"grumpy my camaro has 4.11:1 rear gears and a 10:1 cpr 383 as you know and while I don,t use it for much more than a weekend toy the gas mileage is killing me, so I,m thinking of swapping in some 3.07 rear gears, but I,m afraid the 2800rpm stall converter, and a th350 trans and the crane 110941 flat tappet solid lifter cam, and 200 cc dart heads, that I put together that, I love won,t run worth a crap, if I do the swap."
your hardly the first guy to think that way, especially with $4 a gallon gas prices so ,well lets look at alternatives, Im going to assume you have a 26" tire because you failed to mention the car year, so use the calculators and info once you measure actual tire diam.
3.07 rear gears would get you down to a 2800rpm cruise rpm at 70mph from your current 4.11 rear gears 3700rpm, that in theory should give you about a 30% boost in mileage and a 30% lose in effective rear wheel torque , but because the cars very likely to be operating out of the engine (SWEET ZONE) you selected the cam and rear gear for 25% is more likely the result.
now I don,t know what a rear gear or rear differential swap will cost you or what parts you have on hand , but theres a second option hear that I find most guys find to be better that swapping to a 3.07:1 rear gear ratio.
viewtopic.php?f=44&t=38
http://users.erols.com/srweiss/calcmph.htm
http://users.erols.com/srweiss/calcrpm.htm
Turbo 350
2.52 1st
1.52 2nd
1.00 third
200-4R
2.74 1st
1.57 2nd
1.00 third
0.67 over drive
that options swapping the TH350 for a 2004r with its over drive top gear, the swap to a 2004r would allow you to keep the rapid acceleration for street and track performance but still allow you top cruise at 70 mph at about 2550rpm, and its a fairly easy trans swap, youll need to fabricate a new trans mount extension or move the current transmission mount but thats generally not a huge undertaking if you have a welder and drill press of skilled friends
viewtopic.php?f=71&t=10690&p=46305#p46305
your hardly the first guy to think that way, especially with $4 a gallon gas prices so ,well lets look at alternatives, Im going to assume you have a 26" tire because you failed to mention the car year, so use the calculators and info once you measure actual tire diam.
3.07 rear gears would get you down to a 2800rpm cruise rpm at 70mph from your current 4.11 rear gears 3700rpm, that in theory should give you about a 30% boost in mileage and a 30% lose in effective rear wheel torque , but because the cars very likely to be operating out of the engine (SWEET ZONE) you selected the cam and rear gear for 25% is more likely the result.
now I don,t know what a rear gear or rear differential swap will cost you or what parts you have on hand , but theres a second option hear that I find most guys find to be better that swapping to a 3.07:1 rear gear ratio.
viewtopic.php?f=44&t=38
http://users.erols.com/srweiss/calcmph.htm
http://users.erols.com/srweiss/calcrpm.htm
Turbo 350
2.52 1st
1.52 2nd
1.00 third
200-4R
2.74 1st
1.57 2nd
1.00 third
0.67 over drive
that options swapping the TH350 for a 2004r with its over drive top gear, the swap to a 2004r would allow you to keep the rapid acceleration for street and track performance but still allow you top cruise at 70 mph at about 2550rpm, and its a fairly easy trans swap, youll need to fabricate a new trans mount extension or move the current transmission mount but thats generally not a huge undertaking if you have a welder and drill press of skilled friends
viewtopic.php?f=71&t=10690&p=46305#p46305