Exhaust brake on a VW TDI

[Wheaties]

You know... if the vanes are variable enough... you could reverse the turbo when the brake provides back pressure, and actually deliver vacuum to the intake. With back pressure AND vacuum, I bet you could throw the wheels into reverse!



(just can't get me to be serious, can you?)

MTE

 

[HEYBOSS]

Why, why

Originally posted by Wheaties

You know... if the vanes are variable enough... you could reverse the turbo when the brake provides back pressure, and actually deliver vacuum to the intake. With back pressure AND vacuum, I bet you could throw the wheels into reverse!



(just can't get me to be serious, can you?)

MTE

All that BS for e-brake, just throw it in reverse and you have a perfect exh brake

:-laf

 

[HoleshotHolset]

Here's more info from our buddy Russell:





"R. E. Miller wrote on 10-30-2002 05:33 PM:

Matt, no problem, post away The main reason for the nay on the vgt at least from cummins/holset standpoint, the ecm works pretty cool, parameters like turbo speed, boost pressure, %throttle, and even vehicle sensors contribute to the ecm's desisions. On the cummins ISBe's over 230hp, you get the vgt, and the computer adjusts the vane rack to provide what is called "integrated" engine braking 230 or below that hp rating, you get the hx35w. Computers, a love hate relationship for me, the new tech gives me chills for both what it can do, and for what might not work right Ha ha, just means that you have to find more elaborate ways to fix them.



Yea, the garret vgt uses a different design that uses tons of moving vanes, where as the holset design uses one moving part. Just fyi, not to bash international or anything, but I can't wait to see how long the garrett vgt's last with 350hp blowing through them



Russell"



I'll let Deo play with the exhaust brake on his new racecar... .



Matt

 

[HoleshotHolset]

Remember this thread?

So, what's stopping someone from putting an exhaust brake on a gasser?



I thought of this on my drive home yesterday.....



Is the compression ratio too low to offer any real compression braking or are they not built strong enough to handle it? Comments, suggestions, etc.....



Matt

 

[Wheaties]

Hey Matt,



Well, I'd be willing to venture a few guesses:



1) cost



2) average jamoke couldn't handle something this complex



3) cost



4) vacuum in the intake does the same thing -- weakly



5) the exhaust valves couldn't handle the back pressure and would get munched



6) so you'd have to install much stronger valve springs which would increase the cost



7) whatcha gonna tow with that? both hay bales at once?



MTE

 

[kchristopher]

Re: Remember this thread?

Originally posted by HoleshotHolset

So, what's stopping someone from putting an exhaust brake on a gasser?



I thought of this on my drive home yesterday.....



Is the compression ratio too low to offer any real compression braking or are they not built strong enough to handle it? Comments, suggestions, etc.....



Matt

They kinda do. They're on the intake side and more correctly called throttlebodies or carbs. No electronics to make them work either - just take you foot off the floor.

 

[98rammer]

maybe a crazy idea... but what about using a big throttle body on the intake side of the motor to starve air out of the turbo (maybe with a couple more holes drilled into it). would it work?--or work enough?

 

[Wheaties]

Tom,

are you talking about a gasser or a diesel?



Here's a thought gasser wise: What happens when you apply both vacuum on the intake side and back pressure on the exhaust side? I bet it would clean out your sinuses, maybe even blow out your eardrums



MTE

 

[HoleshotHolset]

"both hay bales at once?"



OMG! ROTFLMFAO!



I envision the use of an exhaust brake more for the freeway jerks that like to inspect my rear window glass at 3' from the back of the car... .



The car would slow down quite nicely (without brake lights... ) with an e-brake. Simply defeating the brake lights with a switch just isn't fun enough for me... . I gotta have the class-8 truck sounds too!!



I would tend to think that a gasser would have strong enough valve springs... . heck my 4. 3L 90° V-6 had double springs on it from the OEM. A lot of gassers are designed to redline at nearly double the OEM B-series spec.



Gassers usually will stall if you apply too much back pressure on the exhaust side... .



The TDI has a 'anti-shudder' valve (same basic idea of a gasser TB)... . that I guess I could try manually closing while I'm going down the road. But, from what I've seen - if this thing gets stuck closed when you are trying to start her up... . if cranks over as if it has no compression and it won't run.



This valve is there to reduce the engine shutdown shake for the wussies that would complain about it.



Matt

 

[Wheaties]

MTY,



I'm beginning to wonder what would happen with 60lb back pressure on the exhaust side of a gasser. What if you get reverse flow? It could make one hell of a back fire is what I'm beginning to think.....



How about a nice cutting torch effect, melting the plastic intake parts and heating the hood like a frying pan?



I can appreciate your goals, we have all had Hondas et al disappear behind us in our trucks. Left mirror check. Right mirror, check. Rear view, check..... hey what's that antenna doing sticking out of my tailgate?



MTE

 

[formula]

A couple of thoughts in no particular order:



If you apply vacuum to a diesel engine turbo, won't it blow out the seals? It seems that a diesel turbo is designed to operate only under presssure due to the fact that there is no airflow control.



As for the exh brake on a gasser... ... you'd need some way to simultaneously kill the ignition, shut off the fuel and hold the throttle wide open while using the brake. Otherwise all you'd get is the little bit of exhaust gas that is produced when the throttle is closed which would hardly create any compression braking for the exh brake.



Also, the potential retarding horsepower of an exh brake or engine brake is a function of the engine's displacement and rotational speed. So with a itty bitty engine you won't get much retarding hp. Unless perhaps you wind it up like an F1 engine



(brain fart is now complete)

Sean

 

[HoleshotHolset]

Brain regurgitation... I like it.



Good thoughts... . keep 'em coming.



MTY

 

[milehigh.o.]

HoleshotHolset,



Being a previous vw tuner and ex TDI owner, goto www.vwvortex.com and go into the forums there and there is a TDI section.



This site should tell you everything that can be done to the TDI engine or you could add value. Of course I have never thought of putting an exhaust brake on mine, been ask if it had one.





Hope this works out.



Russ

 

[HoleshotHolset]

Cool, I'll have to check that out... .



Matt

 

[Eric Kahn]

the TDI already close's the vanes when you let off the throttle, this increases the exhaust speed over the turbine to keep it spooled up, if you put an exhaust brake on, you would lose this effect and have greater turbo lag

exhaust brakes on gassers would be a bad idea due to the overlap in the camshaft where both the intake and exhaust valves are open at the same time, Can you say BOOM?

 

[HoleshotHolset]

I don't care about lag when I'm going down an off-ramp now do I?



This is more for making people look at the car with the... . "What the heck was that??!!"... look on their faces.



They already look at the car funny in-between shifts..... the VGT vanes close really quick and it makes a pseudo blow-off-valve sound out the mufflerless tailpipe..... the little sound is kinda neat..... it's a bug-fart... . or perhaps its the German rollerskate fart... .



Matt