How much horsepower can a 4.0 handle?

Jezza

Jezza

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Probably a strange question to ask in the midst of a fuel shortage, but does anyone have an idea how much the 4.0 will put up with? I don't plan on doing any more internal parts in this engine. My plan is to run this stock engine while I build a different stroker setup to swap in later. The only mods to the stock engine is a high volume oil pump, MLS gasket, head studs and roller rockers. I'm currently running 240 whp at 5 psi, but I would like to turn it up.
 
Look up Power nation on Youtube, they did a series on the jeep 4.0 but I forgot how much HP they got out of it. I think it was around 250 HP or something.
 
Boosted tech superchargers run 8 psi with stock internals. Consider they have a 7th fuel injector to add fuel while in boost. With a tune to keep AFR in the green I would assume you can also run up to 8 psi on a turbo.

I have the Boosted tech setup with Harlan Sharp rockers and no issues on 91 pump gas.
 
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AMS417 said:
Boosted tech superchargers run 8 psi with stock internals. Consider they have a 7th fuel injector to add fuel while in boost. With a tune to keep AFR in the green I would assume you can also run up to 8 psi on a turbo.

I have the Boosted tech setup with Harlan Sharp rockers and no issues on 91 pump gas.
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Good to know. I was thinking more along the lines of :cough: 15 psi or so. I have a stand alone already, and probably add flex fuel before long.
 
I used to run a Kenne Bell supercharge on an I6. 6 psi would put out about 300 power and 400 torque at the flywheel. KB also offered an 8 psi pulley, and said that extra power generated was no problem for the stock rotating assembly. But, they did not recommend running the higher boost with cats.
 
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defenderu said:
Ya i wasn't being serious. Generally speaking these engines arent known for modding for HP gains.
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Sorry, it's difficult to tell sometimes over the internet. I have a problem of modding everything I own to destruction. I'm working on that.
AMS417 said:
I see your future, it’s bent rods and broken pistons. But it’ll be a blast for a short while.
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Wouldn't be the first time :D
I can tell ya that a 4 cylinder S10 will hold 25 psi and make 350 wheel for a dyno pull or two.
Maybe after I get the new engine done we'll strap it to the dyno and see what the limit is.
 
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There are so many different angles to this with so many different variables. The way you asked the question, you are asking about the limits of the motor holding together. That's going to be limited by block strength and keeping the head planted on the block with lifting under yuge cylinder pressures (which also assumes forced induction which you will need to get even close to the limits of the motor). Nobody has really pushed these motors that much. Newcomer which is linked above has done the most that I've seen. Note they used block fill to strengthen the block then haven't updated in a while which makes me suspect they turned it up then popped the motor.

If you are asking how much you can turn up your current setup, that's completely different. Note that there is no magic "x" psi because it doesn't work that way. 10psi from one turbo/supercharger ≠ 10psi from a different turbo/supercharger. Not even close.

With good tuning and a decent sized turbo, 4-500hp has been done on a number of builds. Flyin' Ryan has tuned several GT35 powered builds like that.
 
Okay the transfer case broke. No rear wheel drive only four high. That was 15 psi.

20210514_173405.jpg
 
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Head Lice said:
Has anyone swapped in a big inch I6 . . . . 292 GM or a 300 Ford?
Both proven powerplants with a wealth of speed equipment available.
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Super not worth it. Horsepower is made in the head, not in the bottom end. I'd even venture to say the amc I6 has more aftermarket support than the Ford with more power potential to boot. I know nothing of the GM. Regardless, if you are swapping motors, sticking with an I6 for form factor sake is pointless. Even if you did, something like an RB or a JZ would have tons more power potential. LS or Magnum would be my go to for a motor swap though.

If you are talking more than 4-500hp though, you have to evaluate what you actually plan to do with it. If you want to actually go fast, it's the wrong platform. If you want something fun to play with and be "quick enough," a v8 swap or bigger turbo on a amc I6 will will do.

I am all for crazy power to the point of being pointless, just understand what your goals are.
 
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I didn't actually intend to "crank it up" yesterday. It was really an accident. The boost control was malfunctioning and the solenoid was going from 0% duty strait to 100% duty cycle. I had the boost cut set for 15 psi and it would have cut except something let go in the transfer case first. Probably saved the engine as I'm not sure I have enough injector for 15 psi. It felt wild on the dyno making 515 ft/lb of torque at 2500 rpm. It also blew the end out of the check valve on the brake booster. I ordered a new check valve and a used transfer case. Should be back up and running in a week or two.
 
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Jezza said:
Probably a strange question to ask in the midst of a fuel shortage, but does anyone have an idea how much the 4.0 will put up with? I don't plan on doing any more internal parts in this engine. My plan is to run this stock engine while I build a different stroker setup to swap in later. The only mods to the stock engine is a high volume oil pump, MLS gasket, head studs and roller rockers. I'm currently running 240 whp at 5 psi, but I would like to turn it up.
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There is a company called newcomer racing that may be the one to answer that....You can see their videos on YouTube.
 
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