...not a controversy again...
RS 40mm down-pips are known to glow when driving in traffic jam, especially on warm -dry- summernights.
There is no way you can expect to see this in day-light.
As with all things in the world - it is not an absolut truth. There were those who did not have glowing down-pipes when subjected to longer periods of idling, and that was considered "weird" back then.
Yes - 1000cc are prone to get the down-pipes glowing. RS 70hp from the 70:ties did simply glow the most.
Undressed beemers do not have glowing down-pipes in corresponding frequency. It -might- thus have something to do with cooling of the whole engine.
As for not seeing that they glow... hardly where once attension should be focused in traffic-jam, at redlights, etc...
If you still are worried - install two pip-fans so that you can get some "wind" on the barrels at idle; my mechanic have done so on his side-rig after he noticed his red down-pipes (after driving some 40 years and >>>1 000 000 miles...).
He has a 90A Bosch alternator installed so there is plenty of electricity to drive his fans - on a stock 280W there is -no- extra ampères at idle for any extra equippment incl drivinglights...
What I have on my primary beemer, that I do think interfer with the glowing, are:
- deeper oilpan / spacer
- belt and pulley driven car alternator
- dual ignition
- s/s exhaust system
The last beemer I aquired, R100RT 1981, does have glowing down-pipes when driving down-town in traffic jam with way too much idling. Hence my guess is that dual-ignition and improved oil-cooling does play a significant role in lowering the temperature of the exhaust fume so much that it is hard to get the down-pipes glowing; and the strong fan on the Bosch 70A alternator (older external version) do also matter I guess.
Just except the fact that most 1000cc down-pipes are prone to glow. RS pre nicasil barrels (pre -81) are more so than other 1000cc's. One -can- get both 800cc and 750cc down-pipes to glow as well, when one tries hard enough (not adviceable!).
Last edited by dc lindberg; 19 Dec 2010 at 15:24.