The owner wants to continue using "Up to 10% ethanol" 87 octane fuel in this truck and Minnesota's ethanol levels vary from 5-8% most of the time. I want to see how the tune reacts under load and find a safe happy medium. I'm actually going to tune this truck twice, once without a trailer and again with a single car trailer hauling a 5000lb off-road buggy.
![2001 chevy 8.1 vortec mpg 2001 chevy 8.1 vortec mpg](https://www.motortrend.com/uploads/sites/21/2015/07/chevrolet-avalanche-2500.jpg)
Hopefully I'll be able to tell what airflow on Friday. So why can't a modern port EFI, OD, dual exhaust, high flow cat, fast burn headed 454 do better? Gotta be something they did to "hurt" it.
![2001 chevy 8.1 vortec mpg 2001 chevy 8.1 vortec mpg](https://i.pinimg.com/originals/47/86/7b/47867b793229c230f62eeb735820acf8.jpg)
2.41 to 2.73 gears, THM400, no TCC, carb, crap "J" heads, aero about as bad as most pickups, and yet it was EPA rated at 12 city and 18 highway. I always look back at the 76 Olds 98 Regency.
![2001 chevy 8.1 vortec mpg 2001 chevy 8.1 vortec mpg](https://www.raylarengineering.com/img/vortec8100-crate-engine.jpg)
Best we can tell they put the cam in so late to flatten the powerband to reduce emissions some. Look how small the factory cam is and then look at the torque peak. Have him shoot for the intake centerline on the cam to be around 112. Then add in timing chain wear/slop and you have a cam that is so far off the engine never will get good mpg, you'll be 1000 rpm away from torque peak at cruise.
2001 CHEVY 8.1 VORTEC MPG INSTALL
) install the cam usually around 5-10 degrees retarded. The bigger issue is the cam installed position. They are usually low on timing, but you have to be VERY careful, if he hooks up a 15k trailer to it and the timing is up too much for that sorta load, pistons will not be so happy. I'll have to wait until tomorrow to see what this truck actually allows me to do but is this normal for an Allison not to be able to change the tire/gear? The tires on this truck are 2" taller than stock.I'd like to calibrate the speedo for the final drive change, but I'm noticing that some Allison tunes don't allow for the gear/tire calculator. I was curious if anyone has an 8.1L tune they're willing to share their DFCO settings and other MPG tips?Ģ. I'll be dialing in VE and MAF, PE, getting rid of some nasty factory spark table dips and disabling all TQM that applies to reverse, 1st and 2nd gear (he's tired of not being able to back up over a speed bump). See question 2 for part of the reason why. The owner drives 100-110 miles round trip to work every day with this truck and he's tired of 7-8mpg highway. A few questions have come up from the last few public tunes I've looked at.ġ. In the mean time, to familiarize myself with the OS I've been looking at repository tunes. One benefit is the stock GM roller lifters can be reused if they're healthy.Tomorrow I'm applying credits towards a friend's '02 Silverado 2500HD with the 8.1L and Allison. Call Raylar to make sure your pistons and cam are safely matched. We pried, but all Hofer would say was that valve lift ranges between 0.500 and 0.660 lift. This trio depicts (left to right) the 203 (high-torque, stock-idle quality, emissions-compliant, safe with stock piston crowns), the 206 (for stock displacement or strokers with deep-relief pistons, choppy idle, 2,500-rpm stall recommended, improved midrange and top-end power), and the 213 (high lift, choppy idle, ideal for extra-displacement applications, requires Raylar deep-relief pistons).
![2001 chevy 8.1 vortec mpg 2001 chevy 8.1 vortec mpg](https://i.ytimg.com/vi/ohyGe6twZK4/hqdefault.jpg)
Thus, Raylar offers nine proprietary performance-proven hydraulic roller cams to suit applications from trailer towing to turbocharged drag racing. Raylar honcho Larry Hofer says he's invested too much dyno time to give away the ideal cam specs. The 8100's LS-style port spacing and 1-8-7-2-6-5-4-3 firing order prevent the use of traditional big-block camshafts.