Twin Scroll Vs Single

[Phobic]

hey guys,

just curious whats the difference between a twin scroll turbo or a single scroll and whats the benefits of it.

example i read somewhere on here about someone thinking that a gt3582r with a 1.06 t4 twin scroll would be a good match for a rb30det

what would be the comparison to this turbo on a rb30det with a straight up gt3582r with a 0.82 rear

is the 1.06 t4 flange twin scroll a custom job or is that the standard for the 3582r when you choose to go the larger 1.06 rear?

thanks

mitch

[juggernaut1]

Ummm....I found I lost my licence much quicker with twin scroll.

Full-Race Motorsport specialise in twin scroll stuff and may make a manifold for the RB....otherwise contact 6Boost for a local product - although may be a custom job.

Edited May 13, 2009 by juggernaut1

[Lithium]

just curious whats the difference between a twin scroll turbo or a single scroll and whats the benefits of it.

example i read somewhere on here about someone thinking that a gt3582r with a 1.06 t4 twin scroll would be a good match for a rb30det

what would be the comparison to this turbo on a rb30det with a straight up gt3582r with a 0.82 rear

is the 1.06 t4 flange twin scroll a custom job or is that the standard for the 3582r when you choose to go the larger 1.06 rear?

I wonder what the odds are it was my post you are referring to. The 1.06 T4 twin scroll I am pretty sure is more of a recent thing to become available, .63, .82 and 1.06 remain to be the "typical" GT3582R turbine housing options.

The main disadvantage to single scroll turbos on 6cylinders in my opinion is the fact that you have 6 pulses which when fed into a common collector allow no gap between each other and as a result of which end up colliding - this generates pressure etc which is not really used for any great advantage other than having messy gas flow where all the cylinders are trying to breathe through. This means energy isn't used optimally to spool the turbo and can result in increased manifold pressure which does nothing other than make life more difficult for the engine to flow nicely.

It just so happens that the firing order of RBs is such that cylinders from the front three and rear three are always fired alternatively meaning if you collect the front three and rear three separately - instead of colliding with another pulse going through the collector, each new pulse is much more likely to hit the low pressure zone which always trails an exhaust pulse meaning instead of having extra effort to "push" gas out the valve there is chance of something relating more to a scavenging effect.

This basically means the exhaust energy is used much more efficiently, which can both spool the turbo better and also reduces manifold pressure meaning that for an equivalent flowing turbine the engine can tend to take more timing before hitting a knock condition (meaning potential for more reliable power!!). This kind of advantage is in my opinion twin turbos can be seen to perform "better" than singles in terms of response and spool on RBs, I believe its more to do with the more efficient use of exhaust energy than anything else and that advantage is completely negated by a well designed twin scroll turbo setup.

Some people I know and I have been discussing this for some time, and the general feeling so far is that an equivalent a/r TS turbine housing on a 6cylinder turbo motor seems to allow more power to be made than with the single yet also spool a few hundred rpm earlier. I'd expect a TS 1.06a/r housing similar to or better than a .82a/r single scroll one on a GT35R, but have a higher power potential on an RB but this is purely speculative as I've not seen any results from such a combination.

Here is a link to a thread about someone who I ended up convincing going to a twin scroll setup on their 300ZX after messing around for some time trying to get a good compromise between lag and power:

http://forums.toyspeed.org.nz/viewtopic.php?t=71870

Atpturbo.com sell Garrett GT3582Rs with 1.06a/r T4 twin scroll and .78a/r T3 twin scroll options.

Hope that helps

Edited May 13, 2009 by Lithium

[juggernaut1]

^^^^ what Mr Lith said.....in effect it improves the VE of the engine for a given rpm. The lower exhaust gas pressure results in lower exhaust gas residue in the cylinder which means you can add more timing and run a larger A/R and still have good spool. The extra timing is also something you will also notice at partial throttle i.e. street car or circuit car. For instance I run a twin scroll .78 A/R 3071 on an SR and it feels no different to the stock s15 turbo in response in the lower rpm - it just has bigger balls and loves a rev. From 4000 rpm its fantastic and revs out to 8000 with ease.

My tuner also noted how much extra timing he could put into it compared to a single scroll setup. In fact I think he's gone a bit conservative on the tune becuase he's not used to being able to add the extra timing, and could probably add more. In my discussions with Geoff Raicer (Full Race Motorsport) he also likes to see bigger cams used with bigger twin scroll A/R's - I guess thats just matching the cams to exploit the bigger exhaust A/R.

