Probably just a restriction versus the foremost restriction (the RHD downpipe entry because of steering column).

Edit- These Bathurst turbos already have less restricive exhaust wheels as well which will help the exhaust housings flow more (wheel diameter/area and widening the exhaust housing scroll slot width when bored larger).

 

Interested in these turbos. What kind of porting was done on this motor? I wonder how these would do on a stock port motor on pump gas with upgraded fuel/ignition and a 3” exhaust instead of 3.5”. So over the BNR’s, these have bigger AR compressor covers, and bigger turbine/compressor wheels? I would add on the upgraded actuators but I read the new BNRs have upgrade actuators now too. Trying to weigh if the extra $1200-1300 these cost over the BNRs is worth it? (BNRs are $2600 with new exhaust housing and these are ~$3900).

Matt

 

I'm in the same boat. Sure would be great if there was easily comparable data.

BNR stage 2 seem good up to 500whp. Claims on Bathurst SP are 600-650 I think. Quite a big gap, but don't know if it's real.

 

There’s very little info that can be found on the web in regards to these turbos other than what has been posted here in this thread. It sounds like they’re a one off by FDmotorsports in Aus but they also seem to be the only ones with hands on experience with them. Their website also has very limited information.

Matt

 

On pump gas and stock ports, it's probably a wash against BNRs.

 

Power goal I’m looking for is 380whp or so on sequential twins. Would like to keep the set up simple so stock port, Greddy V Mount, 3” exhaust with HFC, twin power, rewired supra pump, and bigger secondaries. Wondering if the extra $ would be better spent on these vs the BNRs.

Matt

 

If only 380 whp, I'd go with the BNR and spend the extra elsewhere.

I want 500, which based on what I've heard would be at the limit of the new BNR Stage 2. But well under the limit of Bathurst SP. but I haven't seen anything that actually shows why one could expect such a big difference.

I wouldn't mind the ability to simply up the boost and get 600whp on sequential twins. The rest of the car is built for it from a fuel, ignition, drivetrain perspective. So why not, haha.

But. I don't want to spend the extra money if that's not real. BNR is tried and true and with the new stage 2, 500whp seems achievable.

 

I hear a lot of people on here talk up bnrs , and i can only concluded that the only reason bnr is good in the USA , is because your cars haven’t got the restricted path like a right hand drive car.

ive tuned bnrs in Australia And there not that popular here , my findings have been that there limited to 280kw (380hp ) at the wheels in a right hand drive car ,
maybe bnrs on left drive car can make more power because of no restriction in exhaust flow.

so I’m guessing with a more free flowing exhaust like a left hand drive car running the Bathurst sp twins would make 600hp at wheels .


But Can someone please post up a pic of the latest bnrs twins and list of changes made over the standard ht10,12 , and then i can explain why the Bathurst sp twins make more power and why they cost extra$$

 

Please don't keep bagging on BNR. We want info on your twins. Post up details so we can understand why they will produce so much power.

You webpage has absolutely no detail. I'm a real potential customer, but I'm not going to dish out a bunch of extra cash if I can't see why yours will actually produce so much more power that you claim.

They seem very similar in size to BNR, so how do they produce 100-150 more whp?

I don't care about the previous claims of durability at the current moment and Garret vs hitachi cores. I want to understand how they can make so much power. Then I'll consider if I really care about hitachi vs Garret.

 

And now you say you are Guessing yours will make 600whp?

That's a problem because your claims say they will. Which was the only reason I was even considering them.

 

Per the BNR website:

GT28 cast turbine wheel (google searches yield 53mm?)
BNR’s billet compressor wheel (20% more volume claimed)
Upgraded wastewater actuators for 3 more psi
30mm ported wastegate

https://bnrsupercars.wordpress.com/1...azda-rx7-fd3s/





I know in the past in this thread the conversation had gotten very hostile between venders and posters. His last post was very mild mannered. I’m a believer that people can change and some of that stuff was posted years ago. Let’s try to keep things chill this time

The biggest difference that I think I’m seeing between the Bathurst SP twins and the BNRs at this point, is that Bathurst twins offer larger compressor covers. This probably in turn offers larger compressor wheels? I’m a NOT. turbo expert by any means. So I’m guess my next questions would be, how much bigger of a compressor wheel is possible, how much does a bigger AR compressor cover help, and what’s the size difference between the BNR and the SP models.

