same displacement, upping the compression, and doing all the other NA mods. what kind of HP could be attained in a setup like that?
 
:biggrin:
what about with 11.5 on a 3.0?
i was thinking about going the NA route, but it doesn't seem like many go that direction without boring/stroking the engine.
i'd be interested in keeping the same displacement, upping the compression, and doing all the other NA mods. what kind of HP could be attained in a setup like that?

That is what I meant to ask! :biggrin:
 
I have been interested in this for some time now. It seems that no one has done this or if so hasn't shared much about it.
 
The only 3.0 engines with increased compression ratios, cams, etc. that I've seen data for are Comptech's. Attached is an article from the May 1994 Car & Driver that I've just dug out of my basement.

Some more data about these engines is in the NSXPrime FAQ section here.
 

Attachments

  • (Car & Driver May 1994) Comptech NSX.pdf
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Thanks for the link mate. So they are claiming 358 BHP. That sounds like a good number for an NA car.

Cheers,

AR
 
that's it? nobody else has done the NA mods, while staying true to the 3.0??? :confused:


From the looks of it it will cost the same as a CTSC for less BHP, so no many has explored it to the fullest.
 
Call Shad he has a Race car project High ~13/1 comp NA in the shop now W/a broken rod.

I wanted to run the 3.5L ,high cams ,at 13/1 ,and on 105race gas but it would only make the power of an CTSC. Shad has the dyno's.
 

Have you increased the compression ratio? Can you get Cometic head gaskets for an NSX that are thinner than stock and thereby increase the compression ratio? If so, by how much?

When you had your cylinder heads off to install the head gaskets, did you have the heads ported and polished?
 
The only 3.0 engines with increased compression ratios, cams, etc. that I've seen data for are Comptech's. Attached is an article from the May 1994 Car & Driver that I've just dug out of my basement.

Some more data about these engines is in the NSXPrime FAQ section here.

Hi Andreas,

Thanks for the link, I did not yet have this article.
I think basically, this is what your car has without the high-compression that is or not?

I'm not really sure you can get 358 HP with just the camshafts and higher compression, but around 330-332 crank HP for the engine should be possible (which would be around 291 RWHP).
 
Comptech milled my cylinder heads for a slightly higher compression ratio (about 10.6:1) when they worked on them. My engine is basically a twin of the engine in the article above. I agree that 358 crank horsepower is optimistic. But however many horsepower it really delivers, it's enough to get you just over 300 km/h if you remember to turn the traction control off!
 
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Have you increased the compression ratio? Can you get Cometic head gaskets for an NSX that are thinner than stock and thereby increase the compression ratio? If so, by how much?

When you had your cylinder heads off to install the head gaskets, did you have the heads ported and polished?

Yes the heads were ported and polished and I went with the larger intake valves to 36mm I believe. The Cometec gasket I think was 91.0mm. My only regret was I didn't have the Comptech adjustabe cam gears installed since they were out of business at the time of the build.
 
My only regret was I didn't have the Comptech adjustabe cam gears installed since they were out of business at the time of the build.

I know how you feel - I managed to find a set of the Comptech adjustable cam gears right after they went out of business and bought them just so that I would have a set on hand. Whenever the next timing belt goes in, I think the gears will go in as well.

Out of interest, who ported and polished your cylinder heads and did you have your intake manifold done as well?
 
I second Mym, the comptech early NA engines were in the 330crank range maximum, and they were optimized better than we could get a street engine. Definately call Shad at Driving Ambitions about the CR, I think he'll tell you to stay around 11.0. You will notice these cars are not fast, it's only for those like be that just HAVE to stay NA. Perhaps you own an oil company, but do you know what race gas is going to cost in a few years? It will be insanely expensive. The problem with NA is you are going to spend 15k or so for that extra 30 HP, so the bang for the buck is terrible. Comptech used to get upwards of 20k to build these engines and I remember at least a couple that were slower than stock, at least as delivered.:confused: I THINK i trust Shad though, but the parts themselves are very expensive. From a very brief discussion with Shad, I think the 3.5 is the way to go, I'm tentatively planning that next year. The ITB induction my find the NA guys another 10 or so HP. But now you're probably talking 30K for a maybe high 12's car.:mad:
 
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