mjims

OK Guys,

Whilst running my TT on the dyno & mapping the Motronic, we experience lots of trouble with the motroinic cutting back the boost. I was running garrett 1Bar actuators, believing the motronic would be happy to control the final .2BAR boost. I was wrong!

I need to decide which way to go to acheive a strong 1.1-1.2bar boost, so I'll put these options to you all;

1/ Motronic with std actuators? (set to what opening pressure?)

2/ external boost controller with std actuators? motronic boost valve disconntected?

3/ Garrett strong actuators set to open at exactly 1.2BAR? with motronic boost valve disconnected?

cheers

viperbob

I would try #2 first. The standard frequency valve on these cars is a problem with fast and high boosting turbos. I install the Greddy boost controllers in my higher HP cars with the proper remapped ECUs. I can dial in any boost pressure I want in my own car with hybrid K24s running standard actuators.

Kevin

This has been a problem for many years.. The Garretts at 1.2 is way to high... You ECU is fighting the internal safeguards.. It takes some t ime to get it correct.. The frequency valve is to fast, there are a few tuners that will slow it down through resistors.. I am a firm supporter on using the factory ECU to control boost.. If you can afford a engine rebuild and new pistons and liners purchase a external boost controller.. It might be okay 90% of the time the other 10% will break rings and destroy your ring lands..

Geoffrey

The frequency control valve is NOT the issue with these cars. I use this valve on all turbo cars with internal wastegate applications and it works beautifully. It is fast, I can run it at 100hz and control boost within a 5kPa range. In general, I would rather see the ECU control all engine functions and not have 2 system in the car.

mjims

So, with some difference of opinion as to the best option I will deduce;

1/ replace the std actuators, and map the motronic to the best of it's ability?

I Plumbed up a device with a boost guage and tyre valve for dialing in pressure to the wastegates and set/balance them together, for either the motronic or external boost contoller what would be the optimum 'set' opening pressure?

........then, if the motronic is expecting higher levels of boost, fitting an external boost controller shouldn't be the road to a big bang as kevin suggests?

The problem with mapping the motronic for boost is that it doesn't actually read boost. It determines what the engine is doing from the different maps and sensor readings and deduces what it believes is the best boost pressure, not exactly an exact science when running close to the engines boost limits and none standard turbos.(GT1's).

This was my thinking behind 'old school' actuators, because I can set these to be tight shut until the exact boost required and viola! never more boost than what you want and maximum spool speed.

The problem when watching the motronic doing it;s stuff on the dyno, is exactly as kevin states, the engine is nowhere near high revs and its cutting back everything because the stronger actuators are providing too much boost. '
arrrrr...

I really wanted to get that extra bit of boost low down for drivablity, and it seams the motronic just doesnt want to play ball.

Kevin

This is the wastegate kit that I made for my new Stage 7 turbochargers... As we start to flow more air through the engine the stock wastegate springs start to be over-powered due to the leverage of the wastegate door and arm.. I started to notice this problem on my Stage 4's.. I wanted a progressive factory spring with higher spring rates at the stock settings and measurements.. It has taken quite a bit of engineering to get the correct rates.. One basically cuts open the stock actuator and installs the new spring.. I CNC'd new clamps to re-assemble the actuator.

The added spring pressure keeps the wastegate door shut longer and allows the turbine wheel to spool up faster and longer.. This kit is not for stock K16's, due to overspeed conditions that will occur..

ScottMellor

I don't understand it all, but just the idea of Kevin's stage 7 made my nipples hard.

ca993twin

Scott,

You always make me laugh. I needed that. thanks.

nman413

The thought of Scott's nipples being hard makes my nipples want to run and hide.

Steve, Scott, when are you guys coming up for a track day? You should definitely do LS sometime..

ScottMellor

Jauder,

We're married, with children. We're lucky to get to Willow Springs or Buttonwillow 3-4 times a year...
I'd love to get up to LS. Not in the cards for me any time soon though.

mjims

Kevin, Thats a clever way of being able to measure the differencies in spring rates,my old Audi Quattro Sport used to have a seperate wastegate which allowed this method of tuning, admittidly with far simpler electronics.

The stronger spring theory was the basis for me thinking 1BAR springs would make sure that no wastegate leakage was going to happen.

If I disconnect the frequency valve and map the motronic to match the AFR and ignition advance when applied to the stronger actuators and considerable increase in lower rpm boost, why would this be wrong?

My theory was to get as much maxiumum (Turbo capable) boost across as much of the rpm range as possible, the stronger spring would maximise the potential of the current GT1 Turbos and any additional power would be down to me sending the turbo's off too you for extra modifications.

I suppose you could look at it as being an 'evolution' of my own engine development.

Rather than just going to the nearest tuning company and saying, 'I want 600BHP, here's a big fat cheque'. Where's the fun in that?

As I learn the potential of the car (which still makes me giddy every time I go out for a play) then I can pick out what I want.

I'm officially hooked with the 'I need more power'! infection and working my way towards the big 4Ltr and K24/26's etc