Matt

 

I like the SP twins. I just think the majority of the benefit of the SPs over BNRs probably comes at higher flow rates, which pump gas can't get into safely.

@Mrmatt345 when you say pump gas, stock ports, cat, and <400hp, it makes me think the SPs are overkill for your build. Even with AI you probably wouldn't want to push 20psi on pump. Skeptical there's a ROI until you're on corn juice or similar. And then you'll start breaking other stuff closer to 500hp anyways, so that's a can of worms.

 

I think the SP (regardless of Bathurst or not) has an improved exhaust exit, which I'm haven't seen any detail on. This could also factor into why it's more free flowing and may make better use of large compressors.

Would love detailed information on that too.

My general understanding of the twins limitation is that the manifold and housings become a limiting factor and prevent taking advantage of bigger compressors in trying to achieve 500+whp. Im really interested in understanding how Bathurst combined with SP improvements overcome that. That will help me determine whether or not to drop the extra money for it. And understanding if the Bathurst SP will allow for lower boost and temps for the same achievable 400-450whp would be good to know in terms of longevity (pushing twins hard build a lot of heat regardless and the less stress the better)

 

The most relevant result I'm aware of was @Ball joint who honed some BNRs and went parallel to hit 470hp+.

https://www.rx7club.com/time-slips-d...record-971246/

So, to see 500+ on the billtech dyno is promising.

 

But I think those are the old stage 3's. Based on what I've seen there are no claims that the new stage 2's flow more, just more efficiently and less modification.

Either way, I think 500whp on e85, ported motor, with boost cranked up in the mid 20's is doable.

I wish we could find something that shows that extra 100whp is really acheivable on Bathurst SP. I'd really think about taking the plunge.

 

I don’t like to talk bad about bnr ,


But bnr is selling refurbished HT10’s,12 for cheaper , and it will start to add up with new exhaust housing which is common for all older HT10’s,12 they all crack .

so how can you compare new to refurbished?


I’m selling total brand new set of Bathurst sp hitachi twins

Bathurst sp advantages

All brand new with hitachi latest improvements
cores with 360 thrust plate and no carbon seal , Replaced with piston ring to seal compressor side shaft and way less fiction on shaft , good for high boost applications.and boost response.

centre exhaust outlet , recasted to divert exhaust gases from each turbine outlet from clashing each other.

this stops boost drop between transition up to 20psi

much larger turbine wheels ,designed to flow and still retaining the weight of standard wheel for response.

larger compressor covers designed by hitachi Japan
std 0.6 a/r
bathurst sp 0.78 a/r

larger turbine housing Area ,and higher amount of inconel in new exhaust housing , no more cracking

upgrades hitachi actuators ,made by Japan with heavy springs , std (0.45 to 0.65 bar )
bathurst sp ( 0.8 to 1.1 bar )
this allows to run factory boost solenoids to control boost .

BRAND NEW made in Japan

The guy that buys these in the USA will be very impressed.
and all this bickering about what’s better will be closed

the power has been improved to 537hp at wheels since the new front pipe design was used and now has removed the restricted steering arm path allowing for the Bathurst sp to flow properly.

the best thing is Usa rx7 hasn’t got this steering arm restriction path .

 

Thank you for sharing all that.

Can you give more detail on the exhaust housing recast? Seems like that is one of the best benefits that allows for higher whp.

I hear you on the new vs remanufactured. I have no issue with remanufacture because it's new wheels, shafts, 360 degree seals, actuators etc. only the core is being reused, which as long as cracking isn't severe, is as good as brand new in this case.

So if the big difference between the two is the better flow from the housing, then that is what I'm interested in understanding the premium. If it was a $500 premium I wouldn't care, but this is a substantial amount.

 

Thanks for clarifying some of the differences. Do you happen to have pictures showing the differences between a stock exhaust housing and the new cast housing? I’m interested to see the changes with regards to how they’ll reduce boost drop during transition.

