Quote:
Originally Posted by retx
Thank you. Just curious. You mentioned 35i has the quiet exhaust. I agree it's not loud most of time, but I can hear about 10-seconds deep and growl sound out of the exhaust when the cold engine is started. I tried to duplicate that sound, but I'm never able to.
When the engine is fired, I recalled there are often people walking toward to the back of my car to see what I have. I said to them it's 35i without mod, and it only last 10-seconds.
Long story short, I guess our quiet 35i exhaust still has the potential structure insides to make the nice sound, but I just don't know how to replicate that sound.
Any ideas? Thanks.
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I'm not 100% sure, but I think that is a so called "cold start" mode that ECU initiates on cold starts for a short duration (around 10 sec like you said). It opens up wastegates to bypass turbos and let catalytic converters warm up faster - only needed on cold start ups. basically in that scenario all gases go directly into exhaust through cats warming them up and as a consequence creating a growl that you hear. In normal mode wastegate is closed to allow gases go through the turbo and spin it up creating boost.
What I'm wondering tho, is if we can electronically open wastegates from time to time to experience that nice growl?