Jeep Strokers

Conversation starter: What do you guys think about this?

Sorry forgot the link. https://youtu.be/WlHrqhwojf0

A 300hp 4.7 stroker is doable. Just needs a slight adjustment to the recipe below (CompCams 68-239-4 cam, 10.5:1 compression).

4.7L medium-buck stroker
Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Custom forged +0.060" bore pistons, compression height 1.380", dish volume 15cc
10.2:1 CR
CompCams 68-235-4 210/218 degree camshaft
Russ Pottenger ported Edelbrock 60cc aluminum cylinder head
Mopar/Victor 0.043" head gasket
0.043" quench height
Flometrics F&B 68mm billet TB
Accel 30lb/hr injectors for '87-'95 engines, Bosch 0280155784 injectors for '96-'04 engines, '01-'02 Chevy LS1/LS6 28.6lb/hr injectors for '05-'06 engines
290hp @ 5100rpm, 340lbft @ 3700rpm

I’m actually building the medium buck stroker with the 235 cam and few tweaks. But newcomer supposedly got the 300hp number with stock head that only had bowl work and valve job. Now he did say the cam was bullet racing cam with over [email protected] and just under .500 lift. It did have 900cfm carb and aftermarket manifold. It also had short rods and looking at the pistons look to be ~9.5:1. approximately. I’m a bit skeptical on those numbers unless that cam was way bigger than they are leading us to believe.

I’m actually building the medium buck stroker with the 235 cam and few tweaks. But newcomer supposedly got the 300hp number with stock head that only had bowl work and valve job. Now he did say the cam was bullet racing cam with over [email protected] and just under .500 lift. It did have 900cfm carb and aftermarket manifold. It also had short rods and looking at the pistons look to be ~9.5:1. approximately. I’m a bit skeptical on those numbers unless that cam was way bigger than they are leading us to believe.

I spoke to keith I was a little skeptical on the output numbers too.He says compression was only 9.0 to 1.I think being run with absolutely no accessories has helped with that figure. It does make me wonder if it had some compression if it would have made 350 ish??

Lots of videos of similar budget builds on YouTube check out golen stroker builds. He must Dyno them for customers. All made ~ 270 hp. Very similar to this build.

I ran the numbers with modest flow numbers for a unported 7120 head with stock valve train and I don’t see how that engine can make that 300hp number. Doing the math I came up with ~269. Which is pretty close to golens numbers. What’s funny is another video newcomer did with fully ported bigger valve head I think on the same shortblock only made 10 more hp. Wtf?
I’m using a Russ Pottenger ported edelbrock head and using his flow# and doing the math I should be able to make~326hp.

I made a mistake with the under .500 lift of my cam it looks like 318hp instead. Obviously the head keeps flowing past .600 lift and is capable of more with bigger cam.

I reread my post just now and I just want to be clear. I’m not saying I’m going to make that 318 number. I’m saying that with everything perfect and certain tweaks that is what is possible with the flow of the ported head. I believe the intake manifold flow will probably be the limiting factor. Now consider the less flowing head on the Newcomer engine with a better flowing manifold and a 900 cfm carb maybe that was a huge contributing factor to the number he got. I’m still skeptical though. I’ll be happy any where near the 300 hp Mark with a nice broad torque curve which is probably more important than a peak hp for a crawler. I really just want a bit more power to get up the mountian to get to my favorite trails.

My question is. Can you run regular fuel or need to run premium. I know with custom pistons you can run regular. But that starts getting pricey

A 300+hp stroker is going to require a diet of 91 octane minimum.

Any decent running stroker will require a diet of 91 minimum.

Trying to save a few pennies on fuel leaves an awful lot on the table. Several tuners wont even try to develop a cal for 87 octane.

So everybody is wrapped up in a peak power number which really has little bearing on what this build will be like to drive unless you are someone who needs to pin the tach at every gear change !
No one has even mentioned that nice flat torque curve.

So a few points of interest, his use of 4.2 rods for starters, smart move for durability in my opinion, ya using the spindly lighter and i'm sure weaker 4.0 rods in a stroker just to get a little better rod to stroke ratio is just a questionable dicey move.
As far as the 707 rods being better than 352 rods (and he says there are alot better!) ? im pretty sure that is pure bunk and in fact if you closely examine the 352 rods you can see they were designed to be better than the 707's they replace, i will leave that one up to matters of opinion and say that i wouldn't hesitate to run the easier to find 352 rods in any stroker build.

The light crank as the prefered choice is based on less rotating weight being an advantage ? we are talking about a jeep here, a bush machine, hunting rig, off road vehicle ready for any terrain, well in my world anyway, so no a light crank is not an advantage !

The pistons, not a bad off the shelf Speed pro hypereutectic choice with a little bit bigger dish than the stock 4.0 pistons to help keep compression under control, they have a 0.008" shorter comp height so add that to the 0.020" you need to shave of the block if your gonna concern yourself with quench height.
Newcomer uses a high grade T-chain because it may be his opinion that the AMC 6 beats the piss out them for some reason, i would tend to agree looking at some of the chains in the motors i have torn down.

Newcomber talks about his head work kind of offhandedly as its just a simple bowl bleed and a valve job, i think he's being way too humble because in my flow bench work i have seen properly done bowl blends on multi angle seat grinds pick up huge flow and i can tell you this, how that bowl blend transitions into that last angle, how that is done is critical , before i criticize his power numbers i would want to see how his heads bench numbers, i would think they are pretty darn good. Also id like to see all the spec's on that cam, saying its more than 210* tells us next to nothing.

I have one of his engines in my CJ. Cam is 218/224 112 .500". My head is blended, with oversized valves.

I can't run 87, and I'm having issues trying to diagnose pinging under heavy throttle. I'm sure it's me, and not the engine. I'm running a Sniper EFI w/ Holley CD box, and distributor. Electric fans keep the engine at 185 if I want it to. Premium fuel at sea level. Have turned timing WAY down, but still have pining. Just moved the 02 sensor closer to the merge in hopes that I'm running lean, and not doing anything wrong.

Keith is an amazing guy though. Has been nothing but helpful in everything I've asked him. I'm going to keep trying to see if I can figure out the issue I'm experiencing. Otherwise I might just swap to a diesel.

Time will tell.