AAN into Ur quattro, 400-450 Bhp Target

[A80Avant]

I had full boost with a bit of surge on higher gears on the 3071R 0.63ar, on stock head and adu cams at about 3500rpm on 3d and much sooner on higher gears. It did go out of breath after 5500rpm though. Porting is always good but might increase the spool times slightly.



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[K Simmonds]

Nice project. Don't think RS2 cams will help that much with spool up, the inlet is the same as ABY/AAN anyway and I'd have thought the exhaust makes most difference higher up the rev range. Head work would probably be the best bet, good quality porting by someone like JP would make a noticeable improvement to gas flow and therefore spool.

[A80Avant]

as the exhaust ports get wider, spool drops instead of improved. However the idea of porting is that more flow+fuel equals more power, so when on boost it will make more power on every level when compared to the non ported head.

[DJones]

Lighten the bottom end, also see if you can add more off boost advance.

[Jamo]

URquattroGus you should read Bram's thread, that is exactly why he changed. the 3071 is a great turbo but it is very on off in feel until it comes on song it's not very progressive.

I would say here a lighter flywheel and bottom end maybe in order or the ghetto stroker conversion

[prj]

0.63 with stroker will just surge like crazy.

Drop your compression ratio, either by running a thicker gasket or by using custom pistons.
You will get gains before the turbo has spooled up, and after as well. You will gain all around in transient response, meaning better spoolup as a side effect.

Of course light load cruise and fuel economy will suffer a tiny bit.

[URquattroGus]

What?? Drop the compression ratio? Surely that would make worse off boost response!?

I did spec an alu flywheel to try and lighten the bottom end a bit.

What other turbos can I consider? Did bram end up with comp turbo? I am looking into porting too.


I think some of the problem is that my everyday focus rs is 2.5 litre and boosts from just 2k rpm onwards, it pulls well low down and you get that lovely surgeing forwards feeling, particularly in the higher gears.

[prj]

What?? Drop the compression ratio? Surely that would make worse off boost response!?

No, it won't, because you are knock limited on the stock engine pretty much any time you are at WOT/high load.
Does not matter if you have 0.3 bar or 2 bar, and the 0.3 bar you get instantly with these turbos when you dip the throttle.

The difference in timing between two cars tuned to knock free MBT at stock CR and 8.3 CR clearly show this, as does the general feel of the car.
Less CR on these cars means faster spoolup and better transient response, except for very light load cruise situations, so basically any time the throttle is over 30%.

I mean, if you ran it on LPG or E85, then you would benefit down low from higher/stock CR. But as long as you are running good old petrol, you are better off dropping 0.5-0.7 points off stock.

[Jamo]

For once I am in total agreement

[DamoM]

3) Change to a MD357 Turbo Dynamics turbo. There may be a problem here as I have a T3 flanged wagner Evo exhasut manifold. I went for the Gt3071 at the time as it was £850 and proven and the MD357 was £1300 and had only been used by one person.

I think that single biggest gain wold be the turbo. It comes as standard with a T3 flange (we had to weld one on the wagner manifold to make it fit).

[A80Avant]

For once I am in total agreement

I'm not in agreement, but I haven't mapped any cars, just my experience on my car. Don't know if it is a good example, probably not but when my compression ratio was pretty low due to cylinder wear, my car ran like chap off boost and my spool went at least 300rpm later. I'm not talking about reaching proper boost just how long it takes for boost to build up. Increasing the timing didn't make any difference, but as I said this is probably not a good example.

With head work though I still run same timing as before and my CR is around 9:1 now. Some areas I run higher timing as well.

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[DamoM]

and my compression ratio is 7.6:1

[URquattroGus]

Turbo dynamics have said they cannot supply the MD357 as they can't get the housings anymore, think it was the K26 exhaust one.

The turbo is also only K26 based (thought they could use another housing to make something similar) so it will not mate up to my t3 flange.

They have said that they cannot improve the response of my GT3071R 0.63 but could offer a different compressor wheel;

"We can however help with improvements to midrange and top end power with the addition of a Turbo Dynamics designed special forged billet compressor wheel offering improved strength, lighter weight and improved flow over standard cast item, however this may have negative affect in the spool time which you ultimately wanted to reduce"

I know this is not necesarily going to achieve what I was after, but hew, more midrange and top end power, who can resist that?

What do you guys think, is a billet wheel a worthwhile mod? I suppose this would almost turn my turbo into smilar turbo to a GTX series one. (incidentally I was told garret GtX turbines not available seperately)

[DamoM]

Turbo dynamics have said they cannot supply the MD357 as they can't get the housings anymore, think it was the K26 exhaust one.

The turbo is also only K26 based (thought they could use another housing to make something similar) so it will not mate up to my t3 flange.

They have said that they cannot improve the response of my GT3071R 0.63 but could offer a different compressor wheel;

"We can however help with improvements to midrange and top end power with the addition of a Turbo Dynamics designed special forged billet compressor wheel offering improved strength, lighter weight and improved flow over standard cast item, however this may have negative affect in the spool time which you ultimately wanted to reduce"

I know this is not necesarily going to achieve what I was after, but hew, more midrange and top end power, who can resist that?

What do you guys think, is a billet wheel a worthwhile mod? I suppose this would almost turn my turbo into smilar turbo to a GTX series one. (incidentally I was told garret GtX turbines not available seperately)

Just gone back over my old paperwork and you're right. It was a k26 but the wagner I had was a T3 and so we had to weld a K26 flange on the manifold. Sorry for the confusion.

I do actually have a brand new turbo (I bought 3) that I was planning on putting in my RR quattro. If you offered me enough I might be persuaded to part with it....

It would however mean you getting your EM modded (not necessarily possible?) or a new EM.

[prj]

The hotside is what is choking the setup, not the compressor.
The compressor can easily flow more, fitting a GTX comp wheel won't do anything for you with this hotside.

Fit meth on the car, run lots of of it. Easy 60-70hp boost for you and better transient response all around.