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Old 07-04-2009, 08:02 PM   #289 (permalink)
cfg83
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stevey_frac -

Quote:
Originally Posted by stevey_frac View Post
...

I don't know if it's wise to assume 100% volumetric efficiency, or that i'll be going down the highway at full throttle. Most of the time i'm way down near 30% throttle, and my car definately dosen't get 100% volumetric efficiency at any throttle, and at any RPM. The goal is not to make a drag car more fuel efficient. Never the less, you are correct in that it would take substantial power to add in 20% hydrogen. That being said, 20% hydrogen lets them massively lean out the AFR while maintaining burn stability. Personally, i'd be trying to target perhaps 5% hydrogen, and an AFR of 16:1 or 17:1.

....
That's inline with the findings of this research study :

Welcome to IEEE Xplore 2.0: Fuel consumption and emission of SI engine fueled with H2-enriched gasoline - August 1989
Quote:
Abstract
A study of the effect of the amount of hydrogen on the fuel consumption and emission of a spark ignition (SI) engine is reported. In the first stage, dynamometer test results for a wide range of engine speeds, engine loads, equivalence ratio, and hydrogen enrichment under steady-state operation were obtained, and the engine requirements for minimum BSFC were specified. In the second stage, an onboard, online hydrogen generator was developed and employed to provide the required amount of hydrogen. The hydrogen was produced by a steam reforming process. A detailed model for simulating a spark ignition engine fueled with hydrogen-enriched gasoline was developed and used to predict the optimal amount of hydrogen supplement as well as the corresponding MBT, optimal throttle position, and emissions level of CO, HC, and NOx
It concluded that the "sweet spot" for hydrogen to fuel mass ratio was 2-6%. Anything over 6% resulted in marginal (aka not worth it) gains.

However, keep in mind that this was done in 1989 with a carburated engine.

CarloSW2
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