Injecting Compressed Air to Kill Turbo Lag?

[gunner_imports]

Hey there,

I've been thinking about this setup recently and wondered why it has not been thought of. My immediate response is that, it probably has been thought of but doesn't work. That being said, if anyone knows why or how this setup might or might not work, let me know...

Would it be possible to hook up a compressed air tank (say 8 Gallon with 150psi) to your intake manifold. When you step on the gas, and your turbos are producing, say 2lbs of boost, this compressed air tank, through a fun arrangement of valves and sensors, would release, say 8lbs of boost to bring you up to 10lbs of boost instantaneously, killing turbo lag. As your turbos begin to do most of the work, the pressure release from the tank would be reduced until it releases no air.

That is basically a simple explanation of the system I had imagined. There would be other technical things invovled in the actual setup (ie. MAP sensor probably, among other things), but the question is would it work.

Two things which have been brought to my attention by people I have run this by (two mechanics), would be 1) the increased pressure on the intake side might blow out backwards through the turbo because the pressure on the exhaust side isn't as high. I was thinking that, as long as there is pressure on the compressor (ie when the throttle is open and your turbo(s) are spooling up), it would hold the increased pressure. And 2) if you were constantly charging and releasing pressure from a pressure tank, condensation would be an issue and filtering that water would have to be considered.

To charge the compressed air tank, you could fill it up at any local gas station, and I'm sure there is many rigs you could make up to charge the tank on board, either using an electric compressor or pulley system (sounds like a supercharger hey?, but if you could only make it function when the pressure tank is below 150psi, or whatever you want it set for).

I did a search online and couldn't find anything related to this... :hit_head:

D

[kelaog]

I've thought of that as well, simple reason is there wouldn't be enough flow unless you had a 4" pipe from the tank. It'd work for like one shot, plus it'd way a ton.

[333]

It would kill turbo lag definately, but also your engine. The engine would lean out because the air you introduce to the intake would not be metered by the airflowmeters and no additional gas would be added for the extra air.
Now if you plummed that to your exhaust side of your turbo.......
Save up for a properly matched set of turbos and your lag will be minimal.

[Gregzilla]

no, the concept it right but it's not practical, the amount of airflow necessary to accomplish what you are thinking is more then a little line could produce, either that or as mentioned it would be a short burst. you would need significant airflow or else you would only create a mild pressure increase before the turbos that would just as easily escape out of your air filter.

[Speeddm]

But if you inject it on the exhaust site you would get rapid expansion in the exhaust. Thus decreasing the rate in which the turbo takes to spool ( in therory). This has also been acomplished injecting Nos directly into the ex side.

[mcfly]

rally cars are using this technology.

one thing you have to keep in mind though is you need the cfm and the pressure, just pressure wont do much for you.

I believe the rally cars are harnessing a pop off valve to fill the chamber of spare air

[Comawhite]

rally cars are using this technology.

Which ones?

[mcfly]

Can't tell you which in specific but i know there are teams experimenting with it

this is also a decent read if you have time

http://www.halfbakery.com/idea/pre-compressed-air_20supercharger

[Wingnut]

Hey mcfly, if you ever talk with Ron from Revolution, I heard once he had a setup using nitrous, sprayed right onto the vanes on his Talon. Just something I heard around town here.

[mcfly]

He has yet to use nitrous on his car. He will be using it this year though from the sounds of things.

He posts over on scmotorsports.

[Wingnut]

Hmm. Proof, you can't believe everything you hear/read.

[Opus]

The anti lag used in rallyecars injects a burst of air into the exhaust manifold combined with fuel injected conventionally and an igintion event out of sequence, to cause combustion in the exhaust manifold. This causes the turbine to spin as in a gas turbine. This is why these rallyecars "pop" on deceleration. It is turned off on transit stages because it is very destructive . I've even seen it with fuel and air injected directly into the exhaust manifold. This is a great recipe for FIRE!

[mcfly]

The anti lag used in rallyecars injects a burst of air into the exhaust manifold combined with fuel injected conventionally and an igintion event out of sequence, to cause combustion in the exhaust manifold. This causes the turbine to spin as in a gas turbine. This is why these rallyecars "pop" on deceleration. It is turned off on transit stages because it is very destructive . I've even seen it with fuel and air injected directly into the exhaust manifold. This is a great recipe for FIRE!

tractor pull guys have been putting injectors straight into the turbine for decades8-)

thanks for clearing that up, wasn't sure how they were using it.

[Opus]

NP

Another thing to do is carry the onboard compressor to do the job . This is also known as supercharging. I'd love to do a twin charged setup .

[gunner_imports]

Flow would definately be an issue... Correct me if I'm wrong here though. Would a 7 Gallon compressed air tank full of 150psi be = to a 70 Gallon tank full of 15psi? Theoretically, wouldn't it be the same volume of air? Getting that volume into your intake would be an issue, but I'm sure it could be done.

If you inject the compressed air after your turbo compressor would you not have to worry about the extra pressure flowing backwards through your turbo, creating turbo surge? If so, I've also thought of a concept to keep the air being pumped into your intake manifold in the manifold until your turbo is creating = or > pressure from the compressor tank. This would be done using some one-way valves and or pressure switches.

I also thought about equalizing the pressure on the exhaust side by injecting air into it, but was told this would probably create back pressure into your engine (probably what some of you were talking about with the rally cars). Would work to spool up your exhaust turbine, but would be quite bad for your engine...

And like I said, filling that compressed air tank could be done many different ways probably. You could fill it up at a gas station and then recharge it on-board via pulley system & compressor (similar to supercharger), electric compressor, or by somehow capturing the pressure from BOV and Wastegates.

And I don't think the system would weigh that much... a 7 Gallon tank weighs less than 50 pounds and the piping would be about the same if plumbed from the trunk.