So I've been researching and looking for some input. We've seen compressed air supercharging using scooba tanks. Results are stunning but not practical for anything other than a dedicated race car. I've been looking at introducing compressed air into an exhaust system pre-turbine. My thought is the added CFM could allow a large turbo to spool very quickly, possiblity instantaneous.

Concerned about the compressed air temperature being too cold causing damage to already hot parts, turbine wheel, exhaust system. Thoughts?

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Looks like Volvo has it figured out.

https://www.roadandtrack.com/new-ca...-diesel-turbo-lag-solution-is-compressed-air/

 

did you see this?

https://www.miataturbo.net/build-th...rbo-board-compressed-air-exhaust-98666/page2/

 

By stock in Turbo Companies or save your money for new turbos if you get aggressive in that direction.
There is a point where the extra heat in the exhaust can damage a Turbine Wheel.

Now if the turbo company is giving you free turbos then go for it.

Tom V.

 

I was questioning whether or not the release of the compressed air would be too cold, causing damage to already heated parts.

 

No data to back this up but being you arent making a bunch of heat before boost , the temp difference shouldnt be extremely drastic. And Im pretty sure the turbine wheels are inconel so they deal with crazy temps while remaining stable.

 

I'm thinking if you pressurize your crossover pre turbine you would backfeed into the engine through the exhaust valves. Through the intake side would be better I think.

 

If you look thru the old car magazines, 1963/1964 time frame, General Motors looked at putting a compressed air boosting system on the Corvair engine. The compressed air acted like a suction device on external air and drew in a larger charge of air vs the assumption that the engine would use only the compressed air to feed the engine. It worked but was not a success because it took several minutes for the air compressor to recharge the bottle. Basically a "One Stroke and I am done honey" deal System was even worse vs the Bottle Babies having to refill their NOS bottles but cheaper to run. One pass and you are on the sidelines of the street race.

Tom V.

 

I wonder if you could design the compressed air system to work as velocity rather than pressure. Set a nozzle to blow directly onto the turbine at an optimized angle (probably a turbine and housing redesign in the case of mass manufacture). The volume requirement would be much smaller this way and there wouldn't be a hot side pressure increase if you are blowing into the exhaust side stream.

Air charge could come from a second AC compressor in our case, they are capable of producing quite a lot of pressure.

 

thats what the guy did in the link I posted.
Well, he aimed it directly in to the turbine port. From the videos he posted the assist didnt even seem to be on for more than a second.

On a split scroll you could aim it into one half and get bunches of velocity on the wheel.

 

How about an electric motor to spin the turbine until the exhaust gasses catch up to the turbine speed, then the motor disengages and the turbo works normal. Some type of hybrid of that garret electric and traditional.

 

What is this on? Dead stop racing? Roll racing? Because for the trouble you may go through getting it to work, you might invest in a launch control for dead stop and for roll racing the same or learn how to brake boost it. I can be going 45-50 mph or whatever speed, put in second gear, hold the brake lightly and give it more gas and I can build boost doing that. No lag.

 

All that takes thought, time and skill. I think the idea behind this is to have transparent and instantaneous access to turbocharger boost.

Its happening, https://www.theturboforums.com/thre...ed-to-production-in-2021.386054/#post-2029528

 

I don't remember the details but we drag raced an XS1100 Yamaha with a Rayjay turbo in 1980. We drilled a port in the turbine housing and sprayed high pressure nitrogen. The solenoid was hooked to a microswitch tripped when the throttle was opened. Lag was a fraction of a second. It worked quite well.

 

What kind of setups would need this? Both of my cars have properly selected torque converters and the boost is all but instant.

 

too much turbine , not enough converter
One or both.
Ive been guilty. And I see people oversizing turbos for application all the time.

 

Really big turbos on small engines comes to mind.

You should see the big turbo diesel guys try to light off at bandemire, their trucks that work fine at sea level but at 6k ft they cant get the turbos lit with several seconds of nitrous.

Running an oversize turbo has all kinds of heat advantages.

Not everyone wants to run a lot of stall on their cars, and some people still rock a manual.

 

S485 with T6 96mm turbine here on 294". It makes boost on the footbrake. But the converter is borderline loose I guess. It flashes 6500+ lol.

I will add the intake can make a difference in lighting the turbo as well. A short runner intake making poor torque numbers where you are trying to light the turbo is at a disadvantage of a longer runner unit making noticeably more torque at the same RPM.

At the end of the day if you have a well put together combo with realistic goals in mind it should not be a problem 95% of the time.