Turbo gas mileage...
01-09-2009, 02:19 PM
#12
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Not quite true. It is wasting energy as the air is spinning the turbo. Like a fan in the wind. Or that "magical" tornado fuel saver crap. The turbo is a restriction when not in use.
01-09-2009, 02:24 PM
#14
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Here's my input:
I've had two different cams with and without a turbo, and two different turbos.
Cam A had tons of overlap and was more suited for nitrous/NA. Cam B had no overlap and more suited for boost (02 LS6).
Turbo 1 had a bigger ex. housing (.81) and turbine. Turbo 2 had a smaller ex. housing (.68) and turbine. Compressor sides were comparable.
Naturally aspirated cam A pulled less manifold vacuum at any given load/rpm/speed than stock. Add turbo 1 and manifold vacuum was damn near the same as NA with cam A. This could be due to the too large exhaust housing.
Cam B and turbo 1 saw increased manifold vacuum, which was probably due to the lack of overlap and less duration. Cam B with no turbo (same everything else) pulled the same vacuum, however part throttle power wasn't there. Reviewing logs showed me having more TPS% at a given rpm/speed.
Cam B and turbo 2 saw manifold vacuum much like cam A and turbo 1. I think this was due to the increased restriction in the exhaust, from the smaller A/R. At highway speeds I had even less manifold vacuum than with turbo 1, but I saw less TPS%.
Make of that what you will. I never did any mpg tests, because IMO hot rodding a full size truck while watching mpg's is like pissing in the ocean.
You're never going to get the money spent on a FI kit regardless of make or design by gaining a couple mpg's. You'd have to own the truck/kit for years and never floor it.
I've had two different cams with and without a turbo, and two different turbos.
Cam A had tons of overlap and was more suited for nitrous/NA. Cam B had no overlap and more suited for boost (02 LS6).
Turbo 1 had a bigger ex. housing (.81) and turbine. Turbo 2 had a smaller ex. housing (.68) and turbine. Compressor sides were comparable.
Naturally aspirated cam A pulled less manifold vacuum at any given load/rpm/speed than stock. Add turbo 1 and manifold vacuum was damn near the same as NA with cam A. This could be due to the too large exhaust housing.
Cam B and turbo 1 saw increased manifold vacuum, which was probably due to the lack of overlap and less duration. Cam B with no turbo (same everything else) pulled the same vacuum, however part throttle power wasn't there. Reviewing logs showed me having more TPS% at a given rpm/speed.
Cam B and turbo 2 saw manifold vacuum much like cam A and turbo 1. I think this was due to the increased restriction in the exhaust, from the smaller A/R. At highway speeds I had even less manifold vacuum than with turbo 1, but I saw less TPS%.
Make of that what you will. I never did any mpg tests, because IMO hot rodding a full size truck while watching mpg's is like pissing in the ocean.
You're never going to get the money spent on a FI kit regardless of make or design by gaining a couple mpg's. You'd have to own the truck/kit for years and never floor it.
01-09-2009, 02:29 PM
#16
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I'd also like to add that I have yet to see anyone do a true scientific test. I really think it's impossible to do anyway. Too many variables. Aside from the human factor 
, the tests would need to be done in the same environment. No traffic, no variances in wind, and especially temperature/humidity. Doing the tests a month apart proves nothing.
In january here can be as cold as 40* in the morning. In february, it can get up to 90*.
, the tests would need to be done in the same environment. No traffic, no variances in wind, and especially temperature/humidity. Doing the tests a month apart proves nothing.In january here can be as cold as 40* in the morning. In february, it can get up to 90*.
01-09-2009, 02:31 PM
#17
I'd also like to add that I have yet to see anyone do a true scientific test. I really think it's impossible to do anyway. Too many variables. Aside from the human factor , the tests would need to be done in the same environment. No traffic, no variances in wind, and especially temperature/humidity.
, the tests would need to be done in the same environment. No traffic, no variances in wind, and especially temperature/humidity.