Seems to mainly be a problem on vehicles that idle a lot like tow trucks. Lifters go bad from time to time, which eats the camshaft. I broke one trying to remove it, ironically, because I was R&R'ing the driver's side head and I didn't want to risk damaging it. I once watched a coworker cut through the floorboard of a tow truck over it.
I also didn't like how much throttle it took to get the full torque of the engine, which is usually one of the main ways that turbo cars are satisfying (lots of torque at mild throttle).Īnyway, I've driven the same truck in 8.1 and disliked it for other reasons (mostly that it needed a tune to remove its torque management behavior), but i'm just saying there's definitely a way of thinking that doesn't fall in love with the duramax over the 8.1.Īs far as 'major problems' on the 8.1, replacing the crankshaft position sensor has been known to turn into a major problem.
I liked the Allison ok but i like the later ones that have a manual shift mode a lot better as i felt the stock upshifts were kinda high/late with no load. I recently rebuilt most of the front end on an early duramax/allison truck and the engine noise actually bothered me enough that i constantly thought about potential ways to make the truck 'not annoying' instead of being impressed that the dash showed 19-20 avg mpg.
They are using denial to avoid hurt feelings at the gas station.AIUI, the 8.1L/Allison combo is great until you drive the Duramax/Allison combo and then you never want to go back. I have a family menber with 6.0L version but haven't touched it. Sorry I don't have any exact recomendations for you truck. Make sure the OEM part your upgrading sucks before you waste time & money replacing it. Not every vehicle needs everything upgraded.
Software was the only thing that affected MPG. By the way all that extra power is with stock air filter and exhaust. HP was my goal I just got lucky on the MPG. My Audi is heavily upgraded with an extra 170 HP and mialage went up 3 in town and 5 on the highway. If you see a MPG trend with a particular chip go for it.Įxtra air in tires, synthetic oils and gearlubes, bed cover or tailgate down will all help but not alot.Īnything you spend comes out of potential savings so do the math and see if you even can recoup what you have spent. Now take what you have learned to the forums and see what other people are getting from the chip upgrades. depending on your altitude and available octanes having to go up to better fuel can kill savings. However better fuel octane may be required. For better milaege you will need software that is more effiecient at cruise RPM and throttle (probably leaner and/or more timing) but when you nail it the rest of the fuel & timing maps can be for power. Call each chip MFG and speak to their genius dept if available and inquire regarding mpg gains. I would ignore the K & N filter and exhaust for MPG gains and look into chips. Using a web site like can get you tire dimensions and you can figure out percentage change.īeware of MPG claims from Performance part folks. Assuming same aspect ratio with 285 tires your going faster than your speedo reads and farther than your odometer says. Tire diameter differences will change distance traveled. My truck has 285's on it, not the 235's that come stock.