Turbo Back Pressure Relief System

[Alan Reagan]

Turbo BOOST Relief System

I'm trying to determine how much interest there is in a turbocharger boost (back pressure) relief system on the CTD. As you know, a sudden lift off the throttle under high boost conditions can cause a reverse spin effect on the turbo resulting in a broken turbo shaft or bearing failure. With some suggestions from Marco, I have been working on a system to prevent this. Soon, the prototype will be tested on a CTD and before going any further with R&D efforts and plans for limited production, I wanted to gauge the interest. Although the device will be useful for stock vehicles, the real benefit will be to owners running higher than stock boost pressures or those investing in various turbocharger technologies currently available.



As it stands at this time, the device will be composed of only two main components. The other parts of the device will be fittings and some tubing.

 

[EMDDIESEL]

I am interested, let me know any details.

 

[Marco]

Gang,



This topic should be named Boost relief valve, not back pressure relief valve! Oh well... .



The idea behind this system is basically a "pop off" valve like the ones used in turboed gassers. The main problem is that a pop off valve used in a gas engine is activated by the vaccum produced in the manifold when the throttle blade is closed. That's not possible in a TD engine. We have no throttle blade.



Alan comes up with the idea of a pressure differential switch.

That's a GREAT idea. All you need to do is to monitor before and after intercooler pressure. If the after intercooler pressure becomes higher than the before pressure the valve opens, et voilà!



The turbo will not be stopped by the boost flowing back through it. That's very good for avoiding turbo failure.



This might be intresting only for a few persons. (Like me)



The best thing is surely that not only the turbo will not be stopped, but it will not be slowed also! In other words, when you lift quickly( a shift for example), the valve opens, bleeds off boost, the turbo will spin FAST with no load on it. Now you're shifting and stomping on it again.....



Got the picture? You will get quicker turbo spool up, thus quicker boost... . Less turbo lag!



Marco

 

[ToolManTimTaylor]

Ummm .....

Isn't that what a WASTEGATE is for? Call me nutz but

 

[Alan Reagan]

A wastegate is used to not exceed a specific boost level in the system. But say you have a wastegate and it is stock opening at 20 PSI. You accelerate hard, are running at 20 PSI and suddenly lift with all that boost pressure. Suddenly there is nothing driving the turbo but all that pressure is built from the outlet of the turbo to the intake. What happens is that the pressure tries to go back the other way, putting a sudden reverse spin on the turbo and doing the damage. Now look at the BOMBed trucks that are doing 30-50 lbs of boost, some with larger turbochargers and the problem and potential damage becomes a lot more severe. If the excess differential pressure can be detected and bled off quickly the pressure on the turbo is gone. The turbo continues to freewheel with the resistance lowered and when throttle is applied again and the differential pressure is already in the desired state: higher at the turbo outlet than the intake so the boost is moving in the right direction.



As Marco stated, race cars with turbos have been doing this to avoid turbo damage. However, they can use a vacuum operated bleed/pop off system. We don't have that. We have to do something a little different.

 

[metal tech]

any way to get a sneek peek on the

28th at STP. Has Jeff given you any input on this? I'm looking forward to the 28th.



AL

 

[Jff24Gordn]

I would take one. Care if I ask what is triggering your blow off valve to trip?

 

[DAWG-1]

I would be interested in the product. I am planning on useing a different turbo.

 

[Jetpilot]

This would be of interest to me..... Let me know how it goes and if you need some testers.

 

[mopars1]

I would be interested, also.

 

[CumminsPower98]

Boost check valve?

Rather than blowing off all that boost and having to rebuild it again how about an inline check valve or flap that when the air tries to rush back it closes this "check valve". Maybe I'm not fully understanding the whole idea but it seems like something like this would work great if built right. Just a crazy little thought of mine.



I would be interested...

 

[dasyure]

Could you just put a micro switch on the throttel to power a relay to power a valve to dump the intake pressure? If I could be convinced it was needed and I could find a valve id try it, I only get 38psi boost and have had no problems with my majestic set up hx40, maybe I need to turn the fuel up more? On the other hand if you dump boost pressure the turbo spins faster then load it isn't that going to be just as hard on the shaft if not harder on it?

Sean

 

[Marco]

CumminsPower98,

The "check valve" you're thinking about would have to close the intake. Right? If you close the intake, where could the engine get it's air from while that valve is closed.....



dasyure,

The micro switch would open the valve every time you release the throttle. That's not a good condition because that would mean that the engine would suck unfiltered air from the valve.



The turbo won't spin faster when the boost is dumped, because at the same time the fuel is decreased (throttle released). Only the boost can't get back into the turbo. This will avoid the turbo getting slowed/stopped/reverse spinned.



Oh yeah Alan, I want one too! A S A P! ! !



Marco

 

[Mopar-muscle]

i'm in ... . hurry!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[TXRam]

I'm interested, but want to know what exactly it is and how it works before I commit. Thanks.



PS - If you want a technical review/opinion (not asking for a freebie, etc. ), let me know. I don't mind helping if I can.

 

[Alan Reagan]

Thanks, Marco. You are dead on.



Metal Tech, I haven't gotten input from Jeff Garman yet. I should be at STP on the 28 th. I'll talk to him then if he's not too busy.

 

[Puff]

That's a great idea Alan.



You guys just won't let my bank account accumulate to any significant degree, will you?

 

[Jff24Gordn]

Yall try having a microswitch mounted on the throtle, to switch when its at idle. And have a electric boodt gauge, and have it trip when its above 10 psi. And when both of these things happen, it will open a electrial blow off valve.

 

[CumminsAholic]

Sweet idea Alan. I have an auto and I'm even interested depending upon pricing. I also get that "back rush" if I let off suddenly at high boost. I hope you and Marco can get it to work out.

Corey

 

[Alan Reagan]

Jff24, I'll have to think about that one a little. I'm trying to stay away from microswitches if possible and deal only with differential pressure. It's not a bad idea tho.