If BNR is indeed selling refurbed HT12’s vs NEW units described in yours, that would also explain the higher price tag. Have you by chance run these on a more stock application?

I feel like the main reason why a lot of people have their skepticism is that these turbos do borderline a single turbo kit in price and there isn’t a lot of documentation of them anywhere. It seems like we’re all waiting for someone to either take the plunge or to have more information in general on these before we all splurge.

Thanks for keeping us updated doctor!

Matt

 

The new centre exhaust pic won’t be visible,
but it stop boost drop up to 20psi

The turbine wheels on the gt28 don’t flow much more than standard.
Turbine wheel sizes

Standard HT10’s :45mm x51mm blade height 19mm

standard HT12 280 ps
45mm x 50mm and 20mm blade height

gt28 turbine size
47mm exducer and 53.8mm inducer blade height 24mm
this blade height is restrictive when it’s in rotary engine .

bathurst sp is lot large I don’t like to disclose the size.
lots of time and testing to get perfect balance .

but I can tell you that Bathurst sp back pressure ratio between boost pressure and turbine pressure is at 1.5 .

compare to gt 28 turbine wheel of 2.5

standard turbine of 2.7

All these tests were done at 20 psi
with old restrictive front exhaust pipe .

test will be improved with new ultra flowing front pipe .


Also y pipe on bnr udgrades require modification extending , because cores and wider ,

 

Y pipe does not need extending on the new ones.

 

Can you please post the sizes of your wheels? If Garrett, borg Warner, etc will post theirs to aid in sales and inform their customers, why won't you? They have more to lose and more invested in the design.

Garret GT28 turbine is a 53.8mm inducer and 47mm exducer. So slightly bigger than the Ht12 dimensions. The aero is also claimed to be better than hitachi which I would tend to believe since Garrett has a much larger base and is used on more OEM and aftermarket cars.

BNR also includes lighter shafts and a billet compressor wheel.

I also think the new housings that are available for only $500 extra have the higher inconnel content which reduces cracking as well.

The revised casting on the SP seems really interesting as that could be the main reason these can flow way more with the bigger compressor.

 

I don’t think BNR lists their compressor wheel size at all. Just that it is billet and flows 20% more. The revised casting is definitely the part most of us are interested in. I know BNR switched to these new versions of the twins because they were easier to make. I wonder what the actual performance difference between the old style stage 3’s and the new stage 2’s are.

Doc, we know you’re hoarding a bunch of pics of the turbos and you’re killing us by not posting them x]

Matt

 

sorry turbine size I can’t disclose,

gt28 turbine wheel blade height is 24mm no good for flow, the ht12 is 20mm lot better flow .

what bnrs is selling now I was doing 10years ago .

if you think bnrs is better that ok .

my power graph is up 23.5psi and power peaks at 8000rpm

ball joint with bnrs says his power falls over at 7000rpm and his running water meth , and the dyno he is using reading high by 10% .

I currently have the highest power from hitachi oem sequential set up in the world .

it’s because I have been doing on going development.

bnrs is is behind by 10years .

knowledgeable People have bought my twins around the world and are very impressed with the results.

 

We’re not really doubting that your developed twins are good. We just have our skepticism and I think it’s within reason.

Are there any builds or anything on an Aussie forum maybe that use your twins? Any other customers tuned by you using your twins? I think it’s fair that you don’t want to just post up the secret sauce to why your turbos are so great. Just more examples would be nice for those of us living 10 years in the past

Matt

 

I really want to like these. The responses are just so difficult to deal with though.

Most people about to drop $5k more into a 20-30k build want customer service a trustworthy behavior. Just saying other smart people have bought it and BNR is doing what you did 10 years ago isn't going to get you sales, especially when you require such a premium in price.

I'm literally ready to buy something, could be BNR, could be an EFR 8374 or 9180 kit, or this SP Bathurst. You could make this a real easy decision by posting details and not bashing other companies. If I buy this, I'll post my dyno results and if it's actually true then you'd get more sales. I haven't asked for discounts or handouts, just details and data.

If you can't provide the detail then I'll drop it and go buy one of the other options.