Diesel Exhaust Brake Valve?

[oldtamiyaphile]

Now, I've long known about Jake Brakes for larger engines, but just now I learned that small diesels also have exhaust brake valves. They're basically a butterfly in the exhaust that partially closes the exhaust pipe to create back pressure and provide engine braking.

Now my Renault Trafic has no engine braking to speak of, but less would still be better.

Right now I'm not sure if P&G is better in gear or neutral, but this would close that gap and make it much easier to accomplish. It could possibly be wired via the brake switch to engage only when actually braking, so you'd have the best of both worlds.

It seems odd that I've never seen this mentioned on Ecomodder, so I'm wondering if other than the possible CEL, there might be any unintended consequences of removing or modding the butterfly?

My first port of call will be to just disconnect the electrical connector and see what happens.

[jakobnev]

Neutral should beat DFCO hands down.

That valve is likely used as a white smoke limiter, it raises combustion temperature which helps complete burn and accelerates warm up.

I would suggest starting with some kind of indicator that tells you when it is activated.

[oil pan 4]

I have seen them called heat risers. On a diesel they help the engine warm up faster and some times may be used to force more EGR into the engine.
I would remove it. Since EGR on most diesels doesn't appear to be helping them and it's just an exhaust obstruction even when opened.

[cRiPpLe_rOoStEr]

I haven't seen those exhaust flaps being used for anything other than engine-braking. I knew that some newer Diesels are featuring throttle-plates for emissions control, but I don't see how an exhaust flap would help on that matter.

[oil pan 4]

Originally Posted by cRiPpLe_rOoStEr

I haven't seen those exhaust flaps being used for anything other than engine-braking. I knew that some newer Diesels are featuring throttle-plates for emissions control, but I don't see how an exhaust flap would help on that matter.

It doesn't. But that's not reason enough not to include them.

[oldtamiyaphile]

Originally Posted by jakobnev

Neutral should beat DFCO hands down.

For a 'normal' car, yes. The situation changes when you have a tiny engine and 2+ tons. With my Petrol Kangoo, neutral coasting was absolutely the way to go, but when I hitched up my trailer for a total weight of 2.3-2.4 tons, I couldn't feel any change in the rate of deceleration when I pushed the clutch in (the effect of the A/C and alternator kicking in was more pronounced), so DFCO was generally the better option.

Same goes for the Trafic, nearly 2 tons and no engine braking to speak of. I'm likely better off loosing a tiny amount of coast distance vs having the engine idling at 1-1.6l/100km. I haven't had a chance to test it yet, but I have tested my Fiat 500 and P&G (neutral or DFCO) doesn't work at all in that one. I don't really have any 'normal' cars

[gumby79]

In the60's, 70's, and 80's gas v engines had a diverter valve it 95% blocked the passenger ehxsost manafulld. Rerouting the hot gas through a passage under the carburetor and out the drivers side . On a 61' GMC 305ci V6 the valve had a bimetal spring to open it ,hence not full blockage. My 79 Chevy K-20 with a 350ci V8 was normally closed vacuum actuated via a thermal valve in the coolent . I had the vac line brake causing the spring to close the valve . At 70mph the passenger manafulld was glowing in direct sunlight, well over 700°f. Let it cool then wired it open as my Edelbrock Rpm Airgap Intake did not have the passage.
---
As to diesel there are 3 ways to slow with the motor .
1) Engine Braking. Just let off the throttle.
Same as a gas but less effective.
2) Ehxsost Brake. The flap in the ehxsost. On my Cummins this up grade requires up-graded ehxsost valve springs 60# vs stock 30# to hold the valves closed on the intake stroke. Exced 60psi on the brake and it will still over ride the spring.
.. Cummins,Duramax, Ford use option 2 by way of the VGT Turbo closing the vains enuph to act like this type.
3) Jake Brake . A device that prevents the ehxsost valves from opening, normally multi stage in pairs 180° out .
... 6.7 Cummins has a kit avaliable. Its the only small US diesel I'm currently aware of with this Big truck technology.

[bandit86]

Make one from an engine throttle plate, put it on the tail pipe, use along bicycle cable to actuate it. If it works, you came it more permanent.

I was thinking of doing the same thing because here, in winter, my truck takes 25+ minutes to reach operating temp

[oil pan 4]

If you don't do it right it's just a blown head gasket.