I've been looking all over for turbo sizing buy I just can't find anything. I'm looking for 300hp nice and snappy, what kind of turbo is best for thar. All I can find is 200hp s4 turbos or more than 400hp gt35r 13bs. Maybe some kind of turbo inbatween s4 and a gt35r

 

You could run a G25 /clone in modern Garret or GT(X)28 or small compressor S200 series in Borg Warner.

If response is your absolute priority and you don't have massive overlap you could go a size down again in the Garrett series to GBC-22.

Very limited options when you go that small in turbine housings. If you can find something around gt30 size you can probably win back threshold/response and have a fair bit more top end potential with a split pulse housing.

 

It’s the exact same method for 12A, 13B, 20B, etc. The HP level typically dictates the compressor and turbine flow sizing, coupled with a general understanding of what those numbers will approx. be relative to the wankel engine. Where you can get into trouble is with turbo manufacturers who don’t produce flow maps for reference. Then it requires more relative direct experience with those brands and how it plays out with them.

300 whp equates to about 40 lb/min peak compressor flow. And if you want it to be peppy then somewhere around 20 lb/min peak turbine flow (where the turbine flow curve flat lines) for stock or street porting.

the only problem with a Garrett G25 is you can only get it with a V-band turbine inlet. Which is not a good choice for a small displacement 2-rotor. A twin scroll turbine housing in either T3 or T4 sizing is preferred. The GBC line isn’t going to pan out either imo.

What I’m seeing is a Pulsar copycat based off the Garrett GTX Gen2 line in a 3067 hybrid size. Compressor is slightly oversized, but it has a 0.85 A/R div T4 housing option that’s right where it needs to be for 300 whp and peppy.

https://www.pulsarturbo.com/product/...-turbocharger/

there’s also the BW EFR7670 div T4 0.91 A/R IWG or maybe the EFR7064, but a much higher entry fee level.

there’s also the BW S257SX-E (7670) or maybe S252SX-E (7070) lines too, but neither ball bearing nor water cooled.

On those “maybe” selections, I’d need to go back and refresh my memory on the turbine A/R flow rates.
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That Pulsar with divided manifold looked like best low cost option from a quick search.

 

Ok what about the manifold I see cx racing one but that WG placement looks bad I would think thst would have boost creep but I can't find many options, what about divided manifolds they seem hard to find

 

If you genuinely want response then it's worth having one fabricated if there are no off the shelf options.

 

There is a weld your own manifold option that comes with a split flange I think that's the best option, or I could source my own parts It would be significantly cheaper

 

What sort of porting?
12A definitely respond to twin scroll/twin gate, highly recommend that

 

Racing beat race port for exhaust and half bridge racing beat intake.

 

if you want to do some searching there was a guy, Jobro, who had a turbo 12A car, https://www.rx7club.com/members/jobro-65256/

 

https://www.rx7club.com/megasquirt-f...ersion-820071/
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g30-660 t4 1.06 with twin gates would be my vote.

T4 housing means if you decide for more power later your not locked to smaller frame turbos etc

 

If you consider that the one Renesis on here from Brettus in NZ is making 350 whp with a G30-660 0.83 open T3, there are several lower cost variants from Pulsar in the equivalent G30 frame that they offer a 0.85 div T4 with. We might be cross-talking some on what 300 whp is in AUS vs USA though. Because I’d consider the G30 1.06 div T4 to be on the lazy response side for 300 whp, and be looking more for low 400 - low 500 whp with it on the -660 or -770 compressor. So you could buy the Pulsar with the 0.85 div T4, and then for more power later upgrade to the Garrett 1.06 div T4 housing.

This is the Pulsar PTG-series equivalent to the Garrett G30-660 and the turbines are directly interchangeable

https://www.pulsarturbo.com/product/psr-5455g-hp660/
(edit: mistakenly had the G25 version listed)


but they also offer another PTA-Series line that has the equivalent Garrett G-series cold side -660 compressor, but a modified hot side turbine wheel they claim improves response and flow but would be limited to low 400 whp max with a 0.85 div T4.

https://www.pulsarturbo.com/product/...hp-rating-660/
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I don't consider Brettus car a great example. Having seen emap for that exact turbo on a renesis at 9000rpm that's a poor turbo choice IMO

Just for reference it was 24-26psi of emap at 10psi of boost at 9000rpm

i

 

The Renesis configuration/emap is a separate comparison discussion and not directly relevant to prior engines imo. It’s an example of making 50 whp more with 10:1 rotors and no AI at the same equivalent turbine flow capacity limit of a 0.85 div T4.

at 300 whp the higher flow capacity of the 1.06 will have lazy low end response, and a full Garrett will cost ~$1,700 USD more (almost 3x).

if the Pulsar PTG version is bought, the Garrett 1.06 turbine housing can be upgraded later for $800 USD. The cost difference between a Pulsar supercore vs with turbine housing is $100. Starting with their 0.85 div T4 housing is a logical choice for the stated goal, but was perhaps overlooked. They also offer two compressor options; 0.70 w/3” inlet or 0.72 w/4” inlet. Garrett only offers the 3” inlet on their -660 cover.

