Staf00

I'm kind of a fan of Xona Rotor turbos, so I was certainly surprised when they released compressor maps out of the blue. Up until now, compressor maps for Forced Performance (and thus Xona Rotor) turbos were not available.

Anyway, check it out:
https://xonarotor.com/technical/xona...mpressor-maps/

I'm probably going to go with an XR 6564S. I think that is a good size for a 2-rotor. I'm pretty much sold on their turbines' split-blade "UHF" design, especially since our Renesis engines could use the reduced EMAP.

I know the latest Garrett turbos are very capable as well, but it's always nice to have options.

Brettus

iTrader: (2)

Thanks for posting this , good to see they have maps now!
Just took a quick look at the 65
As I speculated a while back when these first came out ...... they make their flow at high boost due to the high compressor Trim. So for a Renesis you need a bigger compressor (relatively speaking) to make the same power as a Garret G series for example. This will negate much of gain from the turbine design IMO.

The 54/67 of the G30-660 flows the same as the 58/79 xona @60% efficiency,60lbs/min and 2.5PR. This is the max for G30 but the xona keeps going to 68lbs/min. The extra flow being almost irrelevant for a Renesis because it wont operate in that part of the map anyway.

Staf00

Perhaps I should go 1 step up to an XR7164S? Same turbine, bigger compressor.

Brettus

iTrader: (2)

No ...I think the 65 is probably the best choice for spool/power combo......... I was just making the comparison with the G30 which I still think is a better turbo for a Renesis.

TeamRX8

iTrader: (25)

on a rotary wankel engine the turbine map is as or even more important than the compressor imo

so the question becomes; what is it that makes someone become a fan of something undefined for the application at hand?

I certainly wouldn’t choose either of those over a G30-660 or 770. Or the Pulsar equivalent either.
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Staf00

Mainly this: https://xonarotor.com/technical/uhf-turbine-wheel/

If it's not obvious why having half as many blades in the way of the exhaust flow would be beneficial, then idk what else to tell you. You are free to come to w/e conclusions you wish.

The half-sized turbine blades would contribute to less rotational mass and thus quicker spool. And even though half the blades are shorter, the part of the blades where most of the work is being done (i.e. where the exhaust gas imparts its kinetic energy) is normal-sized. Basically, you have the mechanical leverage of a 10-blade design but the restriction of only 5 blades. You said so yourself that the turbine is more important than the compressor on a rotary application. But I agree that Garrett's G-series are hard to beat. Those things are just so damn efficient. But in the end, I'm willing to lose out on a bit of HP and/or efficiency if it means the engine can breath a bit easier and potentially live longer as a result.

Btw, there tons of successful builds utilizing turbos that are definitively inferior to a Garrett G-series, so idk why you make it seem like the end of the world if I go with something like an XR6564S. Just like how there are 8 owners who are completely content with their Greddy kits despite the known inefficiencies and issues w/ those.

Edit:
What if I don't intend on running it up to 2.5PR? That would be 21psi of boost (at my elevation)! I'm shooting for 2.0PR tops, actually. If 2.5PR corresponds to 60lbs/min, then a lower PR would naturally equate to less lbs/min. I'm guessing 2.0PR would be something along the lines of 50lbs/min? If that is the case, then both the XR6564S & G30-660 would sit around ~68% efficiency.

Brettus

iTrader: (2)

My point is ............. the Renesis engine flows too much to work in the most efficient parts of the map for the xona because the turbos we are looking at were really designed for 4 cylinder engines up to around 2.4L , you can't change that (unless you go with a 4 port). Because of that, you need to pick the 65 compressor which is a lot bigger/slower spooling than the G30-660 compressor. So any advantage that might be there from the UHF turbine is lost because you had to run the bigger compressor.

Staf00

Ah, I see what you mean. Yea, the Garrett can match the Xona in flow while being physically smaller. Too bad I can't just mix 'n match a G30-660 compressor with an XR6564S turbine lol. Anyway, my next dilemma is whether I should go with the "X2C" vs "X3C" housing for the XR6564S turbo. They have different dimensions and different A/R as well.

