Twin Scroll Vs Single

[juggernaut1]

Has anyone used Billet turbos? http://www.billetturbochargers.com/

It does not seem that a lot of people have used them, I am assuming you could get a turbo built to specification with twin scroll housing, billet wheels look awesome too.

Mike

A member on NS used a twin scroll Billet turbo equivalent to a TO4Z on an SR. I'll see if can locate the dyno....and report back.

[Angus Smart]

Yeah i agree on the 188 bieng a pretty poor choice, but i was not quiet thinking of going that big.. i just have the whole t88 kit minus the turbo at home.

Could the reason on the 3788 be its relativity new? or will it end up bieng a mis match affair.. does it really fall short bieng between 3582r-4088r what kind of power would a 3582 bring to a built 2.6 like mine?

will be running 98 pump fuel, was considering giving e85 a go but my engine builder is a bit iffy with it at the moment and recommends i wait a little till it gets established more. + i've bought all the fuel gear to run 98.

[juggernaut1]

SR 2.2 litre Billet ZP turbo with twin scroll 1.0 ex a/r

300rwhp by a tad over 4500rpm, 400rwhp by 4,850rpm, 488rwhp 7500 rpm - looks like power was still climbing at 7500

Edited May 14, 2009 by juggernaut1

[bigmikespec]

SR 2.2 litre Billet ZP turbo with twin scroll 1.0 ex a/r

300rwhp by a tad over 4500rpm, 400rwhp by 4,850rpm, 488rwhp 7500 rpm - looks like power was still climbing at 7500

That looks like a pretty sweet set up, equivalent to a TO4Z and you are at full noise at just over 4500rpm on a 2200cc engine. Looks pretty good, as I said I am not sure why more people do not go down this route?

Even a set of twins with billet wheels and fancy bearings (silicon nitride), able to flow the same as GT-RS's mounted on the standard cast manifolds would be cool as, I-rection.

Mike

[underground]

I've had the GT4088R, The Borg Warner S374, the S372R, and now the Billet 6765....soon to try the Billet 6262.

Being a Precision Distributor, I wanted to find out whether the hype surrounding the billet wheels was fact or fiction.

Going from a Borg Warner 72mm to a Precision 6765 netted me full boost 1700 RPM's sooner. (7000 vs 5300).

I lost about 40whp at peak, but picked up power throughout the powerband, which was worth the switch.

Here is my latest dyno graph, showing the T4 .68 A/R. Notice that torque/boost falls off, indicating the exhaust housing is too small. I have a .81 A/R backhousing on order, and should have some new dyno numbers to post this week.

They also make a .96 A/R, though I feel the .81 A/R is probably the housing to use on a street setup RB26.

25 PSI

33 PSI (Full Boost at 5300 RPM)

33 PSI with -4 Degrees Timing on the Intake Cam Gear (Full Boost at 5600 RPM)

[Lithium]

Awesome cheers for sharing - very keen to hear how the 6262 goes on it Any chance of overlays of any of the different turbos?

[juggernaut1]

A tech article on twin scroll turbo systems I came accross:

http://www.full-race.com/modified-twinscroll/index.html

[discopotato03]

Good article that one , pretty much explains the differences advantages/disadvantages of both systems .

In the last section backpressure into TS/SS turbos is a crude term to use , exhaust gas pressure is a bit more informative to the wide audience these magazines get IMO .

Note that the "Minis" turbo is not huge and many of the OEM Mitsy and IHI turbos used on TS EJ's aren't either .

They are all about making lots of torque without lots of hot side restriction in front wheel drive based cars .

Evolutionm.net punters are just getting stuck into the Garrett bolt on TS GT3076R for Evo 10's , the results should be real good once they get around the hurdles of tinkering with late model cars .

As I keep saying twin scroll twin integral gate turbine housings is what makes a proper TS system a practical reality in a road car . The above mentioned GT3076R is probably the first aftermarket one and if it's a run away success we may see more as the petrol head world wakes up to their potential .

