Exhaust Brake Idea. Feedback?

4x4dually

4x4dually

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Exhaust brakes are cool. Exhaust brakes are expensive. Exhaust brakes are nothing more than a flapper with some fancy controls. So, here's my thoughts and questions.

The build:

A short stub of pipe with a pin through it and a flap. (highly techinical junk)
A two speed type switch mounted to the shifter like my class 6 trucks.
A solinoid valve off the vacuum line. Flip the switch, it pulls the flap closed. Flip it back, it opens.
Simple huh?

The questions:

How much backpressure is too much? Can I put a pressure sensor right before the device and monitor the pressure and tune it so it won't close off too much? I know some drill a hole through the flap. Is there any type of PSI limit as to what would hurt the turbine or motor if closed off too much?

How fast do they normally move? If I use vacuum, they will move slowly I'm guessing. What if I used a coil type plunger that would slam it shut and return by spring once power was removed? Can I close it to fast?

How much force does it take to close the device? I'm certain there is a lot of variables here. RPM, CFM, etc will all play a part in this. Ease of closing can be helped by a longer lever on the pivot and as the brake works, the CFM drops, the more closed it will become.

Does anyone have any first hand knowledge of any of the questions I have posted here? I'd be grateful for some input. I do have a line on a air operated one pretty cheap....but don't really want to install a compressor.

As usual..I think to myself "it can't be that hard. I can make one"...which will normally turn into "I never had time to finish it". :D
 
I once saw a home made exhaust brake very similar to what you describe. The pivot pin was offset in the pipe allowing exhaust pressure to open the "flapper". The pin had a long arm with many holes drilled in it which was attached to an electric solenoid via a spring. He could adjust the pressure it would hold by moving the spring closer to the pin for less, and farther away for more pressure.

I don't think he ever completed the tuning, he was having issues with getting the flap to seal enough without binding in the pipe, and something to do with cfm vs pressure? I don't know enough about this stuff to even take a wild guess what his prblems were, but the idea seemed sound to me.

Hope this sparks an idea for you.
 
So there ain't nobody on this website that has any ideas about operational specifics of these things? LOL Com'mon fellas.

A gilletien (sp?) would be the easiest to control....but sealing it up would be a biddy. :D
 
The manifold pressure limit is ~530kpa on a 6.7L when they use the turbo brake. With stiffer valve springs you could probably increase that pressure.
 
JWhite said:
The manifold pressure limit is ~530kpa on a 6.7L when they use the turbo brake. With stiffer valve springs you could probably increase that pressure.
Click to expand...

Thanks. Interesting. So if I monitored the pressure with a sender post turbo and pre-brake....and keep it below 70 psi or so... hmmmm.

So what all engine components would be in jeapordy of shellin' out due to too much back pressure? HG, cylinder walls, ????? I'm definately not well versed on engine 'internals' so any info would be great.

:thankyou2:
 
They are mainly worried about valve float, but Im sure blowing the HG was a thought. Not sure what kind of pressure it would take to hurt a turbo seal. If it is a studded head and you have a good seal on the manifold I dont see where more pressure would be an issue. I just know thats the limit on the stock tables.
 
I think the pressure created by an exhaust brake doesn't even come clost to the pressure of the compression stroke. Keeping the exhaust valve shut is the issue, and possibly pressure on exhaust components like gaskets.

If you could design a system that would relieve the back pressure at a set point, by opening the brake, or a wastegate type system. Probably too complicated...

Don't mind me, I just find this very interesting and am posting random thoughts, lol
 
So a "pop-off" type valve could be placed pre-butterfly and it could be set to bleed any pressure above what we think is safe?
 
I'm thinking a used or new vacuum actuator like this or similar:

$(KGrHqZ,!iQE4sSE0jo(BOQI8jV+Y!~~_1.JPG


plus a valve like this or similar:

Compact-Solenoid-Valve-4TR81_AS01.JPG


plus a switch like this or similar:

$(KGrHqF,!nsE63V3Vp9gBPDFGQurb!~~60_12.JPG


I'm almost certain I can find all of these items really cheap or free and the welding and metal fab I can do myself.

On the shifter...pop switch up...brake...pop it down...back to open. The design challenge is in the "how much force to block it off and how much to hold it shut" part. :D
 
I would use vacuum operator. I think the solenoid plunger would be too large for it to work. You could also put in a storage tank with a check valve and let turbo boost fill the tank, then use air pressure to operate the butterfly. Also you could put a stop on the butterfly to eliminate how far it closes off. Start with it barely closing and increase the closing until you get the results you want.
 
Jory, I have seen at least 50psi on my truck with the 351VE when I crank it closed, but only at higher RPM. Below 1600 or so the brake is not really that effective, above 2200 it will chirp the tires :)

Have you thought about just using an actuator type solenoid and doing away with the valve and cylinder?

On the cylinder, let me know some specs on what you need, we have a pretty good selection at work, rod ends too. Not many 12VDC coil valves though, but if you have a way to get 24VDC I can hook you up six ways to sunday.
 
I would just try to make a copy of a vacuum operated brake like BD and PacBrake sell. It's simple and you know the method works. Tee off the vacuum pump, use an two-position four-way valve, and a largish air cylinder. It only takes about a half of a second for mine to build pressure (30-55psi depending on RPM)

Here's what the one on my truck looks like: You can see the valve mounted to the intake horn and the lines running to the cylinder.
DSC00667.jpg
 
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Derek, that is exactly what I was thinking and then I'd put the switch on the gear shifter....I just love the old two speed switch. It gives my pinky something to do while driving....I just spin it ..... and spin it.... :D

So, basically I need to come up with the vacuum operator doo-da. Anyone got a used one or a part number of where do I start to find which one to use?

I don't want to make it fancy enough that it has v-band clamps and required downpipe mods...I was just going to put it where the dp ties to the FTE resonator. It would be further from the heat down there and the engine bay has eough crap in it already.
 
4x4dually said:
Derek, that is exactly what I was thinking and then I'd put the switch on the gear shifter....I just love the old two speed switch. It gives my pinky something to do while driving....I just spin it ..... and spin it.... :D

So, basically I need to come up with the vacuum operator doo-da. Anyone got a used one or a part number of where do I start to find which one to use?

I don't want to make it fancy enough that it has v-band clamps and required downpipe mods...I was just going to put it where the dp ties to the FTE resonator. It would be further from the heat down there and the engine bay has eough crap in it already.
Click to expand...

Ditch the vacuum, use pressure and everything can be so much smaller.
 
zstroken said:
Ditch the vacuum, use pressure and everything can be so much smaller.
Click to expand...

But...buy an air compressor or try to rob it from turbo...power wires for that plus lines. Adds $$$s and routing and time. I'm going for simple, cheap, and works on any truck. :D Basically, "so easy a caveman could do it". KISS
 
4x4dually said:
But...buy an air compressor or try to rob it from turbo...power wires for that plus lines. Adds $$$s and routing and time. I'm going for simple, cheap, and works on any truck. :D Basically, "so easy a caveman could do it". KISS
Click to expand...


Do you realize how little energy your taking from the turbo? I actually used a $20 harbor freight compressor on my old airbag setup. I put the $70 one on my new one. I think once you look at the size and cost of the vacuum stuff, you will come back to pressure.

The turbo was just a simple idea, condensation might be an issue in the tank and such.
 
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