Dyno Results

[CobraMarty]

Today went to the local Mustang Dyno.
1998, 162,000, auto, volant CAI, 62mm TB, magnaflow cat back exhaust.

150rwhp at 4850, 174 rwtq at 4100.
About 22% driveline loss. Dynoed in 2wd.

 

[streetxj]

Did it have large tires?

Just wondering why it's so low since 4.0 cherokees have great acceleration. Maybe the transfer case provided extra drag?

 

[CobraMarty]

Why so low? So low compared to what? Did put stock tires on rear.

Considering it has 190HP/230TQ at the crank when new, for rear wheel HP and Tq and only about 22% loss thru auto and transfer case, this is actually very good especially on a conservative Mustang dyno.

 

[streetxj]

Why so low? So low compared to what? Did put stock tires on rear.

Considering it has 190HP/230TQ at the crank when new, for rear wheel HP and Tq and only about 22% loss thru auto and transfer case, this is actually very good especially on a conservative Mustang dyno.

Now that you've mentioned it that way, it does sound pretty good. I remember now that mustang dynos tend to read a bit low.

Isn't the peak torque at 3000 rpms?

Factory peak torque rating is at 3000 rpms.

 

[CobraMarty]

I was expecting lower considering the mileage but I did do seafoam gas and intake treatment, added 'Restore' to oil, synthetic oil throughout-engine, trans, transfer case, both diffs.

 

[DanMan2k06]

Just wondering why it's so low since 4.0 cherokees have great acceleration. Maybe the transfer case provided extra drag?

Like he said, you can't compare actual reading with a spec on a piece of paper. If you think your XJ has 190hp, you've got somethin coming to ya. I will concur with the great acceleration comment though... if we're doing a car vs. foot race.

 

[CobraMarty]

I think 22% drive train loss is pretty accurate, so 150rwHP = 190 crankHP.

 

[streetxj]

Like he said, you can't compare actual reading with a spec on a piece of paper. If you think your XJ has 190hp, you've got somethin coming to ya. I will concur with the great acceleration comment though... if we're doing a car vs. foot race.

You're right. I don't think jeep 4.0's have exactly 190 hp. Factory ratings are never 100 percent accurate. For example, Ford under rated the 93 5.0L cobra mustang. They rated them at 235 hp and people that have dynoed them are reading more or less around the 265 hp mark. It might be over rated or under rated, even though I think they would be more likely to under rate them for insurance purposes (I think).

 

[CobraMarty]

Could be, who uses an engine dyno anymore. But the 22% drive train loss is pretty much what I have seen in other auto vehicles.

 

[Dr. Dyno]

Today went to the local Mustang Dyno.
1998, 162,000, auto, volant CAI, 62mm TB, magnaflow cat back exhaust.

150rwhp at 4850, 174 rwtq at 4100.
About 22% driveline loss. Dynoed in 2wd.

Which gear did you use for the dyno run?
What tire/gearing combination do you have?
Can you post the chart?

The numbers don't look bad on the face of them but it's hard to judge without knowing more info.

 

[CobraMarty]

2nd gear, 3.55 gears, 215/75 15

 

[Dr. Dyno]

In that case definitely not bad. Those numbers are about what I'd expect from a bone stock 4.0 automatic dyno'd in 2nd gear with stock tires/gears. A newish 4.0 with your mods would be putting down about 160-165rwhp but with the high mileage on your engine, there'll be some degree of ring/bore wear and a slight compression loss.
Unfortunately I can't view your dyno chart where you have it right now.

 

[CobraMarty]

Next I want to install the Banks headers, ignition upgrade, and '99 intake with 703 injectors and re-Dyno it. Then while on the dyno, also load the different Superchips programs and see what it does. Maybe see 180HP and 200+TQ.

 

[Talyn]

Those numbers are about right. Mine was about that w/ bolt-ons and 31" tires w/stock 3.55s