LS3 (376/525) MPG - Real world #'s?
02-12-2023, 12:48 PM
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LS3 (376/525) MPG - Real world #'s? Hey everyone,
I've posted this at a couple other forums without much success and was pointed in the direction of you fine folks. I'd like to know what mpg folks are pulling with the GM Connect and Cruise 525 (LS3 w/ ASA Cam).
I have around 4,000 miles on the block, T-56 Super Magnum, and 3.23 gears on a 67 Firebird and I'm only averaging 9-13 mpg in city/cruising. Car has stock tune from GM computer that comes with the package.
I know the car is expected to run rich with the overlap and prevent damage from running lean but I'm curious about real world baselines for comparison. There are few historical threads on the internet with numbers, and a couple do mention 10-12 mpg, but this is a far cry from the 15-28 people report with a stock LS3 or other variants.
And at a recent Saturday morning car gathering someone with a C3 Vette swore he was pulling 31 on the freeway with the same engine/trans combo.
Appreciate any responses!
I've posted this at a couple other forums without much success and was pointed in the direction of you fine folks. I'd like to know what mpg folks are pulling with the GM Connect and Cruise 525 (LS3 w/ ASA Cam).
I have around 4,000 miles on the block, T-56 Super Magnum, and 3.23 gears on a 67 Firebird and I'm only averaging 9-13 mpg in city/cruising. Car has stock tune from GM computer that comes with the package.
I know the car is expected to run rich with the overlap and prevent damage from running lean but I'm curious about real world baselines for comparison. There are few historical threads on the internet with numbers, and a couple do mention 10-12 mpg, but this is a far cry from the 15-28 people report with a stock LS3 or other variants.
And at a recent Saturday morning car gathering someone with a C3 Vette swore he was pulling 31 on the freeway with the same engine/trans combo.
Appreciate any responses!
02-12-2023, 03:56 PM
#2
A bit different than your combo. I built a L92/TKO 5 speed combo. 3.73 gears. Went in a 73 Camaro. 225I/230E cam. On the Power Tour on the 60 mph back roads I got 26 mph. I was a bit shocked at first so I topped off the tank to the very top at the next gas top. Drove about 200 miles and filled again. Same 26 mpg.
I think you need a really good chassis dyno tune.
I think you need a really good chassis dyno tune.
02-12-2023, 04:34 PM
#3
Hey everyone,
I've posted this at a couple other forums without much success and was pointed in the direction of you fine folks. I'd like to know what mpg folks are pulling with the GM Connect and Cruise 525 (LS3 w/ ASA Cam).
I have around 4,000 miles on the block, T-56 Super Magnum, and 3.23 gears on a 67 Firebird and I'm only averaging 9-13 mpg in city/cruising. Car has stock tune from GM computer that comes with the package.
I know the car is expected to run rich with the overlap and prevent damage from running lean but I'm curious about real world baselines for comparison. There are few historical threads on the internet with numbers, and a couple do mention 10-12 mpg, but this is a far cry from the 15-28 people report with a stock LS3 or other variants.
And at a recent Saturday morning car gathering someone with a C3 Vette swore he was pulling 31 on the freeway with the same engine/trans combo.
Appreciate any responses!
I've posted this at a couple other forums without much success and was pointed in the direction of you fine folks. I'd like to know what mpg folks are pulling with the GM Connect and Cruise 525 (LS3 w/ ASA Cam).
I have around 4,000 miles on the block, T-56 Super Magnum, and 3.23 gears on a 67 Firebird and I'm only averaging 9-13 mpg in city/cruising. Car has stock tune from GM computer that comes with the package.
I know the car is expected to run rich with the overlap and prevent damage from running lean but I'm curious about real world baselines for comparison. There are few historical threads on the internet with numbers, and a couple do mention 10-12 mpg, but this is a far cry from the 15-28 people report with a stock LS3 or other variants.
And at a recent Saturday morning car gathering someone with a C3 Vette swore he was pulling 31 on the freeway with the same engine/trans combo.
Appreciate any responses!
I put an ls9 cam in my ls3.
02-12-2023, 05:36 PM
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You’re the first person to confirm a mpg on all three forums.
It’s definitely an incredibly smelly motor ….probably would have gone with the 480 in hindsight if i knew how it would behave and the nuances but the dealer gave me such a great deal on the 525 i didn’t feel like i could pass it up.
I’m just trying to gauge whether anyone has different numbers or tuned it and made a noticeable difference.
Cheers!
02-13-2023, 06:41 PM
#5
Up to 16 city / 26 on the 08 Corvette.
It also has 6 speed with 5 and 6 gears are both overdrives.
1st Gear 2.66:1
2nd Gear 1.78:1
3rd Gear 1.30:1
4th Gear 1.00:1
5th Gear .74:1
6th Gear .50:1
Final Drive Ratio 3.42 on the manual and 2.56 on the automatic.
With this gearing the car will get over 20mpg at 100mph.
Your differential ratio is lower 3.23, and your coefficient of drag a litter higher.
Your the equivalent of running the Vette in 5th gear. That would lower the mileage only 2mpg.
Seems the logic is the issue is likely the tune or the camshaft?
It also has 6 speed with 5 and 6 gears are both overdrives.
1st Gear 2.66:1
2nd Gear 1.78:1
3rd Gear 1.30:1
4th Gear 1.00:1
5th Gear .74:1
6th Gear .50:1
Final Drive Ratio 3.42 on the manual and 2.56 on the automatic.
With this gearing the car will get over 20mpg at 100mph.
Your differential ratio is lower 3.23, and your coefficient of drag a litter higher.
Your the equivalent of running the Vette in 5th gear. That would lower the mileage only 2mpg.
Seems the logic is the issue is likely the tune or the camshaft?