Ignition timing and compressor maps.

[S2tuner]

Minhea, I like the sound of that combination of boost and timing!

So do I even if the turbos end up going pop one day

Can you post the spec of the larger K04 intake plumbing you're talking about?

Here they are:
http://www.mrctuning.com/intakek04.php

The problem is lead times on getting them, and the fact that you need an RS4 Y pipe along with them, other than that, I love them, and smurfbus has them too.

[spen]

smurfbus - sorry missed your post due to my posting a long message!

Yes, I got the table column headings wrong. Thank you. Those figures represent airflow through both turbos.

24 psi till the redline feels great. The feeling of the car scrabbling for grip out of corners is unreal... dropping to 22/21 is measurably slower, even with the timing adjusted to suit.

I did not take in to acount pressure losses through the intake tract - I assumed turbo exit nozzle pressure to be equivalent to inlet manifold pressure. Obviously it's not, but then KKK must have a tolerance on the 183k rpm limit for the shaft! Quite a tolerance if Minhea's experience is common.

You are right about backpressure - my timing numbers are not great even once volumetric efficiency starts falling. I'm capped by the compression ratio lower down but near redline I think it's exhaust polluting my intake charge.

I think I'm going to leave it as is. CF are generally <5, overall timing is lack lustre but the airflow and inlet manifold pressure graphs are impressive even if they are worrying.

Can anyone tell me about the compressor wheel in a RS6 turbo?

The 17th of Nov might shed new light once all the dyno numbers are in... If I'm overdriving the turbos for no power increase over the people running 21 psi then I'll stop it. If they pop I'll be a lesson to others and then I can bolt on something bigger.

[S2tuner]

Spen, I've mapped a customer's car in the US on race gas to run 26 psi near redline on K04s and it works, it produced 412 at the wheels on a dyno dynamics dyno in 4th gear. How long the turbos will last only time will tell, but the car is super strong and runs fine. The mapping was done on old leaded 114 US octane, we dynoed it 2 days later on good new US 109 octane and it put down 480 wheel HP on a dynojet (which reads high by all means). The car was the record for a stage 3 S4 at waterfest last summer and the dyno owner/operator congratulated me on the numbers, which he's never seen out of an S4 on his dyno before. The tune was more than outright aggressive and not with long term turbocharger reliability in mind at all, however, the car has been running like this for a good few months now and is still doing fine.

[spen]

That's more shiny engine porn to save for. I really must buy some new brakes!!

I'm very interested in the US car you mention. If I run 26 psi at redline the car is a bit of a handful, with peaks of 28 psi I do occasionally suffer from 'max charge pressure exceeded' and the ecu switches the n75 duty cycle to 0. It also picks up a weakness in one of my coilpacks

[s4woody]

sorry bud..i got that from your MRC500 link on ya website..

RS4 engine in there, and my old ported and polished turbos are on another french customer's S4 engine

[S2tuner]

Yeah, the MRC500 link hasn't been updated yet, also because my state of tune is rather a temporary and experimental one...