My 20v 2.5 stroker track day ur quattro

[cooperquattro]

i had similar issues using a gt35r,its the surge thats the issue i would say,the turbo is supppsed to come alive at 4000rpm not tale off,if your getting surge after this rpm then the turbo has done all the work allready and cant produce any more boost,try altering the map to give lower boost pressure until say 3000rpm then ask it for more boost after,it could also be down to poor flow on the cooler
what boost is it running??
what intercooler is it??

[DamoM]

i had similar issues using a gt35r,its the surge thats the issue i would say,the turbo is supppsed to come alive at 4000rpm not tale off,if your getting surge after this rpm then the turbo has done all the work allready and cant produce any more boost,try altering the map to give lower boost pressure until say 3000rpm then ask it for more boost after,it could also be down to poor flow on the cooler
what boost is it running??
what intercooler is it??

I know what you mean, but because the hotside is designed for quick spool and brutal delivery of torque it I think it is running out of it's efficiency range at higher revs at 2bar! I have a large fmic and we have measured for pressure drop across it and there is virtually nothing.

My ecu has a switchable map and when it is dynoed on this map the power is much more linear and the line is smooth whereas on the max boost the power curve is all lumpy. The dyno operator said that the surging was very loud.

[cooperquattro]

also which d/v do you use and where is its location,
mine is too near the compressor and i found that the boost pressure was lifting it causing surge,i found that running no d/v at all was a vast improvement,but had to put it back on due to popping the boost hose off when the throttle was shut

[DamoM]

also which d/v do you use and where is its location,
mine is too near the compressor and i found that the boost pressure was lifting it causing surge,i found that running no d/v at all was a vast improvement,but had to put it back on due to popping the boost hose off when the throttle was shut

It's a bailey one and it's quite near the turbo.

I'm only thinking that this is a turbo issue because the hotside is small and DJones has suffered the same issue with his car on the same turbo. Turbos are such a minefield...!

[cooperquattro]

i ran a bailey one(terrible they are),the spring wasnt up to it,now i have a turbosmart one and its better,but i still need to move it closer to the throttle body,if its too close to the turbo the boost will open it slightly before it gets negative pressure from the inlet source

[Rocco]

For those that are interested re the Link ECU I got it from Thor racing. They are in the Midlands. It cost £1800 including wiring in of the ecu loom to the S2 one that was in the car (it uses all of the motronic sensors except the MAF which it doesn't use), before and after dyno runs and full mapping session. You get the software (very easy to use). I put in switches for anti lag and launch and also a high and low boost switch. It's all so easy!

I really thought it was good value considering that was roughly the cost of 3 remaps with MRC!!

Also works with knock sensors?
Can you map it yourself ?

[DamoM]

Also works with knock sensors?
Can you map it yourself ?

Yes to both questions although the engine is very noisy sonically and this can be interpested as knock by the ecu so you have to adjust the sensitivity.

[djh]

i ran a bailey one(terrible they are),the spring wasnt up to it,now i have a turbosmart one and its better,but i still need to move it closer to the throttle body,if its too close to the turbo the boost will open it slightly before it gets negative pressure from the inlet source

Agree with this, only cars i've ever seen bailey dumpvalves work well on are fords.
Turbosmart dumpvalves are a lot better and i've used them a few times with good results.

[URquattroGus]

I was so glad that you took the time to do some of your dyno runs, I think I had a similar predicament, and was scratching my head...

Maybe be carefull going too far the other way with turbo size, maybe you would miss some of the low down response?

I see that garrett have launched this as a new option:

http://www.turbobygarrett.com/turbobygarrett/turbocharger

I have the GTX2867R and i think this is the same turbo but with the larger GT30 Hotside.

Maybe a bit too small for your needs/track? and there are plenty of more tried and tested routes.

[DamoM]

Thought I'd give a quick run down as to how we got vacuum brakes into my ur.

We got the vacuum servo from a MK4 VW golf, the bolt pattern is the same as the Quattro. The push rod from the old unit had to be cut off and welded to the new servo

The master cylinder and reservoir is off the MK4 golf

The high pressure hose from the power steering to the rack needed to be made to bypass the hydraulic brake booster. Pirtek did this for £60. We replaced the old power steering reservoir which had too many ports with a Noble M12 reservoir which is the same as a BMW, Landrover, ford etc.......

We removed the ABS module (although you can keep this) and fitted a brake bias valve.

Fitted a 'rigid' vacuum pipe with a one-way valve to the inlet manifold.

We made brake pipes from the master cylinder down to both front callipers. A pipe from the master to the proportioning valve then a pipe from there to the t-piece just in front of the rear diff.

You could probably get away with bending the existing pipes to fit but it will not look great and there is a chance the pipes will crack on these old cars.

Think that was it!

[adam g]

Where did you get the link ECU mapped. Does it have user friendly rpm vs boost grids for timing/fuel that a lot of aftermarket units tend to have.

I dont think the #6 KKK hotside was intended to flow 2 bar at high revs so you probably are on the limit. I have the MD357 too (unused as yet) but dont intend to run quite that much and will taper the boost off at higher revs if it chokes. I would prefer this to a turbo that gives nothing until 4K (on the road at least) but you never know until you try it. As I recall Craig at CR told me the GT30 BB units are good for 32psi so you arent far off the limit of that either.

[DamoM]

Where did you get the link ECU mapped. Does it have user friendly rpm vs boost grids for timing/fuel that a lot of aftermarket units tend to have.

I dont think the #6 KKK hotside was intended to flow 2 bar at high revs so you probably are on the limit. I have the MD357 too (unused as yet) but dont intend to run quite that much and will taper the boost off at higher revs if it chokes. I would prefer this to a turbo that gives nothing until 4K (on the road at least) but you never know until you try it. As I recall Craig at CR told me the GT30 BB units are good for 32psi so you arent far off the limit of that either.

Thor engineering did the base map and we have added other stuff to it since (like launch control and anti-lag) and also tweaked it for timing and boost but they pretty much got it spot on to start with. It was part of the deal when I bought the ecu.

We make copies of the map before any tweak so that we can revert if necessary and yes it is quite user friendly. You can download the software for nothing I think and have a fiddle if you like.

We dynoed my RS2 last night (plots to be posted) and the results were equally as disappointing. The power stopped climbing at 4750 rpm. This turbo is mapped (by MRC who estimated 400 bhp) and runs 25 psi dropping to 21 at the redline. AFRs were all good. In my opinion, this turbo is really not suited to the Audi I5 at all, unless you are looking for low lag, max torque (rallying?).

There has to be a better compromise and our investigations are pointing towards the GTX3071r. It's never ending!!

[DamoM]

RS2 dyno plot

[DJones]

Kind of underwrites why i felt the need to go to a larger hot side the .6 is just to explosive and then runs out of puff..

[URquattroGus]

Kind of underwrites why i felt the need to go to a larger hot side the .6 is just to explosive and then runs out of puff..

And because it puts hairs on your chest!