From: Bjorn Brandstedt (super_deuce@hotmail.com)
Date: Sat Nov 06 2004 - 04:56:46 PST
Morning,
Based on the number of visitor to the imageevent site, I'll assume that
others may have similar questions and this is therefore posted to the list.
My answers are posted here following each question:
Bjorn,
Well, I must thank you once again for educating me.
I would also like to commend you on your natural ability to explain things
without "talking down" to us of little knowledge about the projects that you
work on.
Four more questions about the exhaust brake.
1) Does the brake obstruct the exhaust while in the open position or is it
the same size opening as the exhaust pipe?
ANS: There is some obstruction. The butterfly valve used here sits in a 3"
dia opening and itself causes a small blockage. I don't have the budget to
purchase a new unit, say, from Pacbrake, made for a 3-1/2 inch pipe, which
would create very little blockage.
2) When the brake is applied, does it cause a dangerous restriction to the
exhaust system or the engine?
ANS: The back pressure must be monitored. I have a pressure gauge in the
system and the maximum closure of the butterfly valve is adjustable with a
stop. My goal is to limit the pressure to about 30 psi. I called Hercules
Engine co and they didn't think that that would be a problem. BTW, they had
no experience with an exhaust brake!!! The potential problem has to do with
exhaust valve springs and their ability to hold back the increased pressure.
Hercules has only one type of spring for this valve.
The amount of braking power created with 30 psi should be in the
neighborhood of 75 horsepower.
3) How is the noise compared to the "jake" engine brakes? I know of
several areas near me where it is illegal to use the engine brakes due at
least in part to noise. My home is located approximately 50 feet off of Rt.
220 with a lot of large truck traffic and the engine brakes coming down the
hill can be quite loud.
ANS: The noise should be nothing compared to a jake brake, just a "whoosing"
sound, but some tests later today or tomorrow will tell. A lot of diesel
pick-ups are equipped with exhaust brakes. This is particularily important
if you are hauling a heavy trailer down a mountain grade. Your service
brakes may not be able to handle it on their own.
4) If you hit upon this I apologize for missing it, but what kind of
expense (minus labor cost) is involved for this modification?
Thanks again, Bill K.
ANS: Since my budget is virtually zero my projects take a long time to
complete. I always look for junk parts and bargains on eBay etc. The
butterfly valve in this installation cost me a grand total of $10.00, that's
right ten bucks. I found it on a junk pile in a muffler shop. Don't even
think the guy new what it was. It had been cut out from a small truck and
needed some cleaning up.
The kits sold by companies like Banks, Cummins/Jake, Pacbrake and others are
"engine specific" in that they contain parts like wiring, switches and
computerized controls that interface with each particular engine for a
preprogrammed installation. The butterfly valve itself is part of an exact
prefabricated section of pipe/elbow, which mounts on the turbo of the
particular engine. My valve is "generic" and is mounted in a straight
section of the exhaust pipe. The controls are manual in my case except fo
the planned installation of a limit switch in the accelerator pedal linkage
(the buttefly valve should only be closed when no significant amount of fuel
is burned = idle position only).
The cost of these commercial kits are is about $1,200 plus $500+ for
installation.
My parts cost so far is less then $100 with $25 for the welding. I did end
up with an extra butterfly valve, which operates on a vacuum. It cost me
$80.00 (eBay), but it will be sold again.
NOTE: I think it is healthier for the turbo to install the butterfly valve
further downstream, but the response time of the system may suffer.
Bjorn:
How do you interconnect the accelerator pedal with the control for the
shutter valve? apb
ANS: A solenoid valve is mounted in line with the air supply to the
butterfly valve piston. It is controlled by a limit switch on the pedal
linkage. I don't have this limit switch installed at this time and plan to
use the manual control only until I do.
The switch I use is the same as used for the front wheel drive on the deuce.
It is mounted next to it.
Bjorn,
Being not all knowledgeable, can you explain the advantages and
disadvantages of a "Jake" (Jacob's) brake, vs an "exhaust" brake?
I thought that a Jake brake closes the exhaust valves, creating compression
against the piston on the upward stroke, rather than on the downward stroke,
which causes the engine torque to slow the vehicle. I am now imagining that
the closing of the exhaust system further down the line at the exhaust stack
would create a similar situation, although not nearly as powerful as that
created by the Jake brake. Is this correct? Certainly, the exhaust brake is
MUCH less expensive than the Jake brake.
ANS: Your understanding seems correct to me. The Jake brake operates on much
higher pressures and can therefore create two or three times the braking
horsepower compared to the E-brake.
Bruce Kalin
Convoy coordinator
>From : Patrick Jankowiak
That is very cool!
Some audio of the big 'BOOOOOOOooooooohhhhhhh...." deceleration sound would
be cool.
ANS: Who knows, I spend far to much time on this anyway.
Thanks for your interest (my apologies for taking up so much
space/bandwidth)
Bjorn
MVPA 19212
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