mmaddock
New Member
I am surprised, maybe the MOT test doesn't test very well under condtions where the EGR is most effective??
The reason I ask is that now I think about it, my P38 has a bit of a problem under certain conditions that could be down to a faulty EGR. Will have a look!
Now you've lost me there! Are you saying that by not introducing hot exhaust gas into the inlet that the inlet temperature is reduced?
Matt.
l3on
New Member
mmaddock said:
Yes.
Exactly as you state, virtually un-cooled exhaust emissions, direct from exhaust manifold, fed back into inlet charge via the egr valve are bound to increase the inlet charge temperature.
'Fresh' air thru air filter, warmed by passing thru turbo by hot exhaust manifold is then cooled by passing thru the intercooler, egr gas isn't.
Cornish
New Member
Thought I'd add a little to this discussion. Bought a 2003 TD5 GS last August and had a PSI Powerchip, uprated Intercooler and K+N air filter fitted after getting a little fed up with it's pulling power, or lack of it!
The difference is phenominal, I can now accelerate and overtake up a long steep hill down here in North Cornwall, whereas before, I was struggling to maintain 60 mph.
Sure, the fuel consumption suffers if you use the power, but on my monthly run to Oxford, a round trip of some 500 miles, I'm averaging 35 ish mpg, at an average 70 - 75 mph.
It's just sailed through it's first MOT with no emission issues.
Now, lets see, where's that EGR valve?
The difference is phenominal, I can now accelerate and overtake up a long steep hill down here in North Cornwall, whereas before, I was struggling to maintain 60 mph.
Sure, the fuel consumption suffers if you use the power, but on my monthly run to Oxford, a round trip of some 500 miles, I'm averaging 35 ish mpg, at an average 70 - 75 mph.
It's just sailed through it's first MOT with no emission issues.
Now, lets see, where's that EGR valve?
mmaddock
New Member
But AIUI - and counterintuitively, introducing exhaust gas (despite it being hot) reduces combustion temperature because of the chemistry involved. i.e. exhaust gas is pretty much inert and therefore does not re-burn, therefore reducing the combustion temperature (and consequently reducing emissions becaue NOx is produced at higher combustion temperatures)
I wonder in reality how much difference it makes? It must do something! Car manufactures do not just stick things on for the sake of it - it costs them too much.
Matt
l3on
New Member
Ah now see, umm err,
Combustion temperature will reduce, but we were talking about inlet charge temperature.
The less-combustible exhaust gas (would be non-combustable if the engine were 100% efficient) increases inlet charge temperature which reduces engine efficiency coupled with less combustable fuel / air mix further reducing efficiency, reduces engine emmissions.
Fit a Turbo Interheater, reduce fuel input accordingly and you will have a vehicle with very low emmissions.......and bugger all power!
Combustion temperature will reduce, but we were talking about inlet charge temperature.
The less-combustible exhaust gas (would be non-combustable if the engine were 100% efficient) increases inlet charge temperature which reduces engine efficiency coupled with less combustable fuel / air mix further reducing efficiency, reduces engine emmissions.
Fit a Turbo Interheater, reduce fuel input accordingly and you will have a vehicle with very low emmissions.......and bugger all power!
l3on
New Member
mmaddock said:
save re-typing my opinion see my rant;
http://www.landyzone.co.uk/lz/f8/edc-29205-2.html
from a former argument err discussion
reply #12
