at what point do i need forged vs hyper eutectic vs stock piston when making a hpde ?
09-23-2018, 11:31 AM
#1
Oil Producer
Thread Starter
at what point do i need forged vs hyper eutectic vs stock piston when making a hpde ?
pretty much sums it up.
09-23-2018, 02:54 PM
#2
Oil Producer
Thread Starter
300 hp and 6k rpm?
400hp and 6k rpm?
500hp and 5krpm?
reason im asking .. 350 stroked out to 383 with a cam and superram, for 6krpm, are cast pistons enough? forged? utectic?
no plans to blow or boost.
400hp and 6k rpm?
500hp and 5krpm?
reason im asking .. 350 stroked out to 383 with a cam and superram, for 6krpm, are cast pistons enough? forged? utectic?
no plans to blow or boost.
09-23-2018, 03:13 PM
#3
Melting Slicks
Member Since: Nov 2013
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I was told the stock pistons are forged.. I do know detonation is very bad for cast pistons, so I would assume the higher the compression ratio, you would want a forged piston because you run a higher risk of detonation.
Last edited by confab; 09-23-2018 at 03:14 PM.
09-23-2018, 03:18 PM
#4
Oil Producer
Thread Starter
i know on the 85 they are.
09-23-2018, 03:41 PM
#5
Race Director
Its only when you get a boosted or sprayed engine you should consider it.
Dont over think the piston situation. Call LPE or a reputable shop and ask what they do in specific HP, RPM type engines. Use of the engine is critical too.
Dont over think the piston situation. Call LPE or a reputable shop and ask what they do in specific HP, RPM type engines. Use of the engine is critical too.
09-23-2018, 03:44 PM
#6
Melting Slicks
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PS: The reason I say that is because, I remember reading an article long ago where they were demonstrating the effects of detonation on both piston types.
It knocked the top ring land off the cast piston in a hurry, but it actually had to beat a hole in the top of the forged piston before it failed. It was a pretty stark difference.
Hot Rod or Car Craft or one of those magazines..
It knocked the top ring land off the cast piston in a hurry, but it actually had to beat a hole in the top of the forged piston before it failed. It was a pretty stark difference.
Hot Rod or Car Craft or one of those magazines..
09-23-2018, 06:38 PM
#8
Race Director
I can answer this well.
Notice a lot of the new boosted cars dont have forged piston tops anymore (though rods and crank usually is).
I have the stock hyperteutic pistons on my boosted 93. 12 psi max boost at 6000 rpm.
They even survived a detonation event when my meth system failed to inject (i have a fail safe device on it now).
i think they survived bc the knock sensors caught it and dropped timing 10 degrees.
the knock event was bizarre. Driving hard out of a toll booth in west pa. Got into 2nd or 3rd gear, all the sudden instead of being thrown back in my seat from acceleration, it felt almost like someone kind of put on the brakeS. Black smoke everywhere in my rear view mirror. I heard the meth system malfunction alarm....
It was going off the whole time but i couldnt hear it over the roar of the engine at WOT...
i had computer in and was Datalogging.
it showed a severe knock count event with 10 degrees of knock retard. I immediately did a compression check and everything was good! I got lucky.
so proper engine control is key. If i was doing boost, i would go forged. But nothing wrong with boosting a stock
bottom end w/ proper tune and working safeguards like knock system
Notice a lot of the new boosted cars dont have forged piston tops anymore (though rods and crank usually is).
I have the stock hyperteutic pistons on my boosted 93. 12 psi max boost at 6000 rpm.
They even survived a detonation event when my meth system failed to inject (i have a fail safe device on it now).
i think they survived bc the knock sensors caught it and dropped timing 10 degrees.
the knock event was bizarre. Driving hard out of a toll booth in west pa. Got into 2nd or 3rd gear, all the sudden instead of being thrown back in my seat from acceleration, it felt almost like someone kind of put on the brakeS. Black smoke everywhere in my rear view mirror. I heard the meth system malfunction alarm....
It was going off the whole time but i couldnt hear it over the roar of the engine at WOT...
i had computer in and was Datalogging.
it showed a severe knock count event with 10 degrees of knock retard. I immediately did a compression check and everything was good! I got lucky.
so proper engine control is key. If i was doing boost, i would go forged. But nothing wrong with boosting a stock
bottom end w/ proper tune and working safeguards like knock system
09-23-2018, 08:12 PM
#10
Le Mans Master
The forged are allegedly noisier... different expansion rate. I'd rather build it too nice.
09-23-2018, 08:37 PM
#11
Oil Producer
Thread Starter
i dont need the intitial/warmup piston slap of forged if im doing a NA engine do i?
09-23-2018, 10:36 PM
#13
Le Mans Master
That is really a non issue... Most LS engines do it from the factory... The price difference isn't much either. You can't really hurt anything unless its excessive. Build it once just in case you want to grow. If you build a 1k hp bottom end and feed it 300hp it'll live just as long as a 300hp based bottom end. But let's say you decide to move up down the line, you'll have that margin to grow. Iirc last I checked the price difference for forged pistons vs hyper was about 30$. Just my 2 cents.
09-24-2018, 12:13 PM
#14
Race Director
I did HPDE and NASA TT for years on the stock short block. Never had a problem with the pistons. Eventually spun a rod bearing. I did use a decent baffled oil pan.
09-24-2018, 12:47 PM
#15
Race Director
09-24-2018, 01:32 PM
#17
Oil Producer
Thread Starter
Thanks everyone for the reassurance.
My plans are to do the usual naturally spirated stuff with a super ram to make the car as quick as possible but still streetable with respect to the cam.
my basement development should be finishing up soon which means my shop (being used for storage right now!) will be emptied and i can install my max jax finally. then im looking forward to doing some serious work to my 86 4+3 which is being built into an hpde car for autocross and road track. im not into the drag but who knows i might give it a go locally.
My plans are to do the usual naturally spirated stuff with a super ram to make the car as quick as possible but still streetable with respect to the cam.
my basement development should be finishing up soon which means my shop (being used for storage right now!) will be emptied and i can install my max jax finally. then im looking forward to doing some serious work to my 86 4+3 which is being built into an hpde car for autocross and road track. im not into the drag but who knows i might give it a go locally.
09-24-2018, 01:33 PM
#18
Oil Producer
Thread Starter
is this from the oil pickup being starved for oil during high speed sustained turning?
any words of wisdom on how to prevent?
09-24-2018, 02:27 PM
#19
Race Director
Keep the temps down! I've seen a bunch of C4 gen go home at track days from heat. Usually head gasket. I did a lot of engine mods before cooling.
09-24-2018, 03:51 PM
#20
Team Owner
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More bang for the buck with forged rods/crank than doing it for pistons so long as youre not putting juice or FI on it. More likely you'll spin a bearing before you destroy the piston.
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