True Twin Scroll Turbo & Manifold Design Discussion

[discopotato03]

Yes some ahh candid thing at times .

Inline six facts . Piston and power strokes are phased 120 crank degrees apart in the 153624 order . Every four stroke cycle will have 720 crank degrees but they each start 120 crank degrees apart in the above order .

An I6 crank is phased like an two I3s joined at the crank but they don't work the same because the three goes 123 123 etc where the six goes 153624 .

I6 exhausts can be grouped like two I3s but the split pulse I6 is only exhausting into each three branch manifold half as often .

I believe the thing to understand about split pulse turbocharging is that it probably doesn't achieve huge differences if the turbocharger is large for high rev big number performance . Any engine that has big passages and big turbines and housings isn't going to have 6.2L NA torque at 2000 revs . It is a lot easier and cheaper to do big with single scroll turbo systems and if you have adequate engine capacity to start with it doesn't have to go like a Morrie pulling a B Double .

I think the thing to realise is that an acceptable pressure balence across the engine when its running on full boost/load is the way to make strong torque .

Doing everything the difficult expensive ways should broaden the engines usefull rev range , with turbochargers the limits are generally the non linear performance of rotary compressors and exhaust driven turbines . The result is being able to enhance half to two thirds of an engines operating range but not the whole lot .

Best overall seems to be the most cubes and the least weight , A .

[mico]

k i totally get it now by how the firing order, a split pulse works

[PJ.]

4. Tomei did back to back testing - split pulse vs single entry and tuned length vs normal runner manifolds in every possible combination and the results were basically nil gain or so minimal it wasn't worth the extra coin

Well, from my experience twin scroll vs single entry = two world's away, every single time.

We have back to backed a Trust twin scroll single gate setup vs 6boost twin scroll twin gate setup and it went down like this.

Test mule was an SR22DET with T78 kit, wouldn't come up onto the converter even after 20 seconds. Changed the manifold and fell over when after 4-5 seconds it had 20psi and the gates were open.

No other changes, true story!

[The Dan]

Well, from my experience twin scroll vs single entry = two world's away, every single time.

We have back to backed a Trust twin scroll single gate setup vs 6boost twin scroll twin gate setup and it went down like this.

Test mule was an SR22DET with T78 kit, wouldn't come up onto the converter even after 20 seconds. Changed the manifold and fell over when after 4-5 seconds it had 20psi and the gates were open.

No other changes, true story!

Did you just agree with me? It's hard to tell

I was talking about split pulse manifolds vs single entry manifolds - not single gate vs twin gate.

twin gates are awesome........if you have a spare $800 to throw away why not?

we will continue to gate off housings. It works and works extremely well.

[DVS JEZ]

Did you just agree with me? It's hard to tell

I was talking about split pulse manifolds vs single entry manifolds - not single gate vs twin gate.

The way i saw PJ's post was the trust twin scroll (split pulse) was a poor design so any testing they (tomei etc) have done may not be to the full potential of a real twinscroll manifold.

[The Dan]

The way i saw PJ's post was the trust twin scroll (split pulse) was a poor design so any testing they (tomei etc) have done may not be to the full potential of a real twinscroll manifold.

They made their own manifolds for testing. I think it was the V35 engine it was tested on, I got it via email in the Expreme newsletter probably about a year or 2 ago

[Weapon X]

This is my twin waste gate setup. I took a non waste gate Full Race and modified it to what I think works best. I just don't like heat that close to the parts I want cool. AC still on mine it's hot outside.

I can pop off the gates in about 5 minutes to change springs.

I understand the idea behind the gate off of the housing I may try it on a car but not mine.....works been done

I

Edited August 5, 2012 by Weapon X

[eXquiSit]

does the length of the pipe from the manifold to the gate affect any type of performance??

[The Dan]

does the length of the pipe from the manifold to the gate affect any type of performance??

Yes. If you make the gas easier to get out through the turbine, it will continue to do so

[eXquiSit]

ie. the shorter the better?

then have a longer screamer if necessary to direct the gas after the gate with no affect on any type of performance?

ps. thanks for the help!

=)

much appreciated!

Yes. If you make the gas easier to get out through the turbine, it will continue to do so

[The Dan]

Screamer length can be long

Gate entry pipe is better short

[eXquiSit]

thanks mate!

=)

[discopotato03]

There are some advantages to mounting external gates off turbine housings and being able to remove the gate with the turbo/turbine houing makes life easy . Also the ducting to external gates on fabricated manifolds means they sometimes have to take packaging into account at the expense of gas flow into the gate .

A turbine housing is basically a collector and provided the passage at the mounting flange is large enough to pass all the exhaust , inc the gates volume , its no problem . Now because the collector "tapers" so to speakits its a good place to vent exhaust gasses because its slightly upstream of a potential pressure rise point . If you can angle the gates entry to face the exhaust manifold you can benefit from the gasses partially directing themselves into the wastegate . If its at right angles to the gas flow you can have problems getting the gas to change direction and flow out the gate - especially when the gas speed is high . There is a picture of something like this in Corkys book Maximum Boost .

Wastegate vent direction is the reason that some integral wastegates aren't the most effective in a high gas speed high output turbo engine . The old Sierra type turbine housing and some European IHI IW housings are a bit better in this area .

I wonder how a big T4 flanged twin entry turbo would work with two external gates mounted off it ?

A .

[Weapon X]

does the length of the pipe from the manifold to the gate affect any type of performance??

On a single yes on two don't think so.

[Adriano]

What are you guys paying for a twin scroll housing, im looking to get one for a gt35r probably a 1.06 if thats what they come in.

[B-rice]

i recommend you guys read through this its a back to back testing of a full race twin gate manifold vs a HKS single gate manifold. Just a summary on the test they compare to see which exhaust reaches full boost quickest. they examine which produces more wheel torque the earliest, and which has the least exhaust back pressure. It seems from the results that the results are just a 100-300rpm difference as said by a few previous comments.

http://www.supraforu...ld-test-results

noticed they also do a comparison on journal bearing and DBB which i think you should have a look at aswell

Edited January 16, 2013 by B-rice

[iruvyouskyrine]

Is it possible to run a single gate off of a twin scroll rear housing? Have seen it done a lot running it off the manifold but never off a twin scroll housing.

I am getting a manifold custom made and don't want the wastegate on there for certain reasons. If i can't do it i will probably run a internal gate turbo, but if it is possible then that is the direction i would be looking to go.

 

[AngryRB]

Yes can be done, don't put the gate pipe too far along the scroll though, 

[iruvyouskyrine]

Why?

[Sick_R31]

Around the 6 minute mark you can see the exhaust side setup.