Forced Performance Hta Turbos

[Lithium]

5 minutes ago, Komdotkom said:

Hmm, if they did reverse rotation I'd be all over one I reckon.

I would say it's a case of when, not if the echo (Xona term for that kind of thing) versions come out of the new ones 

[Lithium]

14 hours ago, Komdotkom said:

Hmm, if they did reverse rotation I'd be all over one I reckon.

Here we go, this car "upgraded" from Precision Gen2 7675s to Xona Rotor 10569S (the previous generation 72mm compressors) using a reverse rotation turbo for one side and here is the video for how they found that: 

This car has just upgraded to the new XR7169S (also mirrored) which goes from being 105lb/min with a 99mm exducer to >120lb/min with a 92mm exducer, and so far have proven to be MUCH more potent than what this R8 was running at the time of the clip but no cost to spool. 

Out of interest that car is supposedly the quickest 60-130mph "street car" in the world according to Dragy results from when it had the old 72mm Xonas:

Edited February 7 by Lithium

[LaurelPWR]

seeing this thread revived makes me very very excited for the future of these guys new tech, especially with them having smaller frame stuff being looked at too. Cheers @Lithium you the man, as always 🖤

[Lithium]

10 hours ago, LaurelPWR said:

seeing this thread revived makes me very very excited for the future of these guys new tech, especially with them having smaller frame stuff being looked at too. Cheers @Lithium you the man, as always 🖤

Haha cheers man ❤️

On the topic of the smaller frame things being looked into (kindof), as much as I love to criticise low mount twins on RBs.... on BMWs they aren't so bad, I have quite a thing for BMWs S58s (which are a 3litre twin turbo straight 6) so was pretty interested when I caught wind that there is a prototype bolton turbo setup based on the latest Xona tech and while this is preliminary stuff, the power and powerband of this looks pretty insane:

500whp before 4000rpm, 970whp up top and that's with engine protection kicking in due to fuel pressure dropping off - they're upgrading that and expecting about 1050whp.   Absolute craziness from a bolt on low mount turbo setup on a 3litre engine, even if you factor in the US dyno thing these are wild numbers.

[joshuaho96]

3 hours ago, Lithium said:

Haha cheers man ❤️

On the topic of the smaller frame things being looked into (kindof), as much as I love to criticise low mount twins on RBs.... on BMWs they aren't so bad, I have quite a thing for BMWs S58s (which are a 3litre twin turbo straight 6) so was pretty interested when I caught wind that there is a prototype bolton turbo setup based on the latest Xona tech and while this is preliminary stuff, the power and powerband of this looks pretty insane:

500whp before 4000rpm, 970whp up top and that's with engine protection kicking in due to fuel pressure dropping off - they're upgrading that and expecting about 1050whp.   Absolute craziness from a bolt on low mount turbo setup on a 3litre engine, even if you factor in the US dyno thing these are wild numbers.

S58s are like what, 25 years of development ahead of the RB26? And the S55/S58 change up the turbo arrangement quite substantially from the N54 which requires both turbo dumps to do a pretty suboptimal turn.

Seemingly the solution to the I6 twin turbo issue is to actually just have the turbos staggered with a different exhaust manifold design for each turbo, that way the intake and exhaust piping isn't fighting each other quite so badly.

[Lithium]

5 minutes ago, joshuaho96 said:

S58s are like what, 25 years of development ahead of the RB26? And the S55/S58 change up the turbo arrangement quite substantially from the N54 which requires both turbo dumps to do a pretty suboptimal turn.

I didn't mean it as a dig at all, I get and agree with all that - I was just pointing out the irony of me being excited about a low mount twin setup when I'm usually so against them   

6 minutes ago, joshuaho96 said:

Seemingly the solution to the I6 twin turbo issue is to actually just...

... have a well match single turbo

The RB engine bay etc just doesn't lend itself well to it, and as you said yourself - an RB is no S58.  May as well build it to it's strengths. 

