Have you heard about CP pistons?

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Have you heard about CP pistons?

Postby silence » Wed Oct 20, 2004 12:11 pm

I just picked up a 185 for a pretty good price...with a blown motor. The purchace included a set of brand new in the box CP pistons with a compression of 9:1. I dont know anything about CP. Are they any good? Worth keeping? or should i ebay them? WHat are the adbantages of raising the compression to 9:1? Isn't lower compression better on turbo cars...i dont know what he was thinking.
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Postby Zeus » Wed Oct 20, 2004 1:16 pm

i have heard of cp...if i recall they are pretty good...

9-1 is pretty common for aftermarket pistons... i beleive that is what the je's are...

now you are only raising the compression ratio two points so it shouldnt affect you that much... a couple bonus' is that you will have slightly better spool up and response... but on the downside you will need to be that little bit extra careful with your tunning if your going to run high boost...

in reality i dont think it would matter enough to me to warrent going with another set of pistons... i believe the evo's run that cr stock now dont they?
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Postby Stubble » Wed Oct 20, 2004 10:10 pm

I recall from the old board that CP was considered very good stuff, because it was started by some ex-JE guys or something. Check out http://www.mr2oc.com/showthread.php?s=& ... 2A+pistons

Lots of MR2 guys run JE 9:1 pistons, so the compression ratio is ok. Be careful if you get your block and head skimmed though, as this will also raise the CR. I went with 8.5:1 pistons, skimmed head and block, and a 1.6mm thick head gasket. Lower CR is good for turbo because it gives more leeway against detonation, but if you properly tune and fuel, higher CR isn't a problem.
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Postby T-spoon » Wed Oct 20, 2004 10:41 pm

If I ran an alltrac in my local weather (hot and humid) with a base CR like that, I'd feel pretty driven to get a good front mount and possibly water injection. In the weather down here, stock alltrac was pulling timing already as it was all through this summer on stock boost. I'm sure you could work around it, but it does without a doubt place a slightly lower ceiling on your maximum safe boost, which probably isn't going to be a big deal unless you're really aiming for big big turbo with lots of boost.
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Postby Gary » Wed Oct 20, 2004 11:42 pm

If I'm not wrong, Pat C. has CP pistons in his ST185.
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Postby silence » Thu Oct 21, 2004 4:38 pm

Thanks for all the info. I'll probably be keeping them. The MR2 guys seem to like them a lot.
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Postby d1alltrac » Thu Oct 21, 2004 6:32 pm

Gary wrote:If I'm not wrong, Pat C. has CP pistons in his ST185.


if Pat C. has them and the MR2 guys like them i would definately trust them.
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Postby ___Scott___ » Fri Oct 22, 2004 4:25 pm

CP's are not _bad_ pistons, but they wouldn't be my first choice if I was shopping for a set. Here is a little info from "another list" that you may find interesting:

CP pistons began when some employees left JE to make a "better" living. Not that it matters, but it's my understanding that they weren't engineers....

You have to understand that JE's pistons, while not as bad as some others on the market, really aren't machined as precisely as many picky engine builders would like...especially their ring grooves. I stopped dealing with them 18 years ago because they were selling my Nascar designs out the back door.....

CP (as the story goes) had a batch of semi-machined pistons that sat in direct sunlight for several days prior to the final machining of the ring grooves, and that batch of pistons made more power than others that weren't "stress relieved". The ring grooves remained straighter after the pistons were run (heat-cycled) in engines, making their cylinder seal better. Everyone knows that keeping the rings sealed to the cylinders is critical for performance, and that's when CP began using the claim that their grooves were the straightest in the industry in advertising.
I think their (CP) pistons are very nice pieces, and I'm flattered that they've adopted many of the (apparent) design features of our Roller-Waves in their pistons, but I can assure you that their offerings for these small-bore engines aren't superior to our pistons.
Dover (who owns Wiseco and JE for that matter) made a committment that Wiseco's pieces would not be second to any in the industry several years ago. To that end, Wiseco has the best machining equipment in the industry, and they are the ONLY company (of JE, CP, and Arias) that actually forges and heat-treats their pistons in-house. You could take all of thwe companies I just named and they'd all easily fit under Wiseco's roof.....

The only example I've seen where a team claimed that CP's offerings were superior was from a ProStock team a year ago. They claimed that the CP's ring grooves stayed straigher (than Wiseco's) after cycling them. Now remember that this is with pistons that are 4.75" in bore diameter, so they aren't even relative to imports. The team that set the all-time one-year win record (last season) in ProStock (Greg Anderson) uses Wiseco's exclusively, as does Warren Johnson's engine program. Jack Roush also used Wiseco pistons exclusively in all his Nascar engines (and for some less-informed individuals, strutted pistons were developed state-side in the 70's, not the 90's) and while the Ford-forced teaming of the Roush and Yates engine group is using "different" pistons now, secret testing, independant of that program recently showed a 14 HP gain with Wiseco's....

Keep an eye on that shot-gun marriage between those two because it's gonna get interesting.

Back to imports.... with the commitment to maintaining the tightest tolerances and offering the finest parts in the industry, I can assure you that if CP's skirts and ring grooves were better than what Wiseco makes to our specs....we'd be using them.

We make several running-changes to our pistons every year that we don't shout about, but fine-tuning details like the corner radiuses in our valve reliefs, changing cam and barrel-shapes of skirts, etc. continues to make our pistons the best on the market.

I've been designing pistons since 1969 for engines I've prepared and raced, as well as those used in all the NASCAR (and USAC/CART) engines I've worked with and I use all those years of combustion experience in configuring our Roller-Wave pieces. Had I been satisfied with any piston company's offerings, I'd have never designed the first Roller-Waves for use in my own Civic back in the early-mid-nineties. I never planned to get into the piston business at all, but people asked me to develop pistons for their specific applications, and I did. The rest is history...
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Postby illGT4 » Fri Oct 22, 2004 5:05 pm

CP are good pistons.

And there is nothing wrong with 9:1 c/r.
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Postby illGT4 » Fri Oct 22, 2004 5:09 pm

T-spoon wrote:If I ran an alltrac in my local weather (hot and humid) with a base CR like that, I'd feel pretty driven to get a good front mount and possibly water injection. In the weather down here, stock alltrac was pulling timing already as it was all through this summer on stock boost. I'm sure you could work around it, but it does without a doubt place a slightly lower ceiling on your maximum safe boost, which probably isn't going to be a big deal unless you're really aiming for big big turbo with lots of boost.


It's really not that dramatic. :)
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Postby MIG407 » Sun Oct 31, 2004 9:44 pm

i myself find the 9:0.1 comp ratio rather superior...expert 3s engine builders i have spoken to on a regular basis also prefer this...
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Postby SeanGTS » Mon Nov 01, 2004 1:00 am

Wheres Chrisk when you need him!

I believe i recall him mentioning that CP pistons are the only pistons he uses. FWIW
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Postby illGT4 » Mon Nov 01, 2004 2:15 am

SeanGTS wrote:Wheres Chrisk when you need him!

I believe i recall him mentioning that CP pistons are the only pistons he uses. FWIW


Yep. He told me the same. I've seen them used before. Nobody complained about them. I'll give them a shot.



I Used JE last time. 9:1.
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