Compressed air supercharging

[Daox]

I still stand by 20% being as far as you'd want to go without adding more fuel, which means either tuning, or larger injectors, or higher fuel pressure, or aftermarket engine management... or some combination thereof.

That is probably a very good rule of thumb. It would be really nice to get the specs of our fuel pump and injectors. I've looked for quite a while to see what the fuel injector flow rate is, but I could not find any data. I also have no idea what the flow rate is on the fuel pump either. It does not seem to be shared with other vehicles. All the guys running forced injection have also never shared what they've done about the fuel system.

So, if you want to get accurate... you're looking at 93.6 hp for a simple "bolt-on" compressed air boost system. The benefit of this over NO2 would be that you could recharge your bottle at home, or even in the car with just an air compressor. (though, I don't know what kind of compressor you need to get to 3,000 psi... maybe you could compromise on that, run a bigger tank with lower pressure?)

They sell scuba compressors. They aren't horribly expensive, but aren't cheap either. I think the cheapest I found on amazon was ~$280.

And then, do you want to run "some" boost all the time, or do you want it to be throttle-triggered to only activate at full throttle?

IMO it doesn't make much sense to provide boost until you're at WOT. Unless you're at WOT, there is more power already available.

And then you can get into the fun stuff... do you want to run an on-board compressor that would run as-needed when you're NOT at WOT (sort of like the AC compressor does) to keep the tank pressurized, and take the FE hit for that... and have the boost available for WOT acceleration when you want it?

Knowing how big and heavy my 220V compressor is, I'd have to say I wouldn't want to shoe horn it in to my Mirage haha.

It's all neat ideas to play with, but at the end of the day, you'd end up with a lot greater efficiency and power by either fitting a larger engine, or going with a traditional supercharger or turbocharger.

And, that is probably why we have never seen this technology gain any traction. Its just not that practical or appealing. However, it is interesting to see what can be done. I think I may tinker around with a few ideas and post it here. I'd like to explore the idea of a low (shop pressure) setup. Can it be done super cheap with regular off the shelf items and some modding? Its worth exploring IMO, even just for funsies. But, then again I rather enjoy going through the engineering exercises of proving or disproving a modification. I learn and grow through every failure or success and I enjoy that.

[Loren]

IMO it doesn't make much sense to provide boost until you're at WOT. Unless you're at WOT, there is more power already available.

There is potential for greater efficiency. Even 2-3 psi of boost is like adding compression. Plus the cooler charge and all that. You could potentially improve efficiency at low-mid throttle.

And could definitely improve drivability at part-throttle. Let's say right now you can see 70 ft-lbs of torque at WOT from 2500-4500 rpm. With a few pounds of boost, you could either see 90 ft-lbs of torque at WOT... or 60-70 ft-lbs at half to 3/4 throttle. Would be much more satisfying to drive.

But, then again I rather enjoy going through the engineering exercises of proving or disproving a modification. I learn and grow through every failure or success and I enjoy that.

Yeah, I'm with you there. It's fun to think through problems and unconventional solutions, and just DO stupid stuff. This is why I'm autocrossing a Mirage.

[Pryme]

Also not sure if anyone mentioned the added weight of a scuba set up. They are not light! I've been diving.
So its definitely not a viable option

[stevedmc]

Also not sure if anyone mentioned the added weight of a scuba set up. They are not light! I've been diving.
So its definitely not a viable option

I was going to say the exact same thing but you beat me to it. Shame on you for having common sense.

[Loren]

I've never been diving, but a 10-second Google search indicates that a typical 80CF scuba tank weighs 30-35 pounds. Perhaps a lot if you're carrying it around on your back. But, not an unreasonable load to carry in a car.

[stevedmc]

I've never been diving, but a 10-second Google search indicates that a typical 80CF scuba tank weighs 30-35 pounds. Perhaps a lot if you're carrying it around on your back. But, not an unreasonable load to carry in a car.

Considering we have people removing speakers and car batteries to save weight, I’d say an increase of 35 lbs in weight is very unreasonable.

[Eggman]

But as an experiment it would be fun to see what kind of difference it makes. Of the various means to boost the charge of air into a internal-combustion engine, this is easier to install than a super- or turbo-charger. It is more easily controllable and adjustable, and cheaper.

I think an easy experiment would be to get up to highway speed, monitor fuel consumption with an OBD-II scanner of some sort, and begin the test, measuring results. Time the experiment to see how long a tank of any given size would last. Standard compressed air tanks don't release a lot of air all at once. I wouldn't expect a SCUBA tank to deliver much volume through it's regulator, which I suspect is why the design in the video describes using a high-volume regulator.

Since there is no power consumed trying to drive a compressor of some sort, the boost pressure doesn't have to be so high. A boost of 2 psi would last longer than a boost of 10 psi. For that matter, the 3A92 draws a vacuum during normal operation. Delivering enough air to maintain atmospheric pressure would be a good starting point, and it eliminates the need for a one-way check valve.

Just think of all the compressible gases that could be injected. Scary to think there are folks out there willing to try this too.

[stevedmc]

One has to wonder what the long term effects of this would be on an engine. It does sound like fun though.

On a serious note, I wonder if a similar effect could be produced with HHO gas instead. I'm not a fan of either of these ideas, just throwing it out there. At least an HHO conversion would save weight.

[A-Aron]

Just a little info.
The PCP air gun world has lots of different tanks and different sized compressors.
Have even seen small compressors that can run off 110v or 12v to charge tanks in the field.
Pumping the tanks to 4500 would give you longer runs out of a small tank but longer fills.
Most compressors or hand pumps for tanks have driers to help remove water.

[Loren]

Considering we have people removing speakers and car batteries to save weight, I’d say an increase of 35 lbs in weight is very unreasonable.

You just can't let anything go, can you, Steve? Personally, I'm tired of your "input", and thinking seriously about just blocking you.