AAN into Ur quattro, 400-450 Bhp Target

[URquattroGus]

Yes I am going to have it remapped eventually, whether I have standard cams or changed cams. I think I will have to wait just over a month or so until a certain someone is free.

In the interim and before mapping with the STD cams the plan was to use my innovate LM2 to log AFR's and check there is no danger with driving the car after just the head work, but no change in cams.

I'm itching to get the car back and enjoy it

[diesel des]

Afr is one thing, but you could get ping and detonation with the better head. I would stick to low boost till mapped.

[URquattroGus]

My plan was to check AFR and disconnect N75. Then not lean on it too much before it's mapped.

I'm hoping that the head work will help keep EGT's down too amongst other things... (not that I know what it runs at currently)

[diesel des]

Sounds like a plan.

[DJones]

Interestingly I finally took mine apart today to fit the larger exhaust housing..

This gave me the chance to measure my wheel dimensions:

Compressor wheel - 53.1mm inducer / 71mm exducer.
Turbine wheel - 52mm / 56mm

This conflicts with your earlier post which referred to the dimensions of the MD357, the compressor wheel is identical to your old GT3071 but interestingly the turbine wheel is 3mm and 4mm smaller than what you believed the MD357 and GT3071 was..

This would certainly aid in the crazy low down aggression i have.

To top it all the housing i have is to big, if my measurements were as you previously pointed out it would probably of fitted.

I wonder if mine is an odd ball which is why it has response low down better than many people think it should.

Anyway i will talk to the turbo shop Monday to see what is the best way forward..

[diesel des]

Sounds like a 28 turbine of some description.

[DJones]

I'm not clued up on the dimensions of others so can't compare it, all I know is it's to aggressive and linnear in its power delivery and this certainly wouldn't help..

[Jamo]

Thats smaller than a 28 wheel which is 53.8 mm iirc they state on the tech doc it's a 25 wheel

Have egt ever been measured in this turbo setup?

[DJones]

No, it has quite a lot of water injected at full boost which would of helped though.

[DJones]

This confuses things a little more... see picture.

It basically states that my MD357 has the identical size wheels to a GT3071r and that the 55/60 turbine wheel you mentioned you had in your previous GT3071 belongs to a GT3076!

[Billman]

From the info I have the GT3071 comes with 3 different turbine impellers:

55/60mm (same as GT30R)
51.78/56.5mm
53.6/56.5mm

[URquattroGus]

Darren, my advice would be to go to the Garrett website and download the PDF catalouge as that has two pages that list all the garret turbos and their dimensions. That website could be slightly wrong, or just list one variant, also probably talking about an internally gated version of the 3071.

[DJones]

Thanks, just printed it off.

So by comparing all the dimensions it would appear that the MD357 is a GT3071r Part No. 700382-3 (with the exception of the KKK housing) rated at 280-480 bhp. This model is fitted with the 56.5mm turbine wheel, which mine does to.

Your old one must be a GT3071r Part No. 756021-1, rated at 300-460 bhp which is fitted with the 60mm turbine wheel.

Interesting how they state the smaller turbine wheel (understandably) comes on to power sooner but then hold on for longer.

I guess this must be the differences we have felt between turbo reactions, notwithstanding other set up differences.

[URquattroGus]

Markings on the turbo where: MM002429 and then 700177-5022 which d doesnt seem to be listed.

The smaller turbine wheel is for an the internally gated version, so I would guess that most people here have not used it and that is one of the main differences with your car, that turbine put into an external housing.

[DJones]

Spoke to Craig at CR Turbos today, interestingly he said my MD357 has got the wrong wheel, the wheel fitted is not what the spec sheet indicates should be fitted.

He is going to swap it back to the standard spec for me then the new housing will fit. Hopefully that will help towards the aggression.