L8T replied to Snorat's topic in 6.6L Gas V8 & HD Transmission Powertrain (L8T/MYD)Year later, still nothing. Thing is don’t even think they need to crack the ecm or be able to flash it to make hp/tq changes. They could go old school like the old edge piggy back systems with sensor foolers and such.
100% this was the case. 4 speed was awful for mileage due to its gearing not its weight. 10-12mpg (at best) empty was not an acceptable number at that time for majority of customers and still isn’t today. And when the 6.0 came out and got better fuel mileage with more hp/tq it was a no brainer to ditch the combo-and the engine altogether. There’s always a few guys with lady boners for that combo out there but the fact remains it was an awful combo. The current 6L90E has a lighter converter than any ever used in an Allison, planetary hubs and gears are all lighter, the entire assembly overall is lighter. It works well as did it’s predecessor. No reason for a trans that can easily hold over 1000 ftlbs tq to be paired with a gas engine with much less. Not to mention a totally different tq curve and rpm range.
L8T replied to Truston Gunter's topic in 6.6L Gas V8 & HD Transmission Powertrain (L8T/MYD)Don’t waste your time or money on a catch can. Just run an oil that’s recommended for this engine, change it when it gets to the add mark or oil life says to, and run an intake cleaner every 3rd oil change and you won’t have any problems. DI engines are known for 2 things, oil consumption and carbon build up on the back of the valves. I’ve owned several different DI engine powered vehicles and this has been common across all of them. I’ve tried catch cans and additives and the problems they created in the end weren’t worth any of the issues I was trying to eliminate.
This will never happen. The Allison is heavy internally and will rob too much hp to make it viable. Not to mention awful fuel economy. Hence why they dropped the 8.1/ally combo years ago.
I drive a 7.3 F-550 with a 10 speed every day at work. Granted it’s a heavy service truck with lower rear gear ratio than my 3500HD gas but it drives so much better. I absolutely hate the 6 speed in this gas truck. It wouldn’t be so bad if I could tune it like I could the 6 speed diesels because there is a lot left on the table for driveability, but seeing as nobody wants to bother cracking the gm ecm the only choice is to hope for more gears. Personally I don’t mind the truck I have but I will wait for either tuning to come available or more gears in a newer truck and after driving this one would recommend others do the same.
Nice looking rig. What size tires and rim offset? I went with 20x10 -18 with 285/65R20 Toyo C/T’s and just turning up the bars isn’t quite enough on the front to keep from rubbing. (Picture is with the Radar Renegade’s I briefly ran)
I’ve got a ‘20 3500HD SRW and for some reason almost every lift maker out there makes them for 2500’s but only a couple do the 3500’s. Some of the fitment comments I’ve found say they won’t work with overloads. For instance the Superlift P/N K1013 3” UCA lift says it won’t work with overloads but they list it for the 3500HD. I’ve reached out to them but no response. Every 3500 has overloads since 2001 so why now do they not make kits? What is so different about the 3500 with overloads that they can’t make a kit? In the past it was just a longer u-bolt required. Anyone in the know about this?
L8T replied to Blac's topic in 6.6L Gas V8 & HD Transmission Powertrain (L8T/MYD)Mine just started flaring the 2-3 shift on occasion. Hopefully that’s just a software fluke and not a hard parts failure on the horizon.
They are nothing alike. More accurately they are a heavier built updated version of the 6 speed that came behind the previous 6 liter trucks. Reliability is probably their strongest plus.
I see K&N has an open top air box design available now. https://www.knfilters.com/gmc/sierra-3500-hd/6.6l-v8-gas/2020/ Has anyone looked into or tried using the ram air from the hood that the diesels use in a gas truck yet? Might be a nice combo with the K&N CAI if a person can make it fit.
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