W.G. Not Opening All The Way

[Karma]

I took my new16g apart and ported it yesterday, I also took away some metal on the back side so the w.g. flapper could open the full 90 degree's. Then I put the wga back on and connected the actuator arm to the flapper. Hooked up a boost hose to a blow gun and then to my wga. But no matter how much pressure I use, the wg will only open about 30 degree's. The weird thing is that my old 14b does the exact same thing. Is there somehting im missing here? The 16g has about 250 miles on it. Basicly brand new.

 

[keymaster]

If you research on the board a bit, you'd find that this is one of the biggest contributing factors to boost creep. Whoever engineered that turbine housing and wg was none too bright. The only way to get it to open more is to weld a post closer to the wg actuator arm on the flapper.

 

[steve]

If you research on the board a bit, you'd find that this is one of the biggest contributing factors to boost creep.

I don't have any creeping problems with my 16G and the wastegate doesn't open any more than normal. I do have a 34mm flapper and a housing ported by FP which might have something to do with it. Blaiming creep on how far the WG opens isn't totally accurate, it opens far enough once you take care of the back pressure issues.

Steve

 

[kenamond]

If you research on the board a bit, you'd find that this is one of the biggest contributing factors to boost creep. Whoever engineered that turbine housing and wg was none too bright. The only way to get it to open more is to weld a post closer to the wg actuator arm on the flapper.

If you have the 34mm flapper upgrade, the increased area leads to the flapper getting pushed open an moderate boost levels (actually, by the backpressure associated with moderate boost levels). You can increase how much the flapper opens by shifting the connection point of the arm to the lever such that it's closer to the pivot point, but this decreases the leverage the WGA has on the flapper which will make this leak worse (flapper will start to leak at lower backpressures than stock leverage).

As for steve's comment, I agree that folks have fixed their creep by porting, larger flapper, external gates, etc., but it sure would be nice to bolt a WGA on there with a longer throw and be done with it - MUCH easier in theory. We just need someone out there to point us at the better WGA and wait for SBR to make a chromed out adapter bracket for $15.99 .

For the time being, go check out the porting section of VFAQ where they talk about porting the WG exit. They point out that the flapper doesn't open all the way and that you have to hog out some material where the exhaust slams into the divider (tan stains on the housing in the picture) so that the exhaust has an easier time getting out the half-open door. Just don't cut all the way through the divider (actually, you probably don't want it to get too thin to avoid cracking).

 

[donmagicjuan]

If you have the 34mm flapper upgrade, the increased area leads to the flapper getting pushed open an moderate boost levels (actually, by the backpressure associated with moderate boost levels).

It would seem that this thought is a point of contention as well. While I don't doubt that many are seeing their boost fall off at higher RPMs due to exhaust manifold pressures, I am able to hold 25 psi very solidly all the way to redline on my 34mm flapper/port job. This problem just seems to be very dependent on the particular mods to the car.

 

[kenamond]

It would seem that this thought is a point of contention as well. While I don't doubt that many are seeing their boost fall off at higher RPMs due to exhaust manifold pressures, I am able to hold 25 psi very solidly all the way to redline on my 34mm flapper/port job. This problem just seems to be very dependent on the particular mods to the car.

To double the amount the flapper opens, he'd have to halve the distance from the pivot point to the arm connection point which also halves the force holding the flapper closed. Do you think your 34mm flapper would leak running 50psi boost?

 

[donmagicjuan]

If you have the 34mm flapper upgrade, the increased area leads to the flapper getting pushed open an moderate boost levels (actually, by the backpressure associated with moderate boost levels).

Umm, I think we're arguing different points. I interpreted this post as meaning the 34mm flapper would blow open without any additional mods to the actuator arm. I agree that reducing the moment arm of the actuator linkage will result in a higher likelihood of the flapper blowing open under boost, and I wasn't disputing that. If this is what you meant in your original post, then I'm sorry for the confusion.

 

[kenamond]

Umm, I think we're arguing different points. I interpreted this post as meaning the 34mm flapper would blow open without any additional mods to the actuator arm. I agree that reducing the moment arm of the actuator linkage will result in a higher likelihood of the flapper blowing open under boost, and I wasn't disputing that. If this is what you meant in your original post, then I'm sorry for the confusion.

Some have had problems with the 34mm flapper leaking at moderate boost levels, but I'm not sure what boost they were running. I just mentioned it within the context of modding the actuator to get more throw. It's all good. I'm sorry for the confusion.