Jeep Strokers

2003 Block 0 deck
0331 Head
4.0L rods
kb 945 10.7:1 pistons
comp 68-232-4 Camshaft
Static 9.47:1
Dynamic 8.13:1
Quench 0.051

What is your opinion on this. I know I will have to run premium, but is there any info on what the stock 2003 ecm will do with this, and what problems could I have. I'm just in the research stage so any input would be helpful. Also is there anything that I will have to modify in the fuel system (besides injectors of course). Thanks

Your math is incorrect. Using the KB945 pistons your SCR will be a good deal greater.

what vehicle is this going into? the same one the block came from? to get teh full effect you may want to consider a chip of some sort, but other than that, just the injectors i believe.

Sorry your right the SCR will be 10.53:1 and the DCR will be 9.01:1.
This engine will be going into a 2003 Rubicon. I already have a edge performance chip, intake and throttle body. Is that chip going to help me or hurt me?

You do not want a DCR higher than 8.5:1 unless you plan on using e85 or race fuel(octane higher than 93). If you plan on using 93, shoot for an 8.3-8.4:1 dcr that way if tolerances/measurements are a little off/wrong you will still be ok. I have compression knock(pinging) w/ 93 octane in closed loop b/t 2500-3000rpms due to my 8.57:1 dcr and the obd2 holding that 14.7:1 afr. Buy the 944s.

If I go with the 944's should I stick with the same cam or go with a different one.

Comp's 231 and 232 seem to be the most popular choices for strokers, so as long as you have calculated the crs correctly, you should be good to use it.

I don't think the edge chip does much do begin with so I doubt it will add or subtract anything.

It adds ignition which makes high comp strokers ping. Some of those programmers have different tunes for different octanes, so I could see how the lower tunes could help out. It'll come down to trial and error to see if it helps you out or not.

SilverXJ wrote:Your math is incorrect. Using the KB945 pistons your SCR will be a good deal greater.

Yeah, it'll be ~10.9:1. Unless you're going to be running the engine only on propane, I advise that you go for the IC944 pistons instead. These will lower the CR to a more acceptable ~9.8:1.

hi , don't mean to hijack this thread but I would like to get an opinion on my recipie. I am building a 4.6 short rod engine and I am going to end up with around 9.1:1 scr and 7.83 dcr with a .056 quench. does this sound like a reasonable combination to run 87 octane, or should I try to get the quench closer to .051?

rammit11 wrote:hi , don't mean to hijack this thread but I would like to get an opinion on my recipie. I am building a 4.6 short rod engine and I am going to end up with around 9.1:1 scr and 7.83 dcr with a .056 quench. does this sound like a reasonable combination to run 87 octane, or should I try to get the quench closer to .051?

Sounds good as it is. I can run mine on 87 octane with the hottest plugs (Champion RC12LYC) and a 0.088" quench. I think people get too hung up on the quench issue.