[GTSBoy]

The answer to the problem of twin turbos never providing the benefit they were intended to provide (earlier spool and better response for the same power level) is always answered by twin-charging.

[joshuaho96]

2 hours ago, GTSBoy said:

The answer to the problem of twin turbos never providing the benefit they were intended to provide (earlier spool and better response for the same power level) is always answered by twin-charging.

Sure, but modern GDI turbo can get deep into the boost as early as 1800 rpm in the case of the pre-LCI S55B30. It's actually absurd how little turbo lag there is because they can scavenge whatever air the cylinder can't aspirate and use it to spool the turbine anyways without having raw fuel shoot-through. And it holds power out to 7500 rpm. I don't think it's actually worth it to add the complexity of a crank driven or 48V compressor in this scenario. Garrett e-turbo style solutions might be worth it though as you can use the turbine as an exhaust energy recovery mechanism and basically eliminate the wastegate in most scenarios.

2 hours ago, Lithium said:

I didn't mean it as a dig at all, I get and agree with all that - I was just pointing out the irony of me being excited about a low mount twin setup when I'm usually so against them   

... have a well match single turbo

The RB engine bay etc just doesn't lend itself well to it, and as you said yourself - an RB is no S58.  May as well build it to it's strengths. 

I still wish someone could just do all the work to put an EFR7163 twin scroll on an RB26 so I don't actually need to apply any thought, just write the check and install pieces. Unfortunately that's just not what sells, anybody going single turbo is going to want something designed for at least an EFR8374. The one result I've seen of a single EFR7163 on an RB26 has been pretty disappointing but I'm unclear on why it seemed so mediocre.

[Lithium]

55 minutes ago, joshuaho96 said:

Sure, but modern GDI turbo can get deep into the boost as early as 1800 rpm in the case of the pre-LCI S55B30

Obviously a complete different kettle of fish, but the N55 thing I run around in these days is quicker than my old GT30R equipped R33 GTS25t and one of the marketing gimmicks they had about my car was it had 450nm from 1400rpm or something silly like that.   Like in real world terms it comes across as slightly laggier than that, sortof.   I can launch at 1400rpm and do a mid 12 so in terms of boost threshold its probably pretty on the money.

58 minutes ago, joshuaho96 said:

I still wish someone could just do all the work to put an EFR7163 twin scroll on an RB26

Why would you do that!?   It doesn't sound in the spirit of an RB26 to me, and per my previous comment - I clearly appreciate response!   

I think the absolute smallest turbo I'd entertain the thought of on an RB26 would be a twin scroll G30 660, I do prefer my EFRs but a 7163 would be a mismatch and a headache for the money and effort put into vs what you'd get from it.  7163 is magic for a small engine though. 

[GTSBoy]

Yeah, I've always looked at the 7163 in the same way that Josh appears to be doing, in that it seems to be a "magic" turbo for what can best be described as "sensible" power levels. And maybe that is more true on a 2L than on a 2.5 or 2.6L engine.

I always sort of thought that if I was going to go to the effort to completely change everything on my (remember, very nearly stock) setup, that I'd want a 7163. And at the same time I knew that there were all sorts of reasons why it wasn't a great choice, to do with flange styles and wastegates and so on. And I would never have demanded 600+ HP out of whatever I did. I think for a daily that is driven in traffic, there is little point in choosing a turbo that can do those sorts of numbers. And I want to be able to knife fight with the Karens in their CX-5s, not be left in the dust by the mad bitches. But....it seems like the G30s are actually the answer, even if they do seem like they are too big according to my possibly misguided priorities of the past.

What I actually want is an RB25 that comes on boost at 2000 rpm (or even better, if possible) so that there is some more torque than you get from the pre-boost threshold output, and is on max boost nice and early, say before 3000, and is happy to run out to 7500 or a bit more, making 500ish (engine) HP, ie, the upper 200s rwkW territory. I want better than stock characteristics at the bottom end and about double stock power at the top end.

I suspect that's why I still think about blowers.

[Lithium]

On 09/02/2024 at 4:06 PM, GTSBoy said:

What I actually want is an RB25 that comes on boost at 2000 rpm (or even better, if possible) so that there is some more torque than you get from the pre-boost threshold output, and is on max boost nice and early, say before 3000, and is happy to run out to 7500 or a bit more, making 500ish (engine) HP, ie, the upper 200s rwkW territory. I want better than stock characteristics at the bottom end and about double stock power at the top end.

I suspect that's why I still think about blowers.

I'll have to get some logs when I do a little bit more work on an R34 GT-R I've been helping set up.  Stock engine, 272deg cams, and a divided hotside Pulsar G35 900 with .85a/r T4 divided hotside and it drives fantastic - it's enough of an improvement over the old -5s that no data is really needed from our point of view to make a call on whether it's more responsive under foot to drive but boost threshold is always a handy metric.  

I'm far from saying that the G35 would be a good choice for the kind of thing you're looking into, more what I'm suggesting is "G-series" turbos seem to respond very well to divided hotsides and middling a/rs (obviously ensuring that it's not so small as to choke the given setup).   If a static cam RB26 drives like this R34 does with a 80+lb/min turbo, then I can imagine a 60lb/min equivalent match on a VCT RB25 would be fantastic. 

[Kinkstaah]

On 2/9/2024 at 2:06 PM, GTSBoy said:

What I actually want is an RB25 that comes on boost at 2000 rpm (or even better, if possible) so that there is some more torque than you get from the pre-boost threshold output, and is on max boost nice and early, say before 3000, and is happy to run out to 7500 or a bit more, making 500ish (engine) HP, ie, the upper 200s rwkW territory. I want better than stock characteristics at the bottom end and about double stock power at the top end.

I suspect that's why I still think about blowers.

I have what you want.

A centrifugal charger could work (with regards to throttle respoonse), but it won't provide enough _power_ at lower RPM to feel like it's really giving you boost early. They really do feel identical to a larger, NA engine.

The truth is I don't think this is going to exist anyway. I split multiple blocks purely on having too much power too early. POWER and low rpm equals a hell of a lot of torque, which creates all of the problems. I had a 2.8 with an EFR. It is as good as it's going to get. I guess you could go a 2.5 with a 7163 (or @CowsWithGuns's ill fated 7064), or go something silly like a bolt on manifold G25-550 with a .49 rear on a RB. I just don't think it's going to work.

I guess someone could run a RB25 with a positive displacement blower, but I'm already scoffing at the first part of this sentence as I type it. I just can't see it working in any reasonable/practical fashion that results in happiness.

My car drives really great and you should buy it. So I can buy.... something probably worse, as is the natural state of things. But I was the same line of thinking which lead to the heretic V8 decision. I wanted ~300kw of power, and I wanted that throttle response to be instant instead of waiting for 'laggy' EFR turbos to spin up, and that was with an EFR and a 2.8 running 11psi on the 7670.

[GTSBoy]

When I say "blowers" I only think of positive displacement. I think that centrifugal superchargers belong only on WW2 fighter aircraft and engines that are already so large that you have plenty of torque down low (ie, the V8 brigade).

I think a blower on an RB25, running 15 psi of boost or thereabouts, should make double the stock power almost everywhere and be a riot to drive. It would feel like a good 5L I don't think that it would be too much boost for the midrange and put the block at too much risk, but there are ways to manage that if it looked frightening.

There was a bloke on PF that twincharged an RB30 using a sizeable blower and a big turbo. It was fairly mental, even with very low pressure ratios across each compressor, because the blower got it moving immediately and fed plenty of gas to make the turbo work. I love the silliness of that and would really like to try it on an RB25, but the struggle to fit it all in is real. Power steering and air-con and blowers and alternators (and inlet an exhaust manifolds) all have to live in the same spaces.

I have my own problems to solve, let alone buying someone elses!

[Kinkstaah]

My problems are solved!

Though to be honest (and be somewhat discouraging) I don't think it's a great plan. Mainly because even in V8 land if you stomp the throttle it's not some night and day difference say, under 4k.

