With all these different GT30R turbo kits out there don’t you get problems with turbo surge???

I didn’t know if “surge” is the commonly accepted term for this phenomenon? The UK guys talk about surge when the turbo is too efficient and tries to push more air into the engine than it’s capable of taking. This is mostly happening just when the turbo reaches full boost and gradually disappears up in the revs. Some UK EVO guys warned me before I bought the ATP kit that it would, and I quote, “surge like a pig” and it seams like they were right. ATP however said they had no such problems when I asked specifically.

I had a very long, expensive and disappointing day on the dyno yesterday. To start with it spools quick for a fairly large turbo, I have full boost at about 3,500rpms but as soon as we try to push some boost it starts to surge BADLY, this happens from 3rd gear and up and disappears at about 4500rpms, in 1st and 2nd it revs past that spot so fast that it’s not that noticeable. Then we had 1000rpms up to about 5500 where everything was fine and then at about 5500-6000 the engine, for some reason that we were unable to find, starts to knock and we had to pull timing, the A/F ratios were fine so it didn’t seam to run lean or anything it just knocks. At about the same rpm we had to lower the boost as well to avoid too much exhaust back pressure that just generates heat. We boosted about 23psi at 6000rpms and had the same in back pressure. We were able to boost 27-28psi from 3500rpms but had to reduce that drastically to avoid surge, I don’t know exactly how low we had to go but it felt too low to be satisfactory.

So now to the big question, what to do about this? Going for a larger a/r turbine would help both the surge and the back pressure problems but I would have to sacrifice spool up which is sad when I bought the 3071 to get a quick spooling street drivable turbo. However I did order the .82 turbine and got the .63 so ATP said that they would send it to me if I wasn’t happy with the .63 but since the surge was that bad I might even need the 1.06 turbine?

Then we have the knock issue which as I said we were unable to find the reason for. We had about 30 dgrs. Celsius outside temperature and even if we had all the fans on max it got very hot in the room. I think we had about 40 dgrs. intake temperature and that might be one problem. One theory on this is that when we get high back pressure maybe parts of the exhausts are forced back into the cylinders and could cause knock?

So any ideas, thoughts or suggestion on what to do? Changing to another turbo is out of the question due to financial reasons. And should I go for the .82 or the 1.06 turbine?

 

just read your post on MLR mate. that bad coz everyone was lokking forward to these turbos and now they an't giving what they said they would.

Chris.

 

Is it just on the dyno you get "surge" or on the road also ?

 

Even worse on the road I really don't see how ATP could run this turbo with any significant boost without surge? They quoted 375atw and I had a hard time reaching 310 and had to back of on that as well. Anybody that knows what kind of boost they ran?

 

im running a 3076 from AMS, and besides a few slight tuning issues, everything is fine...i have a standalone ecu though....aem.

 

Lucky you, what a/r turbine are you running? And what boost? And when do you get full boost by?

 

Get a surge-ported compressor housing. Or a leaky blow off valve.

Or increase the A/R of your exhaust housing.

Either way, you can't get high flow, low lag, and no surge in a single package.

 

You can often solve turbo surge problems with just an inlet pipe size change. I had a turbo once that surged so bad it was undrivable. Sounds like exactly what you are describing. The surging went away with changing the intake from a 2.5 to a 3.0 pipe. Changing the pipe to a larger size has the same affects as the surge ports in the compressor housing. Dont know why or how it works but you may want to give that a try first. If you have a three inch inlet pipe try four inch.

 

Thanks Josh,

I will definitely get a larger a/r, .82 seam to be the general recommendation. I guess that would be the most effective measure to take? I don’t know where or how to get the compressor inlet ported, not here in Sweden anyway. I have seen pictures of GT30s with what looks to be an extra collar in the inlet, is it that kind of porting you are talking about? Doesn’t seam to be that easy to do?

 

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I already have a 4" inlet pipe, it's made of two 45 degrees alu elbows straigt on to the 4" compressor inlet and a 4" HKS filter in the other end. On the other hand I get lots of exahust back pressure as well so I think a larger a/r turbine is the only reasonable sollution?

 

You can't get a housing surge ported, you have to buy a new housing.

The GT35R's compressor housing has surge ports. Not sure if it is too big for your turbo, though. You might want to look into it.

You can just barely see the surge ports on this compressor housing:
http://linux.forcedperformance.net/m...65001_full.jpg

See that there is an inner ring inside the main inlet ring. Between the two rings are ports from the snail of the compressor that lead to the inlet. They serve to slow the air down inside the snail and prevent surge.

 

What are your supporting mods? External wastegate? MBC?

 

swe srry to hear about yr problems. I have the same turbo you have (exact) and I have no surge of any any kind infact on race gas i am boosting 30 psi and my car is cutting through other cars like a rocket no joke. I get full boost by 3700~3800 RPM. What do you have? What parts ? whats difference? whats your CR? I dont know what to say but call ATP and see what they would say. 3071 is great track turbo I spool so quick its not even funny and pulls so hard as many people have ridden my car and loved it. Hey do you have MSN massanger account if so me and chris can chim in to help more. PM me.

 

Whats up bro? I was waiting for see what you came out with. OK Here is my 0.02! First i would have gone with teh .82 housing that will help back pressure and possibly some surge. Also what manifold are you running. I have brought this up multiple times and it is always a fight but i would seriously think about getting a Twin Scroll Manifold to get the problem of gases running back into the exhaust ports. ALso what gas were you running? What kind of timing are you running on pump and on race along with boost for both? PM me and we can talk more private but we can compare some stuff since we have allot of the same mods just different turbo. Also can you send a log from the Motec so i can see what it looks like? Are you running your knock table to retard or richen the fuel when it sees a certain amount of knock? Honestly with your setup you need to get .82 housing at least with that turbo or go with the 3037 or the 35/40 with a .63. But i would be very interested in seeing all these variables. Also you are running the tomei 260 with 11.5 of lift right so there shouldnt be any worry of overlap with the bigger turbo? Talk to you soon!!! We will get it figured out!

 

We need some help Shiv can you jump in and tell us what you think? Thanks