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If Carl Ryan is reading this. I'm not on the UK site (yet) as I'm having registration issues. The guy that commented re the turbo choice is not me (It's likely to be Staf00).
FWIW I agree with what he said though.
glad to hear it, deleted a few replies because I didn’t really want to post pointing those those things out.
So to reiterate several points relative to what’s going on there; the peak turbo flow is irrelevant, the flow in the target PR range is what matters. Further, the turbine flow relative to that is even more important, but in addition to not providing that number there also aren’t compressor or turbine flow maps available for that manufacturer. So you have no way to know what the flow is where you need it.
Turbo selection for a rotary is more critical than a piston engine. I haven’t found a single rotary build yet with that brand turbo either. You’re going way out on a limb making a decision to use that particular turbo brand. The people talking the brand up don’t seem to be very experienced on the subject. That’s not a good combination and should be pause to stop and consider if a sound decision is being made or not.
The perfect turbo for what’s being proposed there is the Garrett G25-660 0.92 AR and it can support the lower hp range as well as getting out to 400+. You can see the maps that support the choice rather than hoping and praying you didn’t go wrong paying just as much for some other brand lacking documentation.
There are a number of quality features and technology going on there, like the high temp turbine impeller material that then also is designed to provide ultra high flow in a reduced impeller size that then has minimal impact on MOI due to the heavier material being used rotating on a much smaller diameter; win-win.
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So to reiterate several points relative to what’s going on there; the peak turbo flow is irrelevant, the flow in the target PR range is what matters. Further, the turbine flow relative to that is even more important, but in addition to not providing that number there also aren’t compressor or turbine flow maps available for that manufacturer. So you have no way to know what the flow is where you need it.
While that is absolutely true and that the flow maps are indeed unavailable, it's not too hard getting a rough idea of where Xona's turbos stand when you look into the company's history: Forced Performance turbos (the parent company of Xona Rotors) early on were based on Garrett GTX turbos as their starting point, which they marketed as their "HTA" compressor wheels. I suspect their succeeding wheels dubbed "HTZ" were based on Garrett GTX Gen II designs. However much they've refined their blade designs beyond the base Garrett wheels is anyone's guess. They claimed ~5% improvement flow, but of course, no maps to back it up. However, I think it's safe to say there wouldn't be a decrease in performance. Most recently, they've put a lot of R&D into their newer turbine designs, which is what you see marketed as Xona's "UHF" turbine wheels. Back in the day, the selling point of getting a Force Performance turbo was so you could basically have a "fully billet" GTX CHRA. That was their starting point anyway, so fast-forward to the 2020s and they've refreshed their product lineup 3 times since their initial offerings. The latest iterations being the collaboration w/ TiAl in the form of Xona Rotor turbos.
Garrett's latest offerings (G-series) are of course a significant and very welcomed advancement in the turbo industry. That's not something I'm trying to downplay btw. But at the same time, the Xona range of products aren't some shitty made-in-China turbos either. I simply appreciate the fact that, unlike most other turbo manufacturers, they seem to be paying more attention to the turbine side of things. The Garrett's G-series claims their new turbine wheel flows 5% more than their GTX turbine wheels. That sounds about right not only by visibly looking at the blade design (9-blade design w/ only minute tweaks to geometry) but by the provided exhaust flow charts. Both the GTX & G-series turbines feature a 60mm/55mm inducer/exducer so no, the wheel size was not reduced. The geometry was simply optimized slightly, granting +2% efficiency & +5% flow.
(left: GTX3076R Gen II vs right: G30-660)
Imo, the true selling point of the G-series is their advancements on the compressor side, but not so much on the turbine side. Contrast that with Xona's UHF turbine wheels, which is a visibly radical departure from the traditional 9-blade configuration. With a splitter-blade design, you get the leverage of 10 blades but the restriction similar to a 5-blade wheel. That's why the UHF turbines are touted as a "best of both worlds" scenario. Why do you think some turbo manufacturers shifted from an 11-blade configuration down to a 9-blade? Basically, they were trying to reduce the restriction caused by the physical presence of a turbine wheel itself. While going from 11 to 9 blades allows the turbo to exhale easier, it also robs it of some of the torque the exhaust applies onto the turbine blades. Of course, MOI is also reduced as well, so it was seen as an overall improvement and worth the loss of 2 blades. Nowadays, tiny optimizations to blade geometry will only get you a couple of % improvements in efficiency/performance. This is why I'm so excited over such a radical departure in turbine design. But let me just finish by reiterating how impressed I am w/ Garrett's new compressor wheels on the G-series, which is truly a feat of engineering. The reason I'd pick the Xona over the G-series is simply because I view modern compressor wheels as being "good enough" and what the Renny really needs is being allowed to exhale easier.
tl;dr: Xona compressor wheels are basically just tweaked GTX Gen II compressor wheels. So just use Garrett's compressor maps as a guideline.
Hey Brettus, how much quicker spool did you see going from your previous turbo to your current G30-660?
Depends on which setup you want to compare it with . I've used many different compressor wheels and turbine housings on the GTX turbo some with twin scroll some without. The G30 spools as well as the best combination GTX I've tried whilst making 3-4psi LESS exhaust backpressure.
Currently it makes 16 psi by 3600 rpm in 3rd gear.
The Garrett comparison made several posts above is incorrect.
The new Garrett G-Series turbines flow approx. the same as the next larger size GTX turbines as originally demonstrated by Brettus and indicated here:
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How any of this relates to the XONA turbo; present or previous version, is anybody’s *guess* because there isn’t a turbine flow vs. Pr map or even a peak flow provided. Neither are there any rotary application results that I’ve been able to find. We only have words (a lot of them no less), but no actual data at all specific to a 1.3L Wankel engine; either earlier 13B or Renesis.
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Ah, so it's actually a +14% increase in flow (28.5 / 25 = 1.14). That's odd that Garrett would under-advertise the gains, which I took directly from the G30-660 product page:
As far as Xona goes, my point was that it's not a wild guessing game as you claim. The pre-UHF turbos are basically just GTX Gen II turbos w/ their own billet center section. From what I can tell, the only differences in blade geometry seem to be a 1-2mm extension to the compressor's exducer in some models. So, you wouldn't be far off using a Garrett compressor map as a result.
Depends on which setup you want to compare it with . I've used many different compressor wheels and turbine housings on the GTX turbo some with twin scroll some without. The G30 spools as well as the best combination GTX I've tried whilst making 3-4psi LESS exhaust backpressure.
Currently it makes 16 psi by 3600 rpm in 3rd gear.
What combination GTX would that be? GTX3582? Sry, the ~95 pages is really...daunting.
Originally Posted by Staf00
Ah, so it's actually a +14% increase in flow (28.5 / 25 = 1.14).
Shouldn't we be looking at 2.0 PR instead of 2.5 PR? In which case, the difference would be a bit less (27 vs 24). That comes out to +12.5% more flow. Oh, not much difference actually...
Btw, I have never used a Xona turbo, but have used a Forced Performance turbo in the past. And yea, they're basically just rebranded GTX turbos. That was an FP "Red" on my old STI. Really no complaints, but of course the G-series didn't exist yet.
well the person promoting it as such is also trying to gauge turbo selection by impeller size, which my previous post clearly shows not to be a valid concept. In reality, it only exemplifies the need for a flow map. Yet also while ignoring other factors relevant to the benefits of the smaller, high flowing impeller size. Which are borne out by Brett’s results.
So they say “ultra high flow turbine”, but without actual values what exactly does it mean and how does anyone assess it relative to anything else? Here’s what’s stated on the website:
Its improvements were observed analytically, validated experimentally on a gas stand and then confirmed in on-vehicle testing.
Well if that’s the case, why isn’t there a turbine map with actual values listed on it then? That’s the process for determining the flow/PR map. It’s a valid question for anyone attempting a logical assessment.
When concrete numbers are avoided it goes a long way towards not being accountable for a variance to any descriptive text claim being made. Which Garrett states clearly 1050*C for their new turbine wheel material; perfect for a rotary. The other site provides words about high temp use, but as usual without an actual value that clearly defines anything useful.
2.5 Pr is valid with E85 fuel and various losses factored. It also just happened to be where all four turbine maps approx. flat-lined at max flow. At which point EMAP is likely to become a concern. There’s nothing preventing anyone from posting it up at 2.0 PR if they consider that necessary.
The actual percentage over the GTX varies quite a bit between all the different sizes and also depends where on the map the comparison is being made. The G25-660 jumped up considerably. Which is why it’s at the top of my list.
What does it say that everything can be questioned here, but nobody over in that UK thread is questioning ringing out an undersized baby turbo to 8000+ rpm as being promoted? Or much of anything else either.
I’ll concede that choosing a 5757S for a Renesis is not likely to be a complete disaster. It’s still a shot in the dark without having any possible idea of projecting how optimized it may or not be.
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Brett, what're the innards of your manifold like? Is it basically hollow, or a negative tube-like structure, or something else entirely perhaps? Just curious cuz this is what was posted in the UK forums:
Brett, what're the innards of your manifold like? Is it basically hollow, or a negative tube-like structure, or something else entirely perhaps? Just curious cuz this is what was posted in the UK forums:
If you are talking about the EWG ...I agree . Then again, with turbo manifolds and the Renesis, any preconceived ideas about what works and doesn't tend to go out the window . His design might just work fine.
Came across something interesting the other day . Mazda uses this block off piece to block off and disable the VDI on 6 port auto S2 models.
Will use this in my LIM next time I'm in there.
finally got my hands on one of these other than it being cleaner on the outside it doesn’t do much because it’s not solid in the VDI cavity. If I ever were to use one I’d probably fill the cavity with urethane or something to reduce unnecessary volume. Not really going to matter much though, but might as well do it right if at all.
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low power with a big enough turbine maybe, otherwise seems like that with IWG will choke worse than a severe case of Wuhoo Flu
You may have called it ! He went for the 54lb compressor I believe and was never heard from again .....
Now that the compressor maps have been posted ...it's obviously not a good match fot the Renesis.
It’s the same issue on the RX7Club G25-660 IWG turbo setup. The compressor is fine on that one as you know, but it needs EWG to handle the appropriate bypass flow level.
Not sure if I'm replying right, first time using this site other than lurking, but I wanted to ask if you have any news on the turbo 8 and how it's been doing lately, trying to get an idea on how I'm going to turbo my rx8 and you seem to have had a really good approach on things
Not sure if I'm replying right, first time using this site other than lurking, but I wanted to ask if you have any news on the turbo 8 and how it's been doing lately, trying to get an idea on how I'm going to turbo my rx8 and you seem to have had a really good approach on things
04-09-2021, 04:44 PM
other than it being cleaner on the outside it doesn’t do much because it’s not solid in the VDI cavity. If I ever were to use one I’d probably fill the cavity with urethane or something to reduce unnecessary volume. Not really going to matter much though, but might as well do it right if at all. 
