Dyno results for stock 4.0 HO?

I'm trying to find dyno results for a stock 4.0 HO like the one in my 91 XJ. A graph would help, but I'm really looking for the raw numbers.

If anyone has a dyno sheet they can post up, or direct me to a link somewhere, I would really appreciate it.

Thanks!

The torque curve will look like the red line curve below:



That was the curve that I mapped for my '92 XJ when it was bone stock over 10 years ago. Claimed 193hp@4800rpm and 240lbft@3300rpm.
_________________________________
1992 XJ Laredo 4-dr - 198k miles - 23k miles on 4.6L HO Stroker
AX15, NP231, D35c, D30

270hp@4950/327lbft@3750, 1/4 mile = [email protected], 0-60 = 5.6secs
Websites - Jeep 4.0 Performance, 4.6L Stroker Build-Up, Dino's Jeep Tricks

WOW those are not bad numbers for stock, and it looks like you have add a lot of power. Good job!

Anyone have one for a Renix 4.0? Always wanted to compare.

Tweeternpi said:

WOW those are not bad numbers for stock..

Click to expand...

They're about average for a stock 4.0 HO. From my site:

Stock High Output 4.0 Jeep Cherokees with an automatic transmission produce 150-155hp/187-195lbft at the rear wheels in 2nd gear. Assuming a 20% drivetrain loss, that equates to 187-194hp/234-244lbft at the flywheel. It appears that the factory correctly rated maximum horsepower at 190hp but should have rated maximum torque at 240lbft instead of 225.

Click to expand...

are those actual numbers, or calculated?

The numbers for my old 4.0 and the stroker are calculated using various formulae (including Bowling & Grippo's formulae for calculating aeroodynamic and rolling HP/TQ losses, a formula for calculating torque delivered to the wheels, and a correction factor for drivetrain torque loss) based on actual performance test results that I obtained from my Jeep. I also made further corrections for weather conditions, the amount of fuel in the tank, and elevation. The shape of my stock 4.0 torque curve is almost identical to the one published by the manufacturers shown below.



The quote from my site refers to actual chassis dyno runs on stock 4.0 XJ's so they are representative of the true HP/TQ numbers put out by the 4.0.

Dr. Dyno said:

The numbers for my old 4.0 and the stroker are calculated using various formulae (including Bowling & Grippo's formulae for calculating aeroodynamic and rolling HP/TQ losses, a formula for calculating torque delivered to the wheels, and a correction factor for drivetrain torque loss) based on actual performance test results that I obtained from my Jeep. I also made further corrections for weather conditions, the amount of fuel in the tank, and elevation. The shape of my stock 4.0 torque curve is almost identical to the one published by the manufacturers shown below.

The quote from my site refers to actual chassis dyno runs on stock 4.0 XJ's so they are representative of the true HP/TQ numbers put out by the 4.0.

Click to expand...

nice how the inline hits its peak about a grand before the v-6

Even nicer that it stays at peak torque for about 500 rpm longer then the v6.....

Dr. Dyno said:

The numbers for my old 4.0 and the stroker are calculated using various formulae (including Bowling & Grippo's formulae for calculating aeroodynamic and rolling HP/TQ losses, a formula for calculating torque delivered to the wheels, and a correction factor for drivetrain torque loss) based on actual performance test results that I obtained from my Jeep. I also made further corrections for weather conditions, the amount of fuel in the tank, and elevation. The shape of my stock 4.0 torque curve is almost identical to the one published by the manufacturers shown below.

The quote from my site refers to actual chassis dyno runs on stock 4.0 XJ's so they are representative of the true HP/TQ numbers put out by the 4.0.

Click to expand...

your calculated graph doesn't have the distinctive notch at 2400 RPM or the table-top smooth torque between 2800 & 4000 RPM. That's why I wondered. The above graph appears to be comparing the 3.7 to the current Wrangler 4.0 which is rated at 235 lbs/ft, not the typical 225 lbs/ft Cherokee version.

That's right. When I showed the 4.0 v 3.7 comparison, that 4.0 wasn't meant to be mine. It's the current Wrangler's so that's why the torque curves differ slightly. I did say that the XJ 4.0 should have been rated at 190hp/240lbft and the current TJ 4.0 is rated very close to that at 190/235.
Every engine's gonna be slightly different on the dyno and my old stock 4.0 had the "flat spot" at ~2000rpm instead of 2400, but the shape of the torque curve is almost identical nevertheless.

Seriously, doesn't somebody out there have some actual dyno numbers? (not just predicted or calculated numbers)

I'm really looking for something a little more accurate than the graph posted above. I'd like to see a table showing horsepower in 200 RPM increments, from about 600 RPM on up to redline. If anyone has had their XJ on a dyno, the dyno sheet should have this information.

The reason I'm asking, is I'm working on an Excel spreadsheet that plots engine power in each gear vs road load measured in horsepower. The variables include rolling resistance coefficient, tire size, and gearing, so I can calculate the optimum gearing for my tire size based on how steep the hills are here and my driving style. I just need some good dyno numbers to make this as accurate as possible.

zthang43 said:

Seriously, doesn't somebody out there have some actual dyno numbers? (not just predicted or calculated numbers)

Click to expand...

Read my second post in this thread. The numbers that I quoted from my site are ACTUAL chassis dyno numbers (yes, real world).
Here's a couple of dyno curves from automatic XJs run in 2nd gear:

http://www.rockcrawler.com/techreports/dynomax_xj/page2.asp
http://www.kandn.com/dynocharts/57-1519.jpg

Divide the chassis HP/TQ numbers by 0.80 to get approximate flywheel numbers.