What are a good forged piston for a standard 360 Magnum.

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maca

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Hey guys I'm just stripping down my Magnum engine as I think I've broken a ring landing on the piston. I'm still running the standard Magnum pistons. Is there a forged option that I can use on the factory rods that won't break the piggy bank
 
OP, do you have any idea why the land broke? Often, this is caused by detonation. How hard are you using your engine? Using any nitrous? Turbo? More info would be helpful.

The pistons above are not cheap. Hyper pistons are reasonably strong and stronger than regular cast. I've used them in a turbo engine at 14 psi boost with no issues. So that may be an alternative. Silvolite has a 3222HC hyper piston....although the catalog says "Not intended for racing applilcations" so I cannot what that means exactly.

KB232 would be a better hyper piston.... But you have to examine gasket thickness and work on overall compression ratio, as these will stick out of a standard Magnum deck by a few thousandths and are a lot higher in the bore than standard Magnum pistons.
 
I'm pretty sure any LA 360 piston will work in a Magnum. But because the LA rods are wider at the pin end, Magnum pistons won't work in an LA. So really any 360 piston you find will work.
 
I've built 2 LA motors with TRW forged pistons, and am happy with them. But that was about 15 years ago, and I have not checked whether TRW pistons for the LA are still available or not. They made both a stock dished model and a flat-top one.
 
IIRC, TRW is now the Speed Pro line for the most part. I don't see no forged ones in their lineup anymore, just hypereutectics.
 
you narrow the small ends of the rods
best to keep tight quench adjust with gasket, if 360 piston adjust for difference in deck in your calcs
which side of the land broke spark plug, pin, intake side?
carefully inspect your rod bearings for signs of detonation
ductile rings this time
dbl check ring gap recommendations for your new specific piston (and application)
 
nm9stheham said:
OP, do you have any idea why the land broke? Often, this is caused by detonation. How hard are you using your engine? Using any nitrous? Turbo? More info would be helpful.

The pistons above are not cheap. Hyper pistons are reasonably strong and stronger than regular cast. I've used them in a turbo engine at 14 psi boost with no issues. So that may be an alternative. Silvolite has a 3222HC hyper piston....although the catalog says "Not intended for racing applilcations" so I cannot what that means exactly.

KB232 would be a better hyper piston.... But you have to examine gasket thickness and work on overall compression ratio, as these will stick out of a standard Magnum deck by a few thousandths and are a lot higher in the bore than standard Magnum pistons.
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Hey guys thanks for the replies,
I'll be having a look at the engine today to try and find out why it broke. This motor is supercharged and around 550 flywheel horsepower. I have been running more horsepower and other Magnums for a long time without issue. I've been running around 800 horsepower for about 2 years and another engine with no problems. So im thinkingit may be timing however I'm running E85 and it's very very difficult to get knock on E85. I'm stripping it down today and will get a better idea. Those forged pistons are quite expensive once I ship them to Australia
 
IMG_20180826_142003_01.jpg
 
Ok so piston landing would be from detonation but I don't know why the skirts are broken
 
Keep in mind too that the Magnum blocks have a shorter deck than the LA, so remember that when figuring compression.
 
maca said:
Ok so piston landing would be from detonation but I don't know why the skirts are broken
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You did a bang-up job there! I'm gonna guess that those pistons experienced detonation too, and the shock load hammered the pistons hard enough for that skirt breakage. The pistons are already seeing some significant side thrust even 15-20 degrees after TDC.

Was your ignition timing running at normal settings?
 
I do not know of an off the shelf forged piston with a quench dome on the intake side and a step or dish on the spark plug side
flat tops do what yours did with any little hiccup
detonation will break anything- did you say which side of the piston?
as I said I'd pick one of the KB hypers that fits your cr needs and either use it or get a forged duplicate made- done it lots of times
 
Wyrmrider said:
I do not know of an off the shelf forged piston with a quench dome on the intake side and a step or dish on the spark plug side
flat tops do what yours did with any little hiccup
detonation will break anything- did you say which side of the piston?
as I said I'd pick one of the KB hypers that fits your cr needs and either use it or get a forged duplicate made- done it lots of times
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I'm in the same boat with my 5.9 magnum turbo, looking for forged slugs. Are you saying you've used the KB hypers in a boosted app?
 
It'll not be easy to get quench/squish with the lower SCR needed for supercharging....he would need a pretty deep dish and a pad to keep the SCR down. A flat top will be too high an SCR. The ICON dish mentioned will be right at 10:1 SCR with an .039" head gasket, and the FHR flat top would be a few tenths higher.

One solution: KB362 (hypereutectic) would be around 9.1-9.2 SCR and quench/squich gap would be around .036" with a .039" head gasket (Felpro 1008). (Stock pistons would give about 8.6-8.7 with the same head gasket.) The KB362 dish would need to be milled about .045" + or - deeper to get a 26 cc total dish + eyebrow + crevice volume to get down to that stock piston's SCR level. Seems doable....

Perhaps there is enough meat in the ICON 741 or FHR flat top to mill a dish deep enough to get a total of around 26 cc's dish + eyebrows volume. It would need to be in the neighborhood of .200" deep however to get that volume... seems like an awful lot to take out.
 
subcom said:
I'm in the same boat with my 5.9 magnum turbo, looking for forged slugs. Are you saying you've used the KB hypers in a boosted app?
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I have used hypers in a turbo application with no problems. Mitsubishi 2.6L (half of a 318 dispalcement) running 14-15 psi boost; rally racing and hmmering on it all the time with all sorts of premium pump fuel from gas stations in the hinterlands and all sorts of atmospheric situations. The key was to stay out of detonation. Hypers will survive better than cast for that, but not as forgiving as forged IF you get into detonation.

IMHO.... anyone running more than 7-8 psi boost ought to be using a knock detector on the block and some sort of indicator that lights up or gives you signal when the knock detector senses knock. It will detect it far sooner than any of us with just our ears.
 
open up the chambers to get 5 cc
run the KB quench dome with deep dish pistons or get forged ones made
I can post up some pics of forged but the KB's look about the same
ductile moly rings unless really high boost
 
BTW, OP, Silvolite has some hypereutectic stock 5.9L Magnum pistons...PN is 3222HC. Their catalog entry has the note of "Not intended for racing applications". Not sure what that means... but IIRC, the hypers I used in my 2.6L turbo were Silvolites or their equivalent...i.e., nothing special.

These 3222HC's would be direct replacements, meaning no crank re-balance which would be expected with any of the ICON's or KB's.... just one more little thing to consider.
 
I suspect something like that is correct... or perhaps they are not designed to keep their dimensional stability at the higher temperatures encountered in racing use. Just trying to list alternatives, so the OP can ponder the the prices versus benefits.

(BTW, with the Magnum head's closed chambers, I am not seeing where the elevated quench pad of the KB232 is needed. Hence the KB362 suggestion....)
 
Oh right-- magnum or closed chamber head- my bad
It used to be we had to dummy up then mill the quench pad to spedcas the CH was too low (this was big blocks)
I think they have raised it needs to be a little higher than the 440 6 pack for the BBM
now with closed chamber heads the need for these pistons should go away
but still those doing retro-resto that can/ should use them
We had lots to dyno and track time in the prototypes- which were forged
Propane/ natural gas fleet users paid for the R&D including City of San Jose Bus line which was MOPAR powered
a rule
change the compression the cam spec should change
the factory HP cam was only good for long life with little lifter noise to get through the warranty period
never was the best for HP or torque (Iknow Iknow) generic use here
It dilutes the combustion charge with the late ex close- which turned out to be a benefit for smog
 
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