Turbo surge protector..??

[shadowmaker]

With 1,6bar boost EMPs were reaching 3bar. So we didn't want to start adding fuel, although there's plenty room for that.  

I didn't say that gt2259v is better than gt2559v, did I? It just that it's from a car that makes 230hp originally and has much better flowing turbine than gt2559v (newer desing).

I do have experience on both of them. On my 2.5L van I used gt2559v some years ago. I wasn't happy with it as it didn't tolerate boost over 1,5bar (1,7bar boost made 5,5bar EMP). I currently have wing from gt2259v (from Audi 3.0TDI) planted inside gt20. I'm running it with 2,2bar constant with almost equal EMP on my Volvo 2.4D.

Well, at least we are going to try this. Maybe it will work, maybe not.

[jimfoo]

Now, surge is just basically an audio resonance, correct? A low frequency sound (pressure) wave bouncing back and forth. Couldn't it also be delt with from that angle also, by trying to remove the elements that support resonance, like smooth transitions? Any audio engineers out there? Just wondering.... Also do cars without IC's (very short tube runs) suffer from surge?

[OM617]

i dont understand no anything from turbo surge, what can be damaged?
how do i know the turbo surge?

The rapid airflow changes puts huge amounts of stress on the compressor wheel. If the surge is strong enough or it occurs for too long it will prematurely wear out the thrust bearing or, in the worst case, snap the shaft.

If the turbo surges, you will hear a sound like loud scissors or barking.
Here is a video with a perfect example of what turbo surge sounds like: http://www.youtube.com/watch?v=mHmdO350xcY

[DVST8R]

Here is a garrett GT30R with an added surge protector housing.

[shadowmaker]

With our MB project we have to deal with surge when gas pedal is lifted up. We are concerned that our GT37vnt won't take the abuse much longer so we decided to put a dump valve in it. Usually it's not necessary to use dump valve on diesels, but clearly that's not the case here. With 85mm compressor we are able to reach over 1,0bar boost @2000rpm.   :wink:

[jimfoo]

So what valve did you use, and how did you set it up?

[jimfoo]

I got an idea. I have an external wastegate that I wasn't going to use. I will reduce the spring pressure so it opens at a low pressure, 2-5 psi. I will then fit a solenoid valve in the air line to it, and put a switch that only closes at low pedal settings. That way I won't loose boost except when it exceeds the spring setting and I let off the throttle. Plus I already have the valve.  :twisted:

[Benjamin]

With our MB project we have to deal with surge when gas pedal is lifted up. We are concerned that our GT37vnt won't take the abuse much longer so we decided to put a dump valve in it. Usually it's not necessary to use dump valve on diesels, but clearly that's not the case here. With 85mm compressor we are able to reach over 1,0bar boost @2000rpm.   :wink:

i dont understand very well, you mean after full throttle you leave the pedal and you have surge? i thought a diesel had the same engine-air-flow when it was in free-load and under-laod becouse you dont have a thotlle?

i also thought it had an anti surge stock, a picture from a previous picture from your MB project
http://i19.tinypic.com/2djv59d.jpg

i wonder where you can get bigger plungers for the inline pump from the MB300td. Like to know more  

Greetz, Benjamin

[jimfoo]

I made my dump valve and screwed around with it for a bit. It would dump down to 6 psi with the only weaker spring I could find that would fit. It would still surge a bit although some of that could have been due to the actuation point of the switch. So I worked on the spring a bit so it would have less force, and tried again. This time the spring was weak enough that it would open the wastegate at 15 psi just from pressure on the valve alone, with nothing going to the diaphragm. I also changed the switch, so it would open the valve to the diaphragm sooner. No surge this time! Then I decided I better hook up the actuator for the vane control as it was getting no boost. With the engine getting revved a bit and the vanes closed, the actuator came down and opened them, like it was supposed to. I decided to disconnect the solenoid to disable my dump valve and see what happened. Well, with the actuator working, I no longer got surge as it wouldn't let the turbo build up as much pressure. Guess I should have hooked it up before I wasted my time making the dump valve. The only good thing is all my plumbing is still in its design phase and made out of ABS for easy and cheap modification. Anyway,
for reference, here are the pics before I take it all off.

The wastegate dump valve.

A small reed switch, which is controlled by the small rare earth magnet on the pump lever.

[Tintin]

You can only used the selenoid valve to bleed extra air flow (boost), it is more than sufficient,  I did not test yet, but according to some experience with all turbo, when there is a little leak or ¼ disconect pipe on the IC piping, the boost fall very low, that takes a very small hole to remove much pressure and/or some air flow.

[shadowmaker]

i dont understand very well, you mean after full throttle you leave the pedal and you have surge? i thought a diesel had the same engine-air-flow when it was in free-load and under-laod becouse you dont have a thotlle?

i also thought it had an anti surge stock, a picture from a previous picture from your MB project
http://i19.tinypic.com/2djv59d.jpg

i wonder where you can get bigger plungers for the inline pump from the MB300td. Like to know more  

Greetz, Benjamin

Yep, I thought the same, but you can hear the surge noise very clearly, when you back down the pedal. Don't know why, although we are puting huge amounts of air into this engine at low revs.

That's a gt42vnt in the picture. We are using gt37vnt in the car. Gt42vnt might be too big...

We have something like hundred modified MB inline pumps here in Finland. There's a shop called Mynä Diesel and they can do this for you. Some of those cars have dynoed over 500hp with silly sized Holsets. We just are the first ones to use vnt with these beast.

jimfoo: We are just planning things out at the moment. Although I don't see anything difficult with it.

[Benjamin]

maybe its a stupid question, but its my understanding a turbo can only have surge problems on boost, i know when you hear much turbowissle (also offboost?) its something to take a look at, but the most important is when you have it on boost the gauge reads no paeks and hills.

offcorse once you leave the pedal, and the vanes close before the boost is gone, you have more backpressure, in this case maybe a dumpvalve should be something good? but you can also change your settings from the vane-vontrol. anyone else have heard about this problem ever?

Greetz, Benjamin

[jimfoo]

You have surge when the turbo has built up a lot of pressure, then slowed to the point where the pressure it built up is more than it can make at the speed it is currently rotating. So the air tries to go backwards through the turbo, slowing it down, making the problem even worse until an equilibrium is reached. So yes, dumping the pressure when you release the pedal would help. If they made a reed valve, like 2 stroke motorcycles have, that flows enough, I bet that would eliminate it also.

[OM617]

Here is an example of what surge sounds like. This is an extreme example because I completely blocked off the turbo outlet to force it into surge.

http://members.cox.net/lnewcomb99/Sound/LMNGT2256V-Surge_extreme_example.mp3

[Benjamin]

when i pull to full boost, and i release on a high rpm, my turbo makes dumpvalve sound, is that surge also? Do i need to use a dieseldumpvalve?
now the vnt is even not fulle adjusted, the vanes dont close much when offboost.

Greetz, Benjamin