Can anyone tell me on which RPM does vanos start and on which rpm does shut down on 20VT? I need this info because of VEMS ECU.

Vanos is the BMW term for it, but the function is the same - a variation of the inlet cam timing in order to maximise low and high speed running (which can tend to be mutually exlusive on a fixed cam timing)

I seem to recall 4,800rpm on the 20vt, but I'm only guessing - someone with access to the workshop manual will be along soon to confirm the correct figure

I was referring to timing variator:)

OK, got it

Manual 20VT

Page 6

Just a side note that Fiat have this setting spot on.

For now car is running fine on idle with Vems ECU. TurboJ I didn't understanded what you said about setting spot on. Can you please elaborate.

He meant that you should use the same switching point (rpm) that Fiat used on the OE setup as it doesn't add anything by moving it higher or lower in the rev range.

I have tested the switch over point. A very simple test. I did a power run with the variator ON. Then did a power run with the variator OFF. Overlay the two graphs and the point they cross is where you switch over the variator. They crossed over at 4800rpm on my engine so spot on.

Try this test for yourself next time it’s on the dyno.

So it is not powered on idle ? just of idle until 4800rpm ?

On idle it should be off... proposal: take a voltmeter and measure the voltage on the variator during various rpm.
it should be on (about 12V) over idle up to 4800rpm and off at idle and >4800rpm.

That makes it completly clear Thanks !

p.s. i would measure it over a standard bosch motronic coupe, if i had one anywhere nearby in serbia there are all 3-4 operational 20v turbos

Regards,

RAle

Its the other way round at idle its off.

I found that it was set too high for my setup. I did the same test TurboJ mentioned, fully mapped on and off and I found the best point for my setup was around 4000-4200rpm. But I was using the C&B cams and their timing was also adjusted (i.e. not C&B standard timing).

Eeeeh?!
I think I told the same?!
On idle the variator is off, means you will measure 0V at the variator.
When reving the engine over idle up to 4800rpm, you will find a voltage of 12V on the variator, means ON.
From 4800 to the end you will find 0V again, means OFF.
TurboJ - can you confirm this?!
Thanks
Juergen

For some reason I think the manual is mistaken as when I remember setting mine up it was the other way round to what the manual says. Have a look at page 37. I could be wrong but I think the relay works the other way round, best thing to do it check my settings. When I get a moment I’ll check this for you and confirm.

Would be nice. Unfortunately I do not have an original ECU any more to do some measurements.

TurboJ did you maybe checked your settings? Can someone please post specification for OEM camshafts for 20VT. Is the camshaft locking tool same for 20VT and Alfa Romeo 156, 2.0TS. I'm asking this because I read this info somewhere, I can't recall where. What is the correct part number for locking tool in case of Laser tool product, 3636?

Anyone?

Sorry dude my car is in one place and my tools are somewhere else. My car doesn’t drive right now so I am unable to test this for you quickly.

Thanks anyway. Anyone comment about other points, I would really appreciate. I'm having issues with camshaft and correct mapping with VEMS.

Basically, the timing variator is off at idle to achieve a wider lobe separation angle, which improves idle quality. Effects of lobe separation angle

Tighter lobe separation angle
The reason for the variator to tick over when you press the throttle is to reduce turbo lag. If we look at the timing chart, we will see that at the on position, the intake cams are open earlier and closed earlier, this will allow the cylinder to build up a higher compression(just like when you seal up a syringe just before you reach the full length, but of course, in internal combustion engine, these's the supercharging effect which increases the VE of the engine). This in turn will reduce the turbo lag. However, this is also the region where most 20VT experiences knock, so the OE chip have turned it off after 4800 rpm, for the Novitec chip, they turned it off at 4000 rpm. All turbo charged vehicle are knock limited at mid revs some how.

Wider lobe separation angle
When the engine reaches 4800 rpm (4000 rpm for Novitec chip), the turbo is already in full boost, so it closes and changes the timing to late opening and closing to allow the turbo to pack in more air. This shifts the power band upwards.This is the reason why the 20VT have a wider power band than the 16VT.

Having said that, I'm using a SMC industrial pressure switch(accurate to 0.01 bar) to turn off the variator when it reaches a boost of 1 BAR, in different gear, the best switch over point is different, so using the boost level as the indicator is better than a fixed rpm. The OE setting is based on rpm (i.e. 4800rpm) coz it does not have a pressure sensor to "see" the actual pressure, it only utilizes the pieberg solenoid to control the turbo boost. IHMO, all tuning related to a turbocharged vehicle should be referenced to the boost level and not the rpm as you can be doing 5000 rpm with zero boost and 3000 rpm with 1.5 bar.

Can someone please post specification for OEM 20VT camshafts? I've found some data but it is not same on both places I've found. Also when timing variator is turned on what influence does it have on camshafts, I need that spec. aswell. Thank you

I didn't want to start new topic....question is since we were talking only about taming variator through RPM (when off, when on) what about throttle position? Does it affect timing variator? Btw, I've fitted C&B meanwhile

I have problem with my variator. It switch off rightly at 3000 rpm with OEM chip and with Gtec2 chip also. Where is problem :(( ?

What switches off?

Sorry, my English is bad. My variator solenoid turned it off at 3000 rpm. but in Coupe service manual is writing at 4800 rpm on OE chip. It`s not all right.

How do you know the variator is switching off at 3000 rpm? How are you measuring that it is doing this?

I measured voltage (voltmeter) on the variator during various rpm. On idle 0V and over idle up to 3000rpm
12V+. Over 3000rpm 0V up to limiter.

In variator solenoid.

Well if you are certain it is 3000rpm and not 4800rpm then do the same test but this time remove the vairator relay and measure the voltage on pin 52 of the ECU and report the results back here.

Thanks, I will try this early.