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Goatbrother70 07-14-2013 06:11 PM

What did I stroke it to?
OK cats,

I am in the USAF and did my first stroker motor about 7.5 years ago. I have a '90 Wrangler, love it, but I tow my boat with it and the Jeep didn't have the power I wanted. At the time of the stroker, I had endured the "craperator" for long enough. I wanted EFI, and a mild this is what I did:

I took my 4.2, gutted it;
- Bored the cylinders .030 over, put hypuretic pistons in it
- Kept the 4.2 crank
- Kept the 4.2 rods
- Put a gone over 4.0 head on it (sealed off some water jackets because they didn't line up)
- Slapped a 4.0 Cherokee EFI setup on it
- Changed the EFI stuff I needed to (brackets and stuff like that)

Then I called it good and fired it up.
I'm in the USAF and was subsequently shipped overseas for 5 years. Put it into storage, up on blocks and when I went to fire it up, it took 3 cranks and vroom! It was back to life! Now that I'm back and with all the stroker talk.....I want to,.....what did I do and what do I have? What liter is it? What is my compression ratio?

The power is OK, not what I thought it was going to be....not a CRAAZY amount better in towing my boat.
After I know what my Motor is at (in liters) I would like to get your advice.....I would like to get a little more power out of what I have. I "may" stroke it again, use a 4.0 block, my 4.2 crank, 4.0 head, etc....but for the short term I would like to get more power out of what I have.

1. I have a squeal in the throttle I need a bigger one? Will that give me more power at the mid-high end? - I think I do but just asking for help and the technology behind it. I want to understand the "Why?" question
2. Do I need bigger injectors? The 24# perhaps? - I think so based on the increased cylinder volume.....
2. If I put in new injectors, do I need a new fuel pressure regulator and what should I set it at?

Thanks for your time - Ken

dukes-o-hazard 07-15-2013 01:27 AM

Nice, sounds like you have a lot going on, although I can't answer any of your questions of what you actually have it does sound familiar and I'm sure someone's been there done that.

1.) The squeal could be something else keep an eye on that. Opening the TB just remember the bigger you go the more you'll get at the top end but the less you'll have at the bottom because when you open it up you start loosing velocity and that is what makes torque on an N/A setup.

2.) The larger injectors can be used but you'll have to "trick" the map/maf sensor electrically into thinking it needs more fuel.

3.) With larger injectors running more fuel a larger fuel pump and or regulator is always a good idea.

The best bang for the buck mod I ever did for my 4.0 was a cam swap from Clifford Performance :: Make 6 = 8 these guys are super helpful and probably have even run what your running now. When I ran there cam with my cut-outs open at the dunes everyone thought I had a V8 under the hood, it is that awesome!

Good luck on your build and keep us posted!

sinbob 07-16-2013 06:10 PM

You didn't really stroke just bored it and put in bigger pistons.
To stroke it you need to change the crankshaft and rods. Most use the 258 crank longer stroke, therefore shorter rods.

Here is a link to a site that will give you more information on what you have to change out to stroke your motor.

JEEP 4.0 STROKER KIT 9.6:1C.R. 4.5L, 4.6L, 4.7L, 242, STAGE 3 - AMC

roadyrob 07-16-2013 06:39 PM

did you change the exhaust? I assume you run a 4.0 exhaust manifold but what about the cat and muffler, going to 2 1/2" will help.
like posted a hotter cam will help.
the bosch 4 hole injectors will help too, you can find them on ebay.

sinbob 07-19-2013 02:08 PM

hesco 62 mm TB will help too

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