[T3] Lean Cruise

Sat Mar 9 06:16:08 PST 2013

Just curious what have any of you seen in cylinder head temps?
I am also curious of what actual combustion temps are in our air cooled engines. In school there was a lot of talk on maintain ideal combustion temperatures and at the time maintain coolant temps in the area of 180-200° F was what was considered ideal and I doubt that our air cooled motors stay in the 192°F area except maybe on cold winter days. My 99 Chevy truck runs in the 192°F area not sure what the current modern autos run at. 

O and don't forget that air temp affects air density also not just altitude. Its why they came up with the intercooler for turbo and super charged applications as the compression of the air raises its temperature and you loose some of the benefits you gained in the process. When I worked at the GM proving ground in Arizona you would be amazed at the amount of testing they do on engine performance. There are so many different things that can affect combustion. They even measure cylinder wall temps in an attempt to get the fuel that is near the wall to burn as it tends to not burn. Well I could go on and on with what i saw needless to say there are a huge amount of thing that affect the burn process. 

Does any one out there know what the actual burn time is during ignition?  Hint its related to spark burn time.
Sorry for those out there that see all my incorrect wording I never got learned in collage ;-) 

Daniel Du Vall
http://1peter4-10.org
http://volkswageninsanity.us

-----Original Message-----
From: type3-vwtype3.org-bounces at lists.vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of Jim Adney
Sent: Friday, March 08, 2013 11:55 PM
To: type3 at vwtype3.org
Subject: Re: [T3] Lean Cruise

On 8 Mar 2013 at 21:40, Max Welton wrote:

> The problem I had was that in my normal day, I traverse a 1500'
> altitude change. The fuel law didn't know that the ambient pressure 
> was changing and for a while it made nailing down the VE-table a real moving target.
> 
> Adding the second MAP sensor is one of the standard megasquirt 
> modifications. It allows the ECU to read ambient pressure continuously. Problem solved.

The MAP sensor tells MS what the air pressure is in the IAD. That and the RPM are only things that control how much air gets into the cylinders. Ambient pressure may have some slight effect on the vacuum advance and the air drag on the car, but it doesn't have any effect on what's happening in the cylinders. That's one of the big advantages of the D-jet system: It's independent of altitude.

I don't see that there was a problem to be solved.

--
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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