Strictly stickng to the catagories listed in OP here's the breakdown as I see it:
Fuel Mileage: Q-Jet, you'll never be able to beat a spread bore on cruising fuel mileage. Wide open fuel mileage however, I'll leave that to the circle track guys to care about.
Power: Holley, Both the Q-jet and Holley can be altered to create very good flow characteristics, but you eventually hit a wall with the spread bore and fuel distribution, atomization, and turbulance. A wall that you dont get with a square bore.
Ease of Use/Tuning: Holley, not only are holley's easy to tune via 4 corner idle screws vs the Q-jet's 2, but they also have a double pumper configuration which is more appropriate for some applications vs a vac secondary which is Q-jet's only configuration. Interchangable pump cams, screw in air bleeds, etc all give the holley the advantage in tuning. The Q-jet also suffers from a severe lack of aftermarket parts, wich the Holley does not.
I'd also like to add the Holley is infinately better looking than the Q-jet, which looks very utilitarian and gruff.
As you can guess, by my avitar, I picked Holley, for all the reasons mentioned above.
I do believe Q-jets have a very good roll to play on street cars, but street cars is about the extent of their domain.
If anything I said about the Q-jet is wrong, I appolagize, I do not work with them much except to repair the few that are on friends cars.
Fuel Mileage: Q-Jet, you'll never be able to beat a spread bore on cruising fuel mileage. Wide open fuel mileage however, I'll leave that to the circle track guys to care about.
Power: Holley, Both the Q-jet and Holley can be altered to create very good flow characteristics, but you eventually hit a wall with the spread bore and fuel distribution, atomization, and turbulance. A wall that you dont get with a square bore.
Ease of Use/Tuning: Holley, not only are holley's easy to tune via 4 corner idle screws vs the Q-jet's 2, but they also have a double pumper configuration which is more appropriate for some applications vs a vac secondary which is Q-jet's only configuration. Interchangable pump cams, screw in air bleeds, etc all give the holley the advantage in tuning. The Q-jet also suffers from a severe lack of aftermarket parts, wich the Holley does not.
I'd also like to add the Holley is infinately better looking than the Q-jet, which looks very utilitarian and gruff.
As you can guess, by my avitar, I picked Holley, for all the reasons mentioned above.
I do believe Q-jets have a very good roll to play on street cars, but street cars is about the extent of their domain.
If anything I said about the Q-jet is wrong, I appolagize, I do not work with them much except to repair the few that are on friends cars.
