I have a 1995 convertible corvette that has the LT1 engine and a performance 3.07 differential. The car has 106,000 miles and it runs really well. It doesn't have any codes and has been a very reliable vehicle for the 5.5 years that I've had it. However, I only get about 22 mpg on the highway and 19.3 mpg when I combine highway and city driving. I see stories about 95's coming out of the factory tuned rich but getting better gas mileage on the highway (around the 25 to 27 mpg range) after they get tuned on a dyno. I've checked around and most of the shops that could work on a Corvette would charge $500 to dyno and tune the engine for better mpg and performance. If I were to get a 3 mpg increase that would increase my range by 60 miles per tank. At 25 mpg that would only save me about $7.20 per tank (at $3.00 per gallon for premium here in Kansas City). Divide the $500 dyno cost by $7.20 of savings per tank and it'll take me 69 tank fulls, or 34,500 highway miles, to break even.

I've got two questions:
1. With the car running well now, can I expect to see an increase in mpg if it truly was tuned rich from the factory and is now properly tuned?
2. If the car is rich from the factory and then properly tuned, will I fell any difference in the horsepower/ torque?

 

I doubt that you will see/notice much in the way of increased fuel mileage or performance with a dyno tune. Most if not all of the LT1 cars you read about getting higher highway fuel mileage are 6 speeds, they have two overdrives. Factory LT1's will run at bit rich at WOT, but cruising they are in a pretty good A/F range for fuel economy.

 

Thanks for the info.

 

my 94 convertible got 26mpg on a 1000 mile trip from north georgia to the mountains of virginia and back.i get 19+ in local driving. I also have a 3.07 rear end.