Great advise......This is exactly my thinking. The 9180 is bigger....mostly because of the size difference in the compressor housing to accommodate the built in recirculate

I run an S366 with a billet wheel and a custom clipped turbine...and it is 500ish @16psi on pump gas and 50/50

If you look at a dyno graph you will see that the torque doesn't climb after 7500....so no need to go past there

Gotcha, I was afraid that the .91 was a little small. There are some holiday sales going on and the s3 is about 575 atm. I was really just hoping to actually use the 9k redline because it on the tachometer and it sounds nice up there, but if 8k is safer and the optimal power cutoff then so be it. I was also looking for a 1.0 a/r, the Garrett on my previous excel sheet posted here would be a 1.06 a/r or something, but I really fell in love with the sound of the BW.

Power goals are 450-550 whp, likely aiming for 500 on lower boost, being under 20 psi. Ideally I would like the get the pressure down as much as possible while providing good response and optimal time in good efficiency range. I would like to get a T4 Turbine inlet, however I personally have a preference toward journal bearing over ball bearing. My personal opinion is that the car's performance aspects are oriented toward higher rpms, so later boost is A-O-K with me. I hear the ball bearing turbos are more finicky and journal bearing is basically more reliable.

As for the turbo manifold, that's no real loss to me. I suppose I am looking for a way to not have to have a custom one made, but that may not be avoidable.

I will be half bridge porting and large street porting the intake as well as opening up the exhaust to a large street port. Hoping to keep the idle under 1500, shooting for 1400.

Well it sounds like an S366 with a 1.10a/r turbine housing is what you're looking for if you want to keep manifold pressure down as low as possible. Could go with a 1.00a/r for a little bit better response and still probably be good to go.

If you can't make a manifold on your own then you have two options, both of which aren't exactly cheap but it'll be worth it. Either pay a fab shop to make you a one off unit (this could range wildly from $500 to $1500 depending on quality and how much time it takes) or there is this option Turblown REW Swapped Rx-8 Turbo Manifold

I would really suggest using twin wastegates and a fully divided turbo system as well but it just depends on what your budget looks like.

Couple other things, first is that if this is a street car, I would just do a street port. You can still make huge power without having to bridgeport it and it is safer and more reliable than a bridgeport and has much better manners. The other is your statement about journal bearing turbos, not really sure where you came up with that? Ball bearing turbos are better in every way except for cost. They not only help with spool threshold but the difference in transient response (on/off throttle response time) is another reason why they are better. There's nothing wrong with going with a good journal bearing unit for cost reasons but they aren't better than ball bearing units at anything.

The wastegate seems very daunting as I am looking at a very expensive unit, but I suppose I will have to do a bit more research. In effort for a quick response, is it simply to keep the exhaust streams fully separate?

I do understand that ball bearing is better for performance, though I have seen posts about burning up ball bearing turbos easier than journal bearing. It is a bit of comparing apples to oranges, but I believe it was on the Rx7club forum comparing a gtx?? and the s366 journal. The assessment was the s366 spooled slower (expected) but took abuse that ended up killing the gtx turbo. I cannot garuntee this is the thread, but I think it was here for reference gt35 or s366 - Page 2 - RX7Club.com

Let me know what you think. Thanks!

Another source of my info, apples to oranges but nevertheless: Ball Bearing versus Journal Bearing? Why the extra $$$ - Yellow Bullet Forums

At 500HP range not sure why you would need twin wastegates....

iI haven't had any issues with a single one on my car...other than the heat cooking them

I suppose 2 smaller gates might be easier to fit...but then you run into complexity issues any time you go to 2 anything?

Dunno ??

I think the twin scroll might be the reason why the suggestion was made and that a single wastegate would reduce the effectiveness of said twin scroll? Maybe? I think the doual wastegate route might be a little expensive for my taste. Likewise I might end up with the .91 a/r and journal bearing, although it is not ideal, it is a great price. The build should be able to grow later on anyway.

Yes it's so the exhaust is kept separate, twin scroll will spool faster and be more responsive than having a collected manifold with a single wastegate dumping into a twin scroll housing.

My guess is that the posts you've seen about ball bearing units failing is people that don't install them correctly, mostly because of using the wrong oil restrictor or not using one at all. It's not apples to oranges, ball bearing units are better, and journal bearing units are cheaper. The reliability of reputable ball bearing turbos (Garrett and Borg Warner) are good, you shouldn't be basing a decision off of a couple threads of people with failing turbos. Most of the time you have no idea what actually happened or why it failed. The most common mode of failure is probably improper installation regarding the oil plumbing.

