I have a 98 5.9 and 46RE in my Jeep. I built it for Ultra4 offroad racing. However, the engine and trans are stock.

Everyone that I know who races these are running LS engines. They certainly seem to be cheaper to build for power, with a plethora of factory performance parts, and aftermarket builder and tuners it makes the most sense.

However, I already have the engine in here, and the radiator for it cost me 1k.

I was taking a look at the power level on Hemifevers dyno charts.

Stock 5.9 is rated for 245/335. Accounting for 20% loss, that's 200/270 on the dyno

Here are the random dyno levels.
Stock 200/300
Tune/rockers 270/300
Tune/cam/M1 280/320
Tune/cam/heads/headers 320/345 This would be 400/430 at the crank roughly?

So tune, cam, heads, and headers will run me around $2500, and get me 150 hp and 100 lb ft.

If I were to get and build a 5.3 or 6.0l (LM7 or LQ4) , it would run me around 1k for an engine and harness.

The 6.0 LQ4 is rated at 300/360 out of the gate. THis is 50 hp and 40 lb ft of torque over the stock 5.9. L92 heads and cam would run me around $1k. Injectors another couple hundred.

This last one would conservatively be 450 hp/400 lb ft. Except for the trans swap expense, for the price of the Edelbrock heads, I can add 150 horse to the 6.0.






What are your thoughts? What else would get me to 450 hp on the 5.9 besides a charger? Or should I say goodbye to an engine that's been in the Jeep since 2007?

 

Suppose it depends on your budget... Granted, there is a LOT more aftermarket support for the LS engines.....

 

Build the 5.9, when it's built you'll have your own unique combo that can still compete.

200/270 stock on dyno is a little generous, more like 180/250. With only an m1, superchips 91 octane tune, and magnaflow muffler swap I laid 223/281. 2/3 of that was due to the intake manifold. Loses some low end but shorty headers will bring it back.

Start with bolt ons- intake manifold ($500), headers ($130-$350), throttle body ($330 for 52mm bbk or $100 for ebay 50mm bored ported), heads ($1300 for Odessa EQ Monster Magnum or Hughes engines has a selection), sct tuning (airram.com to get FlyinRyan,hemifever fries pcms), and cam (im not as well versed here and too much to factor in price) will push you above 300 to the wheels.

Those gm motors have more power yes, but that's also a lot higher in the powerband than these old 5.9s. These motors will have more tq at usable rpms.

 

This is my dilemma: you've listed $2500 in parts to get to 300 at the wheels. A set of $800 heads and a $100 cam will get me there on a 6.0. If I spent $2500 on a 6.0 (once it's in the Jeep), I think I could get to 400-450 to the wheels.

Damn GM...

 

That's a good point. It's strictly my opinion to build the 5.9 over a 6.0, I don't like the idea of gm engines in Mopar vehicles. Likewise, non ford engines in ford vehicles or non gm in gm vehicles. No matter the application.

But like I said above, the 5.9 will get you more usable tq, won't have to rap it out to 7k to have power. Can save the price on the intake by modding the kegger to open up usable rpm to nearly 5k while still making great tq.

In the end, it's your jeep money and call. Yeah you can get an LS and put a bunch of power into it for not much cash and build it farther in the future thx to large aftermarket support. At the same time power is way high in rpms where you wont be for most of your racing and takes a lot more money to build it to make tq at lower numbers. Plus money to swap tranny.

 

Peppers right. Budget is your concern. As you already have the motor and transmission setup it would probably be cheaper to stay with it. The 5.9 is definitely a work horse. I know the 6.0 is a nice motor but you should compare hp/torque curves of the 2. As well as the cost to swap out the motor and tranny into your budget

 

Don't forget longevity... how long between rebuilds (having to spend more money)?
An LS might be a cheaper build, but if you have to do it more often, are you really in front?... being that the LS is higher revving to get the power, it is likely to wear out sooner for the same amount of work achieved.

We know the 5.9 is good for at least ~200k, if you remember to do oil changes.

Another thought; if the LS has it's power and torque at higher rpm, for it to be usable in a 4x4, you will need to have lower ratios in the axles to be able to use the engine at the ground speeds desired.
Changing axle ratios is going to add further to the cost of going to an LS.

 

Thanks all for your input.

I'm not neccesarily concerned about the budget, but when racing stuff adds up. Not worried about axle ratios, I'm on 5.38s and 37s. Plus I'll be changing the transfer care to a 3:1. A lot of the racing is actually higher speed, not worried about torque curves or low end power. I'll build both to maximize that. Remember the 6.0 or 6.2 is what I'll be building.


What would it take to get a 5.9 to 450 hp? I don't want turbos or a supercharger.

 

For those kind of numbers, you would end up with a high RPM motor, that had nothing in the lower end..... For racing, probably ok, but, if you do regular trail rides, it would suck.

 

Nobody mentioned stroking it up to 400+ cubic inches. Sure it take a chunk out of your budget but it will be easier obtaining higher hp ratings with more displacement.