Replacement 5.9l Piston Recommendation

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Iceworkz

Iceworkz

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Hi All

Looking for recommendation of replacement pistons based on experience for my mild 5.9l Magnum rebuild. I'm happy with 9:1 comp and want to keep the narrow metric style ringset. Seems I have 3 choices, either the silvolite 3222, 3222HC which looks the same as factory or the Sealed Power H655CP which is different in the skirt design below the pin and is slightly heavier than the OEM piston. Any thoughts from the group members ?

Thanks
 
Most magnum pistons are .035"-.060" in the hole, which will net about 8.7-9 ratio. What I am getting at is that the cam you listed probably wants closer to 9.5. now if you are only .035" in the hole not a big deal but if you have a .060" in the hole block, you will be pretty low for that cam. What does Dave say about comp ratio with that cam? 9-9.5? The only reason I am saying this is if you have a tall deck height and factory pistons, you might want to choose a non factory piston or step down one cam size. If you want to do the math, the formula for comp distance is A-(B/2+C)-D with A being Deck height, B being stroke, C being rod length and D being deck clearance. Magnum deck height is 9.580" Stroke is 3.58" , Rod length is 6.125" deck clearance at .050" A quick calc comes to 1.615 so if I added correctly and the scummit catalog is correct for 3222HC at 1.605 that piston should put you .010" in the hole which should get you much closer to 9.5. Like I said, "if" i calculated correctly, being fairly brain dead after a long typical Monday, and assuming summit is correct, that would be the one I would choose but you might want to re run the numbers just to make sure, 3 crushed disks and 12 hours on my feet cause enough pain to make me fairly brain dead. Hope this helps. I would also call Dave and see what comp he wants with that cam along with piston recommendations. You will also need a spring kit like Dave or myself sells. Evan magnummopar.
 
I would stick with the high quality exact factory replacement. Not a thing wrong with them.
 
magnummopar said:
Most magnum pistons are .035"-.060" in the hole, which will net about 8.7-9 ratio. What I am getting at is that the cam you listed probably wants closer to 9.5. now if you are only .035" in the hole not a big deal but if you have a .060" in the hole block, you will be pretty low for that cam. What does Dave say about comp ratio with that cam? 9-9.5? The only reason I am saying this is if you have a tall deck height and factory pistons, you might want to choose a non factory piston or step down one cam size. If you want to do the math, the formula for comp distance is A-(B/2+C)-D with A being Deck height, B being stroke, C being rod length and D being deck clearance. Magnum deck height is 9.580" Stroke is 3.58" , Rod length is 6.125" deck clearance at .050" A quick calc comes to 1.615 so if I added correctly and the scummit catalog is correct for 3222HC at 1.605 that piston should put you .010" in the hole which should get you much closer to 9.5. Like I said, "if" i calculated correctly, being fairly brain dead after a long typical Monday, and assuming summit is correct, that would be the one I would choose but you might want to re run the numbers just to make sure, 3 crushed disks and 12 hours on my feet cause enough pain to make me fairly brain dead. Hope this helps. I would also call Dave and see what comp he wants with that cam along with piston recommendations. You will also need a spring kit like Dave or myself sells. Evan magnummopar.
Click to expand...
Post 4,and please measure......
 
magnummopar said:
Most magnum pistons are .035"-.060" in the hole, which will net about 8.7-9 ratio. What I am getting at is that the cam you listed probably wants closer to 9.5. now if you are only .035" in the hole not a big deal but if you have a .060" in the hole block, you will be pretty low for that cam. What does Dave say about comp ratio with that cam? 9-9.5? The only reason I am saying this is if you have a tall deck height and factory pistons, you might want to choose a non factory piston or step down one cam size. If you want to do the math, the formula for comp distance is A-(B/2+C)-D with A being Deck height, B being stroke, C being rod length and D being deck clearance. Magnum deck height is 9.580" Stroke is 3.58" , Rod length is 6.125" deck clearance at .050" A quick calc comes to 1.615 so if I added correctly and the scummit catalog is correct for 3222HC at 1.605 that piston should put you .010" in the hole which should get you much closer to 9.5. Like I said, "if" i calculated correctly, being fairly brain dead after a long typical Monday, and assuming summit is correct, that would be the one I would choose but you might want to re run the numbers just to make sure, 3 crushed disks and 12 hours on my feet cause enough pain to make me fairly brain dead. Hope this helps. I would also call Dave and see what comp he wants with that cam along with piston recommendations. You will also need a spring kit like Dave or myself sells. Evan magnummopar.
Click to expand...

Thank you Evan for taking the time to make such an informative response to my question. I just realized that I quoted you the wrong cam so what you said about going down 1 size applies, the cam I ordered was the SB HYD RLR CAM 218/222 -110ºLSA. I had also ordered the matching springs and was planing on using the Mr Gasket gaskets 1121G which should be good for about .3 of a comp ratio more compression.
 
I spoke with the tech guys at Speed Pro last week and they claim that the H116CP will have low 9's compression in a 360 with 70 cc heads....

I'ma gonna try a set to see...
 
image.jpeg
I used sealed power with eq heads and had Oregon cams do a custom grind on the roller cam. I haven't put it on the dyno but it's much healthier! Magnumswap.com was great help
 
krazykuda said:
is that a true measured number of just one out of a book???

It will raise the compression a little, but you also have to take the block deck height into consideration...
Click to expand...

That is the correct volume, unlike LA's the Magnums never came with any other chamber size from factory and EQ's are same. I believe Edelbrock might offer different but we dont use them in our shop, too many issues with them. Off the top of my head, I would say at least a whole point or more going from 70 to 63, probably put you at around 10.5+
 
After considering the comments here and doing as much research as I can I'm leaning towards the Sealed power H665CP as there isn't really much to separate them from the Silvolite 3222HC except the listed compression height is 7 thou higher and their nearly half the price (Not always a good thing). What I find strange is Silvolite say their Hypereutectic coated skirt 3222HC is "Not intended for Racing applications" but no such comment on the stock replacement 3222. Are they just saying don't use this as a forged replacement ?
 
They are referring to max RPM and HP they are rated for and are for a non boosted or juiced application. They look very racy and are inexpensive so they dont want claimer guys ringing them to 8K or using them on a 250HP nitrous shot. They are great for anything with a cast crank as they will both crap out at anything over 7500. It doesnt mean you cant go play at the strip on weekends, just keep the R's respectable and no power adders. You should be very happy with them.
 
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