Inliners International Forums General Discussion Drive Train RPMs and mileage

Hello. I have a stock 194 6 in a 3:36 geared Nova wagon. I have added a T5 tranny and found 4th (1:1) RPMs at 2900. OD brings the RPMs to 2088 at 65MPH. I've found this to be too low and bad for mileage. Lately I have been playing with different OD and rear gear ratios on a calculator and changing just the OD from a .72 to a .86 brings the RPMs to 2494 at 65. In addition I tried putting 60 series tires on and changing the rear gears to 3:55s getting 2813. Not much of a difference from the original 1:1 number. Do you think my engine can operate at or just under 2500 and not lose mileage or am I better off with swapping gears and tire sizes? Thanks.

Martin

Dear Martin;

You'll need to leave it in 4th till you can drive 65+ safely, or there's a slight downgrade/tailwind situation etc.

Otherwise you'll need a lower 'rear end' ratio.

I would think it okay 'as is' with a little practice.

Good luck.

I've noticed that if I go above 65 (3000 RPMs) or more the gas mileage starts dropping off. I make a couple of 200+ mile trips a year in the car and the Interstates, as you know being a fellow Californian are 70MPH. I realize I'm probably just being picky. The car is my daily driver and maybe I should just be thankful for what I get. But what if I can make it better?

Are you sure your speedo is accurate after making the tranny change?

The speedo is not very accurate. The speed is based on calculations with tire size and rear gear ratios.

Martin

Hi,

Your experiancing low torque syndrome from the 194. I have a warmed over 292 with a T-5 with an .72 OD and a 3:55 rear. I also have 31" tall tires on the back. I have an electronic Tach and Speedo and have it calibrated perfectly. At 65mph, I'm taching 1875 rpms and get 19mpg. At 70+mph, the mileage drops to 16mpg and 2200rpms.
I have no problems with acceleration as I have the big block with approx. 270 HP. If you swapped a 3:55 rear, your acceleration would pick up and with that engine, you should be getting over 20+ in OD at 65mph! Have a buddy drive along side you (in a new car)and check the speedo.
Was your T-5 from a S-10? If so, your gear ratios might be higher than mine. My T-5 was from a v-8 Camero.

RapRap
1940 ChoppedChevyCoupe

The tranny was actually from an '85 4 cylinder Camaro with a 3.75 first. Overall the car does well. Just can't use the OD without making some expensive major changes.

Martin

Don't forget you're getting extra frictional losses when in fifth gear... even if they're minimal.

I'd stick with what you've got, only use fifth at higher speeds. Keep it there as an option rather than set everything up to use it because you have to.

try to gear the car so that at 70 mph it is at 2500 rpm. i think you will find the motor will be much happier there. the 194 is not a high torque motor, but you knew that. with that at 60 it should be close to 2000 rpm in od. tom

Would it make more sense to just drop in a 250 or will I face the same issue?

Martin

I had a 194 in my '63 Nova wagon about 30 years ago and got 20+ mpg with it doing 60 mph. It had 3.55's and no OD.I'd think that the 250 should give you better torque to be able to make better use of the 5th gear's reduced rpm's, but I don't have anything to back it up.

Was it a 3 speed or Auto?

Martin

I am running a 250 with turbo 350 automatic, no overdrive, with a 3.08 gear and 235/75R15 radials. The truck weight is 3300 with two people and full load of fuel. I also have three small one barrels off of a Corvair. I can get 18 to 19 mpg at 65 mph and still have plenty of passing power. Rpm is in the 2400 range. I don't even have passing gear hooked up, just step on down and away you go! I say go for the 250, you will be happy, Joe

Sounds like more cubic inches rather than gearing is the way to go. Thanks for your advice everyone.

Martin