Paul aka "pblamire" at MLR gave this explanation on surge, it seam to be just what happens to me:

"Essentially what is happening during surge is the air going into the compressor doesn't have enough speed and momentum behind it. Since we are not (with modern turbos) dealing with just radial staight blades on the compressor, we need air velocity over the blades to help generate more pressure difference. If we lose that (air) speed, the pressure difference is so great that the air stalls altogether, and escapes out through the inlet. Then it rushes back in and the cycle happens all over again, which is when you hearing fluttering and pulsing.

It's the exact same thing that happens when you back of the throttle without a dump valve fitted, except then the velicity drops because the air has nowhere to go, and the compressor no drive. The worst thing you can do if the turbo is surging is partially back of the throttle.

Using a bigger ex housing can help surge by improving the VE of the engine, but more often it just slugs the spoolup till later in the RPM range so you cant bring the compressor into surge."

 

yup i read that yesterday on LRand let me tell you what he said explains alot

 

Az, have you had time to make that little test yet? I presume you ment your friend will time the runs not literally count the time as you wrote? And remember to do it in 4th gear.

 

looked at your attachments and your website. what's the inlet on your GT3071R? they are made in constant and pulse configurations, I believe, and I see that your manifold is pulse.

 

Im running the atp GT35r with a flash and safcii and have no problems at all, the car runs awesome. who tuned your car? what do they have to say?

 

no. I will do it today. last night i went out and i cant remember whats my last name or even how i got back home. thats what happes when you drink 12 beers( lost count after a while)

 

hey shaheen when we are going to have abother dyno like we did early this year? I am trying to go to the track today but i have no idea which one or where to go? any ideas

thanks

 

I have the ATP 3071 which has a custom turbine housing that bolts on to the stock manifold or one with a stock design flange like mine.

 

A company called Trollspeed here in Sweden, they mainly do rally and rally cross cars and they had never seen a car doing this in they way mine does.

 

Hehehe, lots of tend to have that affect on you. So hows the head today then?

I’m still puzzled on why your car is working so well and mine isn’t, the only explanation I could think of is that my supporting mods makes my turbo even more efficient and thus brings it into surge. I will call ATP tomorrow and see if they have come up with any ideas. The general opinion seam to be to go for the .82 turbine as I originally ordered.

Would be great if you could make a few of those pulls and have them timed. Don’t know exactly what they would tell me but at least we will see how much faster your car is. Then if it is, say, 2 sec faster I have no clue how much more power that would be.

 

Hey, I tried to do the 4000 rpm to 7000 rpm last night on 4th gear I dont have a stop watch my friend was looking at a normal watch and it was between 7~8 sec. I cant tell exactly.

 

You could be having bov issues.

I am running a 3052 which is quite a bit bigger turbo. Before, with the greddy type s, at above 23 psi, I would have some compressor surge in 5th gear at 120+.

Swapped bov to a new crushed 1g and that cured it. Basically the bov was causing a cyclic boost leak.

The new crushed 1g bov just works. The mr and the stock both share the same design also except for the mounting flange but the stock being plastic sucks because it leaks and you can't crush it to raise the level of boost you can run without leaking. With the stock, the boost leak is constant so no surge but loss of power.

I could of run a crushed mr but they are higher cost and mounting the 1g was easier the way I did.

https://www.evolutionm.net/forums/sh...ad.php?t=92909

good luck

 

Im in the same situation kinda. Im running a crushed 1g and it works great but i have a new HKS Racing Type II BOV sitting here and dont know if i want to try and throw it on or not. Im thinking why mess with somthing that works? Plus the HKS wont hold much more then a crushed 1g from what im seeing. They say the Type II can hold 40psi easy and im at 30 with the 1g with no problems. Anyway if anybody is interested i got the HKS Racing Type II for sale PM me with offer. Hey Swe i havent heard back from you how are things going? I still havent pulled the engine out of my car yet hopefully will get around to it today. Let me know if you have found anything out!

 

LOL thats funny that it looks like the same manifold i got. And everybody was talking crap about mine saying it was terrible. I find it to be a very good manifold with good welds, supports, and porting and polishing. Actually if you look our manifold is identical to the DNP manifold that everybody knows and loves in Japan only mine was about 1/3 of the cost.

 

Thanks Az3ar, when I did that on my car before the ATP kit I had an average of about 9sec with 3” exhaust, HKS RS and stock ECU at around 20psi, now I have around 7sec, similar to you then BUT my friends EVO6 TME would easily do it as fast with his stock turbo. I’m not sure this is a very good comparison though?

What BOV are you running? I might try to change my BOV just to make a quick test, I have got some indications like “gt40” pointed out that it could be bov related. Might not cure it totally but well worth a test.