Stock Pistons?????

[excobraguy]

Can anyone explain to me why my engine builder/machinists insisted on me using stock pistons over forged pistons? Everything I read says that forged pistons are better..........???? Who can explain why this guy feels this way? He tells me they hold up better under high heat conditions than forged. The guy has a VERY well known name and a very good reputation. Just trying to understand. He says the stock one will take more abuse and more detonation than a forged piston.....what do you think?

 

[83ttypecooled]

Hi,
My machinist may be old fashioned, but he insisted on my use of a Forged piston. So that's the way I went.I think modern cast pistons are pretty tough;infact the new Corvette Z06 uses cast pistons on TITANIUM rods.An interesting sidenote to that tidbit would be, however, that the new Corvette badboy,the ZR1,with 6.2L and a blower,uses a new forged piston. I have always trusted in pros that at least SEEM to know more than I do, so I will continue to use forged stuff in my engines,until they are proven to be a lesser possibility.

 

[six slinger]

i dont know what youre performance goals are, if you plan ongoing no further than say 12s,then you could make a case for stock pistons,but since you have the motor apart, and since you will be going faster in the future,i would highly recommend forged pistons![ much stronger,handle detonation way better] but if he insists for what youre goals are [hopefully not faster than 12s] than either get him to use hyperutectic pistons,or use another builder!! just my two cents brother!

 

[83ttypecooled]

Hi,
And a good two cents it is! I strongly agree that a lightweight forged piston will outperform a cast unit 9 times out of 10. The castings are very strong, as has been seen ,but I don't think the average cast piston will OUTPERFORM any Forging. Sorry, just my opinion.

 

[rodman99999]

Was this builder's rep founded on Buick/boosted engines? Sounds like he's just a little old-fashioned. Forged pistons are definitely stronger. Why not go with the better choice, as long as you're rebuilding anyway? If he's not a Buick man: Better make sure he knows how to clearance your motor for sufficient oil pressure. (Flatlander Racing - High Performance Racing & Engine Parts: TRW Forged Buick Pistons)

 

[excobraguy]

I stated to him my mods and said I would be running low 11's with the car. He's even putting the RJC girdle on it. Anyway, yes....the guy comes highly recommended. I'm not here to smear his name or anything cause I like the guy. He helped in the development of the Syclone pickup. He was a GM engineer......I will leave it at that.

 

[Brutusturbov6]

I stated to him my mods and said I would be running low 11's with the car. He's even putting the RJC girdle on it. Anyway, yes....the guy comes highly recommended. I'm not here to smear his name or anything cause I like the guy. He helped in the development of the Syclone pickup. He was a GM engineer......I will leave it at that.

forged pistons are much better than stocks, but on a side note there are a lot of guys that have taken the stock pistons way down into the low 10's area without a problem, I say get a set of Jegs forged and be done with it, those will take you way down to the 9's with no problems..

 

[83ttypecooled]

Hi quality pistons ARE the way to go.

 

[Brer Rabbit]

No way.

Sounds like a certain engine builder may have a set of cast pistons laying around that he wants to get rid of. I find it hard to believe he would actually recommend a cast piston. If he wont do it ur way, then just pay him for what he has done and take it to someone else with Buick experience.

 

[83ttypecooled]

Hi,
If I was the poor dumb sucker involved, I sure wouldn't worry about a thing or two. Buy all the best stuff,forget the rest. Best luck with your plans.

 

[turbofish38]

Why not ask him? Not every type of piston is the same. There are many ways to skin a cat as the saying goes. Forged pistons need a lot more clearance than cast or hyper. Maybe he doesn't want excessive piston slap and ring clearances in a boosted motor? I've got Diamond forged in my GN and it's a tad bit noisier than I'm used too.

 

[excobraguy]

Why not ask him? Not every type of piston is the same. There are many ways to skin a cat as the saying goes. Forged pistons need a lot more clearance than cast or hyper. Maybe he doesn't want excessive piston slap and ring clearances in a boosted motor? I've got Diamond forged in my GN and it's a tad bit noisier than I'm used too.

I did ask him and my first post had his answers "He tells me they hold up better under high heat conditions than forged. The guy has a VERY well known name and a very good reputation. Just trying to understand. He says the stock one will take more abuse and more detonation than a forged piston....."

