i'm getting ready to do the s5 to s4 swap but I'm curious as to why I can't keep the egr operating. if at all possible I would like to keep most the emissions stuff on the car for now including the egr valve.
is it just sapce issues? if so can it be moved?
or is there something else involved with this?
I tried to search but mos the post I found don't quite answer this question

 

There is no EGR passage on the series five engine so it can't be done. I find the EGR on my series four engines does close to squat for yearly emissions testing.

 

not too worried about emissions on this car as I don't have to pass. only thing I would find nice about the EGR is it is supposed to help with gas mileage but I can do without it if need be

how do the S5 cars get away with no EGR or is it located in a different way rather then through the intake?

 

never mind you said through the engine. and makes sense being I don't remember seeing a passage on the manifold anytime.

oh well no lost there.
now it's just on to finding the parts to do the swap

 

EGR is only on the US spec S4 models to lower emissions... it serves no other purpose, and does nothing for gas mileage, except perhaps lower them because combustion temp is lowered slightly with one working on the car.

And even the emissions effect is pretty minor. I just passed the stringent California emissions with a quarter of my allowed NO without one (I told the guy that the ACV was the EGR valve).

If you look in the FAQ for FC sticky thread there is a emissions related table that shows if you fail what to look for, the EGR only shows up once.

 

understandable and I'm not going to fight to get an EGR on the car. it just isn't worth it.

as far as the EGR though I was always told it should help with fuel mileage. i could see a little of each path idea there. wish I had a way to find out for sure just for laughs if nothing else

 

EGR if anything will lower gas mileage, it will never help get better mileage.

I don't know who keeps repeating that lame *** rumor.

If it helped gas mileage it would have been on a S5...

It is only for emissions. Just call the next person that you hear say it helps gas mileage a dumb ***. Because they are speaking out of their ***

I mean come on- how can recirculating CO2, CO, and NO back into the intake mixure help anything??? It raises the intake mixture temp and lowers the temp of the combustion, both of which lower power output so you use more gas to get the same power.

 

main reason I heard (and I'm not saying it's correct) is something to do with allowing for a slightly lower pumping loss due to the already burnt gas taking up space so there less of a vacuum for the engine to overcome
and I think the other part was with the lower combustion temps and slower burning mixture it might be able to allow for more spark advance. but then again the extra spark advance can be a double edged sword I know. that is not even counting the detonation issue. too much spark advance even without having detonation can make the motor work against itself lowering gas.


as far as intake temps I still almost think that higher intake temps should mean better gas efficiency. but havn'e been able to prove it or try it out.
my thinking, and you can call me a dumb *** if you want, is with higher temps you have to open the throttle more to get the same mass of air into the motor. that higher throttle opening should make the motor work less to get that same mass of air being it's going through less of a restriction. kinda like a dirty air filter vs a clean one. sure hot air per cubic foot of air has less mass and potential for maximum energy then colder air but we aren't talking wot throttle here so it shouldn't matter there. also motors tend to be more efficient the closer to WOT they run.

 

I think people get confused because on Supras they got a water cooled EGR that does increase gas mileage.