EGR Delete - VT Ecotec

[immortality]

So I'm doing a little work on the engine in the VT and I want to clean some stuff/move around some wiring and it would be really convenient if the EGR disappeared.

Does the EGR actually provide any benefit on a petrol motor other than reducing NOX?

It looks fairly straight forward to remove physically but what needs to be done in the tune to keep it happy?

TIA

[Charlescrown]

Yes it reduces pumping losses improving fuel economy and cools down the combustion process helping the exhaust valves to survive. You need to consider it works mainly when cruising so I think deleting it has little gain. On the other hand yes they do problems with things like carbon keeping them open which can cause the engine to have starting issues and cutting out at idle.

[immortality]

When we build the turbo kit it'll be a mute point anyway

[Charlescrown]

Mute point so why ask?
It all depends on what the most use of the car is. Drag or circuit racing get rid of it. Road use keep it. If you get pulled over it's a defect but that dosn't concern many but if so block it off and take the risk. I don't see much change with the tune except maybe in the cruise range but Turbo is a whole new ball game.

[immortality]

I'm interested to see what it does which is why the question.

I was watching something about EGR on Diesel and it got me intrigued.

[vlad01]

I'd def keep it if you can, the ecotec wasn't eco until they fitted them. The VS came out without EGR and the economy on them is horrendous, even in the best possible case, manual, wagon, AFRs spot on, fresh healthy engine.

Much effort to diagnose what was just inherently inefficient. EGR came out on VT and despite a heavier car, marginally better aero, the economy improved quite a bit. But in VX and VY, they doubled down on extracting the most out of the EGR and engine tuning to push lower emissions. And boy does a VY and VX sip fuel. Easy 6-7L/100 on average when all or nearly all highway.

Best I ever got out of the VS my nephew has which I confirmed no issues anywhere, is 10L/100 when nearly all highway and babying it. Average is around 13.5.

Not sure why the ecotec is so bad on fuel without EGR, but I am guessing the very wide LSA their cams run not being what the engine actually needs, but I reckon it was probably designed like that with EGR being a prerequisite from the start. But Holden always had a habit of cheaping out and removing stuff the US designed and normally shipped them with.


The VN-VR was also built with ERG in mind, but also was not included by Holden. But interestingly, the old engines got good economy despite this and close to the US stated specs. They have a reasonable tight LSA which often acts as a natural EGR at lower speeds.

I mean it makes sense, pumping losses should be less with tighter LSA when designed carefully as there is less work on the piston as some of the filling (pumping) is kind of free as it's from the scavenging/resonance, and less needed to be done mechanically by the piston.

The cam can only do so much of the work and is limited in ways, EGR is the better way, but EGR plus VVT is even better.

[immortality]

I got our VS eco into the 7's and 8's economy wise but it was hard as it required speeding, I always found I was using less fuel at 120km+ than I did at 100km/h. It's my belief they just geared these cars wrong. I also got better economy in the VN with 3.45 gears and a manual trans.

I guess I'll have to experiment and see what happens. Fairly much everything I've played with before has not had EGR (VN-VR and L67 in later models).

[delcowizzid]

Bin it lol my vx didn't have it working for years noticed 0 difference In economy

[Wade]

Data log maf before and after. You’ll see the difference egr makes. Airflow through the maf is greatly reduced while egr is in operation as it’s recirculating x amount and obviously the maf doesn’t see that x amount. It’s even more with diesels. Look at diesel egr’s, there the size of a small waste gates. It lowers emissions as that x amount goes through the burn cycle twice. You’d need to re tune with egr delete as it would be baked into the tune. With the egr turned off obviously the maf is going to see more airflow being pumped through it. That’s why I pointed out that this should be taken into consideration with maf tuning and or when changing maf’s. The maf curve is obviously going to be different with and without egr active. And I dare say ignition timing requirements would be different as well. As previously mentioned cam timing will greatly effect egr as well. In a turbocharged application with an optimised cam, egr would be mute. In a road car with basic mods, yeah keep it. But once you start looking at cams and boost ect yeah nah.