Comments on: GM Road Tests HCCI Engine

By: Jonathon

Jonathon — Wed, 07 May 2008 17:34:56 +0000

I think what that means is that there is not a flame front moving through the cylinder—it all burns at the same time. You could always, you know, look it up. ;)

By: gawdodirt

gawdodirt — Wed, 07 May 2008 17:13:32 +0000

Good point. No such thing as “flameless combustion.” Credible?

Same as “dry water?”

Good for them. So why the bashing anyhow?
Seems like regardless of the financial woes, they’re still trying to produce.

Guess they don’t read the blogs!

By: joeaverage

joeaverage — Wed, 07 May 2008 16:57:18 +0000

So that 15% increase in efficiency will guarantee 15% larger vehicles?

How about 15% BETTER vehicles?

FWIW I think the technology is pretty cool. Any little thing helps.

By: Wolven

Wolven — Wed, 07 May 2008 00:28:40 +0000

Flameless combustion? Are you sure about that? Or is it just “sparkless” combustion?

By: golden2husky

golden2husky — Wed, 07 May 2008 00:13:34 +0000

It will be interesting as to how this pans out. This reminds me of what Ford was trying to do in the late 70’s. Does anybody recall PROCCO? This stood for PROgrammed COMbustion. The idea was to emulate the combustion dynamics of a diesel engine but with gasoline. IIRC it worked in a lab but there was no way to put the needed computer power into a car in 1979. The drop in fuel prices after the ‘79-81 stagflation ended the program; the engines were allegedly destroyed. Also, I have to ask this question: Does anybody at TTAC recall “Shell of the Future”. This was unleaded gas in 1972 sold out of a baby blue pump. Anybody?

By: jaje

jaje — Tue, 06 May 2008 23:29:50 +0000

I believe it’s from the fact that the combustion in a compression engine is much more controlled and complete versus gas spark ignition engines. It’s that unburnt portion that is the most noxious.

By: Stingray

Stingray — Tue, 06 May 2008 21:30:51 +0000

I think they’re burning gasoline. Combustion is flameless… so lower temps and I bet that’s why NOx are not formed.

By: miked

miked — Tue, 06 May 2008 21:16:59 +0000

If this is compression ignition of a lean mixture, much like a Diesel cycle, then how do they lower the NOx? I thought NOx formed best during high temperature lean conditions.

By: paradigm_shift

paradigm_shift — Tue, 06 May 2008 20:33:54 +0000

I’m curious, what issues have Vee Dub had with direct injection?

By: Bunter1

Bunter1 — Tue, 06 May 2008 19:58:21 +0000

In sparkling contrast to some of their other “technology to save the world” GM has a reasonable launch estimate (2015 IIRC) on this.
But then the media isn’t all hot for it. Go figure.

On the other hand, in many road tests (don’t give me EPA estimates, puhleeez) they seem to lag 10-15% behind the mileage of the best in class.

So yippee.

Yes, I am not pumped about GM. Boo hoo.

Bunter

PS-I’ll be out for a week so if I don’t rebutt a rebuttal, I’m not stiffing any of you.
Tootles.

By: jaje

jaje — Tue, 06 May 2008 18:22:08 +0000

Several other automakers are working with HCCI including Mercedes and Honda. The other two are trying to eliminate the need for retaining the electric ignition component and have a normal redline. Supposedly the difficulty with HCCI engines is the powerband is smaller and the engine has trouble running at lower and higher rpm. If they can perfect this and get similar gains to diesel using gasoline then all the better. Gasoline runs cleaner in particulate emissions but since it uses more gas than diesel has higher carbon dioxide and water vapor emissions.