I've always wondered about this. Corvettes get awesome gas mileage and I've wondered if it was because of high compression. If I were to Go FI and change the internals of my truck to Dish pistons and lower my compression, would I also lower my gas mileage?

 

I did not know corvettes got awesome fuel economy. But they're being all fiberglass body's might have something to do with it

 

Higher compression helps give more explosive combustion(higher cyl pressures) which produces more power and noticably lower torque. Corvettes are light weight(C5's ~3200lbs) and C5's have the lowest coefficient of drag of any production car ever made. That is why they get such good mpg and very little to do with the more compression. My 2000 C5 6 speed averaged around 24-25mpg with everyday driving and I knocked out 32.2mpg once on the interstate running 78mph.

 

Are you seriously wondering why your truck doesnt get as good gas mileage as a car that has better aerodynamics and weighs several thousand pounds less

 

No not at all. It's just that I was wondering if I should try to increase my compression to help out with fuel economy. I know trucks are very heavy and Im not expecting awesome gas mileage just something decent.

 

Just doing the math. Say a better flowing head and higher compression miraculously gained 2mpg. Say you drive 20k miles a year. The way I figure it after a year you would save $450 in gas. Now now much is that head swap going to cost in total? Realistically you might get 1mpg and save around $200 a year. Maybe.
That is kinda like someone trading in their car that they have 1 year left until it is payed off on a new car that gets 4 mpg better mileage and say they are doing it to save money.

 

yes but mjhoward people do stupid **** like that.

I have a buddy and his mom has a tahoe. Bone stock, gets like 17mpg. its an 01-02. she went out and bought a 10k dollar s10 to save on gas. No that 200+$ a month payment she makes on the s10, plus insurance and anything else could be spent in gas and then she would save money probably. Some people are just stupid.

SOrry for gettin off topic

 

.....So, would having lower compression affect gas mileage??

 

I have no way to prove it but I feel that the higher compression could increase mpg due to the increased torque. But not by much.

 

IMO, it seems that Lq9's get better gas mileage than Lq4's.