Cast Pistons, are all created equal?

[CTX-SLPR]

Howdy,

Well I'm working on sorting out the parts for my low power 3.0L destroker Buick V6 and since power is low and the budget is tight, I'm highly considering cast pistons to start with since I'm only shooting for 300hp at ~16psi boost.

Are all cast pistons from any given manufacturer pretty much equal or are there better quality castings from one over another.

Thanks,

[Barry Donovan]

I'd consider the v6 never being happy.

go as hard as gm made that block.(I know its a hard one)

[dulcich]

I don't know off hand what is available for your application, but I have found the Federal Mogul Speedpro hypereutectics are very good; durable and not prone to blowing up. I would choose OEM over the low line cast units. I have found the dirt cheap rebuilder's pistons like Badgers will work great right up until they pull the pin boss out and take the engine out with them. Pistons are a risky area to skimp. Get the best you can afford.
-dulcich

[squirrel]

What's the cost difference cast/forged?

[Bob Holmes]

I'm with Steve.

I would highly recommend a forged piston. If that isn't in the budget, a high quality hypereutectic is the ticket. Frankly, if forged are not in the budget, you may want to slow down your program until they are.

The tune will need to be right on for the hyper to live.

[Beagle]

Forged... the speedpro's look good but I wouldn't put them in a boosted motor. They're not known to be very tolerant of tune mistakes. It's a shame the 4.020 stage two BME pistons I have are way too big, could make a deal on them.


I sound like a broken record from above, lol. You will sleep easier dropping the extra couple of hundred now. Make your mind up before the block is machined though. Haha. I bought some KB hypers for a 393 build and after thinking about it and thinking about it, I went back and bought forged. There was only a couple hundred difference, actually like 150.00 IIRC. The KB's look pretty good too but... I'm skeered of them.

[Beagle]

Question - what are your dimensions going to end up looking like? I noticed you mention some other rods in another thread. You may have to go custom piston, but if you do then you can leave the pin bore alone and have them cut to fit it since it won't likely add any cost to a custom piston. They're not "That" expensive when I looked last.

Pin size
Compression height
Bore
stroke (in case other rods may be viable) / big end diameter
Ring size (going low compression thin rings and a pump?)

need more info...

[CTX-SLPR]

I'll fill in what I can on that list plus a bit more that frames the question. I understand the leariness of the general group against cast pistons and I may end up toning down the power and/or rpms to match the cast units if that's all I can afford at the time. A running low power engine is better than an incomplete "high power" engine due to budget. To answer the question on how much more are forged pistons... Well that depends on the rods but for the BBC rod combo, they don't exist in off the shelf form and Diamond (my preffered custom piston maker) charges $142 a slug with no pins or rings. A set of cast pistons is ~$80 for all 6. The idea using Buick or Pontiac rods uses Ford 2.3L turbo pistons in 0.020-0.030in over bore and those are available forged at around $540 for 8 but no pins or rings.

Specs for those like me who like digging around for combos of parts that will fit:
Block
Deck height: 9.522in is blueprint so a bit less won't hurt to allow for cleanup on the deck
Bore: 3.800-3.810in, any more and I bust the cid limit for the class and really 3.800 is preffered to give some chance at a rebuild
Crank
Stroke: 2.66in
Rod Journals, Stock: 2.25x0.854in, they are split so that's for one rod
Rod Journals, Max change: 2.20x0.890in
Pistons
Target Compression: 9.0-10.0, though I could live with high 8's but 110+ octane gas is available why not use some compression
Dish cc range for above compression assuming 0 deck: 0-6cc's
Compression Height: no pin through any of the ring lands
Rings: whatever will work but no vacuum pump till I've got the rest of the combo sorted out (i.e. when I do custom pistons) 1/16-1/16-3/16in and 5/64-5/64-3/16in are the packs on the pistons I've looked at so far
Rods
I'm willing to use decent OEM rods such as the BBB which swing coffee can sized, very heavy pistons to 6500+ rpm reliably enough but would preffer forged units as long as a set of 6+ can be kept under ~$600 (used is fine). Also the exact length may not be right but since the pistons could be using a smaller wrist pin, I'd offset bush them down to get the C-C length right and use the pin for the piston. Also the split pin even fire crank uses offset rods, I really need to be able to narrow the rod 0.090in to 0.854 or 0.890in wide to keep the rod centerline down the bore centerline.

Thanks,