What Size Wastegate for a 20G

[99GST]

I cant really decide what size? Should I go with the 35mm Tial or the 40mm Tial?

Also, why? There are a few people who tell me the 35mm's are kinda crummy, and people seem to have a hard time tuning them on a 20g. That is their reasoning in going with a 40mm. Just wanting some more opinions.

Thanks,
Nathan

 

[rdrkt]

I have a Br57 which is a bit larger than a FP red. I have a 35mm Tial and I have no problems with boost creep this is running the boost as low as 16 lbs.

 

[fast4dr]

35mm is fine for a 20G I have a friend of mune running just fine with one. I have have 40mm but only because I got a good deal on it.

Russ

 

[KenTSIII]

35mm should be more than enough... people only get 40mm when they are planning on going w/ a larger turbo later on or plan to run really low boost. I'd recomend it off the O2 housing... as it works much better than off the #1 runner...

Mounting the wastegate. this is one of the most overlooked areas of boost control. In a perfect world you would select a mounting location for our wastegate that allows the gate equal access to all cylinders or rotors. This promotes equal exhaust port pressures between cylinders/rotors and avoids mysterious tuning problems resulting from uneven exhaust port back pressures. Another aspect to keep in mind is the high velocity of the exhaust gas inside the exhaust manifold, sometimes exceeding 800ft sec. Gas that is traveling at such high velocities will not easily make 90 degree turns of zero radius into the wastegate inlet. Remember Newton's second law, "bodies in motion tend to stay on motion". That particle of air is not particularly inclined to make a 90 degree turn and 800ft/sec. It must be persuaded to do so by giving it a gentle radius and easy access to the exhaust flow. Simply welding the gate to the side of a tube may work in some cases where the manifold back pressure is thru the roof, but in modern high efficiency turbochargers the pressure inside the manifold can be quite low and special through should go into wastegate runner geometry. The penalty for poor gate placement and poor gate runner design is having to use a larger gate.

That is straight off the Tial site http://www.tialsport.com/questions_&_answers.htm. & seems to be the general consensus on why the O2 housing mount is better (alot easier than me trying to explain it after just waking up.