Quote:
Originally Posted by Daox
I don't think I would call a 7.7% gain very limited. As mentioned, there aren't a lot of mods that will bring you that kind of gain for a single modification. In smaller engines, which run at a higher load for a given speed, you should be able to see even higher gains I would imagine due to being able to run more EGR.
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You are right in reference to what we can expect to find from the typical mod. I am speaking in reference to the overall picture of thermal efficiency (TE). An engine with 30% TE will reach a limit of 32-33% TE at increasing EGR at which point the combustion becomes unstable and torque falls off drastically. The SwRI paper makes it clear the 30% savings were at heavy loads where the cooled EGR was used to replace the overfueling needed to avoid detonation.
The thrust of my investigation lies in the lean burn regime. Instead of adding noncombustible EGR, I add more air that can still be part of the reaction. Now I add enthalpy. The addition of heat, pressure, turbulence and chemical seeding can allow us to run lean but strengthen the combustion to produce greater torque. Roughly a decade ago, College of the Dessert published a report on their use of bottled hydrogen in a ford V8 engine and used the wide flammability limit of hydrogen to run without a throttle. Tel Aviv University published a paper in the 1980 issue of Power Magazine and outlined the ability to sustain combustion in a methane/hydrogen mix with the addition of heat and turbulence to an air/fuel ratio of 100:1. All the Legos are there to build the Smokey Hot Vapor engine. With the aforementioned HCCI engine as a target, I think we can push past the 40% TE and approach the 50% TE with a gasoline engine. We may exceed that. We won't know until we try.