not all the way true the way the hotside is its not going to throw all the exhaust gas straight into the hks its gonna bleed off to the side where the iwg opens up... bellmouth is better since it wouldnt have any restriction

 

Racer x is right cause the ewg negates the need of the iwg entirely so there's no purpose to have a bellmouth for the fact that no exhaust is coming out of the iwg because it should be closed off

 

k ill try and explain this easier i know people like pictures and colors....
not the best drawings but you get the idea


red is badddddd (thats where the iwg would let exhaust out)
it creates a pocket

regardless of iwg or ewg it still benefits on having a bell mouth





now heres a bell mouth

 

Ok I see what your saying

 

congrats man...glad it all came together

hows the car feel now?

i give you about 9 days before you do more mods lol

 

While I understand where that thought comes from, fluid mechanics are neither that simple nor that intuitive.

Here's my college-level fluid dynamics opinion: Having that eddy flow next to the stock IWG could definitely be BETTER than the alternative presented by a bellmouth DP. If such an eddy current were to form in that region, then (assuming it was semi-stable) the exhaust gasses exiting from the turbine would simply shear right past it. With the bellmouth, you're still going to get turbulence as the air 'wraps' around behind the IWG. However, now the turbulence can propagate down the exhaust, interacting with the more-laminar airflow further away from the IWG and slowing it down. Furthermore, dumping into a bellmouth and necking back down to 3" piping now presents itself as an unnecessarily large sudden pressure increase immediately post-turbine, which is never a good thing. With an IWG, I think this is still a beneficial trade-off over having the wastegate gasses slamming into the turbine gasses at a 90 degree angle, but without one, it's really just a negative... Again, this is just another viewpoint, and I couldn't confidently say it was one way or another without running it through Cosmos Floworks at the very least.

Here's an analogy though: A pickup truck driving either with its tailgate up or down. As can be shown, you'll get better gas mileage with the tailgate up. This isn't exactly intuitive, but it turns out that with it up, a large eddy is formed in the bed and the oncoming air simply flows right over this current, whereas, with the tailgate down, turbulence is generated behind the cab, and this turbulence interacts with oncoming air as it curves down to the bed of the truck. In this case, tailgate up is HKS-style, tailgate down is bellmouth-style.

 

you too man, well.. the limited had the ewg and a few other mods, so it was bound to make more numbers somewhere lol.

 

yeah thanks for the all of the help josh. the stress is finally over with. the car feels awesome, i wish i had an 07 though. their gearing is enough to keep up with me on their stock turbo lol.

 

I came to the conclusion based on the pickup truck theory, myself

 

very good numbers, matt! and thanks for the props on the bumper cutting