Jeep Strokers

casual wrote:Dino can you do a 9.7:1 SCR & a 7.4:1 DCR on 91 octane?

With a DCR that low I'd expect the engine to run on 91 octane with ease.

OK, I think I have a plan, again all depending upon how the block looks when it's checked out.

I might get away with only 20 over (square engine), but the norm seems to be 30, so I'll base my plans on that.

3.905" - Bore (30 over)
9.440" - Deck Height (~0.013 mill)
3.895" - Stroke (Scat 942010 Crank)
6.125" - Connecting Rod
1.353" - Pin Height (Keith-Black Silvolite (UEM) forged stroker IC944 Pistons, 21cc dish volume)
0.041" - Compressed Gasket Thickness (Mopar/Victor 0.043" head gasket)
0.0145" - Deck Clarence
0.0555" - Quench Height
60cc - Increased Head Combustion chamber
Comp Cam 68-232-4 (Intake valve Closing Value 55)
9.28 - Static Compression Ration (SCR)
7.97 - Dynamic Compression Ration (DCR)
89 - Targeted Octane rating
Not sure where the HP and Torque will end up, but I suspect somewhere close to 245/320 area.

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Keith-Black Silvolite (UEM) forged stroker IC944 +0.030" bore pistons
Leave piston dish volume at 21cc and Polish
9.3:1 CR
CompCams 68-232-4 Duration 250/256, Lift .460/.476 camshaft
Ported & Polished HO 1.91"/1.50" cylinder head
Mill block deck ~0.013"
Mopar/Victor 0.043" head gasket
0.0555" quench height
Ford 24lb/hr injectors with adjustable FPR (Part no. FMS-M9593-A302 & Hesco HES9195FR)

Thoughts,
Will

Good plan but be sure that you get the Mopar Performance valve springs/retainers/keepers and not the CompCams versions.

Not sure where the HP and Torque will end up, but I suspect somewhere close to 245/320 area.

Good estimate. I was going to say 250/320 but it depends on the quality of the head port job.

Cheromaniac wrote:Good plan but be sure that you get the Mopar Performance valve springs/retainers/keepers and not the CompCams versions.

Cheromaniac,

Thanks. I was assuming I needed the Comp springs and retainers. So i need to Mopar's? Any part numbers for the Mopar Performance valve springs/retainers/keepers? Any special cam timing requirements with this setup?

Note, in the above post I stated the rods wrong in the descriptive part of the recipe. It should be Jeep 4.0L 6.125" rods.

Thanks,
Will

W_A_Watson_II wrote: Retlaw01XJ, how does those cams effect the torque level and curve?

Thanks,
Will

Firstly, a cam should be matched to the compression ratio for best performance.
Keeping the same SCR and installing a larger cam will produce less low-end power but increase top end power.
DCR is usually reduced in those cases since the intake valve closes later as duration is increased.
BUT.... a bigger cam can tolerate more compression ratio, so if you also increase the CR (static) , you can maintain the low-end power and also increase the top-end power!
There are computer dyno sims out there where you can try different cam and CR combinations. Dyno 2003 is one that's avail free online.
Look in the 'software' section:
http://loco4fomoco.com/video.html
I'm getting better numbers with the Comp 231 cam when compared to the Comp 232 cam....

W_A_Watson_II wrote:Cheromaniac,

Thanks. I was assuming I needed the Comp springs and retainers. So i need to Mopar's? Any part numbers for the Mopar Performance valve springs/retainers/keepers? Any special cam timing requirements with this setup?

Springs # DCC-5249464, retainers # DCC-4452032, keepers # DCC-4529218 from Summit racing

No special cam timing requirements. Just install timing set dot-to-dot.

Retlaw01XJ wrote:I'm getting better numbers with the Comp 231 cam when compared to the Comp 232 cam....

Same here. I'm getting 10hp more at the top end with the 231 cam but with almost identical HP/TQ numbers to the 232 cam from 4000rpm and below.

Walt,

Hey thanks for the explanation, Also thanks for the link to the software. I own a copy (I think 2000) somewhere, and several computers ago and can't find it so this helps a lot.


Cheromaniac,

Thank you for the part numbers, and confirmation on the cam comment.


Will

Just a quick up-date. I'm about 20 hours into my "Transmission Job" (http://jeep.wawii.com/93YJ_TrannyJob.htm) and have the head off the 4.0L. cylinder walls look good, carbon on the heads and intake, but I'll soon have the block out and to the machine shop.

I dropped the Block and Head off at the Machine shop today, and the Transmission and shoot torque Converter off at the Tranny shop as well. So progress continues.

Cheromaniac wrote:The low buck stroker has an aftermarket cam and requires upgraded valve springs/retainers/locks ....

Cheromaniac,

I thought I had received the a recommendation on the for parts/numbers for the valve springs/retainers/locks, but I can't seem to fins any. Do you know where I can get them, Comp Cams just said contact Hesco (which I have, just waiting on a response).


NEVER MIND, I didn't look at Page 2:

Springs # DCC-5249464, retainers # DCC-4452032, keepers # DCC-4529218 from Summit racing

Thanks,
Will

Got the response from Hesco on the valve springs and retainers. So to go with my selection of COMP Cams Xtreme 4x4 Cam and Lifter Kits (SK68-232-4) I need to add Hesco 4.0L Performance Valve Springs & Retainers (HESSPRSS6).

W_A_Watson_II wrote:Got the response from Hesco on the valve springs and retainers. So to go with my selection of COMP Cams Xtreme 4x4 Cam and Lifter Kits (SK68-232-4) I need to add Hesco 4.0L Performance Valve Springs & Retainers (HESSPRSS6).

Hesco's stuff is usually very expensive but shiver me timbers, their spring/retainer kit is actually a lot cheaper than the Mopar springs/retainers from Summit Racing. Wow.

But the Hesco springs require machining the spring pockets in the heads....so add that to the total cost.
I searched hi and low for some affordable drop-in replacement springs without luck.

I had to machine my 7120 head to accept the Mopar springs to achieve the correct spring pressure.

In addition to the Block and Head Machining that's underway, I now have the following parts on order:

304 STAINLESS STEEL JEEP SINGLE MANIFOLD 1991-00 4.0 L # PH-051 - eBay
4.0L Performance Valve Springs & Retainers #HESSPRSS6 - Hesco
Jeep 4.2L 3.895" Crank & Bearings - Donnelly Automotive Machine (Carquest)
6.125" - Connecting Rod, Jeep 4.0L - Donnelly Automotive Machine (Carquest)
Keith-Black Silvolite (UEM) forged stroker IC944 Pistons, 21cc dish volume (30 over) & Rings - Donnelly Automotive Machine (Carquest)
Engine Gaskets & Seals Set - Donnelly Automotive Machine (Carquest)
K&N PS-2004 - K&N Pro Series Oil Filters - Summit Racing
COMP Cams SK68-232-4 - Xtreme 4x4 Cam and Lifter Kit - Summit Racing
COMP Cams 104 - COMP Cams Engine Assembly Lube - Summit Racing
COMP Cams 159 - COMP Cams Engine Break-In Oil Additive - Summit Racing
E3 Spark Plugs E3-58 - E3 Spark Plugs - Summit Racing
Summit Racing Delivery and Handling Charge