Turbo sizing...T4, 13BT SP, 9.4 rotors.

[RotaryProphet]

Have you given thought to an individual throttle body setup (ie, what I was running on my 12a) coupled with a water-air intercooler? For 9 minutes balls out, you're going to have a lot of heat to move, so being able to start with ice water, or even a heat exchanger in the back with dry ice in it might just get you there. (particularly when you're at altitude and the heat output from the turbo is going -up- while cooling efficiency from the air-air intercooler is going -down-)

The intake'll let you make use of more power from less boost as well as keeping the intake path nice and short so that lag is virtually eliminated. You still have to size your turbo for the boost threshold you want, but I find that if you port the exhaust to open ten or so degrees earlier, you'll spool it much faster. (ie, the turbo 12a I had would make positive pressure at 3000rpm and was boosted at about 4500; the same exact setup on the bridgeport made positive pressure as soon as I floored it and boosted at 3000)

Also, have you considered any kind of swanky anti-lag setup? For a real rally car setup, you'll need a ceramic exhaust wheel in the turbo to handle the EGTs, but for 9 minutes all out on a rotary, you probably want that anyway, no?

I would think that a T3/T4 hybrid is what you want for the response, but are you worried about the top end? It'll really suffer if you force the engine to exhale through that tiny exhaust wheel full time. A gigantic wastegate set to ~9-10psi would help alleviate that, though. More boost than that and you'll have backpressure issues no matter what you do.

[Whizbang]

Originally Posted by RotaryProphet

Have you given thought to an individual throttle body setup (ie, what I was running on my 12a) coupled with a water-air intercooler? For 9 minutes balls out,......

The intake'll let you make use of more power from less boost as well as keeping the intake path nice and short so that lag is virtually eliminated. You still have to size your turbo for the boost threshold you want, but I find that if you port the exhaust to open ten or so degrees earlier, you'll spool it much faster. (ie, the turbo 12a I had would make positive pressure at 3000rpm and was boos.......ime. A gigantic wastegate set to ~9-10psi would help alleviate that, though. More boost than that and you'll have backpressure issues no matter what you do.

Actually the idea of running an air-water inter-fooler didn't even cross my mind. Might be a worthwhile option since i could use some good cooling aids. Only downside is there is a lot more complexity to it and possibly weight. My other option was to run a standard intercooler (cheaper and simple) and run a CO2 fogger on it with a larger bottle.

I'm probably going to run the stock intake manifold system, at least for now, mostly due to funding. The cage is going to come in at about 3200 dollars, so there is some other costs i need to handle first.

I am thinking about running the intercooler and radiator in a v-mount because i feel i could get better cooling and the units could be better protected when the skidplate is placed. Plus there would be little charge pipe to worry about.

As far as a turbo goes, i can get a very small T4 (even down to .69). So will have to play with it. In regards to heat and the testing different setups, i might just run master power turbos and just replace them cheaply when i either destroy one or want to try another setup.