Jeep Strokers

After having some issues with Dyno2003 I got my hands on Engine Analyzer Pro, I'm hoping this can shed some light into accurate numbers for stroker builds. I'm pretty new to all of this and the amount of specs is overwhelming. If the community can help me put this together/verify everything I can run simulations with various engines, cams, etc. I definitely need verification on a couple points, I underlined these areas

I'm going to use the following engine specs for the first run
Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Keith-Black Silvolite UEM-IC944 +0.060" bore pistons
CompCams 68-231-4 206/214 degree camshaft
CNC ported HO 0331 1.91"/1.50" cylinder head
Mill block deck 0.020"
Mopar/Victor 0.043" head gasket
0.051" quench height
63mm over bore TB
Accel 24lb/hr injectors for '96-'04 #150124

I'll be referencing the EAP manual heavily for a lot of this http://performancetrends.com/PDFs/EAPMan4.pdf

Block Specs


Bore - 3.935" (0.060 over bore)
Stroke - 3.895"
Cylinders - 6
Piston Rings - From what I read Sealed Power 50076CP-060 Mahle rings are standard tension
Piston Skit Reference manual shows the following

I can't seem to find this info on the IC944's
Piston Top Another tough one to source, I'm assuming the top isn't specially coated
Cyl Leakage I want to say typical or low leakage for this
Design This is for the crankshaft design in terms of windage drag, typical should be good for this

Crankshaft Inertia


Component Wts - Considering the 12cw crank I used old '60s production
Flywheel weight - Replacement crown flywheel is 21.4 lbs
Flywheel diameter - Replacement crown flywheel is 13" diameter
Rotating mass Weight and Diameter - This is for the dyno specs, EAP manual suggests 25lbs and 9" for a typical water brake dyno

Bearing Size Coef


# of Main Bearings 6
Main Bearing Diameter - EAP manual says 0.05" accuracy is OK. This being said I think using the journal diameters is ok? My 02 TJ FSM says this is 2.5001" for journals 1-6. I measured 2.533" with my electronic caliper but these were very worn bearings
Main Bearing Width - 0.98" measured with electronic caliper
# of Rod Bearings 6
Rod Bearing Diameter - 02 FSM states journal diameter is 2.0955
Rod Bearing Width - 0.833" measured with caliper
# of Cam Bearings 4
Cam Bearing Diameter - These are different sizes, average journal diameter is 2.015"
Cam Bearing Width - I couldn't measure the bearings in block or find anything online, best I have is 0.8" but I'm not 100%

Head Specs


I'm based a lot of these specs off of these two sites
http://www.jeep4.0performance.4mg.com/tech_specs.html
http://users.erols.com/srweiss/tablehdc.htm#Chrysler

Intake Average Port Diameter - Typing in the following gives me the calculated values
Port Width - 1.375
Port Height - 1.625
Port Shape - Rounded Rectangular

Exhaust Average Port Diameter - Typing in the following gives me the calculated values
Port Width - 1.250
Port Height - 1.375
Port Shape - Round Rectangular

Head Anti-Reversion
This one I have no clue on, the manual states this on page 28 of the pdf

Describes how well the port, valve and manifold resist flow in the reverse direction. For the intake this would be flow leaving
the cylinder and "back flowing" into the intake. Ports which flow equally well in both directions would have 0% anti-reversion.
A port with reed valves (check valves) which only allow flow into the cylinder would have 100% anti-reversion. See Section
2.9.5 and Example 4.4 for calculating anti-reversion from flow test data. Note: Most heads have very little or 0 anti-reversion.

Head Flow Table


This wasn't too hard with the specs readily available for a ported 0331

Chamber Design
Here's what the EAP manual says

From the sounds of it the 4.0 has a hemispherical chamber design, opinions?

Intake System Specs


Design - I think straight runners apply here as they have constant width throughout?
Manifold Type - Single Plenum EFI
Intake Heat - I think reduced heat is the right option here -manual states

Production individual cylinder fuel injection manifolds or carbureted manifolds with blocked exhaust crossover.

Runner Diameter @ Head

Runner width - 1.26
Runner Length - 1.53
Runner Shape - Rounded rectangular

Runner Flow Coef

Flow Data Head Only
Test Pressure In. Water - 28"
# Valves - 1
Valve Diameter - 1.9"
Valve Lift Tested - min for program .4
Flow w/o Runner, CFM - 219.5
Flow Data with 1 Runner
Runner Diameter - 1.26" - I used to intake runner port width for this
Flow with 1 runner - Not sure where to source this one

Fuel Delivery Specs
Injector Rating lb/hr - 24.3
Injector Raed Pres, PSI - 43.5
Operation Fuel Pres, PSI - 49.2 (02 TJ FSM Specs)
Pressure Control - Pump is internally regulated - hold constant pressure should work here
Total # Injectors on Engine - 6
Firing Method - Once/Cycle (2 revs)

Throttle Body Specs

I pulled these from Dino's website for a 62mm bored TB. Converted 1.5 inHg to 20.392 inH20, does this sound right?

Plenum Specs
Dino's intake spec website says the newer manifold total volume is 4300ml, this converts to 262.402 cu. in. Now for some shoddy math because I couldn't find the plenum volume. Let me know if someone actually knows this value

Runner Length - 9.5" (can someone confirm this is true for 00-06 intake?)
Runner Width - 1.26
Runner Height - 1.53
Total Runner Volume (All 6) - 109.8846
Plenum volume = total intake volume - runner volume = 262.402-109.8846=152.5174 cu. in.
Throttle body length/area - For some reason I can't seem to edit this

Cam Specs
Taken from spec sheets for COMP Cam 68-231-4, waiting to hear back from them on the dwell over nose angle


Exhaust Specs This is one I really need help on... with everything haha. I don't have any data for any of these


I'm almost close to having everything fairly accurate, I'll continue working on this and post results!

You'll need to adjust the cam specs that you've entered. The 0.050@ duration numbers are 206/214 and the 0.462"/0.485" lift numbers are at the valve, not the lobe. Divide those numbers by 1.6 (rocker arm ratio) to get lobe lift.
The IC944 pistons have a 1.353" pin height.

Yarg! I always get the cam values wrong! I fixed these and I'm getting 356tq@2000 and 297hp@5000, seems a little high. I still think my exhaust/intake values are off