Hey there turbo forum, a car I bought came with this turbo manifold that has a division between exhaust ports. Is this engineered correctly, my common sense is telling me that it could introduce problems. My concern is the wastegate position. It's only on the rear division and it makes me wonder if boost problems would occur? Any feedback or input would be really awesome.

 

This looks sketchy. A divided/twinscroll manifold is a great setup, however both pipes need their own WG or to be joined into a single WG. I assume you are NOT running a turbo with an internal wastegate?

If it was my car I'd throw it out and replace it with a better manifold.

 

Thanks for the response, that is what i had been thinking, now i didn't mention that the turbo im running isn't sequential. (although i am considering one down the line.) i wouldn't want to get rid of it if it would be safe/usable for a standard non sequential turbo.

 

I think you may be confusing terms. Sequential vs non-sequential is a reference for twin turbo systems where sequential has one turbo spool at low rpm then transition to both turbos at higher rpms. Non-sequential means both turbos spool together.

On a single turbo the "twin scroll" just means that the exhaust pulses are separated all the way into the exhaust wheel. That bridge in your manifold looks like it's intended for a turbo like that.

Regardless, I'd trash that manifold since it looks like a very poor design.

You haven't specified what gen this is for, but there are plenty of merchants that sell good quality manifolds.

 

That is one weird looking manifold... Appears that whoever made it originally intended to add another dump tube on the right side, identical to the one on the left side, but then just said F-it and didn't bother to finish the job.

 

Oh snap, im aware of what both are but I definetly confused the terms up, the whole time I was writing sequential I was thinking of twin scroll, (like the veloster N), nice catch. I am not planning on sequential, but I am planning on twin scroll in the future.

I've already started looking for a new manifold, car is an original 87 turbo II. I'd like an HKS cast but they discontinued and are hard to find. Open to suggestions though

 

I know Turblown makes a cast manifold for the FC, I'm not sure how much you'd need to change in your existing setup for that to fit though.

Turbo fitment, downpipe fitment, and intercooler piping going from the turbo to IC are all things to consider.

 

I kinda like that manifold. Its giving me ideas for packaging problems in tight engine bays. The wastegate on one runner thing is a bit weird tho. It wouldnt be hard (or expensive) to modify it to two gates or one central wastegate runner.

 

All that I've found so far is the various turblown setups, which would definetly require an overhaul for intake and exhaust routing.

I have one final question regarding my manifold.
If I were to delete the twin scroll divider in the manifold, would it make it usable. Or if I were to ad another wastegate to the front side as a wankfactor suggested, would that make things operate safely.

I dont want to ignore the suggestions of experienced people, but if I were able to save the existing manifold by modding it, it would save alot of time and money.

The welds on this thing are actually pretty quality from what I can see and the manifold has held up nicely but I've always been concern about the single wastegate on a twin scroll manifold like this

 

Ideally you'd want to either have a single WG joined to runners from both front and rear pipes, or two wastegates mounted.

Adding a second wastegate would be easier than trying to merge the front runner into the rear WG pipe and far more effective than cutting out the flange divider and hoping.

 

You could easily cut or drill a bridge in that divider.

 

you could, but would it really serve to relieve enough pressure to control boost reliably?

 

Whos to say it wasnt controlling boost as it was?

 

True.

 

That may be true, but that manifold is less than optimal design with regards to controlling boost. From the picture, it looks like both runners are completely divided & isolated paths to the turbine, so even when the external waste gate is wide open, the turbine wheel will still see full exhaust from one of the 2 rotors.

 

yes, thats why i would suggest cutting an opening in the divider. Even if it does control boost the way it is (if it even does), i wouldnt like the idea of such uneven exhaust manifold pressure and heat between the two rotors.

op, what size wastegate is it?