mr2peak

So what happens when the twins fail? Will the compressor break and mulch my motor with the bits that make it though the intercooler? Will they leak oil all over my intercooler? Will it launch bits into the exhaust ports and write-off the keg? Will it be a nice slow death where they simply no longer build boost?

I'm getting everything together to go single, but I kinda want to max out the twins "for fun" before I do the actual turbo swap, with a gradual re-tune for more and more boost and all the single supporting mods, until I reach the point of no returns. How poor of an idea is this? This is a toy, I wanna play..

Sgtblue

iTrader: (16)

I think end-of-life in most circumstances is evidenced by smoking. And yes, oil in the intake track. Sometimes a lot of endplay but they usually stay together.
The stock twins are only good to maybe 14 psi before they become really inefficient. Plus, not a tuner but I think turning up boost to that level will require bigger injectors, pump and probably ignition mods.
What’s more likely is you won’t be able to tune properly with it and damage the engine.
What you’re talking about doing has historically been done, and is why the rotary developed such a fragile reputation in the first place.

j9fd3s

iTrader: (3)

i've never seen one that did damage to the engine, usually the twins get smokey, or when you have them off the cracks are so big its hard to keep the tourists away.

i do know of one where the shaft broke, and the compressor wheel was just sitting there, but the turbine wheel and shaft fit through the exhaust so it was just missing. also since it happened at full chat, the exhaust was full of oil. engine was turned off before anything bad happened, but it took weeks to burn the oil out of the muffler, fun times

Testrun

Without an afr gauge your playing with fire. I wouldn't worry about the twins failing,, I would worry about detonating and blowing up.

You could add the fuel system, add an ecu (if you don't have one already), tune it and probably have a lot of fun. Enough fun you may consider staying twins and swapping them out for "sp" twins like me or bnr.

IRPerformance

iTrader: (41)

Usually the twins will start pushing oil when they get near the end of their life cycle. This will get worse and worse. Coating the intercooler and intake with oil will promote detonation. Catastrophic failure is not common unless you severely overspin them or send a ton of blown motor debris through them. In over 20 years I have only seen 1 set of twins break a shaft. The turbine wheel ended up in the cat. The car smoked more than any other car I've seen but there was no other damage.

mr2peak

I'm already near the limits of the fueling now as is. All the requirements to support a single would be done before attempting this.

That said, an intake or exhaust full of oil isn't the best thing, along with smoky turbos. A car fire is the last thing I want to deal with.

mr2peak

Yes this did cross my mind many times, I specifically bought a car still on twins so I had the option of choosing my own adventure. The BNRs seem solid lots of available info. SP twins, nobody seems to have an actual comparison to the BNRs, and they are significantly more expensive

Testrun

I haven't seen too much on the new "stage II" BNR or the SP.... I will have mine on the dyno for a final run soon. Just chasing down a voltage issue.. They are probably a bit more expensive as they are Hitachi and are a perfect match..

Sorry I never meant to stear the thread lol.

mr2peak

That's ok, I got answers from some knowledgable people, I don't think there's much to add to my original question

I'd be very interested to see how it works out for you

billyboy

Had an upgraded set let go on track - compressor nut backed off - and did a better smoke screen than James Bond in his DB-5. Turbine wheel bounced around in the manifold but didn't damage the engine or opposing turbo. Compressor wheel thrashed around in the intake and killed the compressor housing....biggest pain was having to use the poor man's CMM, to work out dimensions and remachine another housing, but they lived again with a new rotating assembly.

I see you're looking at the 650hp, version of SP turbos, rather than other ones also confusingly being marketed as SP in the US. If you can winnow the wheat from the chaff in the long line of BS, supposedly Hitachi have stopped making the chra required, last he was claiming, which might have implications, if you ever have troubles as above. Raceonly has a dyno sheet on his own personal car with them installed somewhere on his facebook page.

Unless there's a compelling reason to stay twins, $Au8k just for the pair could go a long way on a single conversion!

Testrun

Lol ... No Dr. Stuff here I have the 3kai "sp".... couple mills bigger and a bit more durable than the stockers.... probably worth 20HP? With quick spool.

I am happy so far.

mr2peak

I didn't realize there are 2 SP versions being marketed.. and yes so much BS with unsubstantiated claims. I know people confuse the "99" spec with the SP fairly regularly. Too bad about the Raceonly.au parts being discontinued.. but realistically I thought they were massively overpriced compared to the competition. I'd love to stay twins for the character of the car, but the triple penalty of heat + price + discontinued parts just doesn't seem worth it. BNRs will likely be supported for a long time, EFR series will be supported for a very long time.

As for blowing up the twins before I switch just to max them out for fun.. I don't want a car fire with oil everywhere.

Testrun

I think I can put a solid 380whp down on much lower boost than what most think with these. They are not discontinued, but the price did increase.
I was going for single until I realized I can still make some pretty serious power, keep the heart of the fd,, and save a couple thousand to put towards suspension and whatever else.. I envy the singles in many ways that's for sure,, but I think it is a longer road to get something really running smooth..

mr2peak

How can you save a couple thousand? Both need fuel and spark, an ECU and a tune, and decent oil/air/water cooling. The only difference is the cost of the actual turbo kit (manifold/lines/turbo) and in that regard a high-end single is still at the very least even $ wise. Usually much cheaper, after all it's 2 turbos vs 1

Yes keeping the heart of the twin turbo FD is cool and a worthy reason to do it. Where did you get your KAI SPs? This is definitely something I want to explore further

billyboy

I don't think there's a huge chance of fire, just makes an unholy mess.

If you want to scroll through endless posts, I see the SP 650 info is in mid May for the "last set".

On a Dyno Dynamics, I think he achieved around mid/low 300kw early this year or late last year, but not invested enough to go back that far on bookface. Can't remember the boost level, but did have the exhaust and IC add-ons which likely put the ticket price well over 10k.

mr2peak

I already have a V-Mount so almost everything is already in place. I'm also RHD so the steering / downpipe issue will limit what I'm able to do with twins. Maybe I can run tiny sequential EFRs and burn even more cash lol

Edit: I'm joking about dual EFRs before you all judge me as an idiot

Testrun

I paid around 3500 for mine.... A good single kit will be around 5k... that's what I calculated. Sure you could find kits for less, but it seemed like you always needed to add a few more things here or there.
Again, I am not trying g to persuade you. I think a proper single should be superior in my ways.

mr2peak

I'm seeing $7700AUD for the Ozzy SP turbos, that's ~$5800. KAI turbos about the same, I think you got very lucky at $3,500. I'd be in minimum $5k for the common EFR setup in hardware

Testrun

I do think the prices have increased substantially according to what Ari told me from RX7.com. I paid 3700 I guess, but I had a big package deal going on with him so he hooked me up a bit.
that should be around 4800aud I think?

mr2peak

I think Raceonly.au charges exorbitant prices. Yes looks like he has them for $3700ish, not nearly as expensive

Testrun

Prices have gone up a lot and his website might not reflect that.

billyboy

The other half of the estranged duo was offering the new twins at $Au3.5k a few days back.....still offering massively bored out stock injectors too.