Internal Engine Work?
- Thread starter naaman
- Start date
Hmmmmmm . . . good question, I am curious to the answer as well. Maybe port\polish the heads? Thats about all I ever heard of Comptech doing inside, I called them and asked them how much to deck a 3.2 and they never called back.
naaman said:
I could be wrong, but I believe the Comptech IEM is just a headwork package. Things like port and polish, port matching, valve jobs, etc...
And not any blockwork like stroking or boring...
stroking an engine is putting a larger crankshaft in it. example if you take a 350 chevy block and put a 400 crank in it, u end up with a 383. engines can tolerate higher revs like that.
this is different than porting heads. porting is grinding away material from the intake and exhaust areas of the heads. polishing them to a fine finish also lets the air flow through them more freely.
this is different than porting heads. porting is grinding away material from the intake and exhaust areas of the heads. polishing them to a fine finish also lets the air flow through them more freely.
So it IS port and polish, then? How much torque does that add?
What about stroak? Will the NSX take a bigger crank?
Thanks, guys for your replies.
What about stroak? Will the NSX take a bigger crank?
Thanks, guys for your replies.
The JGTC guys run 3.5L stroked engines so yes it is *possible* but the question is whether its cost effective or not.
You'll get more cost effective results by just buying a set of JUN or TODA High Comp Pistons and getting some ehadwork done by Gerry Johnson or Bruce Nomura..
You'll get more cost effective results by just buying a set of JUN or TODA High Comp Pistons and getting some ehadwork done by Gerry Johnson or Bruce Nomura..
Yeah, but there's always all of that PLUS stroaking the engine, right?
How much would it cost to upgrade the crank vs the high compression pistons etc...?
How much would it cost to upgrade the crank vs the high compression pistons etc...?
Edo said:
i have to disagree with that.... u don't get cost effective results by changing your pistons. that's a complete engine teardown and the only thing you can possible gain is increased compression.
the most bang for the buck is always nitrous. other cost effective gains are short gears and supercharging.
hlweyl said:
In terms of actual performance gains for the money, gearing changes are not very cost effective. Changes such as exhaust and headers will give you better performance improvement for the money.
Non-performance factors ("feel", "sound", etc) should also be considered and may make some mods worth the money though.
hlweyl said:
Three questions:
1) Isn't power affected by compression? Surely there must be some reason why high compression pistons exist.
2) With 91 Octane as the highest available in L.A. pumps, would higher compression do anything for engine performance? I've read that people make faster 1/4 times with 102 Octane than with premium pump fuel... which seems to suggest that the NSXs compression ratio is "too high" for 91 octane... would high compression pistons cause detonation with 91 pump?
3) Is high compression an impractical modification for everyday driving? Would it be "unrecommended" for a daily driver NSX?
You can run up to 12.1 compression on the street using 91 depending on elevation. The Jun piston kit is 11.25.1. Think about it stock S2000 is 11.1 and so is the Integra type r, I think stock NSX is 10.2? I run 93.3 in my car, but I'm also 6,000 feet above sea level. Just some 411 you can change the length of the stoke with rods, not just the crank.
At one time, IEM included new valve springs & retainers http://solar.innercite.com/comptech/610021.html, new cams with a higher lift “VTEC” cam lobe grind http://solar.innercite.com/comptech/610020.html and extrude honed intake and heads. I’m not sure if they still do all this…it was around $4k I think
DanO
DanO
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- 3 February 2000
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See this thread for some more info: http://www.nsxprime.com/forums/showthread.php?s=&threadid=5011
Thank you, Lud.
When you stroke a motor you usually must change the rods and the crank. There has to be room for longer rods and most engines are not built to accomodate longer rods w/a stock crank. In order to make room for longer rods you need a crank w/a shorter stroke. AKA short stroke motor. Otherwise your pistons will hit the heads and valves on the up stroke (not good). Shorter rods will not accomplish anything with a stock crank because there will be too much space between the top of the pistons and the heads at TDC and they may twist out of the cylinder bore on the down-stroke or BDC. With shorter rods you will need to increase the distance between the TDC and BDC therefore increasing stroke. AKA long stroke motor. Stroke - the distance between TDC and BDC. Short-stroke motors rev faster and long-stroke motors take in more fuel and have more compression. So just changing the rods or the crank is not possible unless you are talking about + or - .001 to .10 of an inch depending on the clearance. Which is more work than any gain in performance is worth. IMO - Shave of a few .001s off the heads or use thinner head gaskets to gain compression. This is less costly and easily done. And while you have the heads off have the ports flowported and polished. Another thing you could do is increase the size of the valves and have them put multi-faceted surfaces on the valve faces and seats. Here again, increased fuel = bigger explosion in the cyl. chambers = more HP & torque.JDM JUNKIE said:
Yeah, that's what I thought. Is there a long stroak crank available to use in the NSX? Or would it have to be custom built? And, I don't suppose that there are any other titanium connecting rods than the stock ones, right?
