ItalianEvo

Hello,

I'm getting full boost ( 29 psi ) and hard surging around 3400 rpm, and high EGTs ( 1740 F. ) at high rpm under full boost in track sessions...

Do you think that turning from 0.63 to 0.82 could resolve my surging problems ( max boost will be later ) and lower a bit my EGTs ( less back pressure ) ?

TIA.

Gruppe-S

iTrader: (206)

In our experience the surging is actually caused primarily by the compressor housing. Which GT3071 compressor housing do you have? You may want to consider a GT3076 .63 turbo with the larger anti-surge compressor if the surging is your main concern, however you will definitely see a decrease in boost response and spoolup. That said, the .82 turbine may also hurt response and spoolup if you're primarily setup as a track car and making less than 400whp? In the 400+ WHP range, we do not see a significant loss going from .63 -> .82, but there is a loss under that power range.

Cheers,

Gary
Gruppe-S

rednoseevo

Im curently looking for a turbo kit and I like the 3071 atp kit. But I havent seen alot of people using it. IM sitting at 290whp and 311t. Im hopping with this kit and some injectors I can get to 350 whp. IM also going to swap out my hks264s and throw in revolvers. If thats not enough then maybe some meth injection. What do you think

ItalianEvo

4" intake and 0.70 ar




Now I'm at 411 awhp.
Could you please explain me better what you see that happened turning from .63 to .82 ?
Do you think i'll have slower spoolup = less surging ?
What do you think could be the surging cause ?


Thank you Gary.

jj_008

iTrader: (8)

A .82 housing will definitely help your surge issue. It slows down the spool up and keeps the compressor from entering past the surge line. You may want to invest in a .70 A/R ported shroud too. Is this turbo on a stroker motor?

ItalianEvo

Ok !

What about EGTs ? Do you think that the less back pressure I imagine I'll have with the .82, will lower my EGTs ?



Where could I find/buy one ?


No, 2000cc....


Thank you !

feldguy

iTrader: (4)

If I had to take a guess Id say that the hotside would help. Opening up flow by increasing the volume would essentially allow the exhaust gas an easier path by which to exit.

Somebody stop me if Im wrong here.

Most Evo owners know that the reason tubular exhaust manifolds arent used from the factory is durability reasons. Why? The restriction of the turbo causes EGT's to rise dramitically. Pressuring anything under heat causes extreme tempratures to arise. Pressure cookers anyone?

So....by having that restriction in there with the smallish hotside would be the cause of rising EGT's. Switching to a 3037 (3076) with the right selection of hot/cold sides would be a good solution, but the larger hotside is the way to go to preserve the awesome spoolup charachteristics of the 3071.

I dont think I am 100% correct, Im just trying to think logically.

jj_008

iTrader: (8)

Answers in bold.

Gruppe-S

iTrader: (206)

What dyno is that? What engine management / who tuned it for you (please PM me if you are uncomfortable posting). I don't think you'll be happy with the .82 (if it's a serious track car) at those power levels - that said we may be able to tune out the surge at those power levels, we usually are able to make a bit more power on the ATP setup on 91 pump gas. Meth will do wonders for you also.

Cheers,

Gary
Gruppe-S

Taz

iTrader: (5)

29psi at 3400 rpm! ao! That's a great spooling turbo kit! It's also some nasty boost for tracking the car. My atp will hit 27 psi at 4000rpm under normal (track) conditions. I'm never below 3800 rpm at the track, are you? A few ??
What are your AFR and what boost controller are you using? Does the surging diminish with small drops in boost? Where's the EGT thermocouple? What size injectors?

ItalianEvo

Don't know...

Motec



Could you please explain me why ?


Thanks Gary !

ItalianEvo

Surging, and the boost gauge hitting and bouncing at 2.0 bar is at 3500 rpm.

I'm getting max torque, 588.2 Nm at 4950 rpm.



10.5:1

Blitz id3 on an ext HKS wg



YES !!!!!!!

You know it ??


EGT is 10 cm from the exhaust valve, 3rd runner... i presume at tubine intake should be hotter....850s

Thank you.

SaabTuner

Tubine inlet temps are usually lower due to some thermal dissipation as the gasses travel through the manifold.

A larger housing should lower EGT slightly, especially at higher RPM as the larger housing reaches choke flow at a later RPM.

A larger housing will probably need a re-tune; it will at least need one to fully take advantage of the larger housing.

1740*F isn't really that bad, but it could be better.