More on the EGR Bypass Valve....Modify or Leave alone

[Jules]

Well I know which Flow path I would choose if my body was made of Air molecules.
I'd say this is a 30% restriction, but hey ho you would think the EGR designers would account for the engines air demand when full power required.

Left:............................................. ..........Right
choked EGR 40k miles.................................EGR Bypass from Dave (has he emigrated?)

[Roverron]

Originally Posted by julesbass

Dave (has he emigrated?)

I think he's back but he's not talking to me (nor even dare email it seems) since he left everyone, me included, wondering what was going on.

Apparently, he has had family problems (her in doors has thrown him out doors) and a new job which involves overseas travel.

Hopefully he'll respond if anyone wants to contact him

[email protected]

I'm really sorry he's got problems but it would have been sensible to simply say he was going to be away for a couple of months and put an autoresponder message on his email rather than just 'disappear'.

Ron

[Jules]

Always sad to hear these things.
It's always a life balance between spending time with your Passion and the wife!!!
Should be the other way round I know.
Glad I bought 3 bypasses from him when I did (only one left now & it's spoken for)

[BigRuss]

I notice that Dave is now selling the bypasses on e-bay again:
http://cgi.ebay.co.uk/MG-Rover-75-ZT...QQcmdZViewItem

Just in case anybodys after one.

Russ

[Roverron]

Looks like he's back in action then!

Ron

[Johnny2R]

This doesn't add anything to the debate as to whether the bypass damages your engine and/or environment, or not, but I just thought I'd say it anyway...

My 2002 CDT, with 166,000 miles on the clock, recently passed its MOT and the tester said that smoke was negligible, really really low. This is despite having a Rover Ron Synergy box set on 10, a setting most likely to be smoky. I wondered why this might be, then recalled that I did the EGR bypass some months ago. I presume it's that which has brought the smoke down so low.

As to NOx emissions, I vaguely recall reading some years ago that EGR valves reduce them in young engines but either don't so much, or are no longer necessary, in older engines. Is this so?

[Jules]

Tend to agree with your sentiments Johhny, and to date there is no evidence on this forum that bypasses have done any damage.

Different scenario altogether if EGR Valve left fitted (unserviced) for life of engine:
A fully stuck open EGR however in my opinion wouldcause some long term damage in that a constant flow of 15% hot exhaust gases going through the inlet would coke it right up to the point where the inlet would "close up" with carbon and suffocate the engine.

[pondweed]

with respect for the item and not wanting to scaremonger (I've had one and its great), surely we know that it may be 30,000 miles before any negative feedback arises? I too had massive smoke reduction at MOT time. But the key bit for discussion surely is the raised temperature in the head over long hours of motorway cruising?
I naively equate the standard EGR as something which effectively decreases the capacity of the engine when power is not needed, through its introducing inert gas (i.e. it just helps fill the chamber but doesnt combust) at these low demand times. Less burnable air means less fuel needed so computer supplies less. So its a double whammy - fuel saved and NOx reduce as temperature is kept lower as the combustion going on is proportionately lower for the size of the space.
Is there any sound engineering precedent for equating the effect of the greater stress put on the combustion chambers in these periods of low-stress running!? (forgetting environmental and fuel consumption factors which are irrelevant for this discussion - I'm interested in longevity for a car I might have from 80k to 180k or longer)

Ron mentioned grinding out some of the obstruction in the standard EGR - and I've done this yesterday with removal of the jagged 1mm-high 'join' between the alloy tubes, around the inner circumference. I'm now interested in which bits of the brass and stainless steel are reduceable. Has any one got a duff one they can attack to see which bits are hollow and which bits might be capable of bit of reduction....?

[GERFIX]

Originally Posted by pondweed

Ron mentioned grinding out some of the obstruction in the standard EGR - and I've done this yesterday with removal of the jagged 1mm-high 'join' between the alloy tubes, around the inner circumference. I'm now interested in which bits of the brass and stainless steel are reduceable. Has any one got a duff one they can attack to see which bits are hollow and which bits might be capable of bit of reduction....?

I toyed with this when I cleaned my EGR but "bottled it". I, too, wondered how much was removeable but more-so, what cavities would be left. Not wanting to start this heated debate going again, but surely if there were holes/cavities left in the wall of the "doctored" EGR then that would be almost as disruptive to the airflow as the obstructions being there in the first place? That's basically why I bottled out of the grinding and cutting.
And then there's the bypass being sold for people not as tight-fisted as me. I do like to have a go myself!!

[pondweed]

the alloy casting (existing EGR) is made up of two tubes end to end that come together around the perpendicular valving sections. They aren't very neatly joined but its fairly obvious that it is all solid and easily gas flowed to gain a few percent more cross-sectional area. On a crude time:benefit analysis of narrowing the walls of the alloy, it doesnt appear to be worth bothering.

Its the small brass bit that seems 'ripe for the picking', if one know what it did or didnt do!