I have a 2005 Yukon with 8.1. I do live in Carnation WA so not to far. In the above questions concerning another yukon you mention that may require passkey relearn and crankshaft postion Procrdures. being not to far is this something you can do at your shop in centraila. 2, does the tune change at what peak torque is obtained. stock is 3200 RPMs. getting another 70 Lbs of Torque and HP. would i need to beef up the L485E transmission? its reted at 460LBs of torque but not sure if that means on the ground or not.
( gary armstrong, 09/04/2018 )

You can call or text and schedule an appointment with Barbara to have this done at our facility. 360-736-9494 You would not need to change the transmission in any way after the tune :-)

I just want to make sure I'm look at this correctly assuming all these numbers are RWHP and RWTQ.

Your stock numbers: 268 rwhp / 419 rwtq
normal gm truck stock 281 rwhp / 341 rwtq (from what I can find behind a 4L80E)
ultrapower tuned 305 rwhp / 475 rwtq

If these numbers are correct, with everything else stock and just your ECM I could possibly gain in my 2005 yukon xl 8.1 24 rwhp and 134 RWTQ?

Am I missing something? If not this is a great deal and I would be very interested.

Thank you for your help. ( whitney thornbrough, 06/05/2018 )

The problem of comparing horsepower and torque numbers at the rear wheel is that all dyno's will measure differently. Type of dyno, elevation, temperature, calibration of dyno, etc. all come into play when you are comparing numbers from different dynos. The gains that we get on the RV's is just about the same as the Kodiaks, Pickups and SUV's with the 8.1L.

1. Have you ever done a dyno for the 8.1 4L80e trans combo?

2. "GM Trucks with 8.1L Engine (May require Passkey and Crankshaft Position Relearn Procedures)" Are these hard procedures? Would it be necessary on a 2005 yukon xl 2500 8.1?

3. You stated your tune requires a higher octane, 89? 91? If i run on 87 will it damage anything or just lose a little performance? Would it ping and knock?

Thanks in advance. ( Whitney Thornbrough, 06/01/2018 )

Yes we have dyno'd several 8.1L/4L80E combo's but mostly in the P32 Workhorse configuration. Results are very similar to what we see with the 8.1L/Allison. We do not state that a higher octane fuel is required, we tune for 87 octane but CAN tune for a higher octane if desired. No pinging or knocking as long as your engine and sensors are healthy :)

The crankshaft relearn will require a scan tool but only takes a minute or two to complete. The Passkey relearn is a fairly lengthy process (~30 minutes) but is very easy, we can send instructions on this if needed.

I pull a Ford Edge and sometimes a trailer which weighs loaded 6000 lbs. Will I have pinging on long uphills in hot weather and need to run higher octane? Can I keep my stock ECM in case smog laws in California become tighter and peace of mind.

Thanks ( Steven Thomas, 05/21/2018 )

We do not push the spark advance to the point that you need to run higher octane, under any conditions. You can keep your stock ECM, you would just not get your core refund back ($150).