Subpage of MembersPage/MarcellGal/PowerAndTraction

Found the 100 lost horses:

MAP now reaches 280 kPa easily. TODO: cleanup the remaining texts from the 206 kPa hassle

Hunt for the last 100 horses; tests in the 206kPa hassle

BoostControl is very important on this engine for several reasons

Wastegate diaphragm problem

We measured airpressure at the pre-cooler nipple to find out why MAP would not climb above 206 kPa: if it's coldside or exhaust-side problem.

The kPa => Voltage of the 400 kPa (in WebShop category sensors/external MAP sensor) sensor we used:

ambient 101 kPa / 380 kPa * 4.6 V - 0.02V = 1.2V, examples:

When MAP peaked at 206 kPa, we measured:

Note that we did not detect the broken wastegate membrane when blowing by mouth ! It seemed to hold pressure.

Wastegate diaphragm replaced => but boost still won't go close to target

Wastegate connection

The factory wastegate is used. It is suitable for much bigger airflow than the limit of the current K26/27 (appr 400 Hp).

However, the wastegate has 2 springs .. what a hack ?

We'll see if the springs are sufficient (not strong enough with the broken membrane).

DROPPED: this connection was under investigation, used by some dragracers with big-turbo:

This would allow controlling boost in a reasonable range:

While the above would be optimal in a dragrace car that only sees WOT and no throttle, part-throttle might be problematic.

DROPPED traditional setup:

In this traditional setup boost pressure opens the wastegate, relatively easy to setup the controller to do the right thing. When it works, it might make sense to investigate the more aggressive pneumatic connection. But it will never allow 280 kPa with our spring.

Se we need to be able to command boost to WG_top while decreased boost (or athmo) to WG_bottom:

2 solenoids are needed, each are 3-way and operated parallel (electrically). This allows very fast control, and very wide range of operation, including full boost to WG_top only.

Boostcontrol solenoid - pneumatic valve

The factory 3-way solenoid is available (greasy, but likely works). We also have boostcontrol solenoid from [webshop Pneumatic valve 3way]

Either should work.

BOV - Blow-Off Valve

A factory [BOV] (also called as "Bosch bypass valve" is installed to protect the tubes, cooler and compressor from pressure spikes when the throttle is suddenly released. Some claims that this valve cannot handle 1.8 bar boost. It's very hard for me to believe this - at least if the MAP hose is connected to the top of the BOV. Anyway, we'll see.

WHAT IS THE PROPER DIRECTION FOR THIS VALVE ? Which is inlet and out-tube ?


for how mine was connected. The boost-air came in via the bigtube opposite the reference-nipple.

Also note that the BOV opens at idle, feeding unfiltered air (aka JUNK) to the engine.

Can someone check these ?

Most notably




These are consistent (also with the bentley manual).

My bypass valve was installed reverse, but I changed it so boost now enters at the side of the BOV. Even with this, max MAP is 206 kPa, Mmax=340 Nm, and max power is slightly under 300 Hp. Not enough (target is 270-280 kPa and 440 Nm).

from irc...

More points of airleak?

The car can hiss at many places. Even outside the engine bay. Even at the right-rear wheel !

Why does the audi200 need vacuum at so many places ? Even though mine has hydraulic braking.