Jeep Strokers

Hey Guys!
Pretty much here it is. Im new to building strokers, not new to building engines. Pretty much wanted to state my intentions, and see what kind of feedback I could get.

I currently have a 1989 4.0, that is bored .020 over. No cam yet, no crank yet.

I have rebuilt the head, new valves, springs etc. Also before the valve work, I had some mild port work done, port matched the intake, and smoothed all ports. I have been really attracted to the 232 combo, but I want to be able to use 87 octane fuel. I read somewhere I could use stock pistons and rods from my 4.0. What do you think?

4.0 Block
4.0 Pistons / Rods
232 Crank
Comp Cam 68-232-4

What do you think I can expect to see out of this combo? Thanks in advance guys!

Oh, my block is .020 over, and I have the Mustang orange 19lbs injectors. Will all that work?

Jeeper89 wrote:I read somewhere I could use stock pistons and rods from my 4.0. What do you think?

4.0 Block
4.0 Pistons / Rods
232 Crank
Comp Cam 68-232-4

The stock pistons are too tall and will protrude about 0.023" above the deck at TDC when combined with the 4.0L rods and 232 crank. You really have a choice of only two pistons if you take the mini-stroker route; the Silvolite UEM-2229 and the Speed Pro 677CP. SCR will be ~10.1 with the former and ~9.8:1 with the latter, so the engine will probably need a diet of 91 octane fuel at a minimum.
Mustang 19lb injectors will be too small for the job. I'd recommend the blue Ford 24lb'ers.

Cheromaniac wrote:The stock pistons are too tall and will protrude about 0.023" above the deck at TDC when combined with the 4.0L rods and 232 crank. You really have a choice of only two pistons if you take the mini-stroker route; the Silvolite UEM-2229 and the Speed Pro 677CP. SCR will be ~10.1 with the former and ~9.8:1 with the latter, so the engine will probably need a diet of 91 octane fuel at a minimum.
Mustang 19lb injectors will be too small for the job. I'd recommend the blue Ford 24lb'ers.

Ok, so how can I achieve a closer 9:1 ratio? Maybe 9.5:1? I dont know I know stock is 8.8:1 I just got those mustang injectors not too long ago, Id like to reuse them if I can.

I just had another thought. Would building this engine to the mini stroker effect CA smog? Especially since your suggesting bigger injectors.

Jeeper89 wrote:Ok, so how can I achieve a closer 9:1 ratio?

You could have more volume added to the piston dishes. Take a look at the milder mini-stroker recipe on my site and you'll get an idea.
You'll need bigger injectors to fuel the engine for the extra HP over stock but since the higher CR and tighter quench will improve thermodynamic efficiency, I'd expect the engine to produce lower emissions and sail through CA smog.

Just been thinking about my CR. So no matter what you say Im going to need new injectors. Will I need to mess with any of my renix sensors? Ive been reading a little into it, looks like some people have needed to swap out the MAP sensor, O2, etc. To get correct fuel readings.

My engine wasnt bored .060 over at the shop, they went .020 over. Doing some CR calculators I keep coming up with way low compression (unless Im missing something? Im sure I am) lol!

I think my bore is 3.895" x 3.5" stroke, 57cc head, (zero deck right?) .045 head gasket, -17cc piston dish = 9.1:1 CR.

Did I miss anything? IM really debating if this project is worth it now. Have to swap injectors, and possibly messing with Renix sensors is worrying me,

Neither the Ford 19lb injectors nor the Renix injectors are going to be up to the job. With the Ford 24lb injectors worst carse scenario your engine might run slightly rich but you can easily correct that with a MAP adjuster. You won't need to disturb any other sensors.
Which pistons are you using? You could still do a +0.020" version of the milder mini-stroker and in your case, displacement with the 232 crank will be exactly 4.1L.

Cheromaniac wrote:Neither the Ford 19lb injectors nor the Renix injectors are going to be up to the job. With the Ford 24lb injectors worst carse scenario your engine might run slightly rich but you can easily correct that with a MAP adjuster. You won't need to disturb any other sensors.
Which pistons are you using? You could still do a +0.020" version of the milder mini-stroker and in your case, displacement with the 232 crank will be exactly 4.1L.

I havent made a decision on pistons yet. Im at the point where my block is painted w/new cam bearings. Essentially ready to assemble. I thought one of the pistons had a -17cc dish, cant remember where i read it. Still debating though.

I found a 232 crank from Northern Auto w/all bearings for $260 shipped. CompCam recommends the 68-232-4 cam. Thats about where I am. Haven't bought any parts yet because Im still trying to research enough to be absolute with my decision before spending the money.

At this point if I decided to not do the stroke, I can just buy my pistons and be on with my rebuild. But if I go with the stroker, I need crank, cam, pistons, injectors, map adjuster, etc. IM just trying to look at all my options ya know? I do appreciate you talking to me about it

Other cam options Im considering are...

Crane 753901
Lift: .456''/.484''
Advertised Duration: .260°/.272°
RPM Range: 1200-4800

Lunati 10680700
Advertised Duration (Int/Exh): 250/256
Duration @ .050 (Int/Exh): 208/213
Gross Valve Lift (Int/Exh): .484/.484
LSA/ICL: 112/108
RPM Range: 1000-5200

Something else I just checked, please correct me if Im wrong.

My deck height is close to 9.5",
232 crank comes to 1.75" stroke,
add 6.125" rod length,
1.585" compression distance pistons

I get 9.46" minus the deck 9.5" you get -0.040" This would be quench right? Isn't this a good number?

IMO if you take the stroker route you really dont need to replace the cam.

akadeutsch wrote:IMO if you take the stroker route you really dont need to replace the cam.

Why is that? Everywhere Ive been reading says these 4.0 wake up more with an aftermarket cam.

akadeutsch wrote:IMO if you take the stroker route you really dont need to replace the cam.

I don't understand that. If the stock cam is too small for a 4.0, how is it going to 'feed' a 4.6L?
I read in JP that on an otherwise stock 4.0L, just adding a 232 cam added 12rwhp and 18rwtq all across the rpm range (1700-4200), not just top end.

I have heard few people say that the stock cam is too small. If you look around there are plenty of people running the stock cam in their strokers. I have also read that the bigger cams matter most only at higher RPMs and since our 4.0-4.9 is a low end motor we never see the gains from a bigger cam. I did however chose the comp 235 grind for my build.

Comp 68-235-4
Advertized Duration 254/262
Duration @.050 210/218
Lift .477/.493
LSA 111