I'm pleased that the article made mention of exhaust gas temperature meaning emissions - NOx .

Fuel consumption can be improved through "cleaner" mixtures but its also a tuning/state of tune issue .

Its these things that stand a good chance of getting major manufacturers attention in this day and age .

Interesting times , cheers A .

[bigmikespec]

All things being equal, for example:

Considering a standard stroke RB26 with mild cams and head work is the extra time and money involved in a properly set up twin scroll, single set up (TS manifold, twin gates, TS turbo housing) worth it in terms of performance over a well set up twin turbo system (assume ported manifold, high flowing dumps/exhaust)...?

Is the extra effort to make a proper TS set up, just to achieve what twins can already do in terms of performance?

[Lithium]

Considering a standard stroke RB26 with mild cams and head work is the extra time and money involved in a properly set up twin scroll, single set up (TS manifold, twin gates, TS turbo housing) worth it in terms of performance over a well set up twin turbo system (assume ported manifold, high flowing dumps/exhaust)...?

Is the extra effort to make a proper TS set up, just to achieve what twins can already do in terms of performance?

Guess it depends on what you started with and what you want from it etc. If you go a twin scroll T4 based turbo upgrade you potentially don't have to change much in future, you have a more efficient setup (nicely designed manifolds/external wastegate setup), the engine bay is much more maintence friendly etc. And of course there is the whole obvious fact its just cooler

[juggernaut1]

All things being equal, for example:

Considering a standard stroke RB26 with mild cams and head work is the extra time and money involved in a properly set up twin scroll, single set up (TS manifold, twin gates, TS turbo housing) worth it in terms of performance over a well set up twin turbo system (assume ported manifold, high flowing dumps/exhaust)...?

Is the extra effort to make a proper TS set up, just to achieve what twins can already do in terms of performance?

The benefits of twin scroll are not necessarily seen on the dyno as that is a WOT application - but partial throttle/transient response and the ability to spool and re-spool (on/off throttle applications) is where its at.

Some of the circuit racers in the US with SR's have switched to twin scroll from single scroll and are claiming to have dropped 2 sec's off there lap times - which is nothing short of incredible when they've probably already exhausted every other avenue to improve lap times.

A 2.5 litre Subaru that Geoff was involved with switched to a GT35 T4 twin scroll setup on an otherwise stock engine and set a lap record - even outgunning the new GTR.

Edited May 26, 2009 by juggernaut1

[GT-RZ]

All things being equal, for example:

Considering a standard stroke RB26 with mild cams and head work is the extra time and money involved in a properly set up twin scroll, single set up (TS manifold, twin gates, TS turbo housing) worth it in terms of performance over a well set up twin turbo system (assume ported manifold, high flowing dumps/exhaust)...?

Is the extra effort to make a proper TS set up, just to achieve what twins can already do in terms of performance?

Twin scroll effectively tries to offer a twin turbo setup using one turbine... twin scroll just separates the pulses untill it hits the turbine where they will collide...

Twin turbos has no collission untill the exhaust, where you could infact run two exhausts and have no collission. Theoretically paralell twins will always be more responsive than twin scroll.

[PM-R33]

A tech article on twin scroll turbo systems I came accross:

http://www.full-race.com/modified-twinscroll/index.html

Good find, very informative article.

[bigmikespec]

The benefits of twin scroll are not necessarily seen on the dyno as that is a WOT application - but partial throttle/transient response and the ability to spool and re-spool (on/off throttle applications) is where its at.

Yes, that is what I am trying to get at. I know you made mention of two examples but neither of them were originally a twin set up from factory like an RB26.

Lith, if you can quantify that increase in efficiency to 1/2 second per lap of what ever, which would be very important to some, then great. If not, then it looks like the extra expense/effort may not be worth it.

I guess this is more of a TS vs Twins not TS vs SS. Sorry, O.T.

