gmgearhead454

After months and months of searching I FINALLY found the rig I've been after! It's a 2001 Chevy Suburban 4X4 2500 with the 8.1 big block, and is in AMAZING condition! I plan on moving up to a bigger boat next summer, so it was time to ditch the old 6.0 Silverado and start the upgrading process. My question is about tuning this engine. I don't plan on going crazy or anything with it, just an intake, custom exhaust, and a good solid tune. Ive been reading that these 8.1s respond awesome with a good tune, in gas milege and power, but I'd like to know which one would give me the best improvement. It currently has a VOLO chip in it, and can't find much specified info on it, but was thinking something like an HP tuner or EFI live would be the best route? Any input you guys have is greatly appreciated, thanks!

Crude Intentions

iTrader: (1)

8.1 strong motor. I wouldn't use the term gas mileage maybe has yardage. They just blow on fuel economy and haven't heard of one making it any better. Lol

gmgearhead454

Yeah I'm not expecting nothing great, but I live 2 miles from the shop and pretty close to everywhere I boat (LOTO & the Mississippi River), so since GM was never able to put the Duramax in the Suburban, this is about as close as it gets, plus I kinda have a thing for big bad non-diesel trucks. Just upgraded to a Gold membership so I can do photos and stuff, but apparently my computer is crappin out on me tonight...

bikepilot

Nice! A buddy used to have one. Strong trucks with massive torque off the bottom. Unusually large gains are had from a tune. It's basically the same engine as a merc. 496.

MILD THUNDER

iTrader: (3)

The 8.1's are pretty much bulletproof workhorses.

Theres a few good tuning places out there. Justin at Blackbear Performance tuned my 454 Vortec truck. Had him remove the torq management, and firm up my shifts a little bit, while he did the tune. Made a noticeable difference in the performance. I believe the suburbans didnt get the allison trans, and that they had the 4L80E? May want to get some input on removing the torque management, or how much to remove, with that trans not being as strong as the allison.

He is very good with GM gassers.

http://blackbearperformance.com/

Gimme Fuel

I have an 03 2500 Avalanche with the 8100 and 4.10 gears. It has headers, modified stock air box with K&N filter (gets within 3 hp for 50 bucks of what $300 cold air gets), Gutted cats, Flowmaster 4" 40 series muffler, 4" mbrp tail pipe. I tuned it on a friend's chassis dyno with HP tuners software. These motors were massively detuned in the burbs/lanches because of the 4L85E trans. That is a great trans and can hold whatever you want to throw at it. I removed all torque management, lowered shift points a bunch below 50%TPS so it shifts like a diesel, forced TC lockup above 30 mph, maxed out shift pressures and cut shift times over half. Used the tow/haul feature to have a lower rpm shifting tow tune with higher TC lockup settings but all of the shift pressures and lower shift times. My trans temps have lowered dramatically after doing this and stay 150-175 degrees towing heavy chit on hot days in overdrive yet. Gained 60 RWHP in spots and much better launch due to removal of torque management. Stock tune doesn't even flash the torque converter when you mash it of the line. Now it will. It is terrible how lean the factory runs these engines. Mine was 15.7 AFR at WOT with better intake and exhaust on it. No wonder why these motors got a bad rap for burning oil and blowing up. After changing this, my motor hardly burns a drop. Only place I loose it is a weeping oil cooler line like they are known for. Just need to replace the lines is all. She puts down 285 RWHP now (roughly 370 hp crank). 340 ft. lbs RWTQ.

Oil: Mine absolutely loves Mobil 1 15-50W oil and suffers no ill effects in winter running this heavy synthetic. I couldn't run 20-50W conventional in winter without the oil pump screaming at cold starts. 10-30W syn got too thin at running temps and I started loosing oil pressure above 4000 RPM. I know, the old girl is a bit loose. I also throw Lucas syn oil stabilizer in there. After running this regimine for a few years, my oil comes out a darker golden transparent color versus black like conventional oils. This is at 150k miles and has been tuned up like this since 108k when I bought it.

Mileage: With the 4.10 gears, highway mileage above 65 mph is a moot point (only get 12 at 70+mph), but 60 and below my economy went up 3 mpg. I can cruise in the summertime (I say this because I loose 2-3 mpg in wither just from that cold dense air) at 16-18 mph with the norm being 16. Towing I drop down 12-13 mpg (27' Checkmate). Weight doesn't really effect mpg, but air resistance does. I get 11-12 mpg pulling an old 25' Holiday Rambler travel trailer (11,000 lbs dry GVW). Pulling down the highway, If I draft behind a good semi, I can pick 2-3 mpg back up sometimes.

This winter I have a 496 HO camshaft, marine injectors and intake, and LS2 throttle body to put on. She should be a rocket. It already runs great for what it is.

There is probably more, but I forget. Feel free to ask.

ICDEDPPL

iTrader: (1)

Anyone Ive ever talked to pretty much says the same thing 10mpg no matter what , my experience is the same except for towing (6mpg) how you ^^^ get 16-18mpg is beyond me.
Blackbear performance tuned my truck, AFR`s are 13.5 cruise, 13.1 acceleration. Ive had long discussions (btw, you`ll never get him on the phone communication is email only)he keeps blaming parts. Ive replaced a few , (MAF, both 0`2s) now he sais its the coolant sensor or its burning oil. (doesn`t use any oil).

Damn Ive just reminded myself how much I can`t stand this truck, I gotta stop thinking about it or I`ll be on the web searching for a Diesel again.

Good luck with yours thou , as long as you don`t have an 80`s heavy resin bucket it should tow just fine

MILD THUNDER

iTrader: (3)

I take internet mpg claims with a grain of salt. The ONLY way to calculate mpg is by tracking your mileage traveled, and how many gallons it used when at your next fill up. This also requires a working speedometer/odometer. If your speedo is off at all, it will throw mpg way off. Whether it be from different size tires, etc.

The meters on the dash are worthless. For a while i was tracking my mpg at every fillup with my 454 vortec 4x4 dually with 4.10 gears. Long highway trip, empty, 65mph, i got a hair over 13mpg. Average city/hwy, around 10. Towing my 38 fountain to Loto 425 miles away, 8 mpg.

I didnt notice any mpg improvments from my tune, but i did notice a much better driving and performing truck. The stock tune was anemic, the shifting and first gear timing retard crap sucked. Best 250 bucks i spent on the truck.

MILD THUNDER

iTrader: (3)

It may be worth it to take it to a good tuner who can tune it live. If afr is 13.5 at cruise, something is wrong. GM had to conform to emissions with these trucks, and at those afrs the hydrocarbon counts would more than likely fail any states air pollution tests.

Plus theyd be able to watch live data i would think and really see whats going on. Lets face it , the truck wasnt stock tuned when you got it, has larger diameter tires on it now, and simply smells rich when you start it and its idling. Who knows, Maybe there is a bad part, or maybe its a bad tune, but i think it be worth checking into. Theres got to be a good efi live type of shop around us somewhere ?

Rookie

iTrader: (4)

When I was out test driving 8.1 Avalanches (7 of them) not one of them was above 9 mpg ave on the dash history. And those usually lie on the high side. Seemed to be a great engine though.