Upgrading from the stock 2.73 to a 3.73 gear will make your car considerably faster, but will wind up your engine around town that much more and reduce your gas mileage quite a bit.

I'm wondering, mileage/RPMs being considered, if you modified your car to be just as fast as the 3.73s would have, but do it with other mods like headers and exhaust and stuff instead, your mileage would be better wouldn't it?

Also, how much more gas will the LS1 eat after heads/cam have been done? I'm talking MTI Stage II heads and a 221/.556ish 114 sized cam in a 382? Has anyone logged their mileage?

Reason I ask is, I will be buying one with high miles (because it will be cheap ) and will then rebuild it shortly with MTI. It will still be the daily driver (will have a 2nd car as the drag only car) so mileage is an issue.

It will be an M6 BTW.

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1983 Monte Carlo, 307 Stroker, TH350, 3.73 10-Bolt - SOLD 8/19/02

Future F-Body Owner

[This message has been edited by BlackHawk T/A (edited August 28, 2002).]

[This message has been edited by BlackHawk T/A (edited August 28, 2002).]

 

how can mileage be an issue on a modded engine? I would think that you should be fine with the speed and not worry so much about the mileage. I just bought mine and its bone stock. Cruising at about 80-90 I got 24 miles per gallon. Not too shabby... But I think that most cars loose some of their fuel effeciency only because you are FLOWING MORE AIR AND FUEL. If you have stock heads on a motor, then replace them with ported heads that also have larger intake and exhaust valves would you not be flowing more? Remember you would have to recalibrate to put more fuel into the mix.

So it makes no sense to me.. but having come from a nightmare modded car, having a highly modded car as a daily driver is not something I would do.

Good luck...

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Psycho Cabbage
2002 Camaro Z28
(6 sp) Bone stock
Webmaster for RaceHer.com
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-Traded in- 1995 Camaro Z28 (A4 (#6 I might add!),ES tranny mount and torque arm bushing,SLP CAI,ASP 34% Underdrive,Strange 3.73's (shredded Auburn),1LE alum driveshaft & intake elbow,Yokohamas AVS Intermediates,160-stat,MAF screen removed, HPP+(for shift points only),Borla Y-pipe, Flowmaster Force-II catback, Gutted Cat, Airlift Airbag, !TB Bypass, J&M LCA's, Bosch Platinums, Moroso BlueMax Wires, Free RamAir, Meziere Electric H2O pump, MAC 3point STB, BMR Panhard, SCR SFC's
Just installed:Nu-tek Heads (mild port) and Comp Cams 1.6RR's! New track and dyno #'s to follow!
best 13.44 @103.26
0-60ft 1.96
270 RWHP/296 RWTQ
0-60MPH 4.8sec
1987 Porsche 944S (waiting on LT1 mod)

 

so your saying your old '95 was highly modded?
jeremy


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'93 z28 m6 (Purple Pearl Metallic)
stock shortblock, 230/236 cam, mildly ported heads, hooker longtubes, csi waterpump, all the usual bolton stuff.....
7.98 @ 88.7mph 1.84 60' (1/8mi)

 

I KNOW that mileage will decrease, that's what I SAID. I was simply asking how much, if anyone had done something similar, and if anyone had logged their mileage.

For example, with the MTI 382 (either All-Bore or the Stroker) with the heads/cam, do you think 20+mpg is still possible on the highway? Highway speed here is 45mph and I do about 50. Which gear is better for 50mph, 5th or 6th? Is 6th too much for that speed and will it actually hurt mileage?

I spend most of the time driving in the city at 35 or under though. Any input from someone with a setup like this would be appreciated.

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1983 Monte Carlo, 307 Stroker, TH350, 3.73 10-Bolt - SOLD 8/19/02

Future F-Body Owner

 

IMO with a cam (especialy one above 220 dur @ .050) you NEED gears in an M6.

I didnt like my 3.73's, after I put my cam in, so I went to 4.11's when I put the 9 inch in. I still feel they arent quite enough, So I will be going to 4.30s.

The gears wont hurt your mileage much in an M6, my 3.73s actualy gained me about 1 MPG in the City, I dont do much Highway, except to the drag strip, so thats not really a very good indication of mileage because of the massive flooring

WIth the 3.73s and cam I never checked mileage, but I had to keep it at least one gear lower than I did before at any given speed to keep it from surging, and bogging. the 4.11's helped this, and some Edit tuning helped even more.

Most people say they dont see any change with 3.73s and about 1-2 MPG less with 4.10's on the highway.

I have heard of people getting 24 MPG on the Higway with MTI head/cam packages.

Hope this helps a little

 

Nope.. I did say that mine was a "nightmare modded car"