Edited May 13, 2009 by juggernaut1

[Lithium]

My tuner also noted how much extra timing he could put into it compared to a single scroll setup. In fact I think he's gone a bit conservative on the tune becuase he's not used to being able to add the extra timing, and could probably add more.

Yeah, have heard the same thing speaking to tuners - I find it a bit frustrating when they stay at timing levels they are used to on a setup which is clearly good enough that it can take noticeably more before it starts getting dangerous. If it were me on my own car I'd leave the same margain of error and enjoy the fruits of a more knock resistant setup

[juggernaut1]

Agreed......but I'm going to try E85 in my setup......that way he has no excuse to hold back

[Phobic]

so with a twin scroll a/r turbo you need to have a twin scroll manifold to suit aswell obviously with the front and rear 3 cylinders separated all the way into the rear housing.

[Lithium]

so with a twin scroll a/r turbo you need to have a twin scroll manifold to suit aswell obviously with the front and rear 3 cylinders separated all the way into the rear housing.

Yeah thats correct, you need to keep each pair of cylinders as separate as possible - ideally running twin wastegates though thats where you really start getting into perfectionism

Here is a pic down into the collector of a good twin scroll T4 exhaust manifold made by Kyle of 6boost:

And a twin scroll T4 turbine housing as I haven't quite been able to ascertain from your posts if you know exactly what it means:

So the pulses from the two sets of cylinders are kept completely separate until they hit the turbine wheel

[Angus Smart]

Correct,

I'd like a bit of advice on this topic too

I currently have a trust manifold from a t88 kit and large gate at home and want to give a single a whack, obviously want twin scroll.

Was looking at the newer Garrett 3788R, i wanted something responsive yet a nice whack of power.

Rb26

Engine specs are as follows,

Head:

270 in/ex 10.8mm lift, springs, retainers, guides, and a bit of porting done.

Bottom end:

86.5 Mahes, Pauter rods arp studs throughout Jun pump, sump mods etc.

3.5inch titanium exhaust. fcon v pro.

Would like some advice on what that turbo would be like. and power etc. what exhaust housing would be advisable also..

[juggernaut1]

so with a twin scroll a/r turbo you need to have a twin scroll manifold to suit aswell obviously with the front and rear 3 cylinders separated all the way into the rear housing.

Correct.....and ideally two wastegates - one for each bank of runners. The runners must be paired based on the firing order of the motor (not simply based on convenience) to ensure even pulses into each scroll - I'm not sure of the firing order of an RB - but Mr Lith has provided some insights in this regard in his previous posts.

Late edit: OK Mr Lith has beat me to it.

Twin gate SR version:

Edited May 13, 2009 by juggernaut1

[Phobic]

ok now i get what it means thanks for the insight.

in terms of power how much difference could it make having a twin scroll setup

Edited May 13, 2009 by Phobic

[Lithium]

Would love to be able to tell you, the whole trick here is its not that common a combination. In the instance of that 300ZX I posted a link to the thread about, he gained around 30kw when tuned to where they could safely take the timing on a T04Z setup but its a whole different car.

[Angus Smart]

I'd like a bit of advice on this topic too

I currently have a trust manifold from a t88 kit and large gate at home and want to give a single a whack, obviously want twin scroll.

Was looking at the newer Garrett 3788R, i wanted something responsive yet a nice whack of power.

Rb26

Engine specs are as follows,

Head:

270 in/ex 10.8mm lift, springs, retainers, guides, and a bit of porting done.

Bottom end:

86.5 Mahes, Pauter rods arp studs throughout Jun pump, sump mods etc.

3.5inch titanium exhaust. fcon v pro.

Would like some advice on what that turbo would be like. and power etc. what exhaust housing would be advisable also..

No body has any advice on this turbo? i know its kind of new. and would quiet possibly be a little less lagier than a 4088

[juggernaut1]

I would probably go and visit the full-race website or better still email Geoff Raicer....chances are if it hasn't been done by them or not being contemplated by them...it isn't worth doing.

Edited May 13, 2009 by juggernaut1

[Angus Smart]

Done and done, the turbo isnt listed on his webs, its kinda new i think... unless they keep their advertising up for ever..

[Lithium]

Done and done, the turbo isnt listed on his webs, its kinda new i think... unless they keep their advertising up for ever..

Sorry I completely missed that question. Umm the GT3788R I'm not so sure about, as it is the GT4088R and GT3582R seem pretty close to each other in performance and I'm not sure what the GT3788R is supposed to achieve. I had in my head it was for diesels, and has been used on them for some time - though it seems a bit reminiscent of the GT3082R - trying to make a good proven combination spool a little bit better by putting on a smaller turbine wheel ends up often just being a mismatched turbo.

