ok i got the stock exhaust that has been str8 piped. I was wondering how much better a 4in exhaust would help control egts? because it is ust stright through and should flow the same or i am just confused. :shrug: any info would be great.:bow:
well a 4inch will flow a bit better. you may notice a 100* drop or so maybe more. On my 24v, I did the exhaust and gauges on the same day, so I could honestly speak from experience. however have the larger pipe will reduce back pressure on the turbine housing which creates a low pressure drawing the high pressure of exhaust gasses out of the exhaust manifold, if there is less hot gas in the manifold, that will lower your temp. will it lower the temp inside the combustion chamber, not significantly and if any it will be indirectly caused by the fact that there will be less heat transfer through the turbo to the compressor side, but this should effect it much.
What you are really going to notice as a result of switching to a 4in system will be spool up. The larger exhaust creates a higher pressure gradiant resulting in faster flowing air through the turbine housing, which causes the turbine to spin faster thus building boost faster. Hope that made some sense. You already did wonders by eliminating the CAT but a 4in system will just help that a little bit more.
Anyone feel free to correct me if I missed something, or got something wrong.
Sounds right to me. I saw a drop of maybe 100* while driving. Where I saw the biggest difference was in temp drop when I let off the accelerator. It cooled from peak temp. much faster. Spool up is a little better and sound is much better. This is on my truck and others may have had different results. I would do it again though. The improvments were well worth the $235.
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