Stocker Pistons....Pontiac
 

How much E.T. is a set of Venolia's or CP's, worth, over TRW's?
Just curious... I have a new set of TRWs(got a smokin deal on them)...
Just want to know if they are worth using on my 1st build... anybody still runnin them? Thanks in advance!
Im on a tight budget, so i will probably go with what i got...any info is helpful...

Re: Stocker Pistons....Pontiac
 

Irregardless of any of the other pistons being lighter than the TRW's, the newer quality brand pistons have more accurately cut ring grooves. Not that many have not gone fast with TRW's over the decades (but then again, all that was available was TRW for decades if you wanted a good forged piston that was affordable). It's all about ring seal and it's worth power.
If you keep the TRW's, just check the vertical and radial clearances with the rings you use. There are shims available to correct problems. Rebco offers plenty of options if you want.

Re: Stocker Pistons....Pontiac
 

Thanks Jeff...I just want to make sure that using them isnt a waste of time and money... Im not lookin to set records, just yet. Building the best shortblock that i can right now, probably makes the most sense. Its easier to swap heads and cams out, as you go... even at that rate, was curious what the overall performance difference is that could be expected.

Re: Stocker Pistons....Pontiac
 

When you combine the advantages in weight, ring grooves, and stability, the difference can be substantial. The TRW stuff weighs a ton, and really can't be lightened a great deal without causing problems. You can, and should, change the wrist pins, and have the pistons pin fitted, that will save weight, and increase reliability. I wouldn't spend any more than that, and balancing, on the TRW pistons.

Re: Stocker Pistons....Pontiac
 

My sons old 318 Engine was a TRW engine with lighter weight pins,

It would run about .8 - .9 under in decent conditions under current indexes.

The lighter better pistons with TriCity Rings were about .15 to 2 Tenths faster,

but half of the difference I would probably attribute to the rings and half to

the pistons.

Re: Stocker Pistons....Pontiac
 

Brent,
Great question. I have been wondering some of the same stuff, as I continue to scratch parts together for my 67 Firebird.

For the knowledgeable ones, another question please:

Would the heavier - less trick piston in a lower RPM Pontiac have less, equal or more impact to the overall motor efficiency, vs a generally higher RPM stocker motor, like a small block chevy?

Brent is talking about spending his money on a really good short block to start with. On a Pontiac 400 specifically, what is the best bang for the buck? Short block, heads, exhaust/headers ???

thanks, and good luck Brent

Ken

Re: Stocker Pistons....Pontiac
 

I'd say, good shortblock, obviously a good valve grind....good headers are a great investment, they can make alot of difference, especially with the high duration cams that we are allowed to run... Make sure you have a machinist thats knowledgeable in the ways of Stock Eliminator... that can make a huge difference on how much power you make, with the same parts...

Re: Stocker Pistons....Pontiac
 

Ring seal is where the difference is, weight is not worth much if anything. The lightest Hemi piston is heavier than the heaviest Pontiac piston.

Re: Stocker Pistons....Pontiac
 

Ring seal - Ring seal - Ring seal
That's the ABC's of a great short block. I didn't mention before that the skirt's are ground differently on todays good pistons which allows for better ring seal on piston rock-over. Plus the wrist pin bosses are better positioned for the same reason, better position and ring stability on rock-over. You won't find any of these benefits in an old TRW piston.
I understand being on a tight budget. But I also adhere to doing it right even if it takes longer. Obviously I adhere to that... :(

Re: Stocker Pistons....Pontiac
 

Jeffy, Jeffy, Jeffy, I agree with you on the ring seal,,, 100%, but the assembly has to weigh a certain amount, no matter what piston, rod, ring set up. I've run fast with FACTORY .030 pistons.... oh wait... that is what I'm still running, and even in the new motor too !!!!!!!!!! You are telling me and the rest of the world that you can't run fast with heavy pistons nowadays?????... tell that to me one more time, and Harry, and Jon, and Fred, and many, many others. I'm putting together a motor for the car that I think/hope will run fast. I challenge you to bring out the AMC/Mopar with stock rocker arms, stock rearend... mine has both. ... Name the date, track and time... I'm there. :) ready, willing and able. Lets see how far under you can go... no scoreboards,,,, just timeslips.

Re: Stocker Pistons....Pontiac
 

Ricky, Ricky...RICKY! I thoroughly reviewed my comments on this subject and nowhere did I say anything about weight. I discussed ring seal, ring grooves, wrist pin position and the shape of the skirt (none of these were specific technical data merely issues that modern pistons have an advantage of. Your results may vary, consult with your favorite piston manufacturer and engine shop for specifics), but I did not say lighten a piston. You sound like a Presidential candidate trying to put words in my mouth! Like Mitt said, "you can have your race car, you can have your own trailer, but you can't make up your own facts!"
But heck, since your running a turbo charged stocker, you might want to run a thicker / heavier piston with the ring groves moved down an extra hundred thou (or more) to better survive the higher than stock boost you have to run to go so far under the index. As a former turo-racer myself, I know how much an extra 10 or 15 pounds of boost can make! Oh, I guess I shouldn't bring that up...:p
You should mention that in your challenge. You'll run stock boost (what is that on a 301, 4#'s?)....I'll have NHRA legal rockers and the corporate rear end that's allowed by every other stocker thank you. And yes, I'll be glad to race you against our indexes. You can do it with stock boost or peg the boost gauge boost. Make it two out of three and steam coming out of your head gaskets or milky oil disqualifies you :D

I just hope we have a local track still open

Re: Stocker Pistons....Pontiac
 

Jeffy, Jeffy, Jeffy,,,,,, As a "former Turo racer myself" you should know that boost isn't everything.... it's a measure of restriction !!!! too much boost and you go slower,,, Factory was 6-9 Lbs. and I'm not running much more than that !!!!!!!!! so Bring it

Re: Stocker Pistons....Pontiac
 

Boys, Boys, Boys........Can't we all just get along??????

This is a question for Brent.....

I didn't see a part number on the TRW pistons that you planned on running?????

I don't know combo you want to run, but for a 400 the only legal TRW is a TRW L2440

Just thought that I would ask.............

Bob