350 hp naturally aspirated Inline 6

[cherokeeproject]

So I've been searching for quite some time and I haven't found any solid information so I figured I start a post. I'm looking to see if anyone has successfully built the 4.0 I6 to 300+ hp without the use of turbo, supercharger, or Nitrous and still run pump gas? I know some of the big bore strokers out there claim 300+hp but I'm looking more for something more reasonable (.030" overbore). I'm looking to buy some stroker parts to start on my build and I would like to get in the 300 - 350hp range, NA, on pump gas if possible.

According to Dr. Dyno's web page (www.jeep4.0performance.4mg.com) the 4.7L - 4.9L strokers are in the 275 - 300+ range but are these numbers with everything else stock? If the 4.7L numbers are with everything else stock then a few bolt on mods should put it in the 300+ range right? But all these builds are based on the .060" overbore, (which I would like to stay away from) has anyone built a 4.7L on the .030" overbore?

So here's my thinking... currently I've got a 96 HO so I'm pushing out 190hp stock, with a few bolt on mods probably ~205hp right now. if I can build a stroker to 4.6L by simply overboring, 4.2L crank & rods, and new pistons, with everything kept the same I should see approx. a 20% increase in HP & 40% increase in torque. That would put me @ ~ 240hp 315lb-ft. But if I increase my CR (Compression ratio, for the newbs who may later read this post) from 8.75:1 to 9.5:1 I should see an improvement in the 30% increase in hp & 45% increase in torque. now with bolt on mods I might be able to squeeze out another 50hp and torque to put me in the 300hp range but im not even sure if that's possible, any insight to this topic from some of the street XJ guys will be greatly appreciated.

 

[MoparManiac]

I personally think you're going to be hard pressed to get a 4.0 in the 300+ HP range without any kind of forced induction or high octance gas.

In all honesty, you'd be better off building a forced induction setup for a stock 4.0 or swapping in a different engine entirely.

 

[GrimmJeeper]

I personally think you're going to be hard pressed to get a 4.0 in the 300+ HP range without any kind of forced induction or high octance gas.

In all honesty, you'd be better off building a forced induction setup for a stock 4.0 or swapping in a different engine entirely.

I agree. i know of at least one 300+ hp NA 4.0 based stroker but i'm pretty sure there's some 110 in the mix.

 

[cherokeeproject]

I agree. i know of at least one 300+ hp NA 4.0 based stroker but i'm pretty sure there's some 110 in the mix.

do you know what CR he's running?


Im looking to stay in the 9.1:1 - 9.6:1 range, that should be able to perform effectively with 89 or 93 octane

 

[cherokeeproject]

didn't someone out there build a 4.7L stroker with a .030" overbore?

 

[WAZZUXJ]

It sounds like you know how you want to build your 4.0, so build it. If you really want 300+ hp, then swap in a V8. IMO, horsepower is not the goal you should be looking for in a off-road vehicle, torque is what you should be after. A stock 4.0 makes great torque and the reason you build a stroker is to increase torque considerably, not horsepower.

 

[GrimmJeeper]

It sounds like you know how you want to build your 4.0, so build it. If you really want 300+ hp, then swap in a V8. IMO, horsepower is not the goal you should be looking for in a off-road vehicle, torque is what you should be after. A stock 4.0 makes great torque and the reason you build a stroker is to increase torque considerably, not horsepower.

i agree with this too, unless you're building a street machine torque is going to get you where you're going even in the dirt instead of the rocks.

 

[cherokeeproject]

It sounds like you know how you want to build your 4.0, so build it. If you really want 300+ hp, then swap in a V8. IMO, horsepower is not the goal you should be looking for in a off-road vehicle, torque is what you should be after. A stock 4.0 makes great torque and the reason you build a stroker is to increase torque considerably, not horsepower.

I want to stick with the 4.0 for financial reasons, I knew it was only a matter of time before someone mentioned a V8 swap, & that's just waay out of my budget. That's why I didn't bother to mention it.

Torque IS a concern with this being used for off road, but this jeep will see almost an equal amount of road time (if not more). The intention here is to generate enough power to run 4.56 or 4.10/11's with 33-35's (haven't decided yet). I know that the focus should be more on torque but that will increase respectively with the modifications.

 

[MoparManiac]

People run 4.56s on 35s with stock 4.0s...

 

[cal]

do you know what CR he's running?


Im looking to stay in the 9.1:1 - 9.6:1 range, that should be able to perform effectively with 89 or 93 octane

You're not going to get there without getting above 11:1 or so. Technically, 100 octane is pump gas - I buy it at my corner gas station..

 

[cal]

didn't someone out there build a 4.7L stroker with a .030" overbore?

