SSI discolouration

Mark McClure · 10-17-2006, 11:32 PM

Hi guys,

After a bit of feedback on this one.

I have recently rebuild my 3.0 motor with SSI's. It need its's final run on the dyno which is booked in for next Thursday......but I have noticed that the SSI's on 1-3 are a yellowish colour where as 4-6 are still grey.

My thoughts on this are that 1-3 are getting hotter than 4-6. I have used an IR thermal sensor and the temps seam to be roughly the same 1-5 degC difference.

Could it be that I have a slight difference in cam timing causing a heat issue or something else bank related?

Thanks

Mark....

azasadny · azasadny's Garage

Mark,
A product called "BarKeepers Friend" will get those stains off the stainless but they may come back anyway.

lindemans · 10-18-2006, 01:21 PM

I think Mark is more interested in the reason why different coloring appears on either side of the engine, not so much how to restore the color again with polishing or so.

Indeed interesting; my guess is that it would require a substantial temp difference to cause visible differences in color.

I would compare plugs on both sides, they are usually a good indicator for combustion temp.

On the other hand, the layout of the system is not symetrical.
The Cat is located on the left of the car so I would expect that area to become substantially hotter. Does that match the color difference ?

mb911 · mb911's Garage

what induction do you have?? Color changes don't require that much difference in heat so plugs would be a huge indicator but if running carbs there is your answer

rsscotty · 10-18-2006, 05:09 PM

But the layout of SSI heat exchangers is symetrical....and with SSI exhaust you don't use a CAT.

Just finished dyno work on (2) 2.2 liter S engines with new SSI and stock muffler. MFI pump was rebuilt with new injectors...proper fuel mixture, cam timing...everything perfect...all pipes on the SSI were a different color on both engines, ranging from light purple to yellow color.
Made me wonder also. The good test would be to install EGT sensors on all pipes, but I not so sure there would be a fix.

Mark McClure · 10-18-2006, 05:22 PM

Thanks guys,

I am running ITB's with EFI.

Will pull the plugs on the weekend and check. I also wanted to raise the plug gap to 1mm anyway. Once I have the plugs out I will get some pictures of both plugs and pipes. I a mentioned the exterior temp seams to be fairly close on both sides.

Thanks

Mark.....