E46 Fanatics Forum banner

DAILY UPDATES

6M views 45K replies 4K participants last post by  yjsaabman 
#1 · (Edited by Moderator)
Welcome to the daily update thread! Post any mods, repairs, whatever you have done to your E46!

Today I

Debadge the trunk lid (roundel still intact)
Added black grills
Yellow fogs
Clear front reflectors (PITA!!!)
6K D2S bulbs

 
See less See more
1
#15,003 ·
I think that it now actually has benefits (other than just emissions). Apparently EGR reduces temperatures in the combustion chamber. That is it's primary function as *** forms at higher temperatures. This improves thermal efficiency by reducing heat loss through the walls. It also means the engine's components experience less wear.
I'm not an engineer or physicist, but from the little bit of thermodynamics that I learned, I was under the impression that a hotter running engine is generally more efficient. Of course wear is a very big reason to limit temperatures. And I think *** formation is the other big one (particularly in the US).

1. This would allow the throttle body to be open wider for any given throttle position without requiring the extra fuel. That increases volumetric efficiency. Very smart.
How does that improve volumetric efficiency? If anything it reduces VE since it is essentially equivalent to opening the throttle a little bit less than you otherwise would.

However since there apparently isn't' much EGR at full load, I guess I don't really care.
 
#15,004 · (Edited)
I'm not an engineer or physicist, but from the little bit of thermodynamics that I learned, I was under the impression that a hotter running engine is generally more efficient. Of course wear is a very big reason to limit temperatures. And I think *** formation is the other big one (particularly in the US).
This is correct. Engines are designed to operate in a happy medium where it's hot enough to meet efficiency standards but not so hot that it creates excess *** emissions.

Also, since we're on the topic of *** emissions, modern DI ultra lean burn engines create much more *** than regular port injection engines. They have catalytic converters that can deal with this, the problem is the fuel in North America has much higher Sulfer content than Europe or Japan which damages the catalyst. Some manufacturers get around this by allowing more EGR (up to 25%) to reduce ***. Even with high levels of exhaust gas in the cylinder they are still able to achieve complete combustion due to the design of the piston and the injector spray pattern.
 
#15,010 ·
Did you have to drill through the trunk so it stays in one spot?
Nope, the mount holds onto the lip by two allen head screws on the bottom part. The mount does have a thin rubber gasket on the part that goes onto the trunk itself so nothing is damaged.

I have one of these



Clean car! Love the headlights. And cb antenna looks fresh too.
Much appreciated
 
#15,014 · (Edited)
I'm not an engineer or physicist, but from the little bit of thermodynamics that I learned, I was under the impression that a hotter running engine is generally more efficient. Of course wear is a very big reason to limit temperatures. And I think *** formation is the other big one (particularly in the US).



How does that improve volumetric efficiency? If anything it reduces VE since it is essentially equivalent to opening the throttle a little bit less than you otherwise would.

However since there apparently isn't' much EGR at full load, I guess I don't really care.
The thermal efficiency is better because if your combustion is cooler, less heat is lost through the cylinder walls into the water jacket. An engine will run more efficiently by either raising the coolant temp (that's the temp you are thinking of) or lowering the combustion temperatures or both. It's all about reducing the temperature gradient across the cylinder walls. However, there is a point at which too much EGR will reduce thermal efficiency. One paper I just read shows that 5% EGR is about the maximum you want to reduce *** and increase thermal efficiency, but another shows that up to 30% would be good. It's gonna take a while to sort through these papers. They are quite interesting though.

You are right about the VE going down. I don't know what I was thinking. I can't justify my prior reasoning. I'm finding a lot of conflicting information though, so I'm still reading about it.

There is actually a great deal of research going into this. I'm finding some conflicting info, but the one thing that is definitely true is that EGR SIGNIFICANTLY reduces *** formation and it does improve fuel economy (referred to as brake specific fuel consumption, BSFC, in most papers).
 
#15,016 · (Edited)
Yep, all I can conclude is reduced *** emissions and slightly improved BSFC. I can't find any papers I have access to that confirm or deny my claim of improved thermal efficiency. It is a bit contrary to intuition though. EGR increases intake temperatures which hurts efficiency. I can't conclude anything on that yet. Does anyone have access to their university's paper database that is interested in finding out more? PM me.
 
#15,017 ·
Started the car, heard a squeal and pop! What am I fixing today?

That's what I did for my car today! Burned up a sick day!
 
#15,019 ·
Exp tank, belt, or pulley
Nope, guess again!

Car was not warm! It was 11 degrees out, Fahrenheit (for those of you using the wrong temp.)

Guess again!
 
#15,020 ·
Top