How does Honda prevent burned pistons in Lean Burn

[JimIsbell]

Has Honda done something to prevent burning holes in the tops of pistons when in lean burn? Or would lean burn work on ANY injected car if properly applied?

[IamIan]

why would lean burn have any increased risk??

Using less fuel per piston cycle ... thus producing less heat per piston cycle... Lean burn would seem less likely to do this than regular air to fuel ratio.

Also Honda did do the increased air swirl to more mix the air and fuel.

[JimIsbell]

A lean mixture burns hotter than a rich mixture.

[Aaron Cake]

EGR.

Also the engine uses a stratified charge.

[JimIsbell]

The injector pulse on my Jaguar is derived from a single pulse, once each revolution, from a Hall sensor on the damper wheel. I was thinking about a switchable 2:1 and 3:1 divider circuit on that line to implement Lean Burn manually. But I would worry about burned pistons and valves. That was why I was asking.

[IamIan]

Originally Posted by JimIsbell

A lean mixture burns hotter than a rich mixture.

Really

That does not seem to make sense to me.

The Honda Insight's Lean burn function has been tested to reduce engine friction by up to 8%... which will directly reduce heat generated.

In lean burn operation you burn less fuel per piston ignition ... it is more efficient combustion but the net is less fuel and less energy used per engine cycle... and less power per engine cycle.

In lean burn you pull in more air from the outside which means you have more mass that is ambient temperature to start with to heat up.

In Lean burn you have more unused / unburned air which is just a thermal mass.

It does not seem to make any sense to me that a lean burn running engine would be a hotter engine.

Do you happen to have any links , or sources I could read / study that would explain why less friction, less energy, and more cooling could lead to a hotter engine?

[Insightful Trekker]

Ian,

Aaron's got the Cake

(and lean mixtures do tend to burn hotter as far as an ICE is concerned).

[IamIan]

Originally Posted by Insightful Trekker

Ian,

Aaron's got the Cake

(and lean mixtures do tend to burn hotter as far as an ICE is concerned).

seems counter intuitive

[Insightful Trekker]

Reverse your thinking.

How hot would a "rich" mixture be in compairson
(Hint: remember combustion _will_ be incomplete).

Ask if your still confused after thinking it out, I'll find you some links.
But only if you promise to never "accuse" me of being link "lazy" again

[JimIsbell]

I dont have any sites for you to go to, but it is a well known fact that a lean mixture burns much hotter than a rich mixture. This is one of the causes of piston burn through on the top of the piston and for burned exhaust valves. A rich mixture, for one thing, while it is wasting fuel, it also lubricates and cools the surfaces with the unburned fuel. You can burn an engine up by going too lean and getting too fast a burn which also causes pinging, another damaging effect on the engine. Generally speaking the only problem with a rich burn is that it can dilute the crankcase oil with too much excess fuel and the excess fuel can wash the oil off the cylinder walls if it is REALLY rich.. But usually a lean mixture is more equated with a damaged engine.

I assume that Honda did something to keep these things from happening with the very lean mixture.