Injecting Compressed Air to Kill Turbo Lag?

[Opus]

Venturi based accumulator supercharging was played with in the 30's and 40's. The idea behind it was the use of compressed air injected into a venturi would have a muliplying effect on air volume at a lower pressure. The problem started with the volume of air that' s required . 2l @15psi at 2000rpm is alot of air volume, never mind @4-6K rpm. If you guys want to develop this concept now, let me know how it works out for you.

[gunner_imports]

Alright... so here's where it starts to get real mathematical.

(for reference 1Gallon = 4.546L)

The ideal AFR is 14.7(air) to 1(fuel). Therefore, you would need a 1029L of atmospheric pressure air (1psi) for a 70 Litre fuel tank.

Now, if you pressurize that air to 10psi, you (theoretically) can reduce your tanks volume to 102.9L (22.64 Gallons). And once again, if you pressurize that air to 100psi, you would need a 10.29L (or 2.264 Gallon) tank .

So, (again) theoretically, a 10.29L tank full of 100psi air should be equal to 102.9L of 10psi air (looks like I'm working backwards here...), or again, let's say 205.8L of 5psi air).

Does that sound right?

On a 2.6L engine (RB26 for example), one full rotation would consume 2.6L of AFM (0.166L of fuel and 2.44L of air). So I now begin to see where the problem lies...

@ 1000RPM, you would be consuming 2440L of air and 166.6L of fuel? Or I guess that would divided by 4 becaue it is a 4 cycle engine? So 610L of Air and 41.65L? That still doesn't sound right...

Gotta get back to work, I'll look some of this up when I get a chance and do some more math :hit_head: ...

D

[WildCard_]

the RB26 is a 6 cylinder first off. Second, its displacement is = 2.6L, it does not require 2.6L of fuel+air to make one full rotation.

[Marke]

^You are correct the RB26 is a 6 cylinder, 4 cycle engine.

[gunner_imports]

the RB26 is a 6 cylinder first off. Second, its displacement is = 2.6L, it does not require 2.6L of fuel+air to make one full rotation.

Ya man, 6 cyl 4 cycle engine and 2.6L of AFM (0.166L fuel and 2.44L of air at full throttle I think... if I'm wrong, tell me the correct mixture, because I'm no mechanic, just plugging in the numbers that I read.)

[gunner_imports]

Alright... so here's where it starts to get real mathematical.

(for reference 1Gallon = 4.546L)

The ideal AFR is 14.7(air) to 1(fuel). Therefore, you would need a 1029L of atmospheric pressure air (1psi) for a 70 Litre fuel tank.

Now, if you pressurize that air to 10psi, you (theoretically) can reduce your tanks volume to 102.9L (22.64 Gallons). And once again, if you pressurize that air to 100psi, you would need a 10.29L (or 2.264 Gallon) tank .

So, (again) theoretically, a 10.29L tank full of 100psi air should be equal to 102.9L of 10psi air (looks like I'm working backwards here...), or again, let's say 205.8L of 5psi air).

Does that sound right?

On a 2.6L engine (RB26 for example), one full rotation would consume 2.6L of AFM (0.166L of fuel and 2.44L of air). So I now begin to see where the problem lies...

@ 1000RPM, you would be consuming 2440L of air and 166.6L of fuel? Or I guess that would divided by 4 becaue it is a 4 cycle engine? So 610L of Air and 41.65L? That still doesn't sound right...

Gotta get back to work, I'll look some of this up when I get a chance and do some more math :hit_head: ...

D

So I guess what I have to figure out here is how much the RB26 does consume, in regards to air volume... and then, how much air volume a compressed air tank can hold. If anyone has an answer for either, let me know.

[mcfly]

with all the work and weight involved you may as well design a twin charged engine.

turbo + super

[Opus]

^ what he said ^

[gunner_imports]

Ok, so I finally have my math figured out (I think 8) )...

If you had a 20Gallon (75.708236L) tank (tank would weigh about 65lbs) @ 100psi in your trunk, it would be good for 5.15022014 of fuel (75.708236/14.7(AFM)=5.15022014).

