Hi guys, I see the Speed Pro hypereutectic pistons on Ebay all the time for $75 uncoated, $100 with coated skirts. Has anyone run these in a 350-400 hp 350 street build? I am building a 10:1 350 with 200cc runner 64cc 2.1/1.6 heads, powder rods, retro roller cam and my Stealth Ram on top of it. Nothing really fancy, but should be good for mid 12s if it hooks up.

Do you think the Speed Pro cheapy hyper coated skirt pistons will be fine? This is a street car that will see very occasional strip use, and maybe 3000 miles per year of driving.

 

I'm running the H423NP30 (non-coated), for what that's worth.

 

i'm running the H45's I think. The speed pro hypers are some of the most commonly used pistons in high perf NA applications. I think you'll be fine.
$75 is a steal too.

 

Thanks guys. 75 bucks is all the non coated hypers cost on ebay, there are several different vendors and they always try to undercut each other's prices by a few bucks. I have seen the coated skirt hyper speed pros sell as low as $89 buy it now. The vendor right now that is selling them has them for $109.

 

Anyone been brave enough to throw the spray to these pistons? I was looking into the Speed Pro forged units, they're cheap but they've got to be better than stock and I'm throwing a 200 shot on my old stockers.

 

The hypers may be stronger than stock but they are also more brittle. Spraying a $100 set of aftermarket pistons is a REALLY REALLY bad idea.

 

Hence my statement "has anyone been brave enough". I've heard that Keith Black states they have sprayed a 500 shot to there hypereutetics with no issues and if the ring gap's wide enough there shouldn't be any problem. I myself don't think I'm going to try it but I'de like to see if anyone has.

 

Speed Pro, the piston formerly known as TRW. I've had their forged pistons in the 396 since 1997. Never sprayed it, though.

 

I've sprayed KB Hypers many times. Hundreds, probably, and never broke one.

Then I used them in my little roots blower motor and started wiping them out from time to time.

The reason is detonation. Apparently I just got lucky or something all the times I was spraying them and never encountered serious detonation. The roots blower motor was a different animal and I was apparently having much more serious detonation issues (roots blowers I didn't have much experience with a few years back), which is what was killing the pistons. Detonation with a power adder will kill the ringlands on a hyper piston real quick (I blew 2 to pieces in a single dragstrip run). Without detonation the sun will probably burn itself out before you break one.

Hypers are STRONG pistons. Every bit as strong as forged, if not stronger. It's how they manage the heat of combustion that is very different than a forged piston.

 

I've never seen a set of hyper pistons blow in an engine that was tuned properly.

 

I have the coated ones. H345NCP +040 or something like that.
"They will also work well in moderate supercharged applications and are suitable for towing and marine use." -Speed Pro

They've been pretty good, can't complain. They have put up with a year of a tip-in lean spike that caused knock retard (detonation) through a gear. I havn't been able to tune it out but I now figured out that its a problem with the upper MAF Table values and not AE.