acer99

2000 XJ Sport with stroked 4.0 and 3.55 gears running on 31" BFG A/Ts.

60mph, rpm is about 1900.
65mph, rpm is about 2100.
70mph, rpm is about 2250.

I'm getting crap gas mileage. I mean real crap. like 10mpg.

Any chance the gearing has something to do with it?

My cam puts the powerband in the mids.

lynskynbnd

Cam...Stroker...

That don't go with good gas milage!

I'd start with a 4 gas analasis before the cat on a dyno to see if the engine/fuel/ignition is even set up correctly before regearing.

acer99

I haven't heard of that, but I know what a dyno is!

The closest dyno is about a 40 minute drive, but I think you're spot on with needing to get it done.

I've just been putting it off until I get my exhaust rebuilt.

salad

Are those speeds taken with a GPS? Because those KPH/RPM readings are stock lol. I'm assuming this is an automatic transmission? Your profile lists "stock" but the 2000 only came with "AW-4" (auto) and "NV-3550" (manual)

acer99

I took em driving down the highway, but since I have 31" tires... they might be a little off.

I have the AW4 tranny.

I'm running a Comp Cam with Lifter:
http://www.summitracing.com/parts/CC...39-4/?rtype=10

Here is a cut & paste of the info for it:
Cam Style Hydraulic flat tappet
Basic Operating RPM Range ..... 1,400-5,700
Intake Duration at 050 inch Lift ..... 218
Exhaust Duration at 050 inch Lift ..... 226
Duration at 050 inch Lift ..... 218 int./226 exh.
Advertised Intake Duration ..... 262
Advertised Exhaust Duration ..... 270
Advertised Duration ..... 262 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio ..... 0.493 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio ..... 0.512 in.
Valve Lift with Factory Rocker Arm Ratio ..... 0.493 int./0.512 exh.
Lobe Separation (degrees) ..... 111
Grind Number ..... X4262H
Computer-Controlled Compatible ..... No
Lifters Included ..... Yes
Lifter Style ..... Hydraulic flat tappet
Valve Springs Included ..... No
Retainers Included ..... No
Locks Included ..... No
Valve Stem Seals Included ..... No
Timing Chain and Gears Included ..... Yes
Timing Chain Style ..... Double non-roller
Assembly Lubricant Included ..... Yes
Pushrods Included ..... No
Rocker Arms Included ..... No
Gaskets Included ..... No
Valve Springs Required ..... Yes
Quantity ..... Sold as a kit.

sthon

With 31's and stock gears you'll be about 5mph off iirc.

This might help. http://go.jeep-xj.info/HowtoSpeedoGears.htm

EVILXJ

http://www.jeep4x4center.com/calculators/index.htm

acer99

The guy that put my stroker together says the reason he chose my cam was to bring the compression down so I can run 87 octane. The problem, I think, is that the durations are so long that the ECU can't get an accurate reading. I'd need to see a fuel mix gauge to know better, but it looks like my powerband is way too high (1500 - 5700rpm) for this cam to be practical for anything other than racing.

I'm wondering if I can advance the cam a few degrees and run a lower gear ratio - possibly 4.56 - to compensate for this.

Ideally I should get a different cam and run 92 octane.

Heck, if anyone wants a free barely used cam, come pull it.

housew

the 31s with stock gears and uncorrected speedo means your gas mileage numbers are off too.

225/75/r15 = 28.28, so your ~9.5% off, so your really getting 11mpg, still pretty bad just saying.

a speedo will not be off by a number, it will be off by a percent, yes 5mph at ~50, but 0 off at 0mph, 1 off at 10, 2 off at 20, 3 off 30.....

evan00xj

i dont get anymore than 15mpg with my stroker...