forged pistons
- Thread starter 87gnNV
- Start date
- Joined
- May 26, 2001
Stock pistons are cast. Don't know of any aftermarket cast turbo Buick pistons?
turbo buicks
ESADAH!!!
- Joined
- Jun 13, 2002
someone told me they were hypers. i guess you know more than i do nick. whats the difference between cast and hyper?
- Joined
- May 26, 2001
I was thinking someone would ask that question!
The stock cast pistons use a steel reinforcement when made. The hypers do not have this, guess they are considered a cast piston by some?
The stock cast pistons use a steel reinforcement when made. The hypers do not have this, guess they are considered a cast piston by some?
To my understanding, All pistons are either forged or cast. Hypers, are a particular formulation of the metal that is are significantly harder that the typical piston. Hypers start as a molten metal that is molded or "cast" into it's shape than finish machined. So all hypers are a cast piston, But all cast pistons are not hypers. Forged on the other hand start as a slug of the original material that is pressed, or forged, under LOTS of pressure to it's final shape then finish machined. Both cast and forged designs are capable of producing an adequately strong piston. The difference is in their respective modes of failure. A cast Hypereutectic piston tends to fail suddenly and more or less shatter. The hardness that giver it it’s strength also causes it to fail when exposed to the sudden shock of detonation. A forged piston tends to go plastic at it’s limits. Sometimes giving you an indication that something is hurt before the point of total failure.
Per my semi-knowledge on this, it appears that Sleeper-6 has defined it rather well.
I can certainly attest to the notion of Hypereutectics "exploding" under detonation! I've blown a couple apart in an old motor, in more than one occasion. It is my understanding that because of the material difference, they react differently to heat, and therefore their rings have to be gapped differently than a regular cast or a forged. I know they were the "hot tip" for TR's years ago, and many people still run them today with great success. Keith Black wouldn't slap his name on them if they were crap...!
However, unless you build a completely non-detonating setup, then be prepared to replace them often. I know they can be made to work on the TR's, but my opinion is to simply spend roughly the same amount of money, and buy the TRW/Speed-Pro forged, or better yet, upgrade to a nice JE piston if the budget allows.
The last motor I built, I ran the TRW/SP forged versions for many years, without any piston failure. Yes, they're heavier, but they seem to be durable. I'm using them in my new motor too. Speed Pro Part # L2481F-30 Forged Pistons (-30 means bored 30 over)
All this aside, the fact still remains - detonation kills parts,,, period! Even a good forged piston will eventually give out under detonation. I guess my point is,,, "don't detonate!!!"
I can certainly attest to the notion of Hypereutectics "exploding" under detonation! I've blown a couple apart in an old motor, in more than one occasion. It is my understanding that because of the material difference, they react differently to heat, and therefore their rings have to be gapped differently than a regular cast or a forged. I know they were the "hot tip" for TR's years ago, and many people still run them today with great success. Keith Black wouldn't slap his name on them if they were crap...!
However, unless you build a completely non-detonating setup, then be prepared to replace them often. I know they can be made to work on the TR's, but my opinion is to simply spend roughly the same amount of money, and buy the TRW/Speed-Pro forged, or better yet, upgrade to a nice JE piston if the budget allows.
The last motor I built, I ran the TRW/SP forged versions for many years, without any piston failure. Yes, they're heavier, but they seem to be durable. I'm using them in my new motor too. Speed Pro Part # L2481F-30 Forged Pistons (-30 means bored 30 over)
All this aside, the fact still remains - detonation kills parts,,, period! Even a good forged piston will eventually give out under detonation. I guess my point is,,, "don't detonate!!!"
Hypereutectic 390 refers to a unique aluminum piston alloy that contains dissolved and free silicon. The material can be T6 heat treated to high strength and stiffness.. i believe these combined are designed to minimize expansion and contraction due to temp. allowing tighter clearances thus less blowby=more cylinder pressure!! OH YEAH
of course they do suck when you detonate.... i have an 80' trans am with a small block chevy that had hypers.. they dont like it when a valve hits them of course thats another reason NOT to put a chevy where a PONTIAC belongs.... go poncho power.(can you imagine the torque if you had one of our gn turbos on a 455???)
of course they do suck when you detonate.... i have an 80' trans am with a small block chevy that had hypers.. they dont like it when a valve hits them of course thats another reason NOT to put a chevy where a PONTIAC belongs.... go poncho power.(can you imagine the torque if you had one of our gn turbos on a 455???)cast/ hypereutectic pistons
Both are of the cast design, the only difference I'm aware of, is the amount of silicone in each.
standard cast pistons,by design have less than 10% silicone, and are cheaper to produce.
hypereutecic style pistons have More than 10% silicone, and are supposedly stronger, this is according to the major piston manufactors.
So the questions is, How hard you gonna lean on it?
I for one will use forged pistons, just for insurance!.
Good luck
cruzn57
Both are of the cast design, the only difference I'm aware of, is the amount of silicone in each.
standard cast pistons,by design have less than 10% silicone, and are cheaper to produce.
hypereutecic style pistons have More than 10% silicone, and are supposedly stronger, this is according to the major piston manufactors.
So the questions is, How hard you gonna lean on it?
I for one will use forged pistons, just for insurance!.
Good luck
cruzn57
All i have to say is that whether you have Hypereutectics or a set of forged pistons, detonation will ruin them. If you have your car tuned so you get little to no detonation, then the forged will probably last longer than the Hypereutectics. If you don't have the car tuned right and you get a lot of detonation, the pistons will melt. Just make sure whatever route that you go, you slowly turn the boost up and make sure you compensate enough fuel and octane for those boost levels. Just my .02
Scott
Scott
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