Rod, What are you trying to accomplish with this ? If you want to be like Lane, flip the turbo 180 degrees & re route the water lines. Why go all the way round ? Or do like I did & cut thru the tank cover, it's not sacred or anything.
Plenums
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Rod, Here's the shots showing the cut out for the charge tube. Not a big deal & still plenty stiff because of the dual forming. I believe an intercooler on the GT25 is a waste of effort unless you are running over 12 lbs continuously. I feel that the larger ( 2" ) tube along with the larger radius 90 degree moved farther away from the outlet will give the biggest improvement. Per Garrett, this unit will support about 270 crank HP, so I have a way to go yet. For me, function takes precedence over form. I'd still like to see a smoked, thermoformed polycarbonate lid, but cams & headwork are my next big project.
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10 penny's worth
I know most of you guys are talking turbo installs here but I thought my observations on our supercharger kits development are worth sharing?
With our plenum which is approx 1.5 litres volume, plus a little in the short pipe from the blower we have virtually no bias in boost to either cylinder. This I know because of the afr in both pipes. The pipes are almost identical in volume, and the afr is the same for both cylinders with the same map for each. This makes me think that 1.5 litres head of air is enough to even out the pressure to both cylinders despite the asymmetrical inlet valve opening. Of course this is with a supercharger that is filling the plenum all the time, so there is always a residual boost behind the throttle valves when closed, keeping the plenum full and so giving the instant throttle response. With a turbo the plenum has to be refilled from off to on throttle. So plenum filling time will depend on volume which would create more or less lag depending on size but I think this would be very little difference, more to do with spool up time and turbo size. Through my 30 odd years of tuning FI I also found that if the plenum roof was closer than one times the diameter of the port the reversion of the inlet valve closing would bounce shock waves of the plenum lid and disrupt airflow. Also it was best to point the inlet of the plenum away from the inlet ports to help even flow. To make the inside of the plenum as smooth as possible to keep turbulence down and aid cylinder filling.
You can see my plenum on the TTS supercharger video I posted recently. I hope this gives you some idea's how to get the best from your install no matter what it is
I know most of you guys are talking turbo installs here but I thought my observations on our supercharger kits development are worth sharing?
With our plenum which is approx 1.5 litres volume, plus a little in the short pipe from the blower we have virtually no bias in boost to either cylinder. This I know because of the afr in both pipes. The pipes are almost identical in volume, and the afr is the same for both cylinders with the same map for each. This makes me think that 1.5 litres head of air is enough to even out the pressure to both cylinders despite the asymmetrical inlet valve opening. Of course this is with a supercharger that is filling the plenum all the time, so there is always a residual boost behind the throttle valves when closed, keeping the plenum full and so giving the instant throttle response. With a turbo the plenum has to be refilled from off to on throttle. So plenum filling time will depend on volume which would create more or less lag depending on size but I think this would be very little difference, more to do with spool up time and turbo size. Through my 30 odd years of tuning FI I also found that if the plenum roof was closer than one times the diameter of the port the reversion of the inlet valve closing would bounce shock waves of the plenum lid and disrupt airflow. Also it was best to point the inlet of the plenum away from the inlet ports to help even flow. To make the inside of the plenum as smooth as possible to keep turbulence down and aid cylinder filling.
You can see my plenum on the TTS supercharger video I posted recently. I hope this gives you some idea's how to get the best from your install no matter what it is
Tts plenum
Here's a close up of the TTS Plenum. The front small tank is for the breathers, front head breather goes straight up the rear is fed by a pipe. Filter on top. The read small tank was for the supercharger oil but we don't need that any more.
Here's a close up of the TTS Plenum. The front small tank is for the breathers, front head breather goes straight up the rear is fed by a pipe. Filter on top. The read small tank was for the supercharger oil but we don't need that any more.
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