Stroker Piston Choice / Recipe

[3XJFamily]

Working with a shop who has been building 4.6l stroker long blocks to run on pump gas. Planning to run it in a 91 Daily driver:

Jeep 4.2L crank and rods
Compression Ratio 9.2:1
CompCams #68-232-4 206/212 degree camshaft
- 113 separation 3 degrees advance ground in
Ported HO 1.91"/1.50" cylinder head
Stock 0.051" head gasket
0.05" quench height

Need to make a piston choice - (they say they "trim a little off the top"): Speed Pro H825CP +0.030" bore pistons or Speed Pro 677P +0.030" bore pistons?

Does this "recipe" make sense?

Thanks in advance for input from the stroker guys!

 

[old_man]

I am running the Sealed Power H802CP pistons and decked the block .030". It runs great, no ping on regular gas.

Heavy crank 4.2L crank and 4.2L rods.

The cam is a Crane #750501 192/204 degree camshaft.

I am running a Clifford header, 2.5" pipes, Magnaflow muffler.

Ford 24# injectors.

 

[Dr. Dyno]

Working with a shop who has been building 4.6l stroker long blocks to run on pump gas. Planning to run it in a 91 Daily driver:

Jeep 4.2L crank and rods
Compression Ratio 9.2:1
CompCams #68-232-4 206/212 degree camshaft
- 113 separation 3 degrees advance ground in
Ported HO 1.91"/1.50" cylinder head
Stock 0.051" head gasket
0.05" quench height

Need to make a piston choice - (they say they "trim a little off the top"): Speed Pro H825CP +0.030" bore pistons or Speed Pro 677P +0.030" bore pistons?

Does this "recipe" make sense?

Thanks in advance for input from the stroker guys!

If you use 677P pistons and Mopar 0.043" head gasket, the CR will be 9.3:1 and you won't need to shave the block nor the head. Your stroker would be almost identical to mine except for the cam and the 0.030" overbore.

http://www.angelfire.com/my/fan/stroker.html

I've done 13,000 miles on my stroker so far and it really kicks ass. I love it!

 

[3XJFamily]

If you use 677P pistons and Mopar 0.043" head gasket, the CR will be 9.3:1 and you won't need to shave the block nor the head. Your stroker would be almost identical to mine except for the cam and the 0.030" overbore.

OK, based on the caliber of the responders, I'm hearing that either the 677P or a "CP" type piston would work just fine. . . The shop typically uses the 677P - any advantage to going to a coated piston?

Crank choice - light or heavy? I've got an automatic with 31's and stock gears (no plan to change from 3.54's) which made me think "light". But then, I was thinking "heavy" since I prefer more of a "pulls like a truck" feel, and have at least 400lbs of accessories bolted on. On the street, I'm light on the gas pedal (rarely WOT) and tend to coast alot in traffic. Offroad, I find my worn out 4.0 spins down too quick for my taste.

 

[Dr. Dyno]

The 677CP's with the graphite-coated skirts would be better since the coating reduces piston to bore friction.
If you spend a lot of time offroad, you'll love the heavy crank. I've allowed my stroker to drop down to 500rpm several times while driving on dirt trails and it never felt like it was going to stall.

 

[old_man]

I am running the heavy crank and wheel the piss out of it. Origionally I had the AX-15 but changed over to the auto due to breaking too many axles. The heavy crank is sweet with a stick. I don't think it is particularly needed with an auto, but I doesn't hamper me with the auto. When I was running the stick I ended up having to stop in the middle of about a 45 degree rock incline when someone stumbled into the trail. I accidentally let my left foot slip off of the clutch at an idle. It lurched and just kept pulling. It never died.

Dr. Dyno, the H802CP's also have the coated skirts.

 

[Dr. Dyno]

Dr. Dyno, the H802CP's also have the coated skirts.

Indeed they do, as do all Speed Pro pistons with the CP suffix.
Remember 677CP = 17.5cc dish, 1.585" compression height, H802CP/H825CP's = 15.8cc dish, 1.592" compression height. Therefore 677CP's add 3.1cc more combustion volume than the H802CP/H825CP's and yield a CR that's ~0.3 lower.

 

[jeep1947]

where would I be able to get the sealed power pistons? Does any autoparts store carry them, or is there a good web site to go to? thanks.

 

[karter74]

yeah they are very common pistons, i think they are from federal mogul (?)

 

[Dr. Dyno]

where would I be able to get the sealed power pistons? Does any autoparts store carry them, or is there a good web site to go to? thanks.

Try http://www.summitracing.com

 

[TJGordo]

Dumb question from a stroker n00b - how do you tell the diff between a heavy and light crank ? Cast # ?
TIA

 

[tazz]

Yeah the sealed power pistons are sweet here's a couple of pic's of the one's I put in the old 3.1L I did up for the cavalier I used to have.

 

[Dr. Dyno]

Dumb question from a stroker n00b - how do you tell the diff between a heavy and light crank ? Cast # ?
TIA

The heavy 258 crank weighs 66lb and has 12 counterweights, whereas the light 258 crank weighs 46lb and has 4 counterweights. The 4.0 crank weighs 55lb and has 8 counterweights. It's all here:

http://www.angelfire.com/my/fan/selection.html