Turbocharging? Vacuum? Too much thinking. Smart people unite

[RustyLugNut]

Originally Posted by Enki

Heat will build up, however. That's the reason I swapped the intercooler back in once ambient temps climbed past 90 on the regular; not a big fan of seeing 180 degrees at the manifold during city driving.

High intake temperatures and high turbulence result in increased fuel reactivity and thus more rapid flame fronts. We all know this to be true. So, couple this condition with a ultra lean homogeneous fuel mix which is a lazy combustion mix by nature, and you can extract useful torque to putter around with.

[Enki]

And if the temps go a little too high and you give it just a little too much throttle:

[RustyLugNut]

Originally Posted by Enki

And if the temps go a little too high and you give it just a little too much throttle:

And if your engine management isn't good enough to prevent that, then you need to get into another line of work.

Honda Insight engines run lean with no problems. Honda VX engines did so back in the 90s. Chrysler engines did so back in the 70s.

[teoman]

From academic journals i have read about HCCI engines, 85 C (or 185 F) was the optimal temperature.
(I have a lot more info and links to the original papers on my steam injection thread).

[Enki]

I ran mine lean with no issues, but I had multiple saftey nets. If you turbocharge an engine that isn't factory turbo, with no intercooling of any kind (including chemical) and run it lean with boost on pump gas, I can all but guarantee you will be buying a new engine.

[Enki]

Originally Posted by teoman

From academic journals i have read about HCCI engines, 85 C (or 185 F) was the optimal temperature.
(I have a lot more info and links to the original papers on my steam injection thread).

Are these not engines specifically designed for HCCI though too? Direct injected, special pistons, etc.

[RustyLugNut]

Originally Posted by Enki

I ran mine lean with no issues, but I had multiple saftey nets. If you turbocharge an engine that isn't factory turbo, with no intercooling of any kind (including chemical) and run it lean with boost on pump gas, I can all but guarantee you will be buying a new engine.

If you are just motivating a light weight, aerodynamic vehicle that needs only a few horsepower to cruise along, boost and ultra lean mixes produce effective torque with little damaging heat ( almost none is left to operate the turbo beyond a few psi ). This is a far cry than what you are talking about. I have burned my share of engines as a young gearhead, but I don't fear lean mixtures like you do. It is a sure fire way to gain 15% fuel economy by limiting your throttling losses. Add in the reduction of heat loss to the cooling and you can gain even more.

[teoman]

Yes indeed they are. It came up 2 posts ago so I thought that i should comment with the little bit of info I had on the matter.

But from my understanding, 85 C is a good temp for the chemical reactions during combustion. Below 80 and above 90 the efficiency starts to drop.

[Enki]

Originally Posted by RustyLugNut

If you are just motivating a light weight, aerodynamic vehicle that needs only a few horsepower to cruise along, boost and ultra lean mixes produce effective torque with little damaging heat ( almost none is left to operate the turbo beyond a few psi ). This is a far cry than what you are talking about. I have burned my share of engines as a young gearhead, but I don't fear lean mixtures like you do. It is a sure fire way to gain 15% fuel economy by limiting your throttling losses. Add in the reduction of heat loss to the cooling and you can gain even more.

I don't fear lean mixtures; every one of the tunes I ran on my car utilized it; there's just diminishing returns past a point where you wind up giving more throttle to maintain the same speed and as a result the fuel consumption doesn't drop any more. I found this to be 15.5 AFR on my car, while others run their cars as lean as 17:1; somehow, I still have the best miles per tank on a mix of ethanol vs anyone on pump gas and leaner mixtures.

The only thing I'm "afraid" of is people bolting a turbo on to their car expecting one result and ending up buying a new engine because their understanding of how it should be done is incomplete.

[RustyLugNut]

Originally Posted by teoman

From academic journals i have read about HCCI engines, 85 C (or 185 F) was the optimal temperature.
(I have a lot more info and links to the original papers on my steam injection thread).

Adding turbulence via boost and heat coupled with lean burn allowed pgfpro to control combustion reactivity. Not to the point of HCCI, but such that you could ignite the very lean ( 30+ AFR ) mixes at a reasonable lead point to produce useful torque. Of course , without the rapid oxidation rates of HCCI we will have to deal with NOx, but I'd rather reduce my fuel use and deal with NOx after-treatment.