Tip turbine boost?

[Licensed to kill]

2 hours ago, Mark T said:

I think he's trying to confirm the easiest place to get into the intake for a manifold pressure gauge. 

👍

[Licensed to kill]

11 hours ago, JoeH said:

You also have another port in the bottom right of the picture it appears.

That port has a line going to the mount on the valve cover that the draft tube come off of. 

[Licensed to kill]

So, if I want to keep the puff limiter, where does it send the intake pressure signal to??. IOW, where does the line from the limiter go?  Also, is there a bench test that I can do to ensure that the puff limiter works correctly? 

Edited November 10 by Licensed to kill

[Mark T]

1 hour ago, Licensed to kill said:

So, if I want to keep the puff limiter, where does it send the intake pressure signal to??. IOW, where does the line from the limiter go?  Also, is there a bench test that I can do to ensure that the puff limiter works correctly? 

There's a cylinder on the pump that goes into the pump and limits the rack's travel.  Should work from air to the reversing relay when the parking brakes are released. No air from to the reversing relay, no puff limiting. This way the rack is ablr to go into the full fuel position for cold starts. (assuming you're parking brakes are set).  I doubt stuff is available to fix it if it's not working. I don't think the relay is servicable and the diaphram and shims for the protrusion into the pump, good luck.  Who knows, might hook it all up and it works ?  Usually took a little trial and error to shim them.

[JoeH]

Some transmissions were tied into the puff limiter I believe. My dad talks about my grandpa's 1981 R686ST that would get a momentary hiss of air when you clicked into 5th gear it'd eliminate whatever torque limiter was in effect and give you balls of power.

[mrsmackpaul]

Correct, first and reverse 

 

Paul

[Freightrain]

18 hours ago, Licensed to kill said:

That port has a line going to the mount on the valve cover that the draft tube come off of. 

Kinda like a PVC system?  Drawing vacuum on the engine while running.

[Licensed to kill]

3 hours ago, Freightrain said:

Kinda like a PVC system?  Drawing vacuum on the engine while running.

Don’t think so. Diesels don’t really produce “vacuum” per se even when naturally aspirated and certainly not when boosted. To my way of thinking, that line will provide air movement FROM the intake TO the valve cover not the other way. The purpose????, not sure but maybe to dilute the blow by fumes before they exit the draft tube, not unlike the air pump on 70’s vintage cars that pumped fresh air into the exhaust to reduce emissions????  I dunno. That’s my current opinion on the purpose and function of that air line, as always, subject to change without notice pending compelling arguments to the contrary. 

Edited November 11 by Licensed to kill

[terry]

23 hours ago, Licensed to kill said:

That port has a line going to the mount on the valve cover that the draft tube come off of. 

That line from intake manifold to downdraft tube looks like a place to lose turbo boost?   terry

[BOBWhite]

Unless there is some sort of check valve somewhere I can't image what that line would be used for. Your draft tube should add a bit of negative pressure to the crankcase when your going down the road but maybe this setup is for keeping a negative pressure when your parked. 

[Mark T]

Has that engine run with that on there ?  Only other thing vented into there (at the valve covers) I ever remember was the oil filter housing. 

[Licensed to kill]

19 minutes ago, Mark T said:

Has that engine run with that on there ?  Only other thing vented into there (at the valve covers) I ever remember was the oil filter housing. 

That is how it was plumbed when pulled from the truck. 

[Mark T]

I don't ever remember manifold pressure bleeding off into the overboard breather. (I could be wrong) 

[Licensed to kill]

2 hours ago, terry said:

That line from intake manifold to downdraft tube looks like a place to lose turbo boost?   terry

It certainly would (I am reasonably sure that there is no check valve or anything in the draft tube housing). However, that little line won’t bleed off anywhere near the amount of boost as the tip turbine itself. I suspect, assuming this line is as it was from new, that the turbo was/is sized accordingly to allow for the parasitic draw of the tip turbine AND that line to still provide the desired boost to the cylinders after such parasitism draws. I dunno, just postulating. 

[Mark T]

The tip fan works on excess manifold pressure. You'll never even notice the little that bleeds off the manifold pressure to spin the tip fan, and the cooler air just helps overcome it anyway. 

[Licensed to kill]

1 minute ago, Mark T said:

I don't ever remember manifold pressure bleeding off into the overboard breather. (I could be wrong) 

This is a 1980 vintage E-350 econodyne. Pretty common engine so there should be someone with one that could compare. The guy I got the engine from was kinda haywire so no telling what may have been changed. I bought the engine trans (twin stick 6 speed) out of the same truck as a unit only to discover much later that the engine being an econodyne snd the trans a maxi torque that they are not compatible. 

[Licensed to kill]

2 minutes ago, Mark T said:

The tip fan works on excess manifold pressure. You'll never even notice the little that bleeds off the manifold pressure to spin the tip fan, and the cooler air just helps overcome it anyway. 

Yes, that was my point. 

[Mark T]

4 minutes ago, Licensed to kill said:

Yes, that was my point. 

That line going to nothing (if it is) is a huge manifold pressure leak.

[mrsmackpaul]

2 hours ago, Licensed to kill said:

This is a 1980 vintage E-350 econodyne. Pretty common engine so there should be someone with one that could compare. The guy I got the engine from was kinda haywire so no telling what may have been changed. I bought the engine trans (twin stick 6 speed) out of the same truck as a unit only to discover much later that the engine being an econodyne snd the trans a maxi torque that they are not compatible. 

I will have a look tonight and see what I find

 

Will report back 

 

P

[MACKS]

2 hours ago, Mark T said:

That line going to nothing (if it is) is a huge manifold pressure leak.

I had an 1983 RD with a 300+, it had the tip turbine and air box,engine looked similar to this one but I’m certain that line was not on it..

[Licensed to kill]

26 minutes ago, mrsmackpaul said:

I will have a look tonight and see what I find

 

Will report back 

 

P

Thanks. If your engine dies NOT have that hose I would be interested in what it has in the two ports that this hose is useing. 

[Mark T]

I don't know if they were charging the compressor intake from the intake manifold back then.

[Freightrain]

8 hours ago, Licensed to kill said:

Don’t think so. Diesels don’t really produce “vacuum” per se even when naturally aspirated and certainly not when boosted. To my way of thinking, that line will provide air movement FROM the intake TO the valve cover not the other way. The purpose????, not sure but maybe to dilute the blow by fumes before they exit the draft tube, not unlike the air pump on 70’s vintage cars that pumped fresh air into the exhaust to reduce emissions????  I dunno. That’s my current opinion on the purpose and function of that air line, as always, subject to change without notice pending compelling arguments to the contrary. 

I realize there is no vacuum,but I was looking at it backwards.  It is actually leaking boost like others said.  Unless there is a poppet valve or regulator in that fitting.

Sounds like the previous owner might have just made a mistake installing it??

[terry]

I have seen a bunch of tip turbine engines, and never one with that line to the draft tube.  Terry

[BOBWhite]

https://www.mylittlesalesman.com/1982-mack-e6-engine-9994460

This 1982 tip turbine has the line. I thought surely someone hooked something up wrong but if you look through the pictures this one has it too.