Jeep Strokers

I have the the block back from the machine shop and have amassed all the parts and will begin assembly in the next couple of days so I want to throw my recipe for my stroker out there for constructive criticism. I will be using the truck for 80% daily driver and 20% offroad. I am perfectly fine with using premium fuel. With that said here's what I'm working with:

92 block bored 30 over deck height .010
258 crank
258 rods
sealed power 30 over stock 4.0 pistons
mopar 29ab? don't have the number handy but its the one with 248 duration
stock 92 head reconditioned with stock size valves, cleaned up the bowl and gasket matched the exhaust/intake ports
rugged ridge header w/high flow cat and flow master muffler
99+ intake w/KN filter
stock ECU
.048 head gasket


when I run it on the calculator I come up with SCR of 10.23:1 and DCR of 8.94:1 with a Quench of .058

I am planning on running my stock injectors with the stock MAF sensor to start out and see how it goes. I have done all the calculations on the it and the stock setup will flow 92% of what my new engine can do and the only time I would run the risk of running lean would be when the pedal it pinned and to be honest with you I never do that.

any input would be greatly appreciated-two head are better than one!

Well, it sounds like you are definitely running 93 octane. That's all I can say though.

What year is your Jeep? 91?

its a 97

I'm no expert, I haven't even finished my own stroker, but I do feel pretty booksmart on this stuff, and I feel like your build is going to be running quite lean throughout the RPM/Throttle range.

Theoretically it is going to run lean throughout, but with a new cam and different intake manifold, the curve in the stock fuel map is going to be off a bit. So, it will be lean from idle to WOT, but probably dangerously lean at WOT.

Your cherokee is going to be getting the same exact amount of fuel as every other 96-99 cherokee out there, but a significant amount more air for these two reasons. More displacement, about 15% more. Better aspiration, (better Intake mani, air filter, header, exhaust) all increasing volumetric efficiency. So instead of 15% more air due to displacement, you are probably looking at 20% air increase or more considering the higher VE.

With your higher DCR, your mixture should also combust more completely, also resulting in a leaner AFR.

Like I said, this is just booksmarts(please correct me if any of it is wrong!), people probably run just like this all the time, just letting you know that you might want to watch it. I am doing a similar build, and will be running bigger injectors right off the bat.

Were both going to be in the premium fuel club most likely, I am running 8.7:1 DCR. But I am doing a lot to get my intake charge temps down, we will see if that helps.

There will be times when you are running lean. Mostly on start up when the engine is in open loop and again on WOT when in open loop. The computer should be able to correct for the most part when in closed loop and reading the O2 sensors. However, you won't be able to know exactly when it switches loops and you don't have a wideband to monitor the AFR. It might take one good WOT run to create a very large problem.

SilverXJ wrote:There will be times when you are running lean. Mostly on start up when the engine is in open loop and again on WOT when in open loop. The computer should be able to correct for the most part when in closed loop and reading the O2 sensors. However, you won't be able to know exactly when it switches loops and you don't have a wideband to monitor the AFR. It might take one good WOT run to create a very large problem.

I seem to remember someone saying that the OBDII computer is pretty bad at correcting. Plus there is only so much it will correct, right?

Thankfully I have WBO2 from my Honda tuning days for when I get mine running, all this money and a DD, I don't like the guessing game everyone else here seems to be so comfortable with.

I appreciate the info, I am also worried about that and want to get it straight before I start it up for the first time cause I'll be breaking in the cam. I would love some suggestions on what injectors to run instead of the stock ones and also anything else I can do from the start to make life easier. I want to know if I should be getting a adjustable MAP sensor, wide band O2, etc.. At this point I am at the mercy of everyone here for answers, any help would be great.

sudo chop wrote: I seem to remember someone saying that the OBDII computer is pretty bad at correcting. Plus there is only so much it will correct, right?

Its actually pretty good at asjusting however so much is changed with a stroker that it can't get it where it needs to me again.

I don't like the guessing game everyone else here seems to be so comfortable with.

Who is guessing?

aurichbb7 wrote:I would love some suggestions on what injectors to run instead of the stock ones and also anything else I can do from the start to make life easier.

On my 2000 with the 49psi fuel pressure I found that Jeep 53032704AB used on the 4.7L engine is a pretty decent fit. Its a 4 hole design and is suppose to flow 25 lbs. It still runs slightly rich at WOT, but they have been the best fit so far. A wideband would help to see what the AFR is, but it is an expensive investment.

Silver XJ, is your setup pretty similar to mine? What vehicles were those injectors found on? I want to settle on something cause I am ready to drop it in the truck early next week. Will the stock MAP be sufficient?

SilverXJ wrote:

sudo chop wrote:I don't like the guessing game everyone else here seems to be so comfortable with.

Who is guessing?

Sorry, I didn't mean to make such a generalized statement about everyone here, and certainly not you. But it seems to me that a lot of people, especially people still doing their build and posting their plans, seem careless about AFR and whether their engine is running or going to run well, just as long at it runs.

Well I went with the hesco 24# injectors and feel pretty good about it. I have the main engine all assembled and took some pics (below). Should be going in the XJ next week.

Sharp looking engine!! I like the paint job! Post back how it runs and on which gas.

will do