Dissapointing lag

[ralleyquattro]

Norm for the 3071... only difference I had was VEMS (no maf) and Wagner Sport Evo exhaust and MTM intake.
HTH

[tomwood_uk]

Norm for the 3071... only difference I had was VEMS (no maf) and Wagner Sport Evo exhaust and MTM intake.
HTH

Interesting, thanks for that. So you made 333hp at 27psi? Presume that's at the wheels on the dynapack?

[DJones]

Talk to Craig at CR Turbos, a good man, knows and respects Mark too. He will sort you out.

Darren.

[tomwood_uk]

Talk to Craig at CR Turbos, a good man, knows and respects Mark too. He will sort you out.

Darren.

Cheers Darren just sent them an email. Did you ever get yours on the rolling road btw?

[DJones]

Cheers Darren just sent them an email. Did you ever get yours on the rolling road btw?

Yes 488bhp 647nm at 1.8 bar. Took AndyP around the block and the police turned up from memory...

Craig is your man he built my 911 turbo's too and they spool exactly as I asked him to make them.

Cheers

Darren.

[tomwood_uk]

Yes 488bhp 647nm at 1.8 bar. Took AndyP around the block and the police turned up from memory...

Craig is your man he built my 911 turbo's too and they spool exactly as I asked him to make them.

Cheers

Darren.

Haha nice

[Billman]

Why should the antisurge housing induce lag?

[diesel des]

TDi Turbos*
44 Balena Close
Creekmoor
Poole
Dorset
BH17 7DY
TDiTurbos@gmail.com
01202 691220
Craig no longer works at cr turbos. He is out with another guy who both started tdi turbos .

[DJones]

Why should the antisurge housing induce lag?

I think it's basically because it's inefficient low down i.e. How it works/controls surge, that's certainly what I was advised it would be like and yep sure was..

[Error404]

As far as I understand it and please correct me if required, the surge is caused by the inability of the engine to ingest the volume of air that the compressor produces at a given speed, causing reversion in the intake. The anti-surge housing "vents" provides a path for the reversed pressure waves to exit the intake track, but then the compressor needs to work much harder to overcome the "vents" in the housing = more lag.

[andy10v]

As far as I understand it and please correct me if required, the surge is caused by the inability of the engine to ingest the volume of air that the compressor produces at a given speed, causing reversion in the intake. The anti-surge housing "vents" provides a path for the reversed pressure waves to exit the intake track, but then the compressor needs to work much harder to overcome the "vents" in the housing = more lag.

http://www.turbobygarrett.com/turbobygarrett/surge_line

Surge is the left hand boundary of the compressor map. Operation to the left of this line represents a region of flow instability. This region is characterized by mild flutter to wildly fluctuating boost and “barking” from the compressor. Continued operation within this region can lead to premature turbo failure due to heavy thrust loading.

Surge is most commonly experienced when one of two situations exist. The first and most damaging is surge under load. It can be an indication that your compressor is too large. Surge is also commonly experienced when the throttle is quickly closed after boosting. This occurs because mass flow is drastically reduced as the throttle is closed, but the turbo is still spinning and generating boost. This immediately drives the operating point to the far left of the compressor map, right into surge.


Surge will decay once the turbo speed finally slows enough to reduce the boost and move the operating point back into the stable region. This situation is commonly addressed by using a Blow-Off Valves (BOV) or bypass valve. A BOV functions to vent intake pressure to atmosphere so that the mass flow ramps down smoothly, keeping the compressor out of surge. In the case of a recirculating bypass valve, the airflow is recirculated back to the compressor inlet.

A Ported Shroud compressor (see Fig. 2) is a feature that is incorporated into the compressor housing. It functions to move the surge line further to the left (see Fig. 3) by allowing some airflow to exit the wheel through the port to keep surge from occurring. This provides additional useable range and allows a larger compressor to be used for higher flow requirements without risking running the compressor into a dangerous surge condition. The presence of the ported shroud usually has a minor negative impact on compressor efficiency.

[gnutz2]

Has anyone checked the pressure drop accross the intercooler core? Some of those Chinese cores are shocking and definately not all equal.

[Jelle..]

But why do you use a .82 housing if you have anti-surge housing and a higher effecienty due to the GTX-design vs GT?
Maybe i'm wrong but i think a GT3071 .82 and a GTX3071 .64 should preform the same on top end. You have the anti-surge housing, so why don't try the .64 housing.

[Audi_CQ]

Its not the boost controller as I initially ran the setup on the N75, made no difference to lag. With the controller turned off using just the w/g spring the lag is still the same.

With the Controller turned off did you check that it didn't feed air to underside of the WG? If it did it would be laggy.
To test max spool up set a boost cut at wanted normal boost, say 1.8 bar, and attach the wg hose to the top of the WG only to force it shut. If it still is slow spooling the wg control isn't to blame and you have to look elsewhere.

[tomwood_uk]

Little update gents, spoke to Craig at tdi turbos. He's not surprised with the poor response and lag I'm experiencing. He seems to think that the turbo is really too big for the 450hp range I'm aiming for. He doesn't rate the GTX line at all, and although they can produce very good power they sacrifice too much down the bottom end to be effective for on a street motor. We've discussed the possibility of changing to a .63 hot side, but he's suggesting changing to a 7 blade billet compressor wheel and a machined gt3071 compressor cover (without the anti-surge). I'm inclined to agree with him.