well awhile i ago i shimmed my wastegate by two shims. And a week after i had that my turbo started to whine really bad, but about a month ago, i started to run Open Downpipe, and since then the whine is no longer existing, and i was actually holding boost. before when the whine would come on my boost gauge would drop to zero, not boosting. Could it possibly be just because it was so restrictive with the Cat and the Exhaust there?
this was on my mind..
- Thread starter Eric_Odie
- Start date
Well, I do know I could turn my boost controller up to max and shim the wastegate and the turbo would not boost past 5 psi with clogged cats and restrictive stock exhaust. When I went full 3 " turbo back, I can easily hit fuel cut with 2 shims and barely any increase on the boost controller.
i had the complete sleved cats 2.5 inch full exhaust and it made a huge difference, then i went to full 3" w/ no 90 elbow and boost went way up again...had to turn it down due to boost creeping up... from 4 to 5.5k rps its amazing now...
edited. it pulls hard past 5.5krpms but i dont do that often..:icon_bigg
edited. it pulls hard past 5.5krpms but i dont do that often..:icon_bigg
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anyone know of a way to hollow out the cat on the downpipe? to hollow out the 2nd cat i just took a pole and a hammer. but i'm not sure abotu the 1st cat if i can get a pole in there since it sits the way it does. anyone done it before. and i would like to add i know i can't pass smog with no cats, but that's why i have a spare cat that i and some friends use when it comes to test days haha =P
i took a grinder and ground some marks into the top of the bend going into the cat and cut my lines in half with a bandsaw or sawsall so i know where to reweld it. smashed the ozone saver out of it, and sleeved it with 2.5 inch pipe, may not be needed,(i just did it to make it flow better) then welded the pipe inside and welded the top of the cat back on... not recomended if you get smog tested or anywhere ever really lol..
i think thats called "surge" or air trying to be forced back out through the turbo,, my first turbo did that just before it died... lol
im looking for a good 3" hi flow cat...
im looking for a good 3" hi flow cat...
aaronc222 said:
You want to shim the wastegate when you are running higher boost, so the boost doesn't fall off at redline. I know when my car was running, I had my MBC set at 12psi, it would fall off to about 10 at redline. If you shim the wastegate it makes it stiffer so it holds the boost better and doesn't fall off closer to redline.
aaronc222 said:
In addition to his post, also when your turbo is not good anymore (cracks in the wastegate, or bad actuator) it also helps to shim it to compensate for the wear of the wastegate.