RS2 Cam timing & components

[twoqu]

Would appreciate some clarification of why the RS2 uses the different components and what exactly the differences are.
As we know the RS2 when timed with all its correct components ends up with the pulley mark one tooth to the left as opposed to the ABY/AAN lining up with the cam cover mark. Why is that?
We know the RS2 has an extra tooth on the cam belt.
We know the RS2 has a water pump with less teeth (26 vs 29 according to one source).
We know the RS2 has a different cam pulley.
Would also like to know whether the cam pulley only differs in the placement of the ignition rotor, being identical otherwise to the ABY/AAN.

[Greg_S]

I run RS2 waterpump and belt with everything else ABY. The difference in belt is for the faster rotating water pump AFAIK

[UrS4boy]

For performance reasons, the RS2 exhaust cam was intended to run 10 deg advanced of the AAN and ABY cams. To achieve that, you install the cam turned one tooth. Since the AAN/ABY cam position hall sender ignition timing shutter would now be out be 10 deg, the RS2 cam position shutter is different (adjusted by 10 deg) from the AAN/ABY shutter. You can only buy the cam position shutter with the exhaust cam toothed pulley as a unit. The RS2 cam belt has one LESS tooth than the ABY/AAN belt because the RS2 water pump has a smaller toothed pulley (so it spins faster than an AAN/ABY water pump).

AAN and ABY = 054109119H 151 tooth timing belt. (151 Z in Katespeak)
NM,7A and 3B = 054109119G "toothed belt" 147 teeth(not 151 for the 3B)
RS2 = 034109119C = 150 teeth according to the photo (not 148)


Photo courtesy of Andy P

[simon20vq]

Hope you don't mind me asking, but has someone a pic of the RS2 with the belt fitted? I want to see how its tensioned. Thanks

[Jamo]

It's tensioned the same was as the aby with the seperate tensioner mid block

[simon20vq]

OK, so is that the same tensioner as ABY Jamo? Got a pic pretty please?

[Jamo]

All the same, if you go RS2 belt and water pump you don't have to change any of the fitting bits the tensioner is just in a different position. got no pics there will be plenty on the forum from the cambelt keyword

[simon20vq]

Thanks found one http://s2central.net/Timing_Belt_Renewal_Rev1.pdf

[twoqu]

For performance reasons, the RS2 exhaust cam was intended to run 10 deg advanced of the AAN and ABY cams. To achieve that, you install the cam turned one tooth. Since the AAN/ABY cam position hall sender ignition timing shutter would now be out be 10 deg, the RS2 cam position shutter is different (adjusted by 10 deg) from the AAN/ABY shutter. You can only buy the cam position shutter with the exhaust cam toothed pulley as a unit. The RS2 cam belt has one LESS tooth than the ABY/AAN belt because the RS2 water pump has a smaller toothed pulley (so it spins faster than an AAN/ABY water pump).

AAN and ABY = 054109119H 151 tooth timing belt. (151 Z in Katespeak)
NM,7A and 3B = 054109119G "toothed belt" 147 teeth(not 151 for the 3B)
RS2 = 034109119C = 150 teeth according to the photo (not 148)


Photo courtesy of Andy P

My bad! Of course its one tooth less!
If all that is true, did Porsche/Audi effectively achieve the supposed 10deg diference in the cam timing purely by installing it one tooth out as opposed to regrinding the profile. Thats why they then had to move the timing shutter to correct that signal and why the camshaft mark is out if you see what I mean.
Is the RS2 pump a different pulley diameter or has less teeth?
I suppose I am suggesting a bit of a conspiracy theory!

[Jamo]

I beliieve It's 1 and a half teeh, 1 tooth is 7 degrees if IIRC, yes this is for the inlet camshaft which is the same part number as the aby

[twoqu]

I beliieve It's 1 and a half teeh, 1 tooth is 7 degrees if IIRC, yes this is for the inlet camshaft which is the same part number as the aby

So 1.5 X 7 deg is pretty close to the magical figure of 10 deg! Which is a bit suspicious!

[UrS4boy]

I beliieve It's 1 and a half teeh, 1 tooth is 7 degrees if IIRC, yes this is for the inlet camshaft which is the same part number as the aby

How do you do 1.5 teeth? Aren't teeth integers, as in 1 or 2 but not 1.5?

[Greg_S]

I guess that on the RS2 they fit a different pulley if the cam is the same otherwise

[Jamo]

How do you do 1.5 teeth? Aren't teeth integers, as in 1 or 2 but not 1.5?

Teeth are integers but last I checked it's not a digital installation with distinct steps.

look at the wheel when it's installed it's always 1/2 tooth not 1 whole tooth out on the mark.

[twoqu]

Also if we accept the pic below is the correct setting for the RS2, then its not really a whole tooth out, more like half a tooth. Which if the difference between tooth to tooth on the cam pulley equals 7 degs (360 divided by 52 = 7) then its less than that.
We know the inlet cams are the same so that any advertised difference in the timing must be accounted for by some other means, presumably the cam pulley.
Of course there may be other differences in the cam pully to add the missing amount.
Could really do with finding that pulley comparsion pic I saw recently!