Best Mileage Mods

[Copdogcorvettes]

Well now that I have sold my Daytona I'm going to start on the next project. As part of the deal when I sold the Daytona I got a 78 4 speed in trade. It is a pure stocker and all though I have not confirm it yet, it just as it came from the factory; Matching number with 110k miles. It has been well care for, in the garage in the winter. Last summer the motor was pulled and anything that needed replacing was done. Then the whole motor repainted to the factory colors.

So I'm not looking to do much to it but drive it. My question for everyone is: what is the best way to get the gas mileage up. The 80 vette I had before it was wreaked had a 305 with a auto. The best things besides the looks was the mileage. 15mpg around town and 20 on the hyway. I'd like to get that kind of mileage out of this one. I know about using the 5 or 6 speed with overdrive and TPI to help the mileage. What kind of mileage do these actually give and which one does the best. Cost is a factor, so I guess I'm looking for help getting to the goal of good mileage at the most cost effective matter.

I know that some of you out there have done these changes. So tell me how much did they improve things and about what it cost to do it. Any ideas of any kind on how to get the mileage up will be very helpful. I want to make this into a daily driver that I can live with.

I thank you all for any help. I know that if the answer can be found it will be here with the CAC members.

Gary

 

[70 LS1]

An overdrive trans is going to be your best bet for mileage. I am using a 99 LS1 and T56 6 speed and I get over 25 mpg on the highway. Most of that I attribute to the 0.76:1 fifth and 0.5:1 sixth gears. Hardly even use 6th.

And for the cost, I dropped over 5 grand for the entire engine and trans swap.

 

[80convertible]

I pulled the mechanical fan and clutch and installed a used 16" electric fan. Removing the rotating mass of the fan and clutch is good for some mpg along with hp and torque. I did this for less than $120.00 and can return the car to stock in about an hour...no permanent modifications required. Plus, working on the engine is a lot safter without a fan. I too have a 4 speed and would love an overdrive but I'm not willing to spend thousands of dollars for it. I'm actually considering adding overdrive to my saginaw 4 speed using the overdrive from an old saginaw three speed with overdrive.

 

[resto75]

I too have pondered a 5 speed transmission for all the benefits it gives. However the price is a little high for a car I might drive once a month for a few hours each time. The $3000.00 plus will buy a lot of gas (well not so much these days) but I would probably only save five bucks each time I used it. Humm let's see: once a month,X 12= 12X5.00= 60.00 a yr,,$3000 divided by 60= 50 yrs.
So I can break even in just 50 yrs.

 

[resto75]

What kind of mileage are you getting now ??? I seem to get 13.8 mph in my not so stock engine with a 4 speed. I don't think thats too bad but yeah 20-25 would be nice.

 

[tscott9330]

2 Words, Fuel Injection


Get a TPI System off ebay or from a junk yard for 500 bucks and get a set of stock heads and you are in business. Besides an overdrive tranny thats the best mod I can think of to give more mpg and more HP

Tom

 

[Robin7TFour]

GARY, my best thing for getting decent mileage,is adjust the pressure sensor on the bottom of your foot. less pressure on the pedal = better fuel conservation.

lol.. i'm just messin' with you. i can't do it either. foot to the floor and turn left

ROBIN

 

[Copdogcorvettes]

THANKS Robin. But even if I try to do it that way the best I get is around 12 in town and about 15 on the Hyway. You know that with a 4speed and nice sounding exhuast it is very hard to be good. At todays gas prices I'm being forced to be good more and more.


Gary