Convert mani to twinscroll?

[Chimmike]

So, runner lineup isn't optimal for twinscroll flow, looks like cylinder 1 and 4 line up and 2 and 3 line up where the flange would be welded on. I think I can weld in a separation to make it a "true" twinscroll, but I'd only be using 1 wastegate.

Any of this seem to present a problem?

Would be going t4 twinscroll on a PTE 5862 cea bb.

[Chimmike]

Anybody? @Tomas; @Ziggo; @silvapain;

[silvapain]

Our firing order is 1-3-4-2, so the runner matchup is correct. However, you need two waste gates with a twin scroll. You need to keep the exhaust back pressure even across all four cylinders.

[Chimmike]

Hrm :/

[Tomas]

Mike, it's not as simple as that. The runners need to be separated all the way to the merge collector. You can't just put a divided T4 flange on that manifold. If the gases from runners 2+3 can at any point escape to runners 1+4 before the merge collector you will loose the pulse charge effect of the twin scroll.

Also, it's hard to tell from the pics but it looks like runners 2 and 3 and 1 and 4 are side by side. That won't do. They need to be front and back on a standard T4 flange. That means when you look at the car from the front, 1+4 are front and back and 2+3 are front and back.

Not too get too technical but this only applies to 4 bangers with flat plane cranks. 4 bangers with cross plane cranks are different but there are very few 4 bangers in the world with cross plane cranks.

Silva pain is partially right about the wastegates. If you have 1 wastegate and the inlet of the wastegate will release pressure from all 4 runners than it's ok. Some people like one of the Cobb dudes had wastegate runners from 1+4 and 2+3 merging into 1 wastegate inlet . That works but it's a lot of piping. If runners 1+4 and 2+3 merge before the merge collector but the pair is always separated from each other you could have 1 wastegate provided half of the inlet port goes to runners 1+4 and the other to 2+3 and that the gases from 2+3 and 1+4 are always separated till the merge collector. All of this is not very easy to explain and I have the English skilz of a 3 year old so meh.

[Tomas]

Originally Posted by silvapain Our firing order is 1-3-4-2, so the runner matchup is correct. However, you need two waste gates with a twin scroll. You need to keep the exhaust back pressure even across all four cylinders.

I think you might be confusing firing order with exhaust gas pulses. Yes, that;s the firing order but the exhaust gas pulses from 1 and 4 are always 180 crank degrees apart. The same goes for 2 and 3. That means 1+4 need to merge on one side of the divided flange and 2+3 on the other. that's what gives you a "true" twin scroll set up.

[Chimmike]

I can weld a separation from the merge to the flange to make it twin scroll but as I thought the pulses would not be optimal to the turbine. Ugh. Guess I have to stick with the vband option. .63 or .82.....hmmm

[Tomas]

.82

[Chimmike]

Guess I need to get in line for your pending twin scroll job later on

[Tomas]

That manifold wouldn't work for garrett turbos. You'd have to change over to an EFR7670 or smaller. It won't have dump tubes for a wastegate(s). As far as I know the EFRs are the only ones internally wastegated for TS housings.

[silvapain]

Originally Posted by Tomas I think you might be confusing firing order with exhaust gas pulses. Yes, that;s the firing order but the exhaust gas pulses from 1 and 4 are always 180 crank degrees apart. The same goes for 2 and 3. That means 1+4 need to merge on one side of the divided flange and 2+3 on the other. that's what gives you a "true" twin scroll set up.

I didn't actually look at Mike's manifold; I was just going off what he wrote.

Sorry for the confusion.

[Chimmike]

Oh well. Vband it is. Maybe in the summer ill mess around with a twin scroll design.

[mituc]

The new CX5 SkyActiv-D 2.2 150/175PS are twinscroll. I'm pretty sure those can be a pretty good research starting point if anyone here would like to go twinscroll. You guys can take a peak to the ex many and eventually rebuild one of those turbos with bigger compressor wheels to match some K04/GTX30 turbos.

[Tomas]

Any idea how the exhaust ports on the cylinder head of the 2.2 diesel match up with MZR DISI? Holly shit. If that manifold fits our head that would be a lot of win.

[Chimmike]

depends on the type of twinscroll flange. If you're talking mitsu, it limits us significantly.