Now I know what you're thinking... 5L of fuel won't last very long. But, that depends on how you have the system set up. You will only be injecting air until your turbo spools up. So... if you have your system set so 5psi will inject until your turbo hits 5psi, you'll only really use it for a second or two in 1st and 2nd gear. While cruising on the hightway you wouldn't be using it at all. It probably be a good idea to configure your system to have a on/off switch to only use it for accelleration also...

If you wanted to prolong the air in the tank, you could also reduce the PSI to 4.

Most 20Gallon tanks come in at least 125psi, and you could probably find some that max at 175-250psi, increasing your total air volume even more. You could also increase the size of the tank (25-30Gallons if you wanted) to futhermore increase the total air volume. You could, very realistically, get 10L of fuel time from a tank, which would probably last you your entire tank (seeing as how you'd only be using it until your turbos hit that pressure).

with all the work and weight involved you may as well design a twin charged engine.

turbo + super

Ya, twin charging would be bad ass... But I still think the compressed air tank system would be lighter. A tank, the lines, and the valves would all probably weigh less than 100lbs, and would probably all cost less than $1000 for all equipment, including a manifold pressure sensor. Of course you'd still need a programmable ECU and a new map but comes with the territory of new hardware.

Also, you wouldn't be taking away HP like a supercharger does to power the pulley (even though it makes up for it through air compression).

Another advantage my buddy brang up, is the fact that there would be a slight amount of condensation from the tank, injecting water into your system. I was under the assumption this would be bad for your engine, but apparently water injection applications have been used to cool engine temperatures, raise compression slightly and get a couple more HP.

[gunner_imports]

Futher correcting myself...

My last figure was the volume of air at 0psi in a 20 gallon (75.708236L) tank.

The volume of air @ 125psi would be 9463.5295L and would compliment (14.7afm) 643.7775175L of fuel)

If I had a 1/2" outlet from the tank which was adapted to 4" to induct into the intake manifold, I would need a steady 40psi at 1/2" which would convert to 5psi at 4" (1/2"@40psi = 1"@20PSI = 2"@10psi=4"@5psi).

So I needed a steady 40psi from the tank...

9463.5295L (air) / 40 (psi) = 236.5882375L (air)
643.7775175L (fuel) / 40 (psi) = 16.0944379375L (fuel)

16.09L (fuel) * 14.7(afm) = 236.59L (air) @ 40psi

Now... since I will not be able to achieve the required 40 psi for the full volume of the tank (obviously after the tank's PSI falls under 40), how much of the tank will I be able to use?

125psi (max PSI in tank) - 40psi (required PSI) = 85 psi (usable)
85psi / 125psi = 68%

68% of 236.5882375L (air @ 40psi) = 160.8800015L (air @ 40psi)
So that ^^ is how much air I will able to use at 40psi.

And respectively, I will be able to mix what amount of fuel... 160.8800015 / 14.7(afm) = 10.9442177975L (fuel).

Sooooooo, I will actually be able to produce 5 psi in a 4" outlet for 10.94L of fuel (or 1/7th of the tank). And since You're not constantly using this compressed air tank, I think that is plenty to last one tank of gas.

I can pick up a 20Gallon air tank for $214.66 and would weigh about 67lbs. Still looking into the pressure regulators/switches...

[Danno]

Holy sig figs batman. I think we need some diagrams up in here to complement those numbers to the 10th decimal place.


An easier way to "kill turbo lag" is to use nitrous.

[victoriaGTR]

I was just going to write that!

[kelaog]

Holy sig figs batman. I think we need some diagrams up in here to complement those numbers to the 10th decimal place.


An easier way to "kill turbo lag" is to use nitrous.

buy smaller turbos' , or a v8

[gunner_imports]

Ya NOS would work I guess, but still not the same as compressed air. With the system I described, you could refill at any gas station or at your house for free.

Anyway, I think I'll try it out on a something like a civic, something I don't really car about blowing up haha. On top of that, 88-91 civics have manifold pressure sensors, so I'd be half way there already :-D .

[gunner_imports]

P.S. I did draw up a diagram... maybe I'll post it up haha.