Yes those gains are very very nice especially with less boost.

 

It looks like you gained 1000 rpms on when your pk tq kicks in. Damn going from 6 to about 5k is a pretty good pickup man nice setup.

 

Nice back to back comparison. Looks to me like the TS housing is choking the power band up top and at very low boost. If this test was at 40-45psi we would be seeing something altogether different as far as results. The comments would be "holy cow look how the power chokes up top!"

TS scroll has the potential to spin turbo faster. But usually this means the back pressure has gone way up along with it.

Sizing the A/R housing of TS can be done many ways. You can size it to see a big spool up change and then your top end will suffer. or you can size it to see no gains or modest gains in spool and there will be a top end gain or modest top loss depending on boost level.. The latter is how mitsubishi sized the exhaust side. they went from 7cm single scroll to 9.0/9.8/10.5cm TS. there goal was to improve all around performance. both turbos are fully capable of maxing out compressor side .

Lucas English has been converting cars to E85 like a madman. He has done a quite a few conversions on the early 7cm/16g and the later TS/ 16g/ 9.8/10.5cm . His observation is the early turbos are making a little bit more power from what he has seen.

http://www.dsmtuners.com/forums/dyno...o-iii-16g.html

last sentence post #1

 

I think this whole TS thing has been beaten to death.

The data is there for both cases.

Make up your mind as an individual and go with it.

 

Twin Scroll is the way to go IMO - great back to back test!

 

I kinda disagree, prior to this there had been very few back to back comparisons. It still seems to be a taboo subject for some reason.

 

The graph clearly shows the open housing does not match the TS in power or torque until almost 8500rpm, and this is despite the fact that the TS is run at ~2 psi less boost. After that the power and tq curves are identical, with power still rising until the very end.

What happens at 40-45psi is conjecture at this point, but 40-45 psi isn't a practicality for most of us. Regardless, there would have to be a substantial difference to make up for the loss of at least 50whp for ~1500 rpm and 700rpm of spool time.


The stock EVO IX turbo, factory TS hotside and all is capable of at least 522whp:

https://www.evolutionm.net/forums/ev...-ix-turbo.html

That is more than anyone can reasonably expect from such a small turbo. If there is something else that can deliver that type of power from such a fast spooling, responsive package, it has not been demonstrated here.

 

Interesting comparison.. can you give us more detail of the test?

For example:

1. exact turbine housing specs of the before and after housings
2. any other changes at all?
3. were both tests on spring pressure or were they both on boost control?
4. what were the differences in ignition advance at a few rpm points?
5. what about afr curves for before and after
6. were both tests done in the same gear?

My 2.4l / open 35r makes 30 psi at 4500 rpm... if I went twin scroll I'd love to believe I'd be making that boost under 4k like an Evo Green but it's hard to believe so I'm always skeptical.

 

There is nothing wrong with being skeptical. But when you consider that my 2.0L has 20% less displacement than your 2.4, and generates 20 psi by 4000 rpm in 3rd gear with an HTA 3582R, I would feel safe placing a sizable wager on your larger motor getting to 30psi easily before 4000 rpm with a comparable setup.

 

Ted the early 16g has been pushed to 507whp. pure bench racing to compare that to your 522whp on the later version. different dynos different cars. the 507 went way faster at track than the 522 car. I would rely more on Lucas comments that the early turbo makes more power on similar modded cars. he has done a handful of both turbos on similarly modded cars now.

comparing TS to SS with out back pressure posted is bench racing at its finest.

changing A/R in SC can have exact same results as graph in post one. may not be due to TS at all.

Norris is my hero. His latest fast spooling TS is just nuts. 3990 full boost on T04Z
http://www.lancerregister.com/showthread.php?t=255018

 

I've seen that boost under 4000rpm's on a few local 35r T.S. 2.3L Evo's....shouldn't be a problem at all.

 

Just about everything Lucas does is on a Dynojet, but that's not really what's important. The important thing is it demonstrates what is possible. If one can get 500whp (or 522whp) from a factory turbo, it would seem counterproductive not to take it in the configuration that delivers the best possible spool and transient response.



I wouldn't think so due to the sheer differences in design. Also, it's interesting that OEMs have virtually all made the transition to TS for their 4-cyl engines instead of downsizing open housings.