Jeep Strokers

I just picked up Dyno2003 today to play with different cams, I'm looking at a 4.7L build and I'm surprised at the output of the simulation, maybe I have some settings wrong?





I noticed the CR calc was a little wonky, I had to play with the volume above piston to get the right total combustion volume CC




I got most of the specs here http://www.jeep4.0performance.4mg.com/tech_specs.html

I lost all of my simulations in a systems crash a while back!? but if I recall the figures you got (I only looked at the graph) with the Comp 232 cam look a little high to me?, after several simulations (several cams) I disregarded the Comp 232 cam as a possibility, I went back with the stock OBDII cam.

These numbers look too high? I was expecting this 4.7L to get around 260-270hp to the crank

Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Keith-Black Silvolite UEM-IC944 +0.060" bore pistons
9.6:1 CR
CompCams 68-231-4 206/214 degree camshaft
CNC ported HO 1.91"/1.50" cylinder head
Mill block deck 0.020"
Mopar/Victor 0.043" head gasket
0.051" quench height
65mm over bore TB

I probably need to edit the head air flow characteristics to reflect port/polish for a more accurate depiction but this simulation peaks at 228hp/299ft-lb

I'm not sure why everyone thinks that by stroking and putting a cam in they're going to get a 50% HP increase??

I think the lift is too high for that cam you used.

IH 392 wrote:I'm not sure why everyone thinks that by stroking and putting a cam in they're going to get a 50% HP increase??

I only expect it because it is advertised alongside all of the recipes online, maybe someone should tweak these to more realistic numbers?

As for the lift in the simulation, I took the values directly from Comp Cams, I'll double check tonight though

IH 392 wrote:I'm not sure why everyone thinks that by stroking and putting a cam in they're going to get a 50% HP increase??

mikalcarbine wrote:I only expect it because it is advertised alongside all of the recipes online, maybe someone should tweak these to more realistic numbers?

It's more like a 30-40% HP increase but the added displacement is only part of the story. The rest of the HP increase comes from external bolt-on mods (CAI, larger TB, header, exhaust), porting the head, the higher compression ratio, and a performance cam (optional). If you leave the stock head unported you can expect about 20hp less.

How could one reflect this in the simulations? Do you know of any head flow tables for ported/polished heads?

Errr found the ported specs right on that website haha, I also read that the induction flow with K&N can be 607 cfm @ 1.5inHg (found here http://jeep4.0performance.4mg.com/intake.html), I stuck with 500cfm to be conservative, I tried 607 and it didn't make much of a difference.

Not sure what cam values I was using for that one, I kept the 232-4 name but changed values to a few others. I fixed the values and I'm still not getting values I think I should be







Am I setting up the cam values wrong? I'm using seat-seat advertised directly from the COMP Cams website

Can't seem to edit my post, I've entered all of the correct cam values based on some threads I found of yours (to use 0.050 values). The values in the 4.0 cam spreadsheet online seem a little off so I used .050 values from COMP Cam's camquest software (seems like a cheap copy of Dyno2003 haha)





Still peaking at 311tq 225hp?? I tried the values in the cam spreadsheet and it made this worse

As you simulations show the Comp 232 cam really isn't a good choice, try the Comp 231 cam or even the OE "OBDII" cam, even the Mopar 229 is as good if not better?,

I tried the 231 and it was better but not much, I've read a few posts where peoples baselines where in the 250's for HP I don't know what I'm going wrong. I was to going to simulate a bunch of cams for comparison and post the results. I think the fact dyno2003 doesn't show results lower than 2000 rpms almost makes this pointless for those wanting low end torque (like I'm going for)

mikalcarbine wrote: I noticed the CR calc was a little wonky, I had to play with the volume above piston to get the right total combustion volume CC

You have piston down from TDC as 0.100" which is way too high. For the 4.7L recipe that I suggested it should be 0.007".
Also try entering only the 0.050" duration numbers for each cam and omit the advertised duration.
You might also want to try entering these head specs:

Ported HO head #7120

Valve lift (in)... 0.1 ... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 68.4 132.6 185.4 213.4 216.5 216.5
Exhaust flow. 64.3 116.9 149.6 158.9 164.8 165.0

For some reason dyno2003 only allows values of 0.1 to 2.0 inches for piston down from TDC? So I put 0.1 in and backwards calculated the volume above piston (including 21 cc dish) to get the right total combustion volume. Does that make any sense?

I'll try those flow numbers next, I did play with actual 0.050" duration numbers last night and it did make some of a difference but maybe the flow numbers are killing it for me

You cam numbers are right. As are the rest. I would change the axis properties to all low range.