Forged Pistons



What's the deal with aftermarket turbo companies and always hyping up forged pistons? I realize that they're more reliable, but unless you're going for huge boost, or experiencing detonation, I don't think they're necessary. The Mopar FWD turbo cars came stock with cast pistons after all. Wouldn't it be cheaper and make more sense to invest in detonation sensors, water injection and intercoolers?
I agree with You.

It would be more desireable to have the forged pistons but a majority of the factory turbo engines had cast pistons.
The Buick ran 8.8 psi boost with cast pistons and had a decent flowing head.
Water Injection is better than an intercooler alone as it changes the nature of the burn. It slows it a little, giving peak pressure at a more favorable crank angle.

IMHO, John
Another problem is that a lot of the riceboys try to run their turbos at stratospheric boost levels without a clear understanding of what they're doing. The turbo suppliers recommend bulletproof bottom ends knowing that their recommendation will be largely ignored. That way when the riceboy calls up whimpering that their turbo trashed his engine (he'll leave out the part about the 2 bar of boost he was running at the time :roll:) they can ask "did you follow our build recomendations?" It saves a lot of hassles, ill-feelings and preserves their reputation.
8) good quality cast pistons are reliable as long as the boost is kept below 10-12psi boost, the rpm kept below 5500 rpm, and detonation is eliminated. otherwise forged pistons give a safety margin.
What happens to the pistons if you overboost it. Has anybody seen a crank get messed up from too much boost or too much nitrous.
The advantage of the forged pistons is twofold, one is the extra durability and two is the soft failure nature of forged pistons. A cast piston will shater and spill lots of nice chunks of alluminum throughout your engine. Nice way to make sure you get a whole new engine!!! Forged pistons will tend to collapse or bend. This means you usually can replace one piston, rings, and hone the cylinder which will get you back up and running. These pistons have saved many a boosted engine from the scrap pile and of course all the work in preparing a new engine for your car(truck). The cast pistons should be fine though as long as detonation and boost is kept at a safe level, think 5-10 psi max. I would go with a drawthru setup rather than blowthru for a first try at turbocharging as it tends to be a bit safer for experiments. Good luck.
If you use old pieces to build your turbo setup and decide on the drawthru design do not use a turbo from a diesel motor. The turbos on diesels will not tolerate a air fuel mixture being run through them. They will fail most spectacurly and probably take the rest of the engine with it. A large gas engine turbo will be the best bet for your needs but you may want to look into a prespooler to help with low rpm boost.
Are there special seals that a turbo needs if it is in a drawthrough application?..i read a forum somewhere on here about that. The seals have to be changed out so they can tolerate the air/fuel mixture as well?
Most turbos on non diesels will be fine with the air/fuel mixture. Make sure any used turbo that you get is in good shape and you should be fine.
A blowthrough gas turbo is no different from a diesel turbo. You have to get one specifically for a drawthrough for it to last.

Emerald 74 4X4":1t0ee1or said:
Are there special seals that a turbo needs if it is in a drawthrough application?..i read a forum somewhere on here about that. The seals have to be changed out so they can tolerate the air/fuel mixture as well?

Yes. Most turbos have a different seal depending if the use is draw through or blow through.
Time and again, experience has shown that stock cast V-8 cranks have a horsepower limit somewhere around 450 hp at the engine's design RPM limit. They can go over that limit and survive if they're making less hp than that figure (lots of overlap on the cam), or they can make somewhat more power if their RPMs are kept well below published red-line (stock cam and higher boost). When one combines high RPM with high hp, the end result is pretty predictable... :cry: