I just made mine the size of the flapper door, and made the inside of the wastegate hole more rounded so the exhuast doesn't have to make 2 90 degree turns like Ted says, it pretty rounded to about 60 degrees or less on both sides, although now my boost bleeds, of coarse I get know spike but if I crank up my MBC to 12psi, it shoots up there pretty quick but only stays there for like 1k rpms then begins to bleed to about 6-7 psi by 7k rpms, is this normal for a ported wastegate?

 

Mine runs at 12psi all the time, but it falls off at high revs too. The turbo is running out of breath at that range, it's nothing to do with the wastegate...

 

prolly cause I ported my engine?

 

Is there anyone who has before and after close-ups of their ported wastegate? If so could you post them or please send them to RTGavin@aol.com

 

No. Thats just spool up. Creep is when you set the boost to a desired amount and it goes past it because the wastegate cant flow enough exh. gas through it. Hence making it bigger. Bigger opening = more air. Similar to a TID


When I was porting mine, I made it so the flapper sits inside of the hole. There is no way its going to get stuck in there (left ample room for metal expansion) but the hole is not 25% bigger than the flapper. Best of both worlds... I guess.

 

more power to ya

 

hey guys, I use a profec A and set to about .7 bar it'll over boost to 1 bar on first on a majorly quick luanch. Is this caused by the wastegate flap being too small?

It happens on other gears too, but not to that extent. maybe 3-4 psi.

Profec ! has fuzzy logic functions, to eliminate boost creep, and also has a active boost sensor on it.

 

Im going to have to disagree with this. My old turbo which was the stock s4 turbo boosted to 15psi solid all the time if i redlined it. I know its because the WG was basically not funtioning and the turbo spooled to its full capacity. Now weather or not an s5 turbo can achieve 15psi im not so sure about but why would an s4 turbo be capable of 15psi and thats with basically no WG and a s5 not be capable of this? I feel that the WG has everything to do with the amount of boost the turbos can achieve.

 

Assassin... was your motor ported? Mine is, that may have something to do with it. If the motor breathes better at high rpm under boost, the apparrent boost in the manifold will be less. ****, I can get 12psi at 2000 rpm in 5th gear because the air has nowhere to go at that low rpm. (not recommended!)

I don't think WG has much to do with max boost unless it's getting pushed open by the exhaust pressure even when it's supposed to be 100% closed, which can happen

 

Whatever you do, remember, doubling the radius of the hole will increase the area for air to flow through exponentially.

area = pi * r ^ 2 (r ^ 2 is r-squared)

Same principle for exhaust.. Going from a 2.5" pipe to just a 3" pipe adds almost 50% to the area the gas has to flow through.

2.5" pipe area - 4.9087
3" pipe area - 7.0685

Going from 2" to 3" more than doubles the area. (3.1415 for 2" pipe)

So adding some size to the porting helps a LOT more than it looks like to the eye.

 

got a photo?

 

Thread started 5yrs ago, resurrected from 4yrs ago.

Outstanding.