For a stock rebuild cast pistons are fine. If you are going to bump the hp up a little and run it hard forged pistons will hold up better. But I've run quite a few motors on cast pistons and have never had one fail. You figure, almost every car that comes off the assembly line has cast pistons and they go for a long time. Don
-What they all said-lol, it's all good, brother got's to take a poke at ya for fun. Every time i've ever used cast pistons in a "hobby" car, i've later been pissed at myself for limiting myself with the choices i made. If you're gonna make her wail, spend the money. Forged. I put my forged slugs to some hard-ass street use in a 4100lb tug with alot of torque and traction and i never sweated it. or: split the difference and run hypereutectic castings. If you just wanna give 'er the beans every now and then, they serve the purpose just fine. http://en.wikipedia.org/wiki/Hypereutectic_piston Not as strong as forged but just fine for a warmed over toy. -Rick
I've got a 283 with cast pistons and a 4-71 blower running 1 to 1 make 10 psi on full pedal. It's a street motor with a summit 1102 cam and really runs great. Goes over 6 grand easy. Cast crank too. Yep -look it up. Cast cranks were available on some 283s only if you are lucky. just kidding but I am lucky and my crank is cast. You can't blow it up if you try. Really. Just do it dude. So many people are such puuuuuswasss building motors these days
I have a couple of 5.0L HO Ford engines and those have the stock forged ((TRW) 9:1 pistons in them... One of those came from a '91 pony that I bought new...
Its all about the grain alignment. If the grains of the metal are aligned and packed together in a perfect form you get more strength. If you are looking for a motor that will put up to a ton of stress go with forged everything( crank, rods and pistons ) but you also have all the other supporting mods. At that point you may as well go with h-11 main studs and head studs and then you are on to good heads and a nice bump stick. Its a chain affect
If no NOS, turbo or supercharger the forged pistons are overkill in my not-so-humble-opinion. "Hyper" pistons worked for me with turbo below 10 lbs. boost.
We built this (O/T, I know) setup at the school. 350 with cast everything inside (low buck rebuilder parts, too). Made 530hp and 605lb ft of torque. 18 full load pulls on the dyno and didn't break a thing... Having said that, I still trust forged pistons a lot more....
Ok, everyone (almost) agrees that forged pistons are stronger. Stronger how? When do they outperform cast pistions? In other words "how" are they stronger, under what circumstances? I'm going to stand on this engine pretty hard sometimes and wondering if that is the moment it matters. Thanks for advice and humor
Heat and detonation resistance. The castings have no "grain" structure, so they are much more prone to cracking in high stress areas such as the ring lands or pin boss.
Cast Pistons PROS: Cheaper Lighter Quieter when cold, versus a forged piston Weaker structurally than a forged piston CONS: Not suggested for nitrous or blown applications Not suggested for high compression applications Not suggested for high rpm applications Forged Pistons THE OPPOSITE OF EVERYTHING ABOVE I'm glad you like your combo, but you had better keep an close eye on your timing and mixture, because you are tap-dancing on a land mine. I like a cast piston in the right application, but they have their limitations. And trust me, I could blow up your engine.
For my money, the most important difference between forgings and hypers, is that any WOT failure with the hyper is usually catastrophic. In other words, the piston doesnt deform, it comes apart. When that happens, the small end of the rod usually goes through the cylinder wall, and one head is usually damaged beyond use. The debris will travel through the next 2-3 cylinders in the firing order, and cam is often broken by the end of the rod as well. If I am really SURE that the engine will NEVER see detonation, and NEVER float the valves, NEVER suffer a valvetrain failure, and that there is ZERO chance of piston/head contact, AND its a real tight budget deal, I MIGHT use the hypers. Food for thought...
What are your plans for the motor? Cast pistons can take quite abit of abuse ( miss a tune or drop a valve your taking it apart). Hell youd be suprised at the RPM and boost cast will take. Just stay out of detination and your fine. Hypers can take some abuse, but when they fail its not good. Forged for racing. But Ive got to say if you drop a valve on forged your taking it apart anyways so...
Now the last 3 comments were the advice I was looking for. THANK YOU!! It's forged for me then. One post earlier suggested forged crank as well. Is that the same as a "steel" crank? Do we have the same thoughts about cast versus forged crankshafts? I know the one I have is cast. Will a cast crank fail under pressure sooner than a forged one? Detonation is a worry as I am going for CR and the poodle piss here in CA is a worry then. Great advice for me guys, thanks much as I am almost at the assembly point with the rebuild.
Little different deal here I used cast in an old flat six and they were camed incorrectly, and siezed, the piston builder made good on them and I put it back together, the next motor I did was an exact copy but they wouldn't build me the cast ones, aparently they were too hard to do correctly so I sent a sample to Aries and had them forged, the difference between these two motors is like night and day, the forged runs so much better I tempted to go back thru the other one.
I had some cast pistons fail in a nice 4V 351 C I put together in the first 3000 miles 20 years ago ….. That was the last time I even considered cast.
You are right about forged being a little noisier until they warm up. The ones in my 331 sbf rattle like mad for a while and never really do quiet down totally. But they are also very short because of being in a stroker motor. I called Scat when I first got it running because I thought something was wrong and the tech there said some rattle and some don't. Don
As far as the crank is concerned, 283 cranks are either cast iron (relatively rare in my experience) or forged steel. Most likely, you have a steel crank, and even if you dont, I dont think the cast crank will give you any grief, unless you are really winging the snot out of it. If its an 8000 rpm plus race motor, I would be looking for a steel crank.
Scat makes cast steel cranks, but for the most part, when guys talk about a "steel" crank, that means its forged.
Needless to say I went with forged after the Hyper deal http://www.jalopyjournal.com/forum/showthread.php?t=629626 I will never use those again
There are rare occasions where I would consider hypers, but I'd be REAL careful about what I used them in, and I'd be REAL careful about piston/wall and piston/head clearances. Maybe a TIGHT budget, hyd cammed motor that was NEVER gonna see over 6000-6500 rpm, had some cushion on the dynamic compression ratio vs available octane, and at least .040 piston/head. But yea, they scare the hell out of me. And the goddam magazines pump them like the be-all, end-all.
also dont forget about hyperutectic pistons, they are stronger then cast and cheaper then forged, hyperutectics are a great choice for moderate street use. and there only a little amount more money then cast
I am fine with cast pistons in most anything (I have several hard, wide open runs in my Uni LSR with cast pistons) but when it comes to force feeding them it's only a matter of time till you bust the rings out of them, or worse. Good luck! you've had it so far.
I don't let it detonate. Btm. It isn't luck. It Also has 76 cc heads so it's low compression listen and see what you think http://youtu.be/IZgs_-RJrZc
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