X2C:


X3C:


There's also a different map associated w/ the X2C housing as well. See attached pdf...
As you can see, going from the X3C to X2C results in a few % loss in efficiency. Obviously the X3C is the preferred option, but I'm afraid that I'll have to settle for the X2C housing due to packaging reasons.

Brettus

iTrader: (2)

If you want to low mount it .... you should go for the X2C

TeamRX8

iTrader: (25)

sorry, that turbine page is just a bunch of marketing text. Because maybe you’re not so technically oriented and then aren’t perceiving that the compressor map results are tied to the turbine. Not really much impressive going on there imo.

So better turbine flow, but compared to what exactly? Because again there is no turbine map or anything else to reference. It could easily mean that the previous outrageously crap turbine is only 2/3 as crappy now as it was before.

Staf00

I provided anecdotal evidence last year, which you chose to ignore. And I don't feel like reiterating things I've mentioned before. Also, just because a map isn't available, doesn't mean something is more or less effective. I've seen several 1st hand examples of builds going from a non-UHF turbo to a UHF turbo and the gains are quite noticeable. As in, they used the same compressor so the only variable that changed was the turbine. Honestly, I think it's you who's technically lacking. Think about it from an engineering standpoint...what modification would have a more significant impact? Miniscule tweaks to blade geometry or a completely different blade design? I'm going with the latter because the slight optimizations that companies like Garrett make to their blade geometries every successive generation is only going to net a couple % improvement, whereas such a large departure from traditional turbine design is going to result in much more tangible difference. Turbines are a balancing act of various tradeoffs. More blades mean more mechanical leverage that the exhaust can exert on the blades. But the gains are often negated by the increased rotational mass. Garrett went with a 9-blade design for their turbines, which I'm sure is a "sweet spot" they settled on after rigorous in-house testing. Now, look at Xona's UHF turbine, which sports 10 blades, but 5 of those are half-sized. As an engineer (assuming you are) what do you think the effects of such a blade design would have compared to a traditional 9-bladed turbine? Cuz honestly, all I'm hearing from you is "No map? It must be crap." I'd imagine if Garrett didn't have maps/data available you'd claim that their turbos sucked as well.

Edit: It's okay though, I intend on using my own 8 as a guinea pig. I'll be going with the XR6564S X2C. I'm aiming for sometime around New Year's or so. Gotta get supporting mods and such in preparation for FI first. Honestly, I was really tempted to go with a Rotrex instead, as in, a centrifugal supercharger. But in the end, I decided against it in favor of a turbo. It's not like I'm trying to break any records or anything. Nor am I claiming that Xona turbos are the best turbos out there. All I'm saying is that they offer something no other turbo manufacturers have, which imo warrants a try at the very least.

TeamRX8

iTrader: (25)

no, just it was just more of your own text. No actual rotary wankel results and details to fully assess and weigh against what is even Brett’s own results, let alone any others.

Staf00

It was on a Porsche... See? You don't even know what I'm talking about...

Edit: And as far as I know, nobody has tried—and documented—a Xona turbo on an RX-8 before. So obviously there aren't going to be any results to compare with, duh.
Edit2: I just remembered that MadTaz/Carl was testing out a few Xona turbos on his RX-8, along with his custom manifold. But he never updated his thread after a certain point. I was really looking forward to the results too! However, it seems that he started out using non-UHF turbines (i.e. the old Xona turbos). But at one point he got a hold of an XR5451S, which imo is a bit too small. It's just too bad he didn't post anymore updates...

TeamRX8

iTrader: (25)

all the emotions and feelings in the world won’t help any turbo be faster, but feel free to keep trying.
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Brettus

iTrader: (2)

It's worse because of the bias towards high pr .........possibly no better than a Greddy in reality . So if he pushed it ...........

Edit : just compared 5451 with an 18g greddy ...... 5451 LESS efficient at 2.0PR peak flow !!

Also ..................Really interesting how the efficiency of the compressor decreases in the identical AR housing as the wheel size gets bigger . I believed the Garrett technical info on this for years when I ran my To4b comp housing ..... that misinformation really took me down a rabbithole!