4.6L Low-buck, low CR "rockcrawler" ?'s

[team ramrod]

Ok i'm new to the board but I have question about the following combo. What I am looking for is a good rock crawler and street driver that I can run on cheap gas. I drive 90 miles to the offroad park and I would like to also take this rig on vacation. But the .035 off the deck just seems like a mile to me! I gave the numbers a quick run on the caculator and it seems to work but Who has followed this and had good results? I need to start ordering parts soon to make vacation with this rig.
Thanks for any help in advance.
4.6L Low-buck, low CR "rockcrawler"

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Silvolite UEM-2229 +0.030" bore pistons
Increase piston dish volume to 30cc
8.75:1 CR
CompCams 68-115-4 192/200 degree camshaft
Ported HO 1.91"/1.50" cylinder head
Mill block deck 0.035"
Mopar/Victor 0.043" head gasket
0.058" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, stock injectors with stock 49psi FPR for '96 and later engines
240hp @ 4700rpm, 315lbft @ 3000rpm

[SilverXJ]

There is a post on here in which a person had a stroker similar to the recipe you posted with the larger quench. He reduced the quench and made a lot more power.

[shawnxj]

if you go with the kb944's and 4.0 rods your quench will be tighter and you won't have to mill the block as much and the difference between the kb's and the silvolites isn't much considering the extra machine work needed to get the silvolites dished out. think i paid $385 for my kb 944's from rpm machine. i only went .020 over and they had them on the shelf.

after i plugged in all my data desktop dyno's telling me i'll be making 263hp at 4000 rpm and 363 torque at 2500 rpm using the lunati 63501 cam and that's with a 9.44 scr and 8.05 dcr. i went with a zero deck and will be taking off around .020 off the block

[Cheromaniac]

if you go with the kb944's and 4.0 rods your quench will be tighter and you won't have to mill the block as much and the difference between the kb's and the silvolites isn't much considering the extra machine work needed to get the silvolites dished out. think i paid $385 for my kb 944's from rpm machine. i only went .020 over and they had them on the shelf.

KB assume that you'll deck 0.020" from the block to reduce the deck clearance to 0.008"(quench 0.051" with 0.043" HG) but that yields a CR of ~9.6:1. If you don't bother decking the block, you'll have a 0.071" quench and an 87 octane friendly 9.2:1 CR.
My stroker has a 0.088" quench, 9.25:1 CR, and runs on 87 octane when it's less than 90*F outside without pinging, and that's using the hottest Champion RC12LYC plugs. The key is keeping the engine cool.

[team ramrod]

Ok to check the compression height with the KB or IC944's
Stroke 3.895
Rod Length 6.125
Piston Compression Height 1.353
Deck Height (Crank C/L to Deck) 9.450
Gives me a Deck Clearance: -0.0245

IC944 +.030
9.3:1 CR with .041 Head gasket
9.11:1 CR with .051 Head gasket
CompCams #68-231-4 206/214 degree camshaft

Is this looking right so far?

[team ramrod]

If I use the following,
Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
IC944-020
.024 Deck clearance

CompCams #68-231-4 206/214 degree camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket

I should have a DCR of 8.05:1 and a quench of .067
I think this is the pump gas stoker I was looking for.
Thanks Shawn and Silver for pointing me towards a different piston.

And now I have more questions like and easy one for starters, What is the CC of the dish in ZH825CP30? (825s 3.905) My numbers come close using 4.2 rods and crank, No decking. I end up with a .077 quench using a MP head gasket. I have played with piston CC from 12-22 and if they are in the 15-18 range this may be a cheaper option then going with the 944s.

[shawnxj]

just remember the 944's are also a forged pistons and will be able to tolerate heat better with a loose quench then the stock pistons

[papasxj]

If I use the following,
Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
IC944-020
.024 Deck clearance

CompCams #68-231-4 206/214 degree camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket

I should have a DCR of 8.05:1 and a quench of .067
I think this is the pump gas stoker I was looking for.
Thanks Shawn and Silver for pointing me towards a different piston.

And now I have more questions like and easy one for starters, What is the CC of the dish in ZH825CP30? (825s 3.905) My numbers come close using 4.2 rods and crank, No decking. I end up with a .077 quench using a MP head gasket. I have played with piston CC from 12-22 and if they are in the 15-18 range this may be a cheaper option then going with the 944s.

Did this ever get built? Any info on the results?

[dragginwagon406]

Any update on this?

[Cheromaniac]

Dunno but yesterday I put up a 4.6L modified "poor man's" stroker recipe on my site which amounts to:

4.6L modified "poor man's" stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Keith Black UEM-IC944-020 pistons
9.25:1 CR
Stock 4.0 HO camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.071" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, Accel 24lb/hr injectors with stock 49psi FPR for '96 and later engines
248hp @ 4900rpm, 306lbft @ 3500rpm (with old intake manifold and early HO cam)

A set of H825CP pistons plus a set of 4.2L rods won't cost much less than a set of IC944 pistons ($416 at Summit Racing), so you can still use the longer 4.0L rods to build a budget stroker and there's less need to use the shorter 4.2L rods anymore.

[papasxj]

I've elected to go with .030 IC944 pistons, 4.0L rods and a new Scat crank. The block's at the machine shop as I type and once the bore is complete and I can get a read on the current deck height we'll determine which why to go as far as decking, cam and injectors. I'll be porting the head starting next week. Since mine is a trail rig I'm after more low end torque than hp.