Hi. i was just wondering if u guys think these pistons will hold up in my Chevy 350 circle track motor? it'll run between 4500 and 6900RPMS for about 30 nights. compression will be around 12:1. cam is 246@.050".


http://store.summitracing.com/partd...k=KeywordSearch


Thanks.

Heavens..I was thinking about that question myself as I have never used the hyperutes..

Hope we hear from some of the builders as I guess we will..

OMT

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If it don't work it ain't pretty!!!!

I will say..maybe. If she stays cool, doesn't lean out and doesn't get too much timing they should work {can you find a full set of forged pistons for just a click more to be on the safe side?}. I'm curious as to what others think also.

I have the same pistons in my (low budget) circle track engine as well and am wondering the same thing.

I know, I know "low budget" and "circle track engine" shouldnt be in the same sentence...

They will likely hold up. you'll want to open up the ring gaps a bit to account for the increased heat generated by a 12:1 compression ratio at WOT. A high dome piston is not the best for making power. You can achieve over 12:1 compression with flat top pistons, shaved heads, block decking and get more power, more detonation resistance and require less ignition timing. Just builds a better motor than one with a high domed piston.
The more conveluted the combustion chamber is the more likely it is to detonate and the more problems with flame travel.
A motor that detonates will self distruct very quickly.

im real short on money, so i have to get these pistons, or a set of forged flat tops from a buddy of mine. what do you think would be better? maybe ill just get the FT's and .028" thick head gaskets and hope for around 10:1 compression.

The forged flat-tops are likely L2256AF TRW/SP items. They won't hold up for long, the skirts will break off. The H617CP will be ok if the timing is in check and they aren't run too loose. The price isn't bad, just $1.88 more per piston more than what I would charge.

tom

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Ya cain't fix stoopid, but ya kin TAX it!

i have a set of hypereuctic pistons myself, but they havn't been ran yet and there going in a everyday driver though NOT circle track. in my understanding there pretty strong and hold up good.

make sure you pay attention to the ring gap spec.s on hyper.'s. there not at all like forged or cast ring gaps there much larger

J

I build a lot of 2bbl circle track engines.You state that you are going to 6900.I have seen the hypers come apart even with the rings opened up.The KB are the worst.I no you are on a budget but if the piston comes apart it is going to cost you more then it would for forged pistons.

Do it wright the first time and it will last a lot longer.

Personally i will not build a circle track engine with hypers. not even a hobby stock.

Yeas Roger said it all.Call to make sure these pistons do not use long slots to drain oil back behind the oil scrapper.In you case small holes is the only oil drainage type acceptable.

Hey Roger.Maybe you did not read my topic a few days back with a 4.3 V6 road racing engine I built.I used JE small dome to reach 11:1 on aluminum Bowtie heads.After only 5 laps the oil pressure lowered and the damper failed.
Upon inspection I noticed that some material migrated from the mains to the caps,as if they vibrated.The bearings were wiped out,the oil pump was allright.The only question mark before assembly was the fact that the new pistons were 45 grams lighter than stock and I had no means to rebalance the crank.Any comments? Thanks Paulo

I have KB hyper. pistons. They have held up well to my 11:1 engine. I don't dwell at high RPMs long though.

Hypereutectic pistons are still a cast piston.

6900 RPM is just too much to ask of a cast piston.

I would spend a little more money on some forged pistons.

I think that hypereutectic cast pistons are good for hot street engines that see a little strip use once in a while. They are cost effective and allow tight clearances, good ring sealing, quiet operation and long life. Not for competition applications however.



You can still get a set of forged pistons at a fairly reasonable price.

To get the proper balance on the 4.3 V6, there are several bobweight percentages to consider. It's probable that you had a severe crankshaft overbalance. That makes the crank want to spin right out of the main saddles. That's why your bearings look like they do.

tom

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Ya cain't fix stoopid, but ya kin TAX it!

I was hoping you would give your opinion Mac Shop Tom! Well,this was the second V6 I built,and I understand that a 90* V6 is sort of a make shift arrangement.Being an even fire project it has absurdly split rod pins that make the crankshaft look like it will crack anytime.But the truth is that this Vortech comes from factory with real 10:2 CR and small duration camshaft,resulting in very high effective combustion pressures at low RPMs.
Since we ordered conservative 11:1 JE pistons and 280* duration camshat I thought the crankshaft would survive this new level of power.The cyl heads and cross ram manifold we bought came from a ASA Doug True team right in Michigan.Even though we bought complete engines we could not bring them complete.Besides they were running semi-even fire crankshafts and corresponding camshafts.Now to the balancing issue.I heard the bobweights would have to weigh 43% for such application.Since I have no means to balance this crankshaft I am considering inserting 45 grams slugs inside the piston pins.This would bring the engine back to its original balancing.What do you think? By the way I used ARP fasteners all around and I do not consider cap-walk a possibility to cause premature bearing wear.