wastegate query..?.

[twenty5psi]

alright i have a tube header that does not have a flange for a wastegate..i was wondering,would it be better to mount the wg on the header or the o2 pipe..i know im going to have to go witht he o2 position but is there an advantage to having it mounted in either spot?..
wouldnt dumping gas before the turbo be worse than dumping after after the turbo?..or is it vice versa?..

 

[allwheelTSI]

it HAS to be before the turbo.

 

[twenty5psi]

Originally posted by allwheelTSI
it HAS to be before the turbo.

thats why i dont get it when i see people who have theres mounted off of there o2 pipe?..can you please at least post to as why it HAS to be before the turbo?..i know its to release pressure off the turbo and engine but then why would i see it mounted on the o2 housing because the exhaust gasses would still have to push through the turbine anyways..

 

[swordfish]

It doesnt have to be before the turbo, just before the turbine wheel. The ones that are mounted on the 02 housings are before the turbine wheel because the are directly plumped into the turbine housing.

Make sure you have a turbo that has access to the turbine volute. Dont try putting an 02 mounted gate on a T31 housing because the only access you will have is to gas that has already passed the turbine.

jeff

 

[turbolover2]

Originally posted by twenty5psi


thats why i dont get it when i see people who have theres mounted off of there o2 pipe?..can you please at least post to as why it HAS to be before the turbo?..i know its to release pressure off the turbo and engine but then why would i see it mounted on the o2 housing because the exhaust gasses would still have to push through the turbine anyways..

It has to be before the turbo becasue if it wasn't, all the exhuast gases would pass over the turbine, and there would no way to regulate boost pressure. Those that are mounted on the o2 housing are using the internal gate passage (usually with an extreme port job) along with the external gate. So the gases are exiting before they hit the turbine. The actual turbine blade is after the internal wastegaste passage.

The actual best spot to mount a wastgate would be right at the front of the manifold, where it bolts to the turbo (right where the radiator is). This is of course impossible, but would be ideal. The reason it would be ideal is because it is a spot that allows the exhaust to be drawn from all cylinders equally, and would also allow a very smooth transisition from the manifold to the wastegate. But, since this isn't possible, the o2 mounted gates are the next best thing (as long as the port in the turbine housing is large enough). Some external wastegates are mounted on the number one runner of the manifold, which also works, but doesn't offer the same equality of the other option. This is because the exaust is being drawn mainly from cylinder number one, instead of all clyinders equally. Of course, in the real world, you have to take into cosideration space and nearby components when mounting a wastegate, so some options turn out to be more feasible than others. The actual affect of these things on performance is very, very small, but it is present. As far as numbers go (HP, 1/4 mile times), you wouldn't notice a difference between the two options.