Turbo gas mileage...
01-10-2009, 02:40 PM
#71
I agree with BC...I think that all of the gains are in the tuning.
My stock 5.3, 5.3 with Radix, 6.0 with Radix, N/A 408, turbo'd 408 with a 76mm turbo, and turbo'd 403 with a 82mm turbo have all had negligible differences in fuel economy. ALWAYS 13-15 mpg on the highway, and 10-12 mpg in the city. I have kept track of my fuel mileage in every tank since I got the truck in 2001. Any gains I think I had always disappear within the next tank or two, so I can attribute those ONLY to changes in driving style. If you hope to be getting better mileage, you tend to drive less aggressively, and your mileage goes up. Or you drive at different speeds, or something else that skews your readings.
It takes a certain amount of power to get a vehicle moving. That is determined by aerodynamics and wind resistance, friction, slope, and vehicle weight. As long as the tuning is set up correctly, no matter what your setup is, you still need that certain amount of power to make your vehicle run at a certain speed in the same conditions. Notice what the manufacturers do to improve mileage....improve aerodynamics, reduce weight, reduce parasitic drag on the engine, improve airflow characteristics in the engine (which are done with intake manifold, head, and cam design). They don't put turbos or s/c's on to improve fuel economy. They put those on to improve power when they reduce the engine size and number of cylinders (which yields less frictional losses).
If simply putting a blower or turbo on an engine yielded better economy, don't you think EVERY manufacturer would be jumping on the bandwagon?? MORE POWER AND BETTER ECONOMY, that would sell like hotcakes. They aren't stupid.
My stock 5.3, 5.3 with Radix, 6.0 with Radix, N/A 408, turbo'd 408 with a 76mm turbo, and turbo'd 403 with a 82mm turbo have all had negligible differences in fuel economy. ALWAYS 13-15 mpg on the highway, and 10-12 mpg in the city. I have kept track of my fuel mileage in every tank since I got the truck in 2001. Any gains I think I had always disappear within the next tank or two, so I can attribute those ONLY to changes in driving style. If you hope to be getting better mileage, you tend to drive less aggressively, and your mileage goes up. Or you drive at different speeds, or something else that skews your readings.
It takes a certain amount of power to get a vehicle moving. That is determined by aerodynamics and wind resistance, friction, slope, and vehicle weight. As long as the tuning is set up correctly, no matter what your setup is, you still need that certain amount of power to make your vehicle run at a certain speed in the same conditions. Notice what the manufacturers do to improve mileage....improve aerodynamics, reduce weight, reduce parasitic drag on the engine, improve airflow characteristics in the engine (which are done with intake manifold, head, and cam design). They don't put turbos or s/c's on to improve fuel economy. They put those on to improve power when they reduce the engine size and number of cylinders (which yields less frictional losses).
If simply putting a blower or turbo on an engine yielded better economy, don't you think EVERY manufacturer would be jumping on the bandwagon?? MORE POWER AND BETTER ECONOMY, that would sell like hotcakes. They aren't stupid.
Last edited by thunder550; 01-10-2009 at 02:50 PM.
01-10-2009, 06:16 PM
#72
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Magna Chargers have a bypass valve in them, that opens while in cruise. It's vacuum/load actuated. While open, they claim it takes less than 1hp to turn. Its conceivable since all you have to turn is the rotating mass of the rotors/pulleys and the friction in the bearings/gears. In a cetrifugal setup there's a surge valve, but I think that just functions like a BOV in a turbo setup where it opens when the throttle is slammed shut. I guess you could get it to open while cruising though, but I wasn't aware that they were designed to do that. Makes sense though.
Hmm, I am confused as well, a 10:1 compression engine would produce more torque per revolution N/A provided the appropriate OCTANE fuel per combustion event than a 8:1 compression engine. So you are correct in stating a 10:1 engine could achieve greater mileage as it can produce greater torque at the same RPM (provided proper tuning).
What the so called "BOV" (which is actually a bypass valve) actually does on the blowers is to allow the engine to operate under vacuum condtition WITHOUT Boost and without additional horsepower sapping strain on the engine. Think of it as close to a supercharger decoupling device as you can get with out actually mounting an electrically Vacuum/TPS activated clutched pulley.
Chris
Am I right Brian?
01-10-2009, 07:02 PM
#74
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I agree with BC...I think that all of the gains are in the tuning.
My stock 5.3, 5.3 with Radix, 6.0 with Radix, N/A 408, turbo'd 408 with a 76mm turbo, and turbo'd 403 with a 82mm turbo have all had negligible differences in fuel economy. ALWAYS 13-15 mpg on the highway, and 10-12 mpg in the city. I have kept track of my fuel mileage in every tank since I got the truck in 2001.
My stock 5.3, 5.3 with Radix, 6.0 with Radix, N/A 408, turbo'd 408 with a 76mm turbo, and turbo'd 403 with a 82mm turbo have all had negligible differences in fuel economy. ALWAYS 13-15 mpg on the highway, and 10-12 mpg in the city. I have kept track of my fuel mileage in every tank since I got the truck in 2001.
Are you saying that with a stock 5.3 you only got 10-12mpg in town and 13-15 on the highway??
Please guys, lets leave gearing out of this for simplicity's sake.
I've often wondered if less rpms in exchange for less manifold vacuum is worth it.
01-10-2009, 07:16 PM
#75
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I wondered that too. Now my radix is for towing. But before buying I was curious if towing in 4th with more boost is better than 3rd with less. What I have found is that it is better to tow in 3rd with less boost by a good 1.5 mpg or so. But I have found that now since I have a blower on and while pulling it never has to drop to 2nd to go up hill my mpg's have improved while towing compared to NA. Going to Branson pulling it would drop to 2nd and that is unsat. Now it just goes into boost and keeps it in 3rd. Never leaves that gear.
Last edited by Prime Power; 01-11-2009 at 07:22 AM.
01-10-2009, 07:20 PM
#76
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I put a Magnuson Supercharger on my truck... I didn't get much better gas milage. I put a turbo on my truck... I didn't get much better gas milage. Constant is me and the truck without either forced induction package. Milage is utterly and completely up to the driving habits of the owner... tuning to an extent IMO (this assuming tuner has tuning knowledge). Trying to determine if a Supercharger or a Turbo allows engine to run better in its sweet spot milage wise... can probably be proven in controlled testing. Controlled Testing DOES NOT equal daily driving. Everybody drives with their right foot differently. I tend to not give a **** if I got 30-50 extra miles per tank if I stay out of PE... as I had the money to buy the truck, mod the truck, and then drive the truck as I see fit without worrying about ANYthing else
Damn, I think I just sprained my ankle stepping off that soap box
My .02
Bill
Damn, I think I just sprained my ankle stepping off that soap box
My .02
Bill
01-10-2009, 08:24 PM
#77
Yup. Always. I have wondered many times why I didn't get any better mileage. I kept thinking that swapping setups would get me better mileage. All I can assume at this point is that it's me. I think I just drive aggressively...that's about as good as it's gonna get with me in this truck.
01-10-2009, 08:52 PM
#79
Yup. Always. I have wondered many times why I didn't get any better mileage. I kept thinking that swapping setups would get me better mileage. All I can assume at this point is that it's me. I think I just drive aggressively...that's about as good as it's gonna get with me in this truck.
Your the LAST guy I would ask how to get good mileage from, buddy 
