EGR deactivation

[Andrew Prince]

On the subject of EGR I have to ask the question WHY?

Ok so it recycles exhaust gas back into the system to try to mininise emissions. But, and this is the odd part, you've already uses up all the oxygen in the gas first time through the cycle so your comprimising the combustion second time through. Just a thought.

It's all about how emissions are measured! Perfect combustion would mean that just about everything that comes out of the exhaust is water and CO2. Incomplete combustion means other products are formed mainly particulates (solid carbon products) and CO (carbon monoxide) being the primary culprits.
Recycling the incompletely combusted products means that more of them are fully combusted to CO2, which is less bad than particulates and CO
In the mean time, as you point out, you're not feeding nice 100% fresh air-fuel mixture into your engine but partially burnt fuel too.

Where the picture gets murky is that diesel engines (without EGR or other emissions control systems) in particular are set-up to minimise production of particulates and CO. This setting is not optimal for max power production or even efficiency. Using an EGR system means that you can set-up the engine to produce more power because youcan ignore emissions to a large extent because you're partially recycling them. Yes, there is a power loss because the air-fuel mixture is partly compromised by recycling exhaust gases into the engine but the power increase due to the optimised settings is usually greater than the losses. So more power overall and emissions limits are obeyed.

The "trick" with removing your EGR is to produce more power (because you're now feeding in pure fresh air-fuel mixture) and not fall foul of emissions regulations, which are supposedly enforced by your friendly MOT tester

Hope that clarifies things a bit!

 

[Ecky Thump]

[quote="Richard Jackaman":6d8ljpka]On the subject of EGR I have to ask the question WHY?

Ok so it recycles exhaust gas back into the system to try to mininise emissions. But, and this is the odd part, you've already uses up all the oxygen in the gas first time through the cycle so your comprimising the combustion second time through. Just a thought.

It's all about how emissions are measured! Perfect combustion would mean that just about everything that comes out of the exhaust is water and CO2. Incomplete combustion means other products are formed mainly particulates (solid carbon products) and CO (carbon monoxide) being the primary culprits.
Recycling the incompletely combusted products means that more of them are fully combusted to CO2, which is less bad than particulates and CO
In the mean time, as you point out, you're not feeding nice 100% fresh air-fuel mixture into your engine but partially burnt fuel too.

Where the picture gets murky is that diesel engines (without EGR or other emissions control systems) in particular are set-up to minimise production of particulates and CO. This setting is not optimal for max power production or even efficiency. Using an EGR system means that you can set-up the engine to produce more power because youcan ignore emissions to a large extent because you're partially recycling them. Yes, there is a power loss because the air-fuel mixture is partly compromised by recycling exhaust gases into the engine but the power increase due to the optimised settings is usually greater than the losses. So more power overall and emissions limits are obeyed.

The "trick" with removing your EGR is to produce more power (because you're now feeding in pure fresh air-fuel mixture) and not fall foul of emissions regulations, which are supposedly enforced by your friendly MOT tester

Hope that clarifies things a bit![/quote:6d8ljpka]

Totally off the subject Andrew, just a question for your chemist type mind.
When I had the V8 Disco I converted it to LPG and was told that the emissions were only H2O. Is that true

 

[Andrew Prince]

Totally off the subject Andrew, just a question for your chemist type mind.
When I had the V8 Disco I converted it to LPG and was told that the emissions were only H2O. Is that true

Nope, not in a million years

To produce H20 only, you'd need to be burning pure hydrogen (H2) - hydrogen power ring any bells for anyone?
LPG will produce pretty similar emissions to petrol - all fossil fuels contain carbon, so all fossil fuels produce CO and CO2 emissions when combusted. The type of hydrocarbon being burnt will determine how much CO/CO2 is produced versus H20 but the ratios are not dramatically different between the main fuel types.

Cheers,

 

[Richard Jackaman]

Re: EGR deactivation - update

Disconnected the vacuum pipes at the weekend and it's fixed the flat spot at about 1800rpm.

Truck seems to go better in general esp at low revs.

Cheers

Richard

 

[Paul]

As we speak, i am having the blanking plates made up so will try to do a fit at the weekend.
The plates will cover the hole in the exhaust manifold and the two openings in the intake pipe/casting across the top of the engine left when the EGR is removed and will be the same thickness as the existing flange so the existing bolts/nuts can be used again.
If they fit nicely then i will have some made that are quite thin in case you just want to blank off the pipes and leave the EGR in place.
I can also source some earth straps as i believe this needs to be fitted to avoid sparks

Anyone know? Will this turn off the glow plug light on my dash?

Adrianr, what did you actually disconnect on the intake heater that made the light come on?

 

[adrianr]

Hi Paul

the heater was disconnected - when i reconnected it light came on again so i disconnected it again.

 

[Richard Jackaman]

Will we need new gaskets to fit the blanking plates?

Cheers

Richard

 

[Paul]

I have ordered gaskets for mine and want to do a complete fit up to check things, the engineering shop has had a delay so probably next week before i do it all

 

[Paul]

Well, the patterns are back, just need a test fit up.

 

[Chas]

The "trick" with removing your EGR is to produce more power (because you're now feeding in pure fresh air-fuel mixture) and not fall foul of emissions regulations, which are supposedly enforced by your friendly MOT tester

Hope that clarifies things a bit!

But how do you get it past an unfriendly tester?
Chas

 

[Paul]

The one on mine is disconnected anyway and they are more interested in the actual emmissions, if you look at ecky's it doesn't have one fitted as standard and its newer than mine!

I can also make them in thin plates so they can be fitted in place so the egr will stay there, but on mine i want it all gone.

Just waiting on the earth strap now so i can fit it all.