What power targets are you looking for, and spool level are you willing to live with so that you started looking at the GT3788R? ForcedPerformance in the states have a range of pretty swish turbos which fit between GT3582R and GT4088R size, and a couple of people have used Precision 6262 and 6765 turbos on 2.5-3litre 6s (Nissan and Toyota ones) which pretty good results which I am still looking into.

The Precision 6262 is one which sits between GT3582R and GT4088R area and seems to be too good to be a true, an EVO 8 in the States running a T3 flanged one ran an 8.9 with full interior on E85 running one recently! If the hype turns out to be true, one of those with a decent T4 twin scroll setup on an RB26 like yours could be an unbelieveable street setup.

Edited May 14, 2009 by Lithium

[Angus Smart]

I might verry well be the first person thinking of the 3788r on a rb26..

would love somewhere around 450kwatw for a track driven car (doubt i will see much street) I was looking at peoples setups that have tried the 4088r and apparently they are a bit dopey, thought the 3788 would possibly make for a little more response.. the 3582 seems a little bit less with power..

i wanted something that had the surge of power of a single, was considering a t88 or smaller to begin with but since they are rather old i'd rather use a garrett since its locally done and i can get pretty good prices on them, i've seen some fairly responsive setups with t88 bieng used for track work and cant really see an issue with revs as your often never below 4000 anyway.

Currently i have something close to a gt-rs with a samller comp housing dont think i will see 400kw with them.. but i could...

i just hope my R34 getrag with nismo imput shaft will be ok for the power..

[discopotato03]

Full Races Geoff Raicer mentioned a while back that those GT3788R's are not that good , probably the same not enough turbine for the compressor or too much compressor for the turbine depending on which way you read it .

The BB GT4088R's (these are petrol spec BTW) are supposed to be very good provided they are not too big for the application . Sadly there is not really a slightly smaller equivalent and shrinking the turbine does not achieve the same thing .

Garrett have a diesel spec GT3782R (same comp as GT3582R) with the diseasel spec turbine - HP not UHP .

Maybe one to ponder is the plain bearing GT4082 , these would have potential if Garrett produced them with a petrol spec turbine and a BB center section . Still GT40 but smaller trim turbine and 82mm GT40 compressor .

I think a well sorted 26 head on an RB30 bottom could possibly use a GT4088R .

Cheers A .

Edited May 14, 2009 by discopotato03

[bigmikespec]

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

[Lithium]

I might verry well be the first person thinking of the 3788r on a rb26..

I think the reason for this is a lot of people have treated them with a certain amount of contempt being the potential mismatch scenario which DiscoPotato also mentioned. I personally would much rather just go either GT3582R or GT4088R those two and the GT3788R were the only choices. Discopotato - The GT4082 uses a less trim comp wheel than the GT3582R, people seem to often fall short of even a GT3582Rs power potential with them though that could be a side effect of them being mainly bought by people looking for a bargain and as such not being willing to spend the money to get the entire setup.

I had a GT4082 which I obtained for under NZ$300 last year and on a 2.5 with a twin scroll manifold it was making 1bar by 4500+rpm, BB core would bring it in a bit sooner but I'm not sure why I'd go one over the GT35R.

would love somewhere around 450kwatw for a track driven car (doubt i will see much street) I was looking at peoples setups that have tried the 4088r and apparently they are a bit dopey, thought the 3788 would possibly make for a little more response.. the 3582 seems a little bit less with power..

i wanted something that had the surge of power of a single, was considering a t88 or smaller to begin with but since they are rather old i'd rather use a garrett since its locally done and i can get pretty good prices on them, i've seen some fairly responsive setups with t88 bieng used for track work and cant really see an issue with revs as your often never below 4000 anyway.

By dopey you mean unresponsive? Imho if with a setup you are going to have a GT4088R being unresponsive, then I am fairly sure that a T88 would be that and a whole bunch more. I would love to have had exposure to a GT4088R setup but in this part of the world it seems they are a very uncommon mix though the UK and some US Supra guys seem to LOVE them on a street/track setup though they are using 3litre engines.

With a stock displacement RB26 you are going to always be exposed to a certain amount of lag, if you are aiming for 450kw @ wheels then in my opinion you should really be expecting to have to live in the 5000+rpm range to keep it full on the boil. Which fuel are you intending on running it on?