RB20 Turbo selection (twinscroll housing advice)

[iruvyouskyrine]

RB20 Turbo selection (twinscroll housing advice)

Hey all,

To start, this is not going to be another "i just bought my mates R32 and it had stock turbo can you plz reccomend an ebay turbo for 300kw maxx plz thanks". I started this topic because i couldn't find anyone or anything on this forum close to what i want even after searching and reading the whole "RB20 turbo upgrade" thread.

The basic info/Supporting mods
> Completely standard RB20DET Silvertop (with the possibility of doing valve springs)
> NIStune with flexfuel setup
> ID1000's
> 3" straight through exhaust
> 45mm divided turbosmart hypergate
> RB26 inlet manifold including ITB's
> Hypertune FMIC
> Gibson Motorsport GTS-R T3 twinscroll exhaust manifold

This is in an S15 that will be my (secondary) daily and 90% drift 10% circuit car. My goal is to make a minimum of 230ish kw on 98 octane fuel, while keeping everything as responsive as possible. Yes i know that responsive and RB20 don't belong in the same sentence and i know that it's never going to happen, but anyway. There is plenty of results all over the net for highflows/GT2871/TD06 in 18 and 20G formats, but these are all using either the stock manifold or various brands of high/low mount open T3 manifolds and standard intake piping with generic intercoolers and long piping.

Basically nobody as far as i can tell has ever gone to the lengths that i have to give the RB20 as much of a fighting chance at making some decent power as early as possible. So my question is what turbo setup should i use. Keeping note that any turbo i will run will have a twinscroll manifold and twinscroll rear housing to try and keep as much response as possible.

I can use something like a GTX2860/63/67/71 or bump up a frame size to a GTX3067 (Note: 67 no 76). Originally i had canned the GT28 series idea because i was under the impression that there wasn't any twinscroll T3 housings available for GT28's so i had basically accepted that i was going to have to run a GT30. But i found that ATP have this housing available that is exactly what i need. 

So now knowing that i am back to the drawing board to try and decide what best suits my application. Things of note, 220-230kw minimum on 98 octane would be ideal, but i will be running E85 and a 45mm turbosmart hypergate off the exhaust manifold and i am happy to run big boost (20-25psi) on ethanol to make some decent numbers. Hopefully the 45mm gate should relieve some pressure on the turbo if i decide to go with a GT28 based setup.

GTX2860/63/67 with twinscroll T3 .82 A/R housing or GTX3067 with twinscroll .83 A/R housing.

Hopefully someone like Lithium/disco/darren can chime in and give me some insight into roughly what power these turbos are capable of on an RB20 that has been given every chance haha.

Thanks

(INB4 why the fark is some idiot wasting his time and money on an RB20)

[Lithium]

I will think harder about this... But fwiw after experiencing a 3SGTE with a twin scroll EFR7163 with a flange adapter so it fit the stock twin scroll manifold I was blown away.  The thing could pass for stock response, one of the first topics me and "the lads" hit on was the amount of feelings you could hurt with that turbo on an RB20.

I straight up reckon it would drive at least comparably to the ever popular RB25 upgrade, but with the ability of achieving your power target with change on 98.

To be honest most turbos in that power range are going to be single scroll or a different flange but another turbo which did pop into my head immediately is the MHI/FP collaborated effort - the TF06-18K which was developed as a factory option ~50lb/min turbo for EVOs.  They spin "the right way", make good power and seem to spool very well for the power they make.  A bit like a turbo that flows more than a 20G and spools similar to an 18G at worst from memory. 

 

Just the first things that came to mind when I read your post but I will think more on it.  I do feel a little that twin scroll may complicate where you are at a bit but will keep it in mind 

[Lithium]

Re-read that.  f**k yes, if you can get a .83 T3 twin scroll GTX2860R and are keen to do E85 then absolutely do that. That would be mad.

I don't have a working lap top so I am not inclined to do the math right now to guesstimate exactly what it would be capable of but I have quite a strong gut feeling that your 230kw+ target would be well achievable.   

Edited April 12, 2017 by Lithium

[NickRB20]

Spending $400US+ shipping on a rear housing?!