I tell people this all the time, my car makes ~210kw at 4k. If you floor it at 4k you get all the power and wildness that 210kw gets you. Not much really. If you floor it at 3k you get all the fury of ~130kw.

And of course over 4k, well it makes less power than 90% of RB turbo setups. You could make the argument that "Well under 4k is where you spend most of your time driving" and that's true, except it's not like people are also spending their time driving under 4k at 100% throttle. 

Which means your intended speed really is determined by how fast the driver wants to go/whether you have traction. I don't think the PD is really a solid plan on a RB. People can commute around under 4k with a RB25 on 0psi just fine, and when your foot gets heavy people just don't stay under 4k and you get the best of both worlds.

IMO the only benefit is mechanical simplicity/less internal issues, and partial throttle car-balance over 4000rpm. I sound like the ultimate wanker, but I will say that the LS really is a handling mod over anything else, in any area where the V8 N/A is comparable in power to a Turbo 2.5L or a PD driven 2.5L which for argument's sake we'll say is similar.

(unless you want a scenario where you want 800KW where a RB+T is going to be just worse everywhere than a V8TT but that's not the discussion here :p)

[GTSBoy]

1 hour ago, Kinkstaah said:

My problems are solved!

Yes, well, what you really want and need is a centrifugal supercharger. Will give you more than the pathetic 130kW down low, more than the underwhelming 210kW at 4k, and put you back into touch with the big boy boosted RBs up top.

[The Bogan]

1 hour ago, GTSBoy said:

Yes, well, what you really want and need on a LS is a  PD supercharger, you already have the traction control that is required.

FYP

[GTSBoy]

And so it begins.

[The Bogan]

13 minutes ago, GTSBoy said:

And so it begins.

Yeah, fair call, but if I was to do it again I would go a nicely sized spooly boy turbo or two, space permitting, instead of a PD, or even over a centrifugal, on any engine

I've seen a few really responsive turbo LS builds that can make really good power down low, and with the ease of controlling boost with RPM/road speed/gear it makes life much easier 

I'll leave now......

[Lithium]

On 16/02/2024 at 4:21 PM, GTSBoy said:

I think a blower on an RB25, running 15 psi of boost or thereabouts, should make double the stock power almost everywhere and be a riot to drive

 

On 16/02/2024 at 5:58 PM, GTSBoy said:

Will give you more than the pathetic 130kW down low, more than the underwhelming 210kW at 4k

I am really trying to resist responding to this, things are getting pretty offtopic but not sure if I'm missing something or maybe you've not had direct experience with centrifugal superchargers but ESPECIALLY a centrifugal charged RB25 on 15psi sounds like an absolute nightmare of a setup - not least because... have you heard an RB25 with an exhaust that would support well north of 200wkw and no turbo in there to "clean up" the sound?   Not good.  Never good.

Also centrifugal chargers make peak boost at peak rpm, I don't know what magic one would need to do to make a centrifugal supercharged RB25 make 210kw by 4000rpm but the best I can imagine would be overspinning the heck of it at max rpm or some such thing to make a compromise that works.  I love all kinds of forced induction and centrifugal blowers are heaps of fun, but best suited to things that you DON'T want heaps more torque down low and instead want the power to increase linearly with rpm.  

To pull things back on topic again, it's hard case that @34GeeTeeTee's result over a decade ago with an old Garrett GT30 based turbo with an FP HTA compressor wheel on it would stand up very well compared to popular options available today.  391rwkw on a Mainline roller dyno would be comfortably into the 400kw @ hubs range, and is making ~280rwkw by 4000rpm if I'm looking at that right. 

They have done multiple generations of compressor improvements and have all new turbines that are in a different league in terms of flow and inertia compared to the GT30 of the time, imagine a modern equivalent Xona based turbo like this on an RB25?

[GTSBoy]

30 minutes ago, Lithium said:

a centrifugal charged RB25 on 15psi sounds like an absolute nightmare of a setup

Yeah, but Kinks has a 5.7L V8 in his R34.