300 hp 4.0 sohc

so i bet one of my buddys the other day that i could get my 98 xlt 4.0 sohc to put out 300 hp without many crazy mods. im kinda doubting myself considering its probably lost some ponies over the years but i thought it be interesting to see if it can be done without a turbo or supercharger. im gunna do some of the basics, intake, exhaust, throttle body, and all the other little things. i already have flowmaster super 44's and a kkm intake but im thinking about swapping them out for a k&n and other mufflers, im wondering what muffler and cats would be best. im also changing my gears to 4:10s but im not sure if that actually adds hp. any other ideas im thinking about putting some jba headers on but ive heard they dont do much for the 4.0s.

 

[Elessar65]

The crank is robust enough to allow off-set grinding since it uses single pin rod journals, so the potential for stroker motors is there, based on the crank.

 

[joecrna]

When designing mine I found someone that makes a kit. It only got to 4.2 liters. Not really worth it to me. Though that would probably get me to 300hp (crank). I'd still pass emission inspection too. Probably wouldn't notice the extra HP towing though.

 

[Jakee]

The only way N/A is with very high compression, stroked, head work (so you can rev past 6K) along with all the bolt-on's, a bunch of custom work and a bad-to-the-bone one time dyno tune that you can't run on the street. The stars will need to be aligned, it's going to cost, and will not happen overnight. And still, reality tells me that 300HP N/A is not going to happen.

Like the other guys say, don't be so concerned with HP numbers. I was when I first started but learned thats just a reference point to figure out if what you did helped. Even that's not exact. With bolt-on's your gaining very little HP number (5 -10 at a time). Unfortunately, you can go to a dyno back to back and gain those numbers which makes it worthless. What a dyno is good for is to figure out problems, if any, which could go undetected on the street. Sort of like an check-up at the doctor.

Numbers change between different dyno's. The numbers are calculated from torque and there are different factors used to calculate the numbers.

If you really want to see 300HP and are serious, save yourself and start looking into a turbo. I say this because it's probably the most cost effective way of making the power.

 

[Jakee]

A 4.0 SOHC can be stoked to 4.3 Max

 

[jah81592]

Supersix motorsports has a 4.3L stroker out. But.. when you said 300 I thought you meant 300 whp since that is what most people talk about. As far as dyno's being important I do think they are very important and very relevent. BUT... we don't race dyno's we race on the track. It is important to see what improves power and what doesn't. So strapping one down is necessary but don't get wrapped up in the #'s too much. If the dyno is operated correctly you will learn a multitude of things. I wish we could have a dyno day and more Explorer tuning on mine than I do now. It would really clear up a lot of misnomers. -j

 

[WhiteLimited]

That would be cool to bet 300+ to the ground. To the crank would be a lot easier. Once summer gets here I will be putting my high gas/performance tune back on and taking my truck to the track. The first car show of the year you get to run the track for free. I have TMHeaders, Cold Air Intake, Exhaust, Tune, on my V8 in a rough in head estimate I have about 230-ish HP to the ground. This summer if all goes right I will be doing mostly body work to my truck but I want to get some more basic performance done. I have $2000-ish done to my truck in performance all ready. It coast a lot of some happiness! Cheers!

 

[joecrna]

Yes James, I was talking fly wheel. The engine isn't in the truck yet. Nor is it complete. Thats why I said, should make 285-300hp. Only on dyno for break-in. Will never by dyno'd in truck. I could care less what the HP #'s are if it pulls the load well. My engine is being done to help with towing. No it won't be raced and everything must get past California emissions inspection.

 

[Limited02]

James, I am really thinking about heading out to see you in the summer for a dyno tune. I am about 10 hrs away, but it will be worth the drive. I will PM you as the time nears to see what this turd is putting down

OP-read my sig about speed

 

[candiver]

so i bet one of my buddys the other day that i could get my 98 xlt 4.0 sohc to put out 300 hp without many crazy mods. im kinda doubting myself considering its probably lost some ponies over the years but i thought it be interesting to see if it can be done without a turbo or supercharger. im gunna do some of the basics, intake, exhaust, throttle body, and all the other little things. i already have flowmaster super 44's and a kkm intake but im thinking about swapping them out for a k&n and other mufflers, im wondering what muffler and cats would be best. im also changing my gears to 4:10s but im not sure if that actually adds hp. any other ideas im thinking about putting some jba headers on but ive heard they dont do much for the 4.0s.

Changing exhaust should increase usable HP, but modifying the gear ratio will only give more acceleration off the line. It will increase fuel consumption and lower your top speed.