EPA MPG '88 GTA 2.77:1?
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Car: seeking '90.5-'92 'bird hardtop
Engine: several
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EPA MPG '88 GTA 2.77:1?
Anyone know the original highway rating for this combo, please? ( 5.7L of course )
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Re: EPA MPG '88 GTA 2.77:1?
I have seen a 1988 Formula 350 sticker listing 16/25 and a 1988 TA 1LE 305 listed as 16/26. My Camaro with a 350 is marked at 16/25 and I've seen 1987 Trans Ams with the 350 at 16/25.
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Car: 1989 Iroc-z
Engine: 350 TPI
Transmission: Auto 700R4
Axle/Gears: 9 bolt - 2.77
Re: EPA MPG '88 GTA 2.77:1?
Dont know what my iroc is rated but I have the 2.77 rear and 350 tpi. Window sticker wasnt in the car when I bought it off a dealer lot in 96. I have calculated the mpg for highway and it was around 21 mpg. +/- a couple miles depending on how my foot was giving it gas on the highway. Good thing is that the engine rpm at 65 mph is about 1750. 40 mph is practically idle rpm.
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Car: 1992 Chevrolet Camaro Z28
Engine: 5.7 TPI
Transmission: 700R4 Overdrive Automatic
Axle/Gears: 3.23:1 Positraction
Re: EPA MPG '88 GTA 2.77:1?
Mine is rated at 15 city and 23 hwy
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Re: EPA MPG '88 GTA 2.77:1?
Error. Which might explain your below-normal MPG. Should be a red 17 tooth drive gear for the speedometer, and a 37 tooth driven gear. Correct is 1640 RPM at 65 MPH. And 21 is a shame. I had a carbureted '78 Camaro with 350, swapped 700R-4, 3.08:1, 235/60R15s on 8s, and the big rear spoiler, do 25.1 MPG at 65 MPH with no centrifugal advance in the distributor, running from SLC to Wellington. Fixing the dizzy would've been at least 26 MPG. That was 1800 RPM at 65 MPH, with 18:43 speedometer gears.
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Car: 1989 Iroc-z
Engine: 350 TPI
Transmission: Auto 700R4
Axle/Gears: 9 bolt - 2.77
Re: EPA MPG '88 GTA 2.77:1?
Error. Which might explain your below-normal MPG. Should be a red 17 tooth drive gear for the speedometer, and a 37 tooth driven gear. Correct is 1640 RPM at 65 MPH. And 21 is a shame. I had a carbureted '78 Camaro with 350, swapped 700R-4, 3.08:1, 235/60R15s on 8s, and the big rear spoiler, do 25.1 MPG at 65 MPH with no centrifugal advance in the distributor, running from SLC to Wellington. Fixing the dizzy would've been at least 26 MPG. That was 1800 RPM at 65 MPH, with 18:43 speedometer gears.
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Car: seeking '90.5-'92 'bird hardtop
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Re: EPA MPG '88 GTA 2.77:1?
Yeah, but Fords have always been bad for MPG. With GM it's not challenging to do 10% better than the EPA highway ratings. To be fair to Ford, I did get a 2.73:1-geared 5.0 / T5 GT to do 30.06 MPG, once. No tailwind, and the pumps weren't suspect, nor was the odometer. Just keeping the MPH down. This thread started after I looked at the EPA ratings for the '84 Z28 L69 / T5 / 3.73:1, and an LB9 / T5 / 3.45:1 IROC-Z, can't recall what year.
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Join Date: Mar 2001
Location: Doghouse ······································ Car: 1989 Formula 350 Vert Engine: 350 L98 Transmission: 700R4 Axle/Gears: B&W 3.27
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Car: 87 Formula T-Top, 87 Formula HT
Engine: 5.1L TPI, 5.0L TPI
Transmission: 700R4, M5
Axle/Gears: Sag 3.73, B&W 3.45
Re: EPA MPG '88 GTA 2.77:1?
My 89 Formula 350 Convertible actually got 26 Mpg from North Carolina to Flint, MI Highway 70 - 75 Mph...
I would be surprised if your GTA has the 2.77 gears, it should have the 3.27 by default, unless it was a Canadian Car or a Trans Am... There are a few out there but the ones I can recall were export models. Almost all LB9/M5 Formulas and GTA's have the 3.42 or 3.45 gears and the GTA 350 and Formula 350's should have the 3.23 or 3.27 gears...
With an Auto @ 70 Mph in OverDrive
2.73 or 2.77 Gear = ??? I do not remember
3.23 or 3.27 gear = 1750 RPM (approx)
3.73 or 3.70 Gear = 2250 RPM (approx)
John
I would be surprised if your GTA has the 2.77 gears, it should have the 3.27 by default, unless it was a Canadian Car or a Trans Am... There are a few out there but the ones I can recall were export models. Almost all LB9/M5 Formulas and GTA's have the 3.42 or 3.45 gears and the GTA 350 and Formula 350's should have the 3.23 or 3.27 gears...
With an Auto @ 70 Mph in OverDrive
2.73 or 2.77 Gear = ??? I do not remember
3.23 or 3.27 gear = 1750 RPM (approx)
3.73 or 3.70 Gear = 2250 RPM (approx)
John
Last edited by okfoz; 07-24-2012 at 03:23 PM.
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