Need guidance on a stroker recipe.

[KaiserJeep]

I have a 2003 TJ Rubicon with a totally stock 4.0 that is still under 50,000 miles, and I have never had an engine problem other than one throttle position sensor. The Jeep is on 33's with stock 4.11 gearing and an NV3550 5-speed transmission. There is maybe an extra 400lbs in armor and mods on it now.

I want to set it up for towing. The trailer will be around 1000lbs loaded. The idea is prolonged expedition use including driving to Alaska and back. I plan to constuct a lightweight but roomy trailer using fiberglass and aluminum, and having a rooftop tent. The trailer will have a couple of fuel cells either side of the axle containiong a total of 40 extra gallons of gasoline to extend my range, by refilling the main tank.

It is already the case that with a heavy load of camping gear, or high altitude, or anything but the gentlest of slopes, I have to drop down to 4th, and often to 3rd gear, to keep the speed up. I expect this will be a lot worse dragging 1000lbs of trailer.

Through certain - irregularities - in some sports cars I used to own, my Jeeps get picked for special attention at a "test only" station, every time. Not just my Wrangler, but the wife's 2001 WJ as well. However I solve my problem, I'm gonna have to pass California emissions testing. Today the engine runs really clean and the history of the three smog tests I have had is that they all showed emissions around 20% of the limits.

Telntatively this is the plan:

1) Re-gear the Jeep from 4.11's to 4.56's or 4.88's. I have not decided which yet, but I do plan to keep the stock Rubicon lockers. I do plan to stick with the 33's.

2) Build or buy a stroker motor, keeping the stock motor as a known good spare. I'm not especially price sensitive, and I could buy a HESCO or Golen long block. But I want it to look stock, work well with the stock exhaust and throttle body, and pass smog by a comfortable margin. I don't mind putting Premium fuel in it. I note multiple stroker recipes here but I don't know which one comes closest to my needs. Although I have never done a Jeep engine, I did build a 2.0L 186hp Alfa Romeo engine a few years ago (it passed everything except the underhood inspection).

3) I understand that there are some practical difficulties tuning the 2003 model year, but I don't know the details. Looking for some input on this as well.

[Missourian]

1st, you could stoke your motor and you will notice a considerable increse in torque. If I were you, I would find another motor to rebuild while you are driving this. You could hold onto your stock motor -or- sell it to pay for the rebuild and core.

2nd, you give up something to gain something every time you change gearing and tire size for clearance. My signature below shows my Jeep configuration. 4.10's would be great with a stroker. I pull a trailer, aluminum bassboat and 70 HP motor without any problem.

3'rd if you stroke, be conservative for reliability and no issues.

I have 15k miles on my motor now and it is solid, and strong. My build is the "modified poor man's" build.

I started with a 2002 Jeep Grand Cherokee 4.0L (core). I added SCAT 4.2L Crankshaft, Keith Black +0.020 forged pistons, moly rings and Bosh/Ford 24# fuel injectors. I needed a new head and went with OEM stock, 4.0L rebuild kit, and reused everything else.