3in. downpipe to ?/Aftermath

[DearDoger]

Well after removing the whole exhaust system an replacing it with a megan 3 in downpipe. Yall was right it is very loud and annoying and can be heard from miles away in the country. I like it But i can not control my boost. Say its set at 13 lbs as the rpms climb so does the boost then about 5k an 17-18 lbs of boost pop fuel cut. Do i need to put some back pressure on the exhaust? or get a better mbc ? Its like really bad boost creep Any ideas

 

[viprez586]

You got it buddy.
Boost creep. You need to do some porting. Read up on boost creep + porting. Add in the 34mm flapper and you'll be set.

 

[LiquidX]

Yes you have boost creep, but it's not that bad. Before I ported my E316G and had my 3" exhaust on there, I was creeping to above 20psi (all my gauge showed). You only have a few options which are as followed, port the hell out of the wastegate hole enterance on the housing or go external off of the manifold. After the 2nd time porting my WG hole area, I no longer have any more creep.

For Viper's comment, only go and do the 34mm wastegate flapper mod if you don't plan on boosting over 20psi as the pressure will blow open the flapper.

 

[DearDoger]

Well i have done a bit of research on creep and i have ported the o2 housing as much as i felt comfortable. I suppose i could port the 16g get my self one of them big ol flapper deals. An sry i said anything about back pressure that was just some crazy talk. Thanx

For Viper's comment, only go and do the 34mm wastegate flapper mod if you don't plan on boosting over 20psi as the pressure will blow open the flapper.[/QUOTE]

Well im definitely goin over 20 lbs so what flapper should i do. For a flapper after i port.

 

[habitatguy187]

I never crept with my 14b and ebay o2 dump. $50 and I like the sound when I go WOT, makes the v8 guys turn their heads.

 

[LiquidX]

Well i have done a bit of research on creep and i have ported the o2 housing as much as i felt comfortable. I suppose i could port the 16g get my self one of them big ol flapper deals. An sry i said anything about back pressure that was just some crazy talk. Thanx

For Viper's comment, only go and do the 34mm wastegate flapper mod if you don't plan on boosting over 20psi as the pressure will blow open the flapper.

Well im definitely goin over 20 lbs so what flapper should i do. For a flapper after i port.[/QUOTE]

The reason why you creep is because of the free flowing exhaust system, which is a good thing. If you are going to port the turbine housing, Turbo Porting. When looking in the turbine housing from the exhaust inlet, there is a large "bump" over the wastegate outlet hole. You want to remove as much of that "bump material" as possible so the exhaust has an easier time making it to the wastegate. Also remove the lip from the wastegate area that's around the gasket on the o2 housing side.
When the gas goes out past the flapper, it's directed to a wall and above the wall is the lip. With the lip there, the exhaust hits the wall to go up and hit the lip which then goes back into the incoming gasses. It creates a lot of turbulance and turbulance isn't good

Search for porting and boost creep. There are more pictures for porting the wastegate hole on the site.

Don't remove the flapper if you plan on going over 20psi and you do not need to remove the flapper to port either.