A 4.6L stroker is typically .030 over. You could do a 4.6 on 91 octane and get into the upper 2's - 260-275 horses, but you're pushing it on the fuel at that point.

 

[old_man]

I run 10.4:1 on the cheapest pump gas I can find. The key is to get the quench height right and use the right cam. I live at 5000 ft elevation but I had no issues at low altitude other than a desire to light the tires up all the time.

 

[cherokeeproject]

You're not going to get there without getting above 11:1 or so. Technically, 100 octane is pump gas - I buy it at my corner gas station..

93 octane seems to be the highest I can find around here.... unless I go to the race track...

I run 10.4:1 on the cheapest pump gas I can find. The key is to get the quench height right and use the right cam. I live at 5000 ft elevation but I had no issues at low altitude other than a desire to light the tires up all the time.

Ever had it Dyno'd? I'm also at sea level here... maybe a few inches above haha My Camaro has a 10.1:1 CR and I've gotten a little bit of pinging at the higher RPM's if I run the low octane fuel. Whichever fuel I run I need to make sure that its readily available across the country as I plan to do some adventuring in this jeep once its finished.

 

[cal]

93 octane seems to be the highest I can find around here.... unless I go to the race track...

If we aren't hard on it (race track hard) we can get away with 11:1 on a 50/50 mix of 91 and 100.

If you don't have a renix, it will be harder to pull off.

 

[Johnnie Walker]

So, you want a stroker with 300+HP, and a V8 swap is "out of your budget"? Quality parts to get you to that point, is probably more costly than a LSx swap. Then there is also the reliability (or lack there of) of the stroker.

No offense intended, but in the words of BBT in Bad Santa
"Wish in one hand, shit in the other.. see which one fills up first".

 

[cherokeeproject]

If we aren't hard on it (race track hard) we can get away with 11:1 on a 50/50 mix of 91 and 100.

If you don't have a renix, it will be harder to pull off.

I wouldn't want to go anything over 10:1, it just makes me nervous... and if I cant get the power I want out of the stroker I may eventually go forced induction. But I would like to be prepared for either one.

 

[cal]

So, you want a stroker with 300+HP, and a V8 swap is "out of your budget"? Quality parts to get you to that point, is probably more costly than a LSx swap. Then there is also the reliability (or lack there of) of the stroker.

No offense intended, but in the words of BBT in Bad Santa
"Wish in one hand, shit in the other.. see which one fills up first".

The stroker will be much cheaper than an emissions legal V8 swap, and is very reliable assuming it is assembled correctly.

 

[cal]

I wouldn't want to go anything over 10:1, it just makes me nervous... and if I cant get the power I want out of the stroker I may eventually go forced induction. But I would like to be prepared for either one.

I think if you were to recalculate your expectations to 270-275 horsepower, you're in the ballpark.

There's an engine builder here on Naxja, Russ Pottenger, owner of Bishop-Buehl Racing Engines in California.

Hit him up and see what he thinks.

Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Work (626) 967-1000
Fax (626) 967-7836
Cell (626) 673-2203
Email [email protected]

 

[cherokeeproject]

So, you want a stroker with 300+HP, and a V8 swap is "out of your budget"? Quality parts to get you to that point, is probably more costly than a LSx swap. Then there is also the reliability (or lack there of) of the stroker.

No offense intended, but in the words of BBT in Bad Santa
"Wish in one hand, shit in the other.. see which one fills up first".

hence the need for this thread... I want to see if the 300+ hp stroker is possible without the significant upgrades such as turbo or supercharger, if I knew all the information I wouldn't have needed to post, nor needed the information on the forum.

The stroker can be built for less than $2500 and be ready to go. If you can find me a reliable V8 motor, manifolds, engine mounts, transmission, transfer case, adapters, wiring harness, ECU mods, custom fit exhaust, radiator, fans, misc brackets and pulleys, fuel pump, etc. for less than that then let me know.

 

[cal]

hence the need for this thread... I want to see if the 300+ hp stroker is possible without the significant upgrades such as turbo or supercharger, if I knew all the information I wouldn't have needed to post, nor needed the information on the forum.

The stroker can be built for less than $2500 and be ready to go. If you can find me a reliable V8 motor, manifolds, engine mounts, transmission, transfer case, adapters, wiring harness, ECU mods, custom fit exhaust, radiator, fans, misc brackets and pulleys, fuel pump, etc. for less than that then let me know.

I would expect to spend more than $2500, with the numbers you're looking at, I'd expect it to be $3200-$3500 as you're going to want something that can spin some RPM's. If you really want to get the top end out of it, add another 1K in head work on top of that.

In comparison, a friend of mine is $5000+ into an LS swap for his TJ right now, after you factor the cost of the engine, trans, harness, custom exhaust, computer, trans controller, cross members, and and and and...