3.4 Conversion
 

I have just rebuilt my engine from 3.2 to 3.4 using Ruf pistons/cylinders and sports camshafts. I am also using a Steve Wong chip. I have just finished running the car for 1,500 km and have changed the oil. A couple of things I have noticed since the conversion :-

1. The engine is running hotter than before (except when cruising along the highway). Very often, I find the temp needle at horizontal or slightly higher.

2. Sometimes, although not often, when I start the engine in the mornings, there is a puff of white/bluish smoke that comes out of the exhaust.

3. Now when I am accelerating in a particular gear (especially noticeable in 2nd or 3rd gear) and I take my foot of the accelerator, there is a slight farting sound coming from the exhaust. Not quite a backfire but a "put-put-put" sound. The sound disappears when I lay on the gas.

Can someone tell me if there is anything wrong and whether I can do anything to eliminate the symptoms described above ?

Thanks.

1. More displacement = more heat = normal
2. Not abnormal on these cars
3. Maybe related to a mixture problem due to the Motronic thinking that you only have a 3.2 displacement...

-Wayne

Re: 3.4 Conversion
 

I think #3 is a backfire, but nothing to worry about. It's caused by the increased valve overlap of your sport cams.

1) You could install a targa switch to turn on/off the fan when it gets to the "Hot" zone.

2) I dont think is anything to worry must do.

3) Get a "Properly tailored chip" and your problems will be solved.