Back Yard Exhaust Brake Build

[SShafranko]

I have parts for an exhaust brake and i've been trying to figure out how to build one without the hassle of solenoids, compressors, vacuum pumps, etc. I want a switch to turn it on when i need it and shut it off when i don't. I think i finally got it. The parts so far cost me nothing. Here is a picture of the set up on a bench being tested today with a leaf blower sending air against the flap. The system is composed of a Jacobs elbow, one carburator spring, Jacobs shifter mounted switch and an electro magnetic actuator to pull the flap shut. It will be installed in the truck by Friday and i will update on how well it works.

 

[tkerrigan]

Make sure that the exhaust back pressure doesn't exceed 60PSI, or your exhaust valves might kiss the piston.

 

[tom sweeney]

hey Tommy... . you going to MM'09???... ..... tom

 

[DCreed]

so youre using a jacobs brake with a home made actuator?

 

[Allnew2Me]

Also make sure there is some provision to turn the brake off when the accelerator is even just touched. A microswitch maybe activating a relay to cut power to the actuator. There is a lot at risk if things go wacky.

 

[SShafranko]

so youre using a jacobs brake with a home made actuator?

The actuator is from an old diesel generator engine. It was used to push the throttle lever to the full throttle position once the key was turned on, and when the motor reached a certain temprature it would disingage. It is composed of an electro magnet, which when turned on pulls a cylinder shaped piece of steel towards it. This cylinder has the shaft attached to it which will pull the butterfly lever to the closed position. Very simple device with nothing to break. Basically works like the solenoid on a western plow.

 

[SShafranko]

Make sure that the exhaust back pressure doesn't exceed 60PSI, or your exhaust valves might kiss the piston.

The butterfly has a small hole in it to let some exhaust thru and is the factory unit from Jacobs. If it doesn't exceed 60psi when running with the factory set up why would it here? The only way that could possibly happen here is if the brake is left on and the accelerator is pressed down. Am i missing something else?

 

[ENafziger]

The butterfly has a small hole in it to let some exhaust thru and is the factory unit from Jacobs. If it doesn't exceed 60psi when running with the factory set up why would it here? The only way that could possibly happen here is if the brake is left on and the accelerator is pressed down. Am i missing something else?<!-- google_ad_section_end --> <!-- / message --><!-- sig -->

Nope, you're not missing anything. The way the Jacob's is designed to work, it will stay full closed up to 1,100 rpm at fast idle. If you raise the idle point above this, the exhaust brake opens again.

I'd invest in a drive pressure gauge so you can monitor what it's doing. You can also adjust the threaded rod on the outside of the butterfly to set how much the valve closes, and therefore, adjusting maximum back pressure.

Looking good!

--Eric

 

[SShafranko]

I have a drive presure gauge ready to go in, and i made the linkage on the actuator adjustable for the flap. Thanks for the input.

 

[tkerrigan]

hey Tommy... . you going to MM'09???... ..... tom

I just entered Nevada today, am I early?



Tom

 

[SShafranko]

Finished the install last night. It works great! There is only one issue however. The way i set it up is a small electro magnetic motor pulls the flap closed and a spring pulls it back open. The motor is not powerful enough to close the flap and pull a heavy spring at the same time so i had to go with a lighter spring which has just enough power to pull the flap open. Under a heavy load ingaging the brake at 2500 rpm if a shut it off it takes 5 seconds for it to open. If i put it in neutral it opens immediately. A small bump in the road but the concept works well. Now that everything is in place i am going to look for a motor which is bit more powerful or one which will totaly eliminate the spring and do the push and pull on its own. I'll post some pics when i get a chance and maybe a vid too. Best part is this cost me a total of $7 dollars and five hours to complete.

 

[DCreed]

Best part is this cost me a total of $7 dollars and five hours to complete.

but you already had the e-brake! thats the most expensive part!

 

[SShafranko]

but you already had the e-brake! thats the most expensive part!

Good point. Friend gave me the elbow.

 

[AndrewKing]

HI,

I'll have to say, for something as simple as an exhaust brake is in operation, the major manufacturers sure charge a lot for them (especially the ones that are simply on and off switch controlled... . The fancy ones that integrate with auto trannys etc..... those I can see being bigger $$ because of all the electronics involved... )

I do like this thread because it gave me the idea about possibly saving some $$ on a exhaust brake build BUT as mentioned earlier it would be nice NOT to have to START with parts from an expensive kit ... .

Although possibly crude, can a back yard mechanic Build the Pipe/Butterfly assy
from say a section of 4" or 5" exhaust piping and maybe cutting a disc out of some readily available material and essentially making the high $$ stuff for less?.

I would think a true home brew system would be easier to make as a downstream install rather than one that hangs off the turbo (for the simple fact that he assy can be cut off a straight section of exhaust or thick pipe).

Also, not sure if it can be done BUT how about using an air can off a big truck airbrake and using it in reverse (i. e. vacuume operated instead of air operated to save $$ by not having to get an air compressor) to actuate the butterfly assy?

Is this practical or possible?

Another thing I would like to see, and it would probably be easier to do with a "stepper" motor controlling the butterfly) would be to see a brake that can be varied as to braking power... . NOT a simple on/off.

Personally I have never used a brake before BUT it would seem to be a pain to have a super good brake and have to turn it on / off to maintain a reasonable speed on a grade (I say this because if a brake is really good, it will slow the vehicle perhaps more than is needed to keep a reasonable speed)... . Hene the stepper motor version... . Dial in the amount of retarding you need for a long constant grade... . Heck if you want to get fancy hook it up to a cruise control type setup only in this case the the exhaust brake is manipulated to hold speed... .

I believe this can be accomplished by the stepper motor controlling the butterfly in small increments rather than making it an on/off proposition

Any tinkerers out there that has done something like that?

Oh I suppose a turbo blow off wastegate can be used to max out pressure at 60 PSI which seems to be the goal as far as backpressure is concerned (hmmm here we go back to factory made stuff!)

Thanks!

Andrew

 

[AndrewKing]

HI Sshafranco,

How about using a custom bracket and using 2 of those electro motors to pull on it?

Great thread by the way... . gets the ol brain crankin'!


Oh just as a side thought to raise the state of the art..... Since most people look to decrease back pressure as much as possible while not braking... . How about running a
5" butterfly assy if you are using 4" exhaust or a 6" butterfly assy when running a 5" exhaust... .

By running a larger brake assy, when open and not braking, the area taken up bu the butterfly assy would be more than made up by the extra diameter of the housing?

On a normal 4" exhaust, 4" butterfly you invariable lessen flow because the butterfly and blocking plate will take up space within the pipe itself... . Of course this may be over thinking things too much BUT the quest is for the ultimate in flow and braking!

Thanks!

Andrew

 

[DCreed]

brakes are not terribly complicated but, they need to operate under extreme heat/ soot/ pressure and be designed to be open as a default in case of failure for safety. the expensive brakes do use a bypass within the butterfly to step brake force. cost of these brakes is also upped by liability insurance for damages caused by potential failures.