[R_34]

The GTX2860 has 39/42lb/min worth of flow around 20/25psi range.

The gen2 is also around this flow (slightly higher actually) at the same PR but it's limited by overspeed, not compressor choke like the gen 1.

The GTX2863 has 42/43lb/min max flow but still has a 68% compressor efficiency around the 40lb/min.

The RB20 is only 2L and not that efficient at breathing so I definitely stay with a GT28 turbine, the 63 is the way to go IMHO but if response is key and the limiter set not too high the 60 is a wiser choice.

And 400usd on an housing is not that high, I was also thinking in going GT28 turbine but internally gated as I'm still on stock manifold and that was a 600usd combo for the ford 5 bolt housing plus the swing valve assembly. Combined with a GTX super core I was right on the same price of the EFR that only require a 50$ T3/T4 TS adapter to be become a bolt-on affair for twin scroll internally gated turbo. Going external gate was even more expensive between the gate price, the turbo + its housing and the need to make my manifold modified somewhere to install a gate on it.

No matter what you choose I'm keen to see what you'll achieve with that little sucker.

[Kinkstaah]

EFR6758

[iruvyouskyrine]

I knew that people would come in here recommending EFR's haha. From what i have seen they don't do a T3 Twinscroll housing for the smaller size turbos that i would be looking at. Plus they are very expensive (i know the cost of a garret, then housing, then wastegate add up but still 3k for a EFR is a lot of money for an engine that cost me $20 haha). If BW did twinscroll T3 in the correct turbo size i may consider it.

Lith so you are saying that a GTX2860 with a .82 A/R T3 Twinscroll ATP housing that i linked before would be the go? I am 100% going to be on E85. Like i said i would like to make around a minimum of 220-230kw on 98 and medium boost, but i am happy to push this turbo and engine very hard on E85 and make some decently high numbers.

R_34, is the 3-4lb/min of airflow between the 60 and 63 a lot? I really don't know heaps about turbo airflow and compressor maps to be honest. I will be spinning the engine to at least 8krpm. Any idea how much difference in response (i know it would be hard to guesstimate) between the 60 and 63?

[R_34]

You still can put an adapter flange T3 to T4 twin scroll and bolt an EFR. But B1 frame like the 6758 doesn't come TS and externally gated you'll need to weld shut the flapper for that.

No the difference in flow is not that much, it's more the better efficiency of the compressor at high airflow that is significant, we're talking almost 10% more efficiency at high rpm on kill mode. For high rpm operation (8k+ rpm) the 63 is the go, if you keep the redline lower (7/7.5krpm) the 60 is the go.

I'd say 300/400rpm later spool and a smidge more lag with the 63.

[iruvyouskyrine]

Yeah i had a bit more of a look at things today and decided that i don't think i will go with an EFR. I don't want to be messing around with adapters and they don't have the correct housings for my application. I know i could weld up the internal gate but then i'm not a huge fan of dropping $3k+ on a turbo to go and weld the gate shut lol. Was having a read through the EFR turbotech PDF and it seems that only the C type rear housing (58mm +) comes in twinscroll?

I know i keep banging on about twinscroll but i think that is going to be a huge part of keeping as much response as possible with the RB20.

300/400 seem like quite a lot. 10% compressor efficiency, i guess that just means that the turbo is working easier to flow the air? Looking like 2860 might be the go then and just keep the revs sane. How hard is a 2860 going to be working running 25psi on E85? (standard RB20 cams)

Thanks for your help so far mate!

[R_34]

Yep TS externally gated begin with the 7064 and up. On 58mm turbine there is no twin scroll EWG option, you either choose to run EWG with a single scroll or IWG twin scroll but not both. If you don't want to run adapter, keep the twin scroll option and a "small-ish" turbo then there is no EFR for you unfortunately. 

And yes the 63 will flow the air with more ease at high rpm meaning the engine will breathe better.

At that pressure the gtx2860 will certainly be close or beyond overspeed and choke. You'll don't need to run that kind of pressure to crack your power goal, 20psi will certainly get you there given you're externally gated.

