??Piston Choices??

[Phatman]

Well.....

I have several choices, I bought a set of TRW .030 for my new motor. I read after I purchased them that Ron and I would assume Jack are big on Diamond's. In reading it wasn't specified weather they were flat top or not but I would assume they would be as he referenced valve relief indentations.

Now, I have access to both the TRW's that I have already purchased or the Diamond flat top's in .015, .025 or .030 over, however I don't think my block will clean up with .015....

That being said, this is my question or questions if you will.
How much will running flat tops raise the comp, just thought someone may know off the top of their head?

Also if running aluminum heads is there enough heat loss through the heads to off set the increase of the additional comp?

Has anyone seen any information on heat loss through aluminum heads verses iron heads? I guess what I'm driving at is if you are running aluminum heads wouldn't you consider bumping your CR anyway and to what level?

The post Lonnie has in Stage2 just kinda got me to thinking and you know that can be a dangerous thing in my case...

 

[Nick Micale]

With your post going off in a few different directions, get a little confusing as to what you are trying to accomplish?

If you already have 0.030 over TRW pistons, you are safe using them like hundreds of other turbo Buick motors have been done similar to yours.

 

[Phatman]

Sorry....

Just a little too much Cuban coffee this morning.

Really just trying to get an idea of what advantage there would be in using the Diamond pistons over the TRW.

I guess while thinking about them my mind got off on CR's, as well as other choices in regard to heads as mine have developed a couple of cracks.

 

[Fuelie600]

Mike, The TRW's are just fine! The Diamonds will get you a few extra ponies due to their reduced weight, but what will it cost you to sell and switch. Good luck! Brian

 

[Phatman]

Brian...

I already have all of the set's mentioned and have yet to start the machine work. I just wanted to do a little research on a few items before I put any plan into motion.

At the moment I've got a case of more time than cash, so I want to feel that I've made the best choices and have left nothing on the table in regard to power with what I have to work with even if it requires a little more work for me. I had already figured the cost of rebalance into my budget.

At the rate I'm moving though I may not even get started before Nick has the new block's on the market which could really screw me up...

 

[blkbart]

Remember the short block only contains the power it doesn't make power. Heads, intake injectors, turbo fuel, downpipe, boost etc makes the power. Therefore Trw or Diamond is just a personal preference choice. Reliability problem however is the problem by how much boost you plan to run, many buicks with stock pistons have run mid to low 10's.Both forged pistons will do the job.

 

[gnx7]

Ryan Guy went 9.99@135mph with a full weight GN and TRW's with lightweight pins (JE pins) and 30psi+ boost. If you can splurge for the extra dough for the lighter pins and have the rotating assembly balanced that is what I would do.

There are quite a few people making 500rwhp+ on Hyper pistons.... but I would go with forged for peace of mind .

I plan to run JE's as the difference between $300 and $500 is not much in the long run and I plan to spin it to 6000-6200rpm.

-GNX7

 

[Lee Thompson]

pistons

Don/t the Diamonds require more clearance, which leads to piston slap on start up.

 

[Phatman]

Understood....

Who has the best prices on JE pins?

Also, can anyone send me in the right direction in regard to heat loss through the heads? Aluminum verses iron, surely there must be some info that I've missed. What I've seen so far pertains more towards V8 applications which I'm guessing would be pretty much the same.

What I've read is that in some applications, flow #'s being equal that when the two were compared the HP & torque #'s actually fell off with the aluminum heads, which was attributed to heat loss through the heads.

Now, I know I'm getting nit picky, but I'm thinking that with a stock block I'm only going to be able to handle so much HP.

I know there would be a weight savings, but I've seen some pretty good #'s from iron heads....yea, yea, yea...I know I drifting again...later

 

[NoNos38]

Go with TRW's.. You will get Piston slap on startup with JE's of Ross.. I run TRW's with light weight wrist pins, and the last time I tore down the motor they looked brand new.. IMO, They are a better piston for a car that gets driven more than 50 miles a year..

Matt


The stocker would also be a good choice.. Intercooler has had good luck with hypers..

 

[bruce]

Originally posted by Phatman

That being said, this is my question or questions if you will.
How much will running flat tops raise the comp, just thought someone may know off the top of their head?

Also if running aluminum heads is there enough heat loss through the heads to off set the increase of the additional comp?

Has anyone seen any information on heat loss through aluminum heads verses iron heads? I guess what I'm driving at is if you are running aluminum heads wouldn't you consider bumping your CR anyway and to what level?

TRW, JE, or Diamond is just a matter of personal preference as far as I'm concerned. DONE CORRECTLY, all have proven to be good ones.

The normal advantage to AL heads ain't that they're AL but rather a newer design. Case in point, the GNs aren't ALOT different, but seem to have some nice points from looking at the slight changes. AND they have a full exhuast port. The oem ex ports, what there is of them just suc, IMO.

With the exhuast port revisions comes room to revisit the coolant passages, and better cooling around the ex guide area makes for being able to better deal with higher EGTs.

I got to spend alot of time on a SBC going form Iron to AL heads. I had to run a little more timing in cruise mode, ie 36 from 32, and was able to lower the WOT timing from 36 to 28d. Lowering the timing that much told me the chamber design was just that much better that the flame in the chamber was so much faster that it didn't need as long to completely burn the charge in the cylinder, so it made more HP with less timing.

I'm not real sure on my footing here, but I have a theory that another advantage might be the out edges of the chambe might run a little cooling with the AL heads, and slow the decay of the gases in that region, Carl Ijames did a post recently about this, that was excellent. And that decay has a profound effect on detonation.

Block Filler, AL heads, and following some of the Evans Cooling system notes all sound like good ideas.

Just on a piston note, I would stick with the dished pistons, because they min the quench area gases, and would seem to promote more cylinder turbulence, just my views. I'm sure others have their own ideas.

Well, back to shoveling..........

 

[Steve Y]

From what I understand Diamond takes some pains to make knock sensor friendly pistons. I have been advised that they may ask what EGT you plan on running and will fit the piston accordingly.

They also may use Wisecos which are a higher silicone forged...I believe. That is what their forged snowmobile pistons are and are advertised as lower expansion.

"You expect more from Diamond.......and you pay for it"

Anyone know any more about that and can add something?

Steve

 

[Phatman]

Thanks for the input Bruce...Steve

Out to cut the grass...

 

[EightSecV6]

We use Ross exclusively on the race engines with tool steel tapered pins, they are by far the most expensive but they are the lightest and the best built IMO.
TRW's work fine for a street engine.
Bill