So you kept the 2.29 gears? No adverse effects with those gears? 25mpg, that would be ideal. I've got a t200r4, sounds as though that would be my best mod.
Best mpg with a 260 and t200 combo
- Thread starter Csilvy2000
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None yet, I'm more of a cruiser type anyway. I'm sure stop light drag racing would take its toll. But still, I put in a posi unit from a 84' trans am for 35$ from the junk yard and with the torque my LT1 puts down I have no trouble burning 245 series tires. Plus the premium gas at 4.50$ a gallon in cali, you tend not to be punchn the gas.
You may need a new cross member for the 200r4, but the driveshaft should be cool to use. And you have to hook up the lock up torque converter to your brake switch.
Couldn't ever get above 20mpg with the three speed trans. I feel that's kind of its limit. You need that extra gear to let the rpms drop while your cruising.
You may need a new cross member for the 200r4, but the driveshaft should be cool to use. And you have to hook up the lock up torque converter to your brake switch.
Couldn't ever get above 20mpg with the three speed trans. I feel that's kind of its limit. You need that extra gear to let the rpms drop while your cruising.
I don't think your 260 would have the torque to turn an overdrive with the 2.29s. I mean, it'll move but I think your MPG will probably get worse.
I agree with DRIVEN. I think the 260 (with OD & 2.29s) would be lugging so bad the acceleration on the highway would make you want to blow your brains out. On top of that you would probably open the throttle so wide trying to get it to get up or keep up to speed on small grades that you may very well use more fuel. I am guessing he is borderline pulling it off with the LT1. I bet that if he put say some 3.08s in there that his mileage would not drop the only change would be much better response and acceleration.
Engine efficiency is power to fuel burnt ie typically the rpm maximum torque is reached. For max mileage you want that rpm at desired cruise speed. But often you can beat this a little with a high torque relative to weight & aerodynamics of car by gearing cruise at slightly below max torque rpm but still above the motor lugging. Naturally things like hills going up or down and into or with the wind make this not quite as specific so you have to gear in a little safety margin from lug. Especially with a weak motor like the 260. Even with the almost diesel like low rpm torque of the long stroke 10-1 compression Cadillac 500 I did not want interstate cruise at less that 1700 to 1800 rpm. When I got my best mileage I was cruising at 2,200 to 2,400 rpm but that was at 70ish mph rolling interstate hills and partially due to more than stock cam.
Engine efficiency is power to fuel burnt ie typically the rpm maximum torque is reached. For max mileage you want that rpm at desired cruise speed. But often you can beat this a little with a high torque relative to weight & aerodynamics of car by gearing cruise at slightly below max torque rpm but still above the motor lugging. Naturally things like hills going up or down and into or with the wind make this not quite as specific so you have to gear in a little safety margin from lug. Especially with a weak motor like the 260. Even with the almost diesel like low rpm torque of the long stroke 10-1 compression Cadillac 500 I did not want interstate cruise at less that 1700 to 1800 rpm. When I got my best mileage I was cruising at 2,200 to 2,400 rpm but that was at 70ish mph rolling interstate hills and partially due to more than stock cam.
Thanks for the posts.
Several things I will have to consider. First of all, the 260 appears to have absolutely zero benefits. I could probably do just as well, milage wise, with a mildly built 350 and t350 transmission. Both of which I have. Even better though, I have a 700r4 I could toss behind it. Nothing but money and time! I'll have to weigh the costs involved.
Several things I will have to consider. First of all, the 260 appears to have absolutely zero benefits. I could probably do just as well, milage wise, with a mildly built 350 and t350 transmission. Both of which I have. Even better though, I have a 700r4 I could toss behind it. Nothing but money and time! I'll have to weigh the costs involved.
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