My S4 build blog for Nerdy details

[AndyH701]

Up to now I've only posted here about my electrical gremlins about no power and non start

Here
https://www.audi-sport.net/xf/threads/2013-audi-s4-has-electrically-died-randomly.410470/

Now I've decided to write a short sweet blog on the progress of my car.
If you're expecting big wheels, typically seen bolts on and just a power figure at the end I'm going to disappoint you. I'm not a follow the flock person

However, if you like data, details and numbers for anything and everything then you're in the right place.

The first thing I wish to tackle is the charge cooling system. There's units on the market but for the money I don't think they do a good enough job. I wish to create a system of equal or superior cooling but at a better value for money.
If it costs the same it needs to do a better job. Any less on cost it must match.

We all know the rough power figures achieved by using such kits and regular bolt on no thought setups. There's nothing wrong with this, it's proven reliable ways to power and if you're after that go for it. But I want to put some science behind them

 

[AndyH701]

First step to testing was a benchmark. Power if irrelevant right now. Its a given that a cooler denser air charge will create more power.

Standard - 0.6bar boost pressure (1.6bar total). Intake temperatures were around 38 degrees across 6 runs (2 interrupted)

Add a map (or "stage 1") - 0.9bar boost pressure (1.9bar total) intake temperature increased around 4-5 degrees across 4 runs

The runs used are 3rd gear 2000rpm to redline. And the same in 4th gear. 1 of each in either direction

So we see an temp increase of 4-5degrees with power increases generally circulating 370-400bhp on these maps

First course of action is a separate fluid section. All other charge cooling set up left standard.
As standard they're coupled with the radiator header tank. Which is thermostatically controlled at 86degrees

A fluid reservoir and separating the system is first up with the same back to back test as before

 

[Dippy]

How were you reading boost? 1.6bar is low for a standard V6 TFSI.

 

[AndyH701]

Using VCDS
0.6 bar is 8/9psi (standard)
0.9 bar is 13psi (altered)

Highly doubt a factory car would be any higher?

A post from here suggests mine is high as standard
https://www.audi-sport.net/xf/threads/boost-level-target-various-models-tdi-tfsi.254186/

 

[Dippy]

Audi specify 1.8 bar absolute (11.6 psi relative at sea level) for the CREC engine which is supposed to have the same power/torque spec as the previous engines. That post you reference specifies 12 psi for the 3.0 TFSI (333 PS) engine.

 

[AndyH701]

The problem with the way these are measured is they don't take into account the drop off that the boost pressure does. Initially you hit 12psi even standard, but by the time you actually get to the redline you've tapered off, you taper off as early as 2500 rpm The operating boost pressure is therfore lower. The bypass valve will bleed off boost pressure. Judging by the 5 degree intake temp increase from removing this bleed off alone is likely why Audi made it this way. The post I reference acknowledges this

The figures are taken directly from the cars data with zero leaks present. This is what makes a "stage 1" initial remap so potent.

I haven't gone here myself but the smaller pulleys net 14-15psi boost pressure, whether they drop off will be tuning related