The other Pulsar PTA version is on sale for $130 less ($770 vs $900), but it doesn’t have the option for a larger div T4 housing down the road. For 300 whp it’s a lower cost alternative.

 

What makes you think it will have a lazy low end response? Have you tested this or this what you think might happen?

Just cause the goal is 300HP doesn't mean it will be lazy? 2:1 EMAP let alone 2.5:1 EMAP at 300HP is silly

Your assuming the renesis makes more EMAP than a normal rotary engine, from what I have seen it actually makes less (with RPM being equal).
I have not tested it yet but I will eventually get some data with those G30 turbines on a REW and I think it will be higher than your expecting, even with a 1.06

Time will tell I guess.

 

for snappy low end response then 2:1 or higher is typical for the top end

I think it’s just not the norm for what you do, but here in the USA it’s common for autocross competition vehicles that want instant throttle boost response.

13B with GTX3071R 0.83 A/R, which is lower flow capacity (tighter, more emap) than the G30 0.83, usually pushing 350 - 400 whp, sponsored by Garrett and Racing Beat

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but I have a Garrett G30-770 div 1.06 T4 along with the Pulsar 0.85 div T4 and 0.92 IWG v-band turbine housings that will be tested with electronic wastegates.

a member here had a g30-660 1.06 on his FD3 and made 500 whp on E85 pushing it way past the turbo speed limit.
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In terms of autocross it makes sense. RPM is not important, area under the curve is everything. EMAP would not be a consideration here and it would just be a side effect you would need to manage.

I have a few cars now with the G30 that are getting closer to the dyno so I am curious to see how they pan out.

 

I wouldn't want to see that much exhaust pressure with a bridge ported engine.... either can the bridges or get a larger exhaust.

 

not trying to argue, but at 300 whp it’s not a significant issue like at 2x or higher power level; that’s not fully being considered imo

the REW I’m presently reconfiguring from the previous owner was low-mid 500 whp with full bp and a non-divided wastegate using a BW S362SX-E 0.91 running 25+ psig. Later converted to a an S369SX-E 1.0 prior to when I bought it to move the tq peak higher attempting to avoid blowing up 3rd gear on the factory transmission that it was doing on the snappier S362SX-E. I had it on the dyno at 30 psi converting it from open loop to closed loop boost control.

He won’t be any where close to that at 300 whp on a 12A and only a half bridge too. But again, he wants it to be snappy on the low end and that isn’t going to happen without emap. It really only needs a large street port, but the half bridge should help to keep the boost level lower. For bigger power at high rpm a larger AR is going to be better. 300 whp is only 40 lb/min compressor flow and then a resulting equivalent turbine/wg flow requirement as well. I’d expect it to not exceed 12 psi boost, if even that, but there are other factors like intake and exhaust system configuration etc. to consider.

consider the FD3 REW dyno on here back in 2018 that had a half bridge with EFR7670 0.92 IWG Turblown cast manifold setup that made 420 whp at 12.5 psig.
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my FC is running a 13B-REW with an S4 based turbo, giant exhaust. with the current V trim (55/70mm) compressor at 13psi of manifold boost, exhaust manifold pressure is around 15psi.
the back of the envelope says i'm doing a little less than 40lbs/minute and its going to tune in at like 290hp (its a little rich still so it says 305hp). its lazy to spool up, but the S4 turbine housing and manifold are pretty lousy. the S4 is a non divided manifold with a turbo flange that is a flat wall with holes in it. a divided setup, like the S5 FC would probably help everywhere.

i know what my setup is like, and i have an area for obvious improvement, but other than that i do not really know, well; anything, lol

 

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Who said 300whp? OP said 300hp, which is about 220whp give or take.

 

it’s a valid point

but in that case, if your assumption is more accurate than my own, then it only results in a 12A half bridge requiring less boost and being less of an issue for the same reasoning stated in the prior post.
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from left to right

Pulsar 0.85 A/R div T4 EWG
Pulsar 0.92 A/R V-band IWG w/T4 adapter
Garrett G30-770 1.06 A/R div T4 EWG




at the time I purchased the 0.92 V-band the 0.85 T4 wasn’t offered by Pulsar and Garrett only offers open T3 or V-band in 1.01 or 0.83.

Pulsar now offers a G35-770 that Garrett doesn’t, with a 0.85 div T4 (~same peak flow capacity as the G30 1.06 div T4) or you could use the Garrett G35 1.06 div T4 housing.
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The G35-770 does look good but I won't use Pulsar anymore. out of 11 turbos I only have 2 still working. The rest all seized up.

Replaced the broken ones with Garrett and have not had another failure.

The 2 that are still running are both small frame turbos, the rest where all G42,G45 etc