 

[six slinger]

I did ask him and my first post had his answers "He tells me they hold up better under high heat conditions than forged. The guy has a VERY well known name and a very good reputation. Just trying to understand. He says the stock one will take more abuse and more detonation than a forged piston....."

im more than a little shocked to hear that you dont have to be an engine builder to see that every truly fast car runs with forged pistons!! i dont care if it was my engine builder who said it, if i heard that comment i would ask his wife to hurry and get his meds!!!

 

[turbofabricator]

He's correct.......sorta. The stock piston DOES hold up better to detonation, due to the fact that they have an alloy steel insert cast into them for the top ring land. The top ring land takes ALOT of abuse, that even a forged piston can't handle if your tune-up is off. Do cast pistons handle high heat better? No. Period. Are cast pistons better for RPM? No, because they weight a TON! Will a forged piston make more power than a cast piston? No. Forged pistons will hold up better to sustained high temps than a cast piston. If your goals are low 11's, then a stock piston is the way to go. Nothing wrong with a stock GN piston. A light weight forged piston "can" rev faster/higher than a cast piston, due to it's light weight. A TRW piston is lighter than a stock piston, BUT, they have a VERY heavy wrist pin to make them a factory replacement weight. I typically replace the TRW pin, with a tool steel pin and have the assembly balanced. A stock piston does not require a balance job, either. So,..........Is your machinst right or wrong? Yep. Opinions vary for each build up. Lots of guys run REAL fast on stock rotating assemblies. Which is better? Forged or stock? yep. That one is.

 

[six slinger]

i respect youre opinion and knowledge turbofab,and you may in fact be right! i will tell you though as a young kid i worked in a verybusy and well respected machine shop who built up a ton of entry level performance all the way to pro mod cars [one of which he owned and raced very successivley]and every motor he built that was going to run under 12s he put forged pistons! again i respect youre opinion, maybe forged is overkill on a car running less than10s. but i think the overwellming amount of people on this board or any board would be going forged!

 

[turbofabricator]

If a block NEEDS to be bored, then always go with forged. If it only needs a hone, AND you only plan on high tens, leave them alone!!! No gain in changing to forged. It is actually a step backwards going to forged at that power level. Tighter clearance, less noise, less blow-by, less wear............Again, I am NOT syaing that forged are bad, just that if you do NOT need to bore the block, stay factory, if target is high tens. If target is mid tens, then go forged.

 

[ronbuick]

Ken is right on about the pistons IMO on list conversations with a Mr. Carruth.
I'm sure Ken knows the gentleman.

Ron

 

[boosted231]

He's correct.......sorta. The stock piston DOES hold up better to detonation, due to the fact that they have an alloy steel insert cast into them for the top ring land. The top ring land takes ALOT of abuse, that even a forged piston can't handle if your tune-up is off. Do cast pistons handle high heat better? No. Period. Are cast pistons better for RPM? No, because they weight a TON! Will a forged piston make more power than a cast piston? No. Forged pistons will hold up better to sustained high temps than a cast piston. If your goals are low 11's, then a stock piston is the way to go. Nothing wrong with a stock GN piston. A light weight forged piston "can" rev faster/higher than a cast piston, due to it's light weight. A TRW piston is lighter than a stock piston, BUT, they have a VERY heavy wrist pin to make them a factory replacement weight. I typically replace the TRW pin, with a tool steel pin and have the assembly balanced. A stock piston does not require a balance job, either. So,..........Is your machinst right or wrong? Yep. Opinions vary for each build up. Lots of guys run REAL fast on stock rotating assemblies. Which is better? Forged or stock? yep. That one is.

Ken is right, the stock piston does have a steel insert and will take alot of abuse. I know the builder your speaking of, he wouldn't happen to be from missouri would he? Anyway if it is the same builder I know he has built alot of turbo 6 motors.

 

[TurboDave]

I'm with Ken on this one. Assuming your goals are high 10's or slower, then the stock pistons will actually be a better choice in many ways. Stronger? Yes. Heavier? Yes. Last longer and take more abuse in a daily driver/racer? probably.
Steel insert in the head and pin area.

 

[excobraguy]

Ken is right, the stock piston does have a steel insert and will take alot of abuse. I know the builder your speaking of, he wouldn't happen to be from missouri would he? Anyway if it is the same builder I know he has built alot of turbo 6 motors.

Yep, that's the one. And he mentioned the steel insert in the piston as well. And yes he has built a lot of turbo 6 motors. My goal is low 11's with the car and it only needs a cylinder hone, no boring required......sounds like the stock pistons are fine then. Thanks for the replies guys, much appreciated! :smile: