KMAR

One of the advantages that someone was talking about was more reliability. Then it got me thinking, Rotary engines are really hot running so the supra turbos would suffer the same fate as our stockers? Reliable on a piston engine but, on a rotary? Just throwing questions out there. I myself will go for BNRs some day. Still interesting though.

Marshall

How about Johnny Depp in "The Mexican"?

FDNena

iTrader: (2)

I don't think heat is what kills turbos as they run sometimes at 1200 deg )exhaust side)

200-300 isn't much..

--Craig

Joe Geiman

I agree, no replacement for displacement.

t-von

iTrader: (8)

The new variable geometry turbos on the new 911 and Acura RDX is what the rotary needs. So much simpler!

Kento

The Acura RDX uses a "variable flow" turbo, not a VGT unit like the Porsche. The Acura turbo uses a movable restrictor sleeve in the exhaust manifold to increase exhaust flow velocity at lower rpms.

Either would require a lot more software complexity to control them.

FDNewbie

iTrader: (10)

Something that can be done by the PFC, Haltech, or TEC3? Also, Kento, are you aware that not all variable geometry turbos are electronically controlled? Some use pneumatic/hydraulic control systems.

Bryan@BNR

iTrader: (1)

Hello guys.

I guess its time for me to chime in . The compressor and turbines in stock HT12's are larger than the supra twins. It wouldn't be worth trying. The supra guys snap shafts anywhere after 16 psi. They have a problem staying together b/c of the lengh and width of the shafts. They are so thin and long, they are just frail to use in any high boost application.

One thing you have to look at with a rotary is it takes 20% more air flow to make a HP than a piston engine. Since the supra makes MAX 500 RW on twins then 400 +/- with the same twins on a wankel.

I am engineering an upgrade for the Supra guys at the moment so I have done some study on the CT12's in the past few weeks. The stock twins from Toyota were actually designed by Hitachi. Looks like a better design on turbine housings and sequential system and cracking isn't an issue. Only thing holding that system back is ofcoarse the exhaust manifold and CHRA's.

Bryan@BNR
205 640 1193

hornbm

End Thread

Kento

No, I wasn't. Although I haven't done too much research on variable geometry turbos because previous to the Porsche unit, all VGT units were for diesel engines, which don't have the same requirements as gasoline engines. Which ones? So all the turbo vane movement functions are controlled pneumatically/hydraulically? As in no outside control of those pneumatic/hydraulic switching functions? I'd think it'd be awfully complex, in the same vein as the FD's system.

FDNewbie

iTrader: (10)

Kento, yea there is one that is completely pneumatically/hydraulically controlled... basically when boost pressure reaches a certain level, the vanes expand.

Borg Warner (designer and manufacturer for the 911 VGT Turbos) offers both electronic boost pressure control systems and purely pneumatic controlled systems, which can only function as a full-load pressure limiter. I believe the purely pneumatic controlled systems are used more in commercial/diesel engines.
http://www.turbos.bwauto.com/en/prod...gn_control.asp

~Ramy

Kento

You mean when boost pressure reaches a certain level, the vanes retract. The variable geometry turbos retract the vanes at higher speeds for better exhaust flow since the turbine wheels already have momentum...
Actually, other than the 911 turbo system, I don't believe they have a VGT unit availalble for gasoline engines. The seriously high EGTs and rpms required some expensive metals in the construction of the turbine vanes and shafts.

FDNewbie

iTrader: (10)

Yea yea lol. I felt kinda weird telling YOU about something...it should be the other way around. So now everything's back to normal...good

Well they claim to have made several turbos capable of withstanding heat of 1050 degrees C IIRC (http://www.turbos.bwauto.com/en/prod...senger_gas.asp) but no other manufacturer has employed them in their gasoline powered passenger cars minus Porsche. I think slowly but surely, we'll see more manufacturers adopting this technology however, once all the quirks that Porsche will inevitably face are made clear, and the method of control and reliability are established in the long run...

Bryan@BNR

iTrader: (1)

Some of the old Saab's had a VGT system. The system never took off on gasoline engines b/c unleaded fuels leave deposites and seized the vanes. The position of the vanes were controlled by an internal wastgate actuator. Boost was controlled by the size of the turbine housing.

The new system developed by Borg warner may be better in design. This set up would optimize and give you everything you would want in response and power output.

Being that we are rotary guys, small turbine housings don't work well for max power. If they make a variety of turbine housings, then it will be usefull for single turbo aplications.

Bryan@BNR

FDNewbie

iTrader: (10)

Thanks for the 411 Bryan

Diamond Geeza

I think the whole point of SnkyDvl's thread was that the control mechanism used on the Supra for sequential operation is MUCH less complicated than the FD. If the system could be adapted to the FD with two larger turbos you could have a high output suequential powerband. Everyone who kept blasting about mounting plates and what not totally missed the point.

DamonB

So you wouldn't use the Supra turbos themselves, but merely their control system? So you'd remove the mechanical components of the Supra's turbo control system and bolt them right onto the FD twins? Then all you have to do is plug the Supra's electronic turbo control system right into the FD computer?

Okey dokey.

Bryan@BNR

iTrader: (1)

You can probably make it work. The CT12's have everything that FD twins have: Y pipe valve, secondary exhaust valve, prespool actuator w/ control valve for secondary. It is a better design that the FD. You would have to put a lot of time and fabrication into it to make it work. The bad thing about a supra system is it weights about twiced as much as stock twins.

shelbyinyoface

hell why not just do the whole swap

DamonB

Those don't look like stock Supra twins to me.

Kento

Not really sure where you got that from. His stated point (and the rest of this thread) was looking into transplanting the whole turbo assembly from a Mk IV Supra onto an FD to make a "fraction of the cost" shadetree engineering alternative to aftermarket turbo setups.

RotaryEvolution

iTrader: (30)

wow, this post was a waste of my time...


fabbing up mounting for a different set of twins would be hell.

snub disphenoid

Not to mention there's not even a guarantee that the turbos would be well suited for the 13B anyways. Supras tend to use .81 A/R turbines on their singles as "big" hotsides, whereas that's bordering on too small for RX-7s...so I doubt the hotside on the stock Supra twins would match up too well with the FD's engine.

Diamond Geeza

Damon- Wonderful way to take a cheap shot when I am just trying to explain another's point. As someone else pointed out in this thread trying new ideas is not such a bad thing, the car your driving doesnt exactly have a conventional motor in it.

Pulling the control system off of a supra and duplicating it/using it for ideas for an aftermarket alternative could give someone a great starting place. I don't know about you but I would be darn interested if someone came out with a way to run twin 3037's in sequential and it didnt include a vaccum "rats nest" of 82 hoses.

If the intention was to "ghetto rig" supra twins o an RX7, then yeah just buy a Apexi single or 3540 setup.

DamonB

So the reason we don't see a bunch of FD's running around with Supra turbos or Supra turbo control systems on stock FD turbos is merely because nobody has thought to try? I bet plenty have thought to try, but after about 10 seconds of thought they realize why it makes absolutely no sense.

I guess the reason pigs don't fly is because they haven't thought to try