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55chevy1 · 04-14-2013, 04:23 PM

I have a 1989 Country Coach with a 300hp 3208T cat and an Allison set in a Gillig chassis I have plans to pull a stacker trailer with a drag car inside roughly 14k pounds. Has anyone done any performance mods like injectors, turbo, or pump? I just put straight 4 inch exhaust and deleted muffler

wb7auk · 04-14-2013, 04:32 PM

Check and see where the waste gate control gets it's boost pressure, if it is directly
from the turbo output you can move it to the intake manifold and plug the line going
to the turbo.
I suggest you not try to remove the line to the turbo as the fitting normally breaks
and that is a lot of work to fix that problem.
Above suggestion is a cheap 7 or 8 dollar fix that will increase performance for you.

55chevy1 · 04-14-2013, 04:40 PM

Quote:

Originally Posted by wb7auk

Check and see where the waste gate control gets it's boost pressure, if it is directly
from the turbo output you can move it to the intake manifold and plug the line going
to the turbo.
I suggest you not try to remove the line to the turbo as the fitting normally breaks
and that is a lot of work to fix that problem.
Above suggestion is a cheap 7 or 8 dollar fix that will increase performance for you.

Good Idea Thanks! How much boost will that add and how much boost does it get now?

Coaster1 · 04-14-2013, 04:48 PM

J hooking the gate is bad idea without the means to monitor boost pressure and exhaust manifold pressure. Check the specs on the tranny to see how much torque it can take.
I think you will have an overheating problem without further mods. As you know from racing, one thing leads to another.

wb7auk, did you change your fuel pin to a Denny or do any pump work on your 5.9?

wb7auk · 04-14-2013, 05:12 PM

Good Idea Thanks! How much boost will that add and how much boost does it get now?
With everything working right your engine should have close to 25 psi right now
with the simple mod the intake should be 28 to 29 psi.
The newer engines had this done by the factory to correct for the pressure drop between hot air from the turbo and cooler air that enters the engine after it has
been cooled by the CAC and other losses.
This mod does not stop the waste gate from operating like some truckers have done.

wb7auk · 04-14-2013, 05:13 PM

wb7auk, did you change your fuel pin to a Denny or do any pump work on your 5.9?

No I have not done any pump or fuel pin work on the Cummins.

moisheh · 04-16-2013, 04:02 AM

I had had a Bluebird with the 3208. Your engine cannot be succesfully modified. Although there are Marine versions running more HP with the 3208, in a MH cooling becomes a problem. Which Allison is in your unit? Many will not handle increased power. There are BB owners towing some heavy trailers as is but you need lots of patience.

jauguston · 04-24-2013, 10:23 AM

You are going to be asking a lot from a relatively small engine. Caution would be advisable. If it doesn't have it drain the transmission and refill with TES295 spec synthetic fluid. If it doesn't have a exhaust brake add one. Stopping will also be a issue as well as controlling your speed down hill. That engine was never intended to pull what you plan to pull.

moisheh · 04-24-2013, 11:19 AM

For some reason I have never seen a 3208 with an exhaust brake. Apparently they do not work on that engine. I have seen tranny retarders, and electric driveshaft brakes. Here is a cut and paste with an explanation:

Pac brakes work better on some engines than others. Example, a Cat 3126 can withstand back pressure of 55 PSI, but my 3208TA will only withstand 25PSI. I can only assume that my system does not provide as much braking as the 3126. I feel very little help from the system, and I would think that the low amount of back pressure a 3208 can withstand is the reason. Do you agree? Thanks. PS. I have a Pac-brake chart on engines should anyone wish to learn more on their engine.

Our Bluebird had a 3208 and I was advised that an exhaust brake would not provide any stopping power

jauguston · 04-24-2013, 12:18 PM

It depends on a number of things whether a Pacbrake will work on a 3208T. It requires a specific camshaft and lifters and a lockup torque converter transmission. The 4 speed Allisons like the AT 542-543 do not have a lockup converter. You see those transmissions mostly in garbage trucks.

If you have the right internal engine components and the right transmission (5 speed) one can work although not very well. That engine is limited to 25 psi exhaust backpressure and that is not a lot. My C-7 is 40 psi.