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Tuning Motronic to burn very clean for MOT / NCT without cats
Against all recommendation, I did order the 5" 100 cell cat. It sure has great flow area and should not be restricting the flow in any way, I hope... If I had ordered a cheaper cat and a bunch of v-band clamps it would have cost me the same, and I still have to change it before and after every MOT.
I think it will restrict...
Will become clear when mapping, if it starts knocking like crazy you will need to use your welder to weld that **** out really quick
Ahaha, maybe I should fit the v-bands anyway so we skip the cutting and welding thing then..?
Edit. In fact that would be fun to test, does a high flow cat add restricton, and how much vs. a straight pipe? Maybe I should fit a pressure gauge to the exhaust after the turbo...
Audi UrS4 Avant 2.5 20vt - twincharged - Project
Audi 80q B4 Sedan 2.2 20vt - Daily user
BMW 320d Touring e91 M-Sport - Daily user
BMW 740iA e38 - Project
Really hard to find any info of the flow of sport cat's. Here is one dyno graph 100 cell vs. straight pipe. http://forums.evolutionm.net/evo-eng...-cell-cat.html 5hp/11Nm drop at 300hp level(had to drop the boost, knock??), so on the double hp level the restriction can be a lot bigger. Of course the diameter of the catalyst does matter, 4" vs 5" has really big difference. Don't know what the size is in the link..?
Audi UrS4 Avant 2.5 20vt - twincharged - Project
Audi 80q B4 Sedan 2.2 20vt - Daily user
BMW 320d Touring e91 M-Sport - Daily user
BMW 740iA e38 - Project
Ok, I think I weld v-bands before and after. We can then test how much it affects the flow.
Audi UrS4 Avant 2.5 20vt - twincharged - Project
Audi 80q B4 Sedan 2.2 20vt - Daily user
BMW 320d Touring e91 M-Sport - Daily user
BMW 740iA e38 - Project
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