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ARAMP1's Ultimate TowRig Build Thread

Overview Gallery Discussion
Welcome back, thanks for your service time:bow: and get this bad boy under construction.
 
Clod_King said:
Stupid question... What is a Jake Brake?
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Jake Brake, or Jacobs Brake, describes a particular brand of engine brake manufactured and sold by Jacobs Vehicle Systems, Inc. While the term Jake Brake technically only describes Jake Brake brand engine brakes, it has become a genericized trademark and is often used to refer to engine brakes or compression release engine brakes in general, especially on large vehicles or heavy equipment.
An engine brake is a braking system used primarily on semi-trucks or other large vehicles that modifies engine valve operation to use engine compression to slow the vehicle. They are also known as compression release engine brakes.

A view of engine compression brake rocker arm (on the left)


Function

When the accelerator is released on a truck, its forward momentum continues to turn the crankshaft and compress air inside the engine's cylinders. When the crankshaft passes the top-dead-center position, the compressed air in the cylinder acts as a spring and pushes the piston back down the cylinder, returning the energy to the crankshaft and pushing the truck forward. Little of the energy absorbed by compressing the air is lost, so the engine does not effectively aid in slowing the truck. Of equal importance, even with zero accelerator input, there will be some trace introduction of diesel fuel (make and model dependent) which will still undergo combustion. Any power created from this will hinder efforts to decelerate.
In a gasoline engine, some engine braking is provided during closed-throttle operation due to the work required to maintain intake manifold vacuum, the balance coming from internal friction of the engine itself. Diesel engines, however, are unthrottled and hence do not provide engine braking from throttling losses.
A compression release engine brake uses an extra lobe on the camshaft to open a second exhaust valve at the top of the compression stroke. The stem of this valve telescopes during normal operation so the valve remains closed, but is locked at full length by a solenoid when the engine brake is engaged so that the valve opens as directed by the cam. This releases the compressed air in the cylinder preventing it from returning its energy back to the piston and accordingly, the vehicle speed is reduced.
The driver controls consist of an on/off switch and, sometimes, a multi-position switch that controls the number of cylinders on which the brake is active. When the compression release engine brake is turned on, it will activate when the driver releases the accelerator. There are also switches on the clutch and accelerator pedals that will deactivate the compression brake when the clutch is disengaged or the accelerator is pressed.
 
doggone it, and i just convinced myself the 6bt and 10 speed would work better for my imaginary ultimate tow rig. very cool build. detroit's sound awesome!
 
76zimmer said:
Diesel engines, however, are unthrottled and hence do not provide engine braking from throttling losses.
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ok, so if that's true, why is it that when i pull my foot off the accelerator my truck slows down crazy fast while in gear? especially compared to the gassers I've driven with a 465 behind them? :confused:
 
pretty sure that's because you are stopping the air flow, right? If i understand how it works, i believe your pedal simply controls how much air is going in the engine, and by throttled he means you are not in direct control of the fuel flowing into the engine. I think...
 
nope. that's for a gas engine, afaik. the old 6.2's don't have a butterfly valve. more pedal equals more fuel - air is constant. i could be entirely mistaken on my tech, i suppose.
 
colbystephens said:
ok, so if that's true, why is it that when i pull my foot off the accelerator my truck slows down crazy fast while in gear? especially compared to the gassers I've driven with a 465 behind them? :confused:
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colbystephens said:
nope. that's for a gas engine, afaik. the old 6.2's don't have a butterfly valve. more pedal equals more fuel - air is constant. i could be entirely mistaken on my tech, i suppose.
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22:1 compression in a naturally aspirated diesel will do that.....if you have no fuel to burn then all your doing is trying to compress air, almost 3 times that of a stock gas engine.......

in a turbocharged diesel you have positive manifold pressure unlike a naturally aspirated one.....thats why they have no vaccum or engine braking ability.....even if the engine has no fuel going to it you are still spinning the turbo with exhaust and in turn the turbo is still forcing air into the engine.......

oh and the jakes on a detroit sound awesome and i know on the 8V92's they are a 1 wire hook up for each side......so you can use the low and high side of the jakes at the flip of a switch.......


unthrottled means that you arent controlling the air flow manually, you are controlling the fuel flow manually.......
 
LOGANSTANFORTH said:
in a turbocharged diesel you have positive manifold pressure unlike a naturally aspirated one.....thats why they have no vaccum or engine braking ability.....even if the engine has no fuel going to it you are still spinning the turbo with exhaust and in turn the turbo is still forcing air into the engine.......
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Gotchya! That makes sense. Thanks!
 
sweet.....

I love when I get a pair of 4BT's in a boat.... sadly it's becoming rarer and rarer that I see them tho...
 
Detroit Diesel never seems to surprise me. I have been working at a detriot distributorship for 1 1/2 years and never knew there was aluminun blocks. We dont see many 2 strokes in the shop though just 60 series and mercedes now.

Very nice build by the way
 
Im wondering what the final weigh of the engine is with all the alum parts?

did you acheve 1300-1450lbs?

Whats a 6bt cummins weigh? is it comparable? It would be difficult to compare the 2 power to weight ratio the cummins is capable of much more I assume.

But the cool factor is WAY up the scale for the detroit I would love to do a 3-53 or 4-53 detroit in my 61 stepside 2wd with jakes and 4" straight side pipes........rat rod style. it wouldnt need to be faster than the average car or truck or need to tow anythng for me just loud and differnt but im betting with thre righ gearing and the relitive light weight of a half ton short bed truck the MPG would be pretty high????

I dunno how it could be done but a clarke 5 speed and a 2 speed overdrive box would be sweet.
 
Oh damn this is back from the dead:waytogo: And looking very cool as well.:bow: I know people have done the detroit or Cat 3208 swap and liked the results
 
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