[iruvyouskyrine]

I guess EWG isn't a necessity but i just love the sound haha. Plus adds a bit of future-proofing. If/when this RB20 lets go this manifold will be going on a RB26/30 so would be nice to have an external gate if i stick with garrett and want to run a GT35 size where IWG would not be a good idea. Still leaning more towards a GT28 than an EFR, despite knowing that an EFR would probably be the best (strictly performance wise) for what i want.

Yes the 2860 should definitely crack my 220-230 98 octane goal, but just wondering what sort of figures i would be looking at when i feed it E85 and really lean on it hard.

[R_34]

I'd guess 250, 270 maybe, not more. Because you're searching the most response you choose a turbo to run it very close to its max capabilities without headroom. It'll do 230 on P98, and you might find an other 30/40kw with E85 and more boost.

[Lithium]

I have been resisting saying so, but honestly - the Kinugawa TD05 16G6 with an externally gated T3 housing really shouldn't be overlooked here if you want an externally gated T3 option.  

They are a seriously underestimated performer - it would definitely hit your power targets in E85 and the response is very good with them, would be a really good match for a stock RB20 aimed at 20-25 psi max.  Not saying it would be as good, let alone better than the GTX286x BUT after experiencing both GT28x and 16Gs on the same motors I really am not convinced in the price reward when there is the effort of going external etc is factored in etc.

 

Edited April 17, 2017 by Lithium

[iruvyouskyrine]

A lot of my mates used to run Kando turbos but apparently since the old owner (Eiki Takada or something like that?) left and started Mamba quality has gone downhill. This seems like the perfect time to mention that i won't be running a genuine Garrett unit, i will be running a Mamba one. A few of my mates have moved to Mamba now and have had excellent results and longevity (fingers crossed) so far. I can pick up a GTX2860 CHRA and compressor housing for $849 AUD, which would suit me perfectly as i can just buy the ATP GT28 T3 twinscroll housing seperately. 

http://shop.mambatek.com/product.sc?productId=1751&categoryId=22

When you say 16G6 what does the second siz mean? I had a bit of a look bt couldnt find anything on it. I presume you mean a 6cm rear housing?

[Lithium]

There is a "normal" 16G which are why people underestimate stock EVO turbos etc quite often, can't remember the exact flow but it's barely over 30lbmin I think.

The 16G6 is the "EVO" version of the 16G which is a more high performance take on It, they are efficient to much higher pressure ratios  (presumably to be more suited to running with a restrictor etc) and are also often suggested to flow in the area of 40lb/min so long as they are in a housing which will allow it.

I would strongly suggest the 8cm if you were to go that direction.  Have tried them on 4AGEs and SR20s  (the Kinugawa version with the 3" antisurge intake) And spool has been excellent and flow been more than satisfactory for those.  Have only tried an EVO2 16G on an RB20 so small housings all around but better in every way than the typical RB25 upgrade.

[iruvyouskyrine]

Okay did a little more looking at it seems you are correct (surprise surprise haha). mitsu went to the 16G6 from evo 4 onwards they went to the G6 flavour, as well as going reverse rotation. It's funny that everything is going full circle because i was initially going to try and run an evo 8/9 turbo on the RB20 but gave up as the reverse rotation was going to make it way too much hassle (had originally planned to do it on the cheap, because RB20, and the fact you can pick up standard evo turbos for not much at all).

From what i can see Mamba don't do a TD05-16G6, infact they only do one 16G, http://shop.mambatek.com/product.sc?productId=1848&categoryId=22

I don't think this is the path i want to go down really, journal bearing and open scroll housings. the GTX2860/63 seems to be the best bet at the moment.

Made up an excel sreadsheet to see the major differences between everything. Didn't find any results for RB20's using the new GTX286X series turbo's, but did find out the the HKS 2530 is basically the exact same size as them. If i could get 2530 type power with even earlier spool that would be perfect. Make 220ish on 98 octane and then really lean on it on E85 with the .83 A/R housing and external gate and make some decent numbers that would make me very happy.

[discopotato03]

I would be looking at trying something with standard RB20 BB turbo sized housings or at most the HKS 0.64 AR one in T3 flange . These don't look too big but they will keep the exhaust gas speeds up . You cannot compare a small bore short stroke 2L six to a 2L four , too many differences .