[Lithium]

Twin scroll effectively tries to offer a twin turbo setup using one turbine... twin scroll just separates the pulses untill it hits the turbine where they will collide...

Which is what you want? The turbine gets the full force of both.... without any "mess" from collisions before hand

Twin turbos has no collission untill the exhaust, where you could infact run two exhausts and have no collission. Theoretically paralell twins will always be more responsive than twin scroll.

I am not actually sure what to really expect, it would be interesting to know how they would compare but I personally can't see any obvious reason why twins would be more responsive. To be honest I'd almost expect a single to be a bit better in overall efficiency. The twins have a bit of a bonus in that they can have REALLY short runners, thats about it that I can think of.

[GT-RZ]

I'm just putting out a guess.

I just think that with twin turbo the exhaust housing is unsplit and maintains an optimum flow path through the turbine.

wheras twin scroll just has a divider over the one turbine (divider leaves a compromised flow path) which can't be as efficient as having two seperate optimum flow paths over the turbine?

twin scroll would certanly work better than one large path but not sure it would work better than two smaller seperate paths

not sure if i'm making much sense:

i think the next thing that is to be adopted is them size varying turbines (dont know what they are called?) from diesel truck world. as the turbine speed increases the turbine opens up creating a bigger turbine so you get response and top end! seen them but only on trucks so far

Edited May 26, 2009 by GT-RZ

[Lithium]

I'm just putting out a guess.

I just think that with twin turbo the exhaust housing is unsplit and maintains an optimum flow path through the turbine.

wheras twin scroll just has a divider over the one turbine (divider leaves a compromised flow path) which can't be as efficient as having two seperate optimum flow paths over the turbine?

twin scroll would certanly work better than one large path but not sure it would work better than two smaller seperate paths

Yeah definitely, we're all really hypothesising

I see what you are saying and not really too sure it would cause that much compromise - you'd pick the a/r to suit the fact its a split pulse housing... ie, with twins you'd maybe go .64a/r whereas on a single you'd be looking at .95-1.06.

Gases are inherantly good at being squeezed/forced places, so I am sure that the divide facing the turbine isn't going to worry them toooo much given that they are basically being forced at a bunch of spinning blades and are bound to expand, squish and swirl in all sorts of weird ways anyway.

I also like the fact that with the twin scroll setup there is a constant stream of pulses hitting the turbine, it will always have leverage on it whereas each of the twins will potentially have a far greater oscillation pre-turbine due to the gap between pulses. I really don't know for sure though, though its interesting to ponder. The twin scroll setups I have been exposed to honestly have blown me away in terms of response and spool, though I have never been in a car with twins that is using a similar engine spec and power level to another car running a twin scroll single to give a fair comparison.

I have however been in GTR running a single scroll .82a/r GT35R making similar power (getting towards 400kw @ wheels) and similar engine spec to ones running twin GT2530s and I reckon the GT35R setup was more responsive (at worst equivalent), so given the range of advantages a twin scroll 1.06 T4 setup on the same car would bring I dare say there would be no comparison between such a setup and a pair of GT2530s. It may not be apples and apples though as I suspect GT2530s might be capable of making more power.

Edited May 26, 2009 by Lithium

[juggernaut1]

Yes, that is what I am trying to get at. I know you made mention of two examples but neither of them were originally a twin set up from factory like an RB26.

Lith, if you can quantify that increase in efficiency to 1/2 second per lap of what ever, which would be very important to some, then great. If not, then it looks like the extra expense/effort may not be worth it.

I guess this is more of a TS vs Twins not TS vs SS. Sorry, O.T.

Whilst I'd love to....I can't show you any real life comparisons of the RB26 with TS vs twins.

[bigmikespec]

Whilst I'd love to....

Ditto, would not doubt be very interesting to see.

[Lithium]

I see ATPTurbo now have a 1.06a/r T4 twin scroll turbine housing for the GT3076R.... this has intrigued me quite a bit! I can't help but think that could be very interesting to try.