Like I said there is nothing wrong with getting a good journal bearing turbo and the S366 is a solid unit. Just don't take questionable information as truth without researching, or try to convince yourself that they are somehow better lol.

Bunch of V8 drag racing guys, and also some pretty dumb comments in there. Especially the "high RPM so boost threshold doesn't matter" statement. Transient response matters. When you're at say 6000RPM, or when you shift, and go from 0% throttle, to 100% throttle, you'll typically be at full boost 15% faster with a ball bearing unit vs. an identical turbo with the only difference being a journal bearing setup.

Twin scroll is better at any HP level in terms of response. There's a reason why OEM's are moving towards twin scroll design (Ford for example). The added boost control is just a plus, and it doesn't add much complexity, you just extend the vacuum/boost lines from the first wastegate to the second one with T fittings. Twin wastegate designs are getting more and more common and have proven themselves reliable when using good wastegates like Turbosmart.

For wastegate size comparison:

Area
50mm gate: 1963.5mm^2
Twin 40mm gates: 2513.3mm^2
60mm gate: 2827.4mm^2

Twin 40mm gates have 28% more area than a single 50mm gate.
A single 60mm gate has 12% more area than twin 40mm gates.

I sort of like the idea of the turblown turbo manifold. Its pricey, but with it I can run the twin 40 mm wastegate setup (which is only like 50 bucks more, a drop in the bucket really). I could also heat paint and heat wrap it myself then.

Yeah, turbo information is often skewed and its hard for me personally because I never owned a FI vehicle and largely put off learning about them until recently. My largest bias came from a video comparing two identical turbos except one was BB and one was journal bearing. The journal bearing spooled 350-400 rpm slower and only made 30 hp or so less (was 580 for the BB and 550 for the journal, I think?) I'll be the first to admit when I hear what I think is beneficial advice I jump on it without question, because I don't have the time to learn everything in depth before my build.

So just to keep it in the same thread I have more info on the RX-85 speed transmission

1st and 2nd are the same as FD tranny ( and Turbo 2)
3rd is a different ratio..it is a little shorter than the FD 3rd gear
4th are the same...1:1 on both
5th Gear and reverse are the same ratios as the Turbo 2 gearbox.....and shorter than the FD box...so a much more useful 5th ;-)

Gear widths are the same...so it looks like Mazda used parts from a few boxes to make this...and made a new 3rd gear to get a shorter peppier 3rd for the RX-8

The tailshaft is beefier than the FD box...the rest of the case is the same...except the bellhousing is for a push type clutch like the FC Turbo2

Hope this helps...I have the actual ratios on a slip of paper someplace and will try to add to this

I'm going to throw in a 5 speed without swapping to the FD center section and see what happens...

Edit: Removed list of gear ratios that were probably wrong.

The aftermarket FD3 trans gear kits should drop right in, OS Giken is the most readily available/economical and two kits:

3-Speed Close Ratio Gear Kit
1st 2.714
2nd 1.742
3rd 1.267

5-Speed Close Ratio Gear Kit
1st 2.578
2nd 1.772
3rd 1.289
4th 1.000
5th 0.821

hmmmmm . these were the JDM specs...............


https://www.rx8club.com/attachments/...r-rx8-spec.jpg

Wow thanks for the 5sp info guys. Stoked and winning.

Brettus if those are the ratios then that is identical to the JDM FD 5 speed. Interesting.

I'm positive the 3rd gear is correct because I have logs vs my old 6 speed box and the speeds at rpm line up .. making it 1.391

With JDMrx8 5 speed :
I'm doing 161kms/hr @ 8019rpm with standard diff.

With JDMrx8 6 speed : (1.539 - not same as US spec)
I was doing 145kms/hr @8060rpm

Euro dealer brochure has 3rd gear listed as 1.484 and 5th gear as 0.762

Ah ... it seems JDM and EU spec are different .

Maybe.....or maybe the brochures are wrong LOL....either way I think we are good for a drop in swap to the 5 speed handling the same kind of power as the FD boxes did

Equals WiN!!!!

In the long run you're better off beefing it up, why bother going to all this trouble and make big power numbers just to pussyfoot with a weak trans

Mazda - FC3S/FD3S RX-7 : PAR - Precision Automation Robotics

For that much money you're better off buying a completely built transmission that is much easier to service and has proven results. There are only two types of people that would buy that gearset, people who are constricted by class rules in a racing environment, and fools.

Here's an example, these can be configured in many different ways as well.
G-Force Transmissions GFT5-SNGF, G-Force 5-Speed T5 Transmission | G-Force Transmissions

Have you ever shifted a stock T5 ;-)

Did I post a link to a stock T5? :rolleyes: