EGT Control

[uncool]

The charge air routing can be done both ways.

You can cool in between stages as he has done.

Charles also had his set up that way and so have others. That routing usually requires water injection to keep temps under control with more fuel. Not always, but most people do it that way. Think of it like an OBS setup, out of the turbo right into the motor. Reason most people install an inter cooler. Also piping runs are a little less complicated.

I personally like cooling after the high pressure charger. Then add water injection at the intake Y if needed. Little more plumbing to keep everything in place on a SD.

Ideal would be cooling both stages, but plumbing that would be a nightmare, let alone where to mount the other cooler.

On the exhaust side, manifolds to the high pressure charger, to the atmosphere charger than out the exhaust. Toss in a few waste gates for fine tuning.

First gate from the up pipes to the hot side of the atmosphere charger to bypass the high pressure charger WHEN the atmosphere gets lit and moving air.

Second gate on the same hot pipe to the atmosphere charger to the down pipe to control overall boost/speed of the atmosphere charger.

If I had more room under the hood I would mount the 98 mm inducer charger I have, feeding the 76 similar to a 6.4 setup. I will NOT run a body lift just to get them to fit.

It is hard to argue with the laws of thermodynamics, you just do the best you can with what you have.

That is just my take. Other opinions will vary.

 

[psduser1]

That is what all my research, and discussions have led me to. Although, I haven't actually done it yet, though.

 

[lincolnlocker]

The charge air routing can be done both ways.

You can cool in between stages as he has done.

Charles also had his set up that way and so have others. That routing usually requires water injection to keep temps under control with more fuel. Not always, but most people do it that way. Think of it like an OBS setup, out of the turbo right into the motor. Reason most people install an inter cooler. Also piping runs are a little less complicated.

I personally like cooling after the high pressure charger. Then add water injection at the intake Y if needed. Little more plumbing to keep everything in place on a SD.

Ideal would be cooling both stages, but plumbing that would be a nightmare, let alone where to mount the other cooler.

On the exhaust side, manifolds to the high pressure charger, to the atmosphere charger than out the exhaust. Toss in a few waste gates for fine tuning.

First gate from the up pipes to the hot side of the atmosphere charger to bypass the high pressure charger WHEN the atmosphere gets lit and moving air.

Second gate on the same hot pipe to the atmosphere charger to the down pipe to control overall boost/speed of the atmosphere charger.

If I had more room under the hood I would mount the 98 mm inducer charger I have, feeding the 76 similar to a 6.4 setup. I will NOT run a body lift just to get them to fit.

It is hard to argue with the laws of thermodynamics, you just do the best you can with what you have.

That is just my take. Other opinions will vary.

right on!

live life full throttle

 

[strok-n]

OK, with that being said, next question i have for you.

How are the exhaust manifolds plumbed to drive the chargers?

If you are driving the 91 first, then to the 71, your turbine wheel/housing has to be perfect for that to work. That might explain the lag that the big charger has.

It would also be why your EGT's are out of control. By the time the big charger comes up, you have no chance to get them back down in a quarter mile.

The exhaust manifolds go to the 71 first, and then the exhaust from that run the 91. The 91 actually spools well, i usually launch with 22psi overall and 12psi on the 91. I will get the pictures uploaded tomorrow.

 

[Gearhead]

Subbed..

 

[uncool]

Pictures are going to be SO help full! I would really like to see the a manifold to 71 turbo picture. Curious about that routing.

We will get to the bottom of your issues.

This my friends, is what this site is about.

 

[lincolnlocker]

Pictures are going to be SO help full! I would really like to see the a manifold to 71 turbo picture. Curious about that routing.

We will get to the bottom of your issues.

This my friends, is what this site is about.

good to see you posting more and more!

live life full throttle

 

[ja_cain]

Good stuff uncool! I like the example of the non intercooled OBS setup and big fuel (relative to stock).

It would be nice to have the real estate to do a cooler after each stage, but such is life.

I feel this is going to be a great thread once he posts some pictures.

 

[Dmstrucks02]

Pictures are going to be SO help full! I would really like to see the a manifold to 71 turbo picture. Curious about that routing.

We will get to the bottom of your issues.

This my friends, is what this site is about.

Interesting set up for sure, I'll be waiting on the pictures as well

Sent from my SAMSUNG-SM-G890A using Tapatalk

 

[ja_cain]

I assume optimal intercooler placement would be dependent on the average pressure ratio of each turbo. The one with the highest ratio would benefit mostly from an intercooler. Or you could just plumb it up the easiest way and inject water after the stage that lacked the cooler (as uncool stated above). What volumetric efficiency does everyone use when working through the airflow calculations? I have been using 80% as an arbitrary starting point for the 7.3 (stock heads and cam).

Sorry about the blather, just want to make sure I'm understanding everything.

 

[strok-n]

alright everyone here are the pictures i got today.

 

[m j]

so the big turbo can blow air out the lil turbo inlet?

 

[uncool]

All right

Pictures helped a lot!

I went back and reread your post about the gates. Keep up with me.

The gate around the 71 is just the way you want it. You are controlling the speed and overall boost the 71 is putting out.

The second gate, you said is on the other manifold and it dumps to open air. <--------- I think this is the place we need to start.

Typically open air dumps are use to control pressure in a larger SINGLE charger set up, or a setup with a healthy dose of N2O.

What pressure/how do you have your gates set?

Now, if you are controlling the open air gate to limit overall back pressure, you are basically dumping all of your drive energy to outside air.

This is what I would try.

Disconnect the open air waste gate and take it for a drive. Use your right foot for boost control. If your truck responds to this change, start adjusting the gate on the 71 to limit your overall boost and back pressure. It will take some time and spring changes to get it right.

If the open air gate wont stay closed, (weak spring) run a line with boost pressure to the top of the actuator to help it stay closed.

I am still curious about you exhaust pipe routing. It looks like you built the passenger side manifold, and ran the driver side pipe up and around the back of the engine and then right above the passenger manifold and joined it to your collector flange.

 

[strok-n]

All right

Pictures helped a lot!

I went back and reread your post about the gates. Keep up with me.

The gate around the 71 is just the way you want it. You are controlling the speed and overall boost the 71 is putting out.

The second gate, you said is on the other manifold and it dumps to open air. <--------- I think this is the place we need to start.

Typically open air dumps are use to control pressure in a larger SINGLE charger set up, or a setup with a healthy dose of N2O.

What pressure/how do you have your gates set?

Now, if you are controlling the open air gate to limit overall back pressure, you are basically dumping all of your drive energy to outside air.

This is what I would try.

Disconnect the open air waste gate and take it for a drive. Use your right foot for boost control. If your truck responds to this change, start adjusting the gate on the 71 to limit your overall boost and back pressure. It will take some time and spring changes to get it right.

If the open air gate wont stay closed, (weak spring) run a line with boost pressure to the top of the actuator to help it stay closed.

I am still curious about you exhaust pipe routing. It looks like you built the passenger side manifold, and ran the driver side pipe up and around the back of the engine and then right above the passenger manifold and joined it to your collector flange.

Ok let me start on the second gate. The reasoning for running it to open air is to limit overall boost. I have it set with a "air regulator" to control the boost pressure. Right now it is set to around 70psi when it opens. The exhaust routing is pretty much what you said. the passenger side is basically turned around, and the driver side has a pipe that runs around the back of the motor and along side the passenger side to join at the collector.

 

[ja_cain]

That's how Ty was talking about doing the passenger side manifold if he ever got around to pursuing the idea of compounds.

Great thread! Looking forward to taking away some good info from it. Sounds like uncool is just the man to get you all straightened out.

 

[uncool]

One small change at a time is the most important thing you do in troubleshooting.

We will get this figured out.

I have to go pull radiator, inter cooler, Hvac blower motor and do some cleaning on my ranch truck purchase. And rebuild the turbo. I will post pics in another thread.

 

[ja_cain]

Good advice! Thats the key to any process control that needs intervention outside of its controlable limits, wether its a mechanical, electrical or biological systems you are trying to tweek. One knob at a time. The data will tell you what to do next.

 

[strok-n]

ok so I messed with the second gate and it doesn't seem to make any change. I tried taking off the line going to it and the spring was too weak to hold it closed once I got above 15lbs. So I put my line back on and adjust the regulator. Did it in both directions and no change in the high EGT's. Any other ideas

 

[psduser1]

Not an expert, but maybe lower the pressure setting on the high pressure turbo to 40-45 psi, and get the big charger turning a bit sooner?
I'm not real familiar with those turbos, but if you can get the 591 moving air around say 2300 rpm instead of 2800? Maybe get on top of it before your egts get past the point of no return. If you can get the big turbo pushing sooner, you should be able to stay closer to a 1:1 on the small turbo. That is your choke point, after all.
Guessing a little here, I don't know what the specs are on either turbine, exactly.

 

[ja_cain]

See my original post a couple pages back. Basically what I was saying, but I don't have experience with this type of setup. Sometimes I feel like I'm just raising the noise floor with my comments. Lol!

He did say that he felt like the 71 was building boost fairly early somewhere above. It would be nice if we could get a data log of the primary and secondary boost relative to rpm so we can figure out the pressure ratios. I know that isn't possible in this case, but it would be nice. Maybe a video displaying the boost/egt gauges and rpm would be possible.