I think Shimming the wastegate isnt worth it, You can get a mbc for about 10 bucks or u could make one your self, and it wont damage your wastegate spring. but its up to u, the shims go between the wastegate and the turbo houseing, where the wastegate bolts on(with 2 12mm bolts) u put them there. and how many depends on the thickness of ur shims. Do u have a boost gauge? If not u should get one before turning up the boost, so u dont over boost and hurt the motor.
Wastegate Shimming How Much?
I know this has been asked before but how much of a shim is required in your wastegate to run about 10 pounds. And where does the shim/shims go?
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you should be boosting @10 psi with, intake, exhaust, and hard pipes.
Thats how i would do it. No need to shim anything. once your there you may raise it to get 12-15psi. Bets way is a EBC and if your too cheap then a MBC will do. Shimming would be my last choice.
Anyhow to answer your Q. trial and error which IMO is dangerous if u dont know what your doing. Shims/washers come in all shapes and sizes just like women. so i would advice you to start with a thin one, keep adding till you reach what you want.
And yes you need a boost gauge
Thats how i would do it. No need to shim anything. once your there you may raise it to get 12-15psi. Bets way is a EBC and if your too cheap then a MBC will do. Shimming would be my last choice.
Anyhow to answer your Q. trial and error which IMO is dangerous if u dont know what your doing. Shims/washers come in all shapes and sizes just like women. so i would advice you to start with a thin one, keep adding till you reach what you want.
And yes you need a boost gauge
Well i have a boost gauge, wideband a/f, 3"downpipe, 3" exhaust, flowmaster 40 series muffler and an intake with a MBC but once it hits ten pounds the the boost controller lets the air by then the wastegate open to stock 6 pounds. I can get ahold of an EBC from my one friend. I guess ill go that way but wont it do the same thing? The car pulls when its at ten pounds then drops off significantly once the wastegate opens.
Hmm, i think your MBC may be screwwy. Im not sure what the stock wastegate/actuator opens at but with your mods and without a MBC you should be seeing 10 to 12psi before fuel cut. i would put the stock hose back on and see what your boosting off the wastegate. Reconnect the MBC and see what you get then. it should be more, if not then something is not right.Well i have a boost gauge, wideband a/f, 3"downpipe, 3" exhaust, flowmaster 40 series muffler and an intake with a MBC but once it hits ten pounds the the boost controller lets the air by then the wastegate open to stock 6 pounds. I can get ahold of an EBC from my one friend. I guess ill go that way but wont it do the same thing? The car pulls when its at ten pounds then drops off significantly once the wastegate opens.
The MBC should let you raise your boost all the way till your engine blows..
It depends on mods.. fwiw Stock it took me 4 washers per bolt to get 10 psi, then it fell to 7 psi by redline
With intake and exhaust I used only 2 and it held 10 psi fine..
With intake and exhaust I used only 2 and it held 10 psi fine..
I didnt understand it either but thats what happens. If i get my buddies greddy profec B 2 that should work fine and do what it is supposed to do as opposed to what is happening right now. Correct. So i should just put on the EBC and all should be good?
do you put the shims right on the bolts.
Shims are the best thing you can do. The reason boost drops off on CT26s is because the exhaust flow overpowers the actuator spring(especially old ones) and forces the wastegate open causing the boost drop. No MBC nor any BC for that matter will truely fix this. The best thing you can do is apply more preload to the actuator spring by shimming it. It is perfectly safe to do assuming no fuel piggy back is installed. The stock ecu will handle it or throw you into fuel cut if it can't. This of course assumes your long block is in proper order and you run the usual BHG risk if you are on an original HG.
You install the washers between the compressor housing and the actuator on the 2 bolts.
Edit: the solution the MKIV guys use for this problem is they run an additional spring from the wastegate arm to another point on the motor to aid in keeping the wastegate flapper closed. It works wonders and is a better solution since the actuator is still working in its proper operating range. This would be a very easy thing to rig on a CT26 as well and would only mean a trip to autozone and buying one of their "HELP" carb springs.
You install the washers between the compressor housing and the actuator on the 2 bolts.
Edit: the solution the MKIV guys use for this problem is they run an additional spring from the wastegate arm to another point on the motor to aid in keeping the wastegate flapper closed. It works wonders and is a better solution since the actuator is still working in its proper operating range. This would be a very easy thing to rig on a CT26 as well and would only mean a trip to autozone and buying one of their "HELP" carb springs.
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