Cast vs Forged Pistons

[khryslerkid]

What's the horse power limitations for a cast piston? Just looking at flat tops. Doing a rebuild, street friendly but might take a pass now and then. Aren't most factory pistons cast? (RB engine)

Thanks in advance!

 

[Moparmatt72]

Not sure the power limit, but if you don't want to run forged which is always better can go with the hypertechic pistons.

 

[khryslerkid]

Hypertechics are normally dished, correct?

 

[super-bee_ski]

Not sure the power limit, but if you don't want to run forged which is always better can go with the hypertechic pistons.

Just go online and do a search such as: Hypereutetic piston VS Cast piston VS Forged piston
Many, many articles...
Here is one interesting article for you: http://www.google.com/url?url=http:...oQFjAF&usg=AFQjCNHE3eLQttrA1UR1QYDw_r9uaI2RYg

Also,
1. Cast pistons are great for plain street driving. A good quality Cast piston today is "Light years" ahead of the Cast pistons of yester-year
2. Hypereutetic pistons have a different construction technique. Stronger and lighter than Cast. Able to "heat-up" to engine temps quicker (My choice for street car under 7,000RPM)
3. Forged pistons: I'm NO expert, but, primarily a RACE proven, extremely "Robust" item. Yup, its for racing.
My point?.. It's neat to be a Chey guy and tell everyone that you have Forged Pistons in your 1969 Camaro. L.O.L!
But, with forged pistons come dis-advantages too...
So, go with what your research tells you. And, listen to some of our members here on the Forum.

Remember; during the 60's many a Muscle car had a cast piston. One of my "old-1967 GTOs had cast pistons, it was a 400 CI "HO Motor"
It ran good...

 

[zyzzyx]

Cast pistons are not as strong as forged and can't be revved as high, and
also are not as "dense" as forged so they do not trasfer heat as well. No
Nitrous Oxide on cast pistons! Other than that they are fine for stock.

 

[Hemi Rebel]

Its been my understanding that hypereutectics are cast pistons. Just really really good cast pistons but brittle. I ouldn't use them in a nitrous or boosted engine. Stick with the tried and true forged pistons there.

 

[bm02tj]

The only disadvantage with forged is you need more clearance and you can get a little piston slap cold
which to me is not a problem because you know why and it goes away when hot

 

[747mopar]

Hypertechics are normally dished, correct?

Nope, I'm running KBs in my 456 stroker and they were domed and had to be milled down to get the compression low enough for pump gas. I personally like them for street motors because of the tighter fit meaning better oil control and less wear.

 

[khryslerkid]

Thanks for the education on hypertechic pistons. Reading the link that Super bee posted cleared it up too.
Looks like I have some more homework to do yet. I've been out of the loop on pistons for sometime and it looks like technology has past me by, yet again!

I'm not going on the bottle or blown. Just wondering how far you could push a cast piston without having to go forged. Hughes has just straight up cast pistons with a hardening treatment optional. Would they stand up to factory specs without going to a hypertechic piston? Or is the hypertechic piston closer to a factory piston?

 

[super-bee_ski]

I'd go the "Hypereutetic" route.
Cost is more but insurance wise...it is a better choice.

Call up the techs at "sealed Power" and see what they say for your application.

 

[Cranky]

Chrysler's cast pistons are not a bad piece by no means but you'll have a hard time finding a good set these days and I'm not experienced in their replacements. Today's cast pistons are better imo and even the factory cast slugs will take some N2O if you make things somewhat rich. Lean conditions will melt them! With the Hypers, you better set things up by the book or they will come back to hit you but so long as you do that, they work well but like factory cast, you need to make sure things are right for the happy gas. As for the cast replacements, I've built engines with as little as .0005 clearance (better have straight cylinders) and have done engines with .004 with the older forged slugs but you need to keep things from running hot with .004. The biggest down side to the older forged pistons is weight....those bastids are heavy but with some ball end mill work, you can take out some of that because they are pretty dame strong and milling, you can reduce the weight from the old school forged pistons. Be advised that it won't be cheap to have them done by a machine shop.

 

[383man]

I can tell you my brother built a 400 with stock cast pistons and he used 915 heads that were cut to get 10.6 comp in the eng. It has the MP .557 cam with the TM6 intake and an 850 DP. It was in a 3100 lb Duster with good headers and converter. The car ran a best ever of 10.94 and normally ran 11.0's to 11.20's on normal days. His son drove it and shifted it about 6800 to 7000 as it had 5.13 gears. He was pushing it to much in my opinion as I dont believe the heads worked to good at that high rpm but they were heavily ported. Anyway he ran it for 3 seasons as it was a race only car and then at the start of the 4th season a piston let go and blew apart ! We were surprised they held up that long as he just threw it together to see how they pistons would hold up as he used alot parts he had laying around in it. So they did hold up good for a cast piston as on a street car thats basically a cruiser cast pistons are fine. I also built a mild 383 in my old Dart with cast stock pistons as I had the MP .484 cam in it and the usual bolt on's. I raced it about twice a year and drove it all the time. It ran 12.30's @ 110 and never gave me a problem. WE pulled the eng when my son bought it to put a stronger 400 thats still in it now running 11.40's @ 117 and it has hypertech pistons in it.

I ran the KB hypertech in my old 440 in my 63 as I built it in 2006 and it is still going strong in my buddies Duster. I raced it some and all and they have held up great and you know I drove it on the street alot also. But I would not put the juice to hypertech pistons as they may blow apart. Also make sure you set the ring gaps at their proper specs in the hyper pistons.

And I have forged pistons in my 493 that work great for me in my street/strip 63 as I shift it about 6000 to 6200.
They all work fine as long as you use them for what they are made for. Myself if I build a street/strip car and can get forged I would but for a mild street car with a few trips to the track cast and Hypertech can work fine as long as you dont over abuse the eng with NOS or way to many RPM's. I have used them all in my street/strip cars and never broke a piston in mine as only my brother broke a cast piston but he did abuse that eng. Ron

 

[khryslerkid]

Thanks guys! Very informative as always. I'm going to get the block to the machine shop next week to have it checked out. I'll have some knowledge on pistons now. He's a good engine builder so I trust him to do the right set up.

Thanks again! :hatwave: