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Old 7th June 2014, 20:17
Mike Mike is offline
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Quote:
Originally Posted by morris View Post
I haven't done the VANOS seals on my M50 but I did do them on my 130K M54B25 as I also perceived a lack of torque low down. The old seals were very brittle and flattened but the new ones didn't make a blind bit of difference as far as can tell, either on performance or economy. I've come to the conclusion that the BMW straight six is just not a very torquey engine low down. My old 3.0 V6 used to pull hard from 1500rpm but the straights seem to be a different kettle of fish.

I hope if makes a difference for you though. Have you got the special tool for setting the cam position or are you going to fabricate something?
Your m54 should have plenty of bottom end torque - have you checked your DISA valve - these are very prone to wearing out?

You may be right about not improving the M50 bottom end torque...... it will be interesting to see? If it solves the strange "rattle/rumble" noise I get at 2700rpm I'll be pleased enough.
If the torque improves then it will be a welcome bonus.

The M50 is known to have relatively aggressive cams, which have been tamed with each new M5x engine. The M50TU is milder than the M50, and the M52 milder than the M50TU. The forums suggest the M50 has been criticised for lack of low down torque, and the M52B28 was introduced to produce its torque lower down the range (due to milder cams).
The M54 introduced DISA which allowed a more aggressive cam to be brought back for the top end, but improved the bottom end torque by changing the inlet runner lengths between slow and fast revs.

I've not looked at the M54B25, but the torque figures for the M54B30 make me very envious! So much more torque, and significantly lower down the rev range too - my kind of touring car engine!

A spot on one of the forums showed a very simple way to set the cams - place a flat bar across the tops of the flat cam lobes, and then clamp them with two G-clamps - very simple and works a treat.
I'll make myself a bar with two pins to rotate the exhaust cam sprocket to push the Vanos unit off. It seems fairly easy for a single Vanos unit.
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