True Twin scroll setup... questions
 

I'm going to be fabing up tubular manifold. I was thinking about going with a twin scroll turbo. My understanding is the collector has to be divided to match twin scroll.

Now.... keeping that in mind... does that mean on a twin scroll collector has to have two waste gates. One on each side of the collector? Can someone please explain or confirm how it works. Thanks.

also is there any draw backs to a twin scroll setup compaired to just regular setup in regards to performance. Is there a trade off between low rpm torque, and high rpm torque all other variable being equal?

Pete-

Yes to all of the above. The manifold is divided and the turbo housing is divided or "twinscroll" Both have to be divided to be a true twinscroll. It will require 2 waste gates, one on each divided section. Twinscroll allows for faster spool up. That way you can use a larger turbo and get better topend, but still get spool of a smaller turbo. I love mine. Be happy to share pics, or read through JoeyBalls GT35R build thread in FI section. He has lots of good pics of a true twin scroll setup (he and I have the same one).

Divided, not twin scroll

Ah sweet dude. Thanks for the great info. If you can post up some pics it would be greatly appreciated. I have a tough time using the search on this forum. So I'll probably never find JoeyBalls thread lol. Thanks

Pete-

Manifold is divided, turbine housing is divided or twinscroll. Can both be used. Not sure why this is always a fight on here...

See Garrett's website, this is taken from there....

A design feature that can be common to both manifold types is a " DIVIDED MANIFOLD" , typically employed with " DIVIDED " or "twin-scroll" turbine housings. Divided exhaust manifolds can be incorporated into either a cast or welded tubular manifolds (see Figure 5. and Figure 6.).


Figure 5. Cast manifold with a divided turbine inlet design feature






Figure 6. Welded tubular manifold with a divided turbine inlet design feature



The concept is to DIVIDE or separate the cylinders whose cycles interfere with one another to best utilize the engine's exhaust pulse energy.

For example, on a four-cylinder engine with firing order 1-3-4-2, cylinder #1 is ending its expansion stroke and opening its exhaust valve while cylinder #2 still has its exhaust valve open (cylinder #2 is in its overlap period). In an undivided exhaust manifold, this pressure pulse from cylinder #1's exhaust blowdown event is much more likely to contaminate cylinder #2 with high pressure exhaust gas. Not only does this hurt cylinder #2's ability to breathe properly, but this pulse energy would have been better utilized in the turbine.

The proper grouping for this engine is to keep complementary cylinders grouped together-- #1 and #4 are complementary; as are cylinders #2 and #3.


Figure 7. Illustration of divided turbine housing




Because of the better utilization of the exhaust pulse energy, the turbine's performance is improved and boost increases more quickly.

Yup I got that part. I know about how cylinder pairing goes. You want the cylinders that fire durring opposit strokes. In the S2000 its 2&3 & 1&4. So for the s2000 a cast manifold cannot creat that kind of division. You have to go tubular.

Cool... pics are always nice :)

I got another question.... Is there such a thing as a twin scroll Vband flang turbo housing? Or do you have to use a standard t3 or t4 flange?

Click on the link in my signature :)

Joey and I use a T4 divided flange. I have not seen a divided VBand round flange. We do have vband flanges on the downpipe though.

They do not make a divided housing v band turbo.

Twinscroll is different from divided housing. Pm the shoden on honda-tech if you want all the info.

You need 2 waste gates, a divided housing turbo, pair the cylinders and a divided collector.

Here are some pics when I built my manifold. Its about to go on the dyno next week I hope.
https://cimg3.ibsrv.net/gimg/www.s2k...3279d4a6a7.jpg https://cimg1.ibsrv.net/gimg/www.s2k...f4b64e529a.jpg https://cimg4.ibsrv.net/gimg/www.s2k...9dc7d6f180.jpg https://cimg9.ibsrv.net/gimg/www.s2k...732b13538a.jpg