Dual 44 to a single 60 wastegate switch opinions
 

My new Xcessive lim doesn't clear my turbo and when I put a spacer flange on the turbo manifold, the turbo is touching the chassis :(

Looks like a new manifold will be the route to go but while I'm at it I want to replace my dual 44 venting out wastegates to a single 60 re-routed wastegate. The other option is to plumb the 44s back but it is more difficult to do.

The main reason for the change in wg configuration is the noise. It is fun on short accelerations but a headache on longer drives.

My turbo is a GTX35R. Would there be boost creep issues or other issues like decreased response with a single 60 wastegate?

First problem I see is the fact that you're going to a larger single wastegate, which actually handles power less effectively.

This is a quote from D-Series (Honda) forum:

Larger wastegates are less prone to boost creep.

More info from Turbosmart here: Technical Articles | Wastegate Myths | Turbosmart USA

Why don't you just route your wastegate dump tubes back into your exhaust? Am I the only one running stacked ceramic mufflers around here?!? Noise should be EASILY solvable on a rotary...thicker wall piping helps with resonance too.

As I mentioned before plumbing the dump pipes back into the exhaust is one of the options but not easy to do with a 3.5" downpipe and with my current exhaust manifold design. Plan B is the single 60mm wastegate setup and I just want to know if there are any trade-offs. How much would it affect the turbo response/spool?

Glease Manufacturing

Talk to John.

Plumbing two wastegates back to exhaust is a massive pain in the nuts. Ask me how i know. If i was to do it again it would be a big single.
One idea to keep true twin scroll effect is to divide the wastegate runner.

That's plan b, still want to see if we can re-route to 44s. Since we will be making a manifold from scratch it may be easier but still time consuming. Just don't want to sacrifice spool and solid boost control that's all.

Yeah its not so much the fab work as having to remove and reinstall a dump pipe with four flanges when working on the car. It might not be as bad for you but mine is a rhd fb so quite tight and fiddly under there.

This is where V-Band Clamps shine. :egrin: Yea RHD is a LOT harder. They already twisted the entire drivetrain to fit your steering clearances! Anyone else notice how the motor/trans aren't inline with the body? :scratch:

When making a manifold from scratch it's not all that hard actually, my fd is RHD and if you're keeping in mind that you have 2 gates and have to plumb both back in you can design it with that in mind. With my manifold i placed my turbo a bit more to the front at a slight angle so my gates and pipes would fit :)

Yep, driveline is about 20mm off center from memory. It could go over more. Sometimes i think v-band are worse. Especially the turbosmart ones where they give you flange nuts for a clamp that was designed to capture a normal hex nut so you cant even get a spanner on it properly, plus the fact that the two wastegates are essentially spring loaded so you have to line up four v-bands, two of them needing an amount of force, in an area where your hands dont fit.

Yeah, its not that hard. I did mine lying on my back with barely room for my welding mask but it was ok. I'm just emphasising why i would consider going single gate. Mine is an fb though so there's probably less room with the steering box and everything.

Looks like we have to remove the turbo more towards the front and we will use a single 60mm wastegate (piping from each manifold runner to keep the dual WG effect). This has two reasons; 1- Better clearance and/so room for WRC style heatshields 2- Space for a bigger turbo in case I decide to upgrade in the future. I am worried about losing turbo response but my mechanic told me these changes won't have a noticeable negative effect on spool and response and boost control should be ok too.