With Mitsubishi they were trying to compete within the restrictor Group A regs and they knew it was going to fall flat on its face at 5500 revs . What they often did was actually reduce the compressor wheel size to a 15G and tried lighter materials like titanium alloy turbines and in a few cases magnesium compressor wheels . IIRC the Evo VI TMEs made peak torque 300 revs earlier than GSRs but the real RS2 based TMEs were lighter cats too . 

More later .

 

[Lithium]

9 hours ago, iruvyouskyrine said:

Okay did a little more looking at it seems you are correct (surprise surprise haha). mitsu went to the 16G6 from evo 4 onwards they went to the G6 flavour, as well as going reverse rotation. It's funny that everything is going full circle because i was initially going to try and run an evo 8/9 turbo on the RB20 but gave up as the reverse rotation was going to make it way too much hassle (had originally planned to do it on the cheap, because RB20, and the fact you can pick up standard evo turbos for not much at all).

From what i can see Mamba don't do a TD05-16G6, infact they only do one 16G, http://shop.mambatek.com/product.sc?productId=1848&categoryId=22

I don't think this is the path i want to go down really, journal bearing and open scroll housings. the GTX2860/63 seems to be the best bet at the moment.

Didn't find any results for RB20's using the new GTX286X series turbo's, but did find out the the HKS 2530 is basically the exact same size as them. If i could get 2530 type power with even earlier spool that would be perfect. Make 220ish on 98 octane and then really lean on it on E85 with the .83 A/R housing and external gate and ake some decent numbers that would make me very happy.

 

Fair enough, was just suggesting an alternative which in ways is better suited to the RB20 - having a bit more turbine, coming natively with a T3 housing and not being too expensive. I'm definitely not saying the 16G is the best thing, though I am dubious of recommending a knock off DBB turbo until I have any indication that it's reliable etc.  We know nothing about the compressor efficiency etc either, you absolutely cannot compare compressor sizes and assume "it's the exact same size" - blade angles, count etc will all affect spool and flow.  

 

8 hours ago, discopotato03 said:

I would be looking at trying something with standard RB20 BB turbo sized housings or at most the HKS 0.64 AR one in T3 flange . These don't look too big but they will keep the exhaust gas speeds up . You cannot compare a small bore short stroke 2L six to a 2L four , too many differences .

With Mitsubishi they were trying to compete within the restrictor Group A regs and they knew it was going to fall flat on its face at 5500 revs . What they often did was actually reduce the compressor wheel size to a 15G and tried lighter materials like titanium alloy turbines and in a few cases magnesium compressor wheels . IIRC the Evo VI TMEs made peak torque 300 revs earlier than GSRs but the real RS2 based TMEs were lighter cats too . 

You talk like I've not long considered all the variables, let alone have a good idea of the history or reasoning behind these things.   Yes, I can compare the behaviour because we tried 16Gs on RB20s over ten years ago.  Thus far they are the best turbos I've experienced on them, not that I've experienced a heap first hand- but imho they drive better than the likes of an HKS GT2535 on them.  There are hardly any turbos you will find that allow an RB20 to start building good boost without too much work comfortably under 4000rpm and also make >200kw @ wheels on 98 or crack 250kw on E85.

 

[discopotato03]

Twas just some thoughts for the OP Lith not a shot at you .

 

Edited April 19, 2017 by discopotato03

[iruvyouskyrine]

Not looking for a magic solution, just looking for the best possible turbo for my application.

Lith I understand what you are saying and this is exactly what I want. Suggestions of things to look into that I would otherwise not consider. I understand your hesitation with the brand but I have confidence in them, my mates have used them with no issues for a while now. Like I said earlier I really don't know the finer details of turbos like the blade count and angle etc affects the performance. I thought comparing the sizes of the wheels would give me at least a basic indication of roughly what to expect from each turbo.

Disco why would you reccomend the. 64 open T3 over a. 83 Twinscroll for the rear housing? I though the divided larger housing would be a best of both world type situation?

Thanks for both your inputs