MrNiftie
Registered User
I copied the following quote from an EEC Tuner discussion forum and thought it would be an interesting topic for our discussions. I make to calims to its (in)accuracies:
"
The advantage (ask any Ford ASSET graduate) to EGRs has nothing to
do with emissions or gas mileage (even though it minutely effects
both as an adverse effect).
The sole purpose of an EGR is to dilute the air/fuel mixture (i.e.,
95% mixture being drawn in with 5% EGR) to lower the combustion
chamber temps. Yes, there may be unburned HCs in the exhaust gases,
but no where near the amount to fuel a fire/burn. Exhaust gases
are, more or less, unburnable (excluding rich WOT pulls, or
accelerations). Mixing this unburnable mixture with an air/fuel
ratio causes the same amount of air to be compressed without
changing the a/f ratio. Thus creating less of an explosion, thus
less temps in the combustion chambers.
Now this rule changes under WOT and 1/3rd throttle (or loaded)
acceleration points because of the richer mixture. That's why an
EGR will only pulse at idle and at light throttle/cruise
applications (stays closed the rest of the time). I could into
those reasons, but that is the just reasons behind an EGR.
Given it might have an 0.1% effect on emissions and maybe an 1%
effect on gas mileage (hurting it with less of combustion, instead
of the improper thinking by most as it tries to `help' gas
mileage). But given the benefits of keeping the overall temps in
the combustion chamber of a constant 300/400/1000 mile drive lower,
is a good trade off.
Now for cars only driven short trips, off-road use (drag/autocross),
or heavy footed drivers, EGRs won't be effective. So go ahead and
delete it, it won't hurt a thing (helps by giving one less thing
that can go wrong). It's people like me that drive from TN to CA
and back (or FL to NYC and back) that reap the benefits of the EGR.
Or even those nasty people that sit, idling 8 hours a day on the
side of the road (I think they are called cops, clocking us?).
"
"
The advantage (ask any Ford ASSET graduate) to EGRs has nothing to
do with emissions or gas mileage (even though it minutely effects
both as an adverse effect).
The sole purpose of an EGR is to dilute the air/fuel mixture (i.e.,
95% mixture being drawn in with 5% EGR) to lower the combustion
chamber temps. Yes, there may be unburned HCs in the exhaust gases,
but no where near the amount to fuel a fire/burn. Exhaust gases
are, more or less, unburnable (excluding rich WOT pulls, or
accelerations). Mixing this unburnable mixture with an air/fuel
ratio causes the same amount of air to be compressed without
changing the a/f ratio. Thus creating less of an explosion, thus
less temps in the combustion chambers.
Now this rule changes under WOT and 1/3rd throttle (or loaded)
acceleration points because of the richer mixture. That's why an
EGR will only pulse at idle and at light throttle/cruise
applications (stays closed the rest of the time). I could into
those reasons, but that is the just reasons behind an EGR.
Given it might have an 0.1% effect on emissions and maybe an 1%
effect on gas mileage (hurting it with less of combustion, instead
of the improper thinking by most as it tries to `help' gas
mileage). But given the benefits of keeping the overall temps in
the combustion chamber of a constant 300/400/1000 mile drive lower,
is a good trade off.
Now for cars only driven short trips, off-road use (drag/autocross),
or heavy footed drivers, EGRs won't be effective. So go ahead and
delete it, it won't hurt a thing (helps by giving one less thing
that can go wrong). It's people like me that drive from TN to CA
and back (or FL to NYC and back) that reap the benefits of the EGR.
Or even those nasty people that sit, idling 8 hours a day on the
side of the road (I think they are called cops, clocking us?).
"