Quote:
Originally Posted by vteco
Received a call from Black Bear Performance. The guy at the other end didn't seem to understand what I was asking. He basically reiterated what the website said about custom tuning through them -- gains in HP and torque but at most only slight gain in fuel economy.
I said I wasn't interested in HP gain or torque gain per se, I didn't tow heavy loads in summer, didn't do long distances at highway speeds in general, etc. That I was ONLY interested in a custom tune that might increase fuel economy at say an average 40 mph rural driving -- if that was possible. Would shift points be adjusted, etc.?
He just reiterated what he said were the benefits. From that I gathered that it wouldn't be a "custom" tune to favor a set of desired parameters, but probably just a flash of stock firmware. Or maybe he was just a phone salesman and didn't understand what might be possible for the back shop to do. I do know they do true custom performance tunes, and even loan out recording engine monitors to gather data to optimize custom tunes.
Well shucks, anyway, no progress on that front. Too bad.
|
For the 350, it's displacement, compression ratio, injectors, fuel pump pressure, valve timing, manifolds, spark timing, exhaust system back pressure, shift points, ECU PROM internal look-up tables, etc. , are going to determine the optimum brake specific fuel consumption ( BSFC ) that the engine is capable of producing, which limits fuel economy potential.
If we had an engine 'map' for your truck, we could see where the 'island' of lowest fuel consumption resides, and the rpm 'band-width' associated with that 'island. It could be just a few hundred rpm, until you're out of it.
Today, a CVT, or 10-speed trans allows small enough gear splits during transient operation that, the engine rpm can be kept close to the BSFC 'sweet-spot,' maximizing mpg.
Once an engine is optimized, all we can do is 'load shedding', with either rolling resistance, aero drag, or a combination of both.
And, even if we're successful in reducing load, if we can't get the engine to see a 'comparable load' at the same 'speed' ( 'taller gears ), we can lose a major portion of savings potential ( happiness is a warm chassis dynamometer ).