17 replies to this topic

[scooperman]

I was reminded of an old forum thread

 

http://forums.autosp...an#entry2860071

 

(hopefully the link works)

 

this week when an Aston owner asked my opinion of compressed air supercharging .

 

http://casupercharging.com/

 

as a way of increasing his car's performance. I think his Aston Vantage is 2004ish. He seemed very enthused about the idea of installing something like this on his car.  He wants more performance but does not want a lot of rework, some add-on he could then remove before selling the car some day.   My opinion was that it was OK for drag racing but not so wonderful in daily driving, definitely not practical.  He was bummed.

 

Basically, I don't like the idea of dragging around a couple of scuba tanks and then having to get them refilled.  But dredging up the old thread idea, I do think a DIY type could replicate the old Ramaire system. For street use I think a compressor/tank makes more sense if you are only needing occasional bursts of acceleration. I could find space for it in a '55 Chevy.  In a Vantage, not so much.

 

(Then I did a bit of Googling on the Ramaire inventors.  Mr. Percival was dumped by GM and he sued them.  No info on Mr. Ahrens.)

 

Anyway, it seems as though I must post a question here to get discussion started.  Do you think compressed supercharging to be a good add-on for a street car?

Edited by scooperman, 03 November 2017 - 01:49.

[chunder27]

Would you not have to have a compressed air notice on the car as van drivers do?

[7MGTEsup]

I would think he would be better off with a small shot of nitrous if he only wants the extra performance now and again.

[Canuck]

I can't think of an easier to install, easy to remove, easy to use and highly effective "supercharger". A full wet nitrous plate between the throttle body and the manifold.

[scolbourne]

Some 4WD's have a compressor on the car to adjust the tyre pressure while driving. The same idea would allow the air tank to be topped up while driving for supercharging the engine.

Edited by scolbourne, 04 December 2017 - 04:34.

[MatsNorway]

NOS is the best power adder there is when it comes to making it possible to return to stock config. You basically need a bunch of fittings and a new ECU and some minor bits, and you get good gains for very little weight added.

Edited by MatsNorway, 28 November 2017 - 18:01.

[ray b]

do a bit of math

2 L motor turning 6k rpm

needs air 1/2 the time so

2L x 3000 is 6000 L of air to run one minute

even at 10x1 compression that is a 600 L tank

and that is only one minutes air for a 150+ gal tank !!!

[gruntguru]

I think the compressed air supercharging systems use a venturi ejector so the compressed air is actually used to force outside air into the engine under pressure.

[Kelpiecross]

I think the compressed air supercharging systems use a venturi ejector so the compressed air is actually used to force outside air into the engine under pressure.

Also called an "eductor". I once had a lot to do with eductors in small suction dredges - very efficient and simple pumps.

I don't know if it's been mentioned but Mickey Thompson used oxygen bottles to supply the oxygen for a dragster - clearly not a long running time was involved. I think he said the combustion temperature was so high it caused a lot of problems.

[7MGTEsup]

do a bit of math

2 L motor turning 6k rpm

needs air 1/2 the time so

2L x 3000 is 6000 L of air to run one minute

even at 10x1 compression that is a 600 L tank

and that is only one minutes air for a 150+ gal tank !!!

 

I'm pretty sure compressed gas cylinders run at about 150bar (or the ones I have seen at least).

Edited by 7MGTEsup, 05 December 2017 - 09:01.

[ray b]

Also called an "eductor". I once had a lot to do with eductors in small suction dredges - very efficient and simple pumps.

I don't know if it's been mentioned but Mickey Thompson used oxygen bottles to supply the oxygen for a dragster - clearly not a long running time was involved. I think he said the combustion temperature was so high it caused a lot of problems.

I tryed to build a water eductor to suck fish poo [koi] out of a pool using discharge water

simply could not get much suction power leaves clogging it constantly

 

so now use the eductor to suck in air with the incoming water from the well to refill [well water lacks air]

and a shop vac to suck out the fish poo

 

what flow rates are need for good suction and inlet jet size to out let pipe size

I tryed about 4 to 8 to one so a 3" main pipe and a 1/2'' jet powered by a 1 hp pump is the current rig

 

but never heard of sucking air in by an eductor or using compressed air to do it for a motor intake

[Kelpiecross]

I have only ever used commercially available eductors - so I don't know much about the technical details - but I do know that the various orifice sizes and water supply pressure/velocity are fairly critical to make the eductor work well. Science lab type vacuum eductors can suck right down to a few mm of Hg of air pressure using the flow from a normal tap. Amateur-type gold dredges can move many tons of gravel per hour using only a small Briggs and Stratton-type engine.

I would have thought you could suck the fish tank water directly through the pump and roughly filter it to remove the poo.

I am always amazed just how much fish crap into their own water - dirty little mongrels.

[ray b]

swimming pool sized 37x17 ft with large koi and too many goldfish

used as a fish pond they produce about 10 gals of poo a week

so I need to pull 30-40 gals of water with the poo that quickly fills a shop vac's 9 gals

 

the bigger commercial eductors tend to be high priced SS or bronze for fire dept's mostly

or for chemicals mixing plants

or too small for my use like garden hose sized that clogg quickly

 

I was trying to home make one out of PVC fittings and funnels

got a 6 to 1 unit that pulls air in ok to mix with the fresh water in but not liquid or poo out

 

any spec on car air in eductors as to how much boost is produced ?

[Kelpiecross]

That's a big fishpond. Now that amateur gold suction dredging is illegal in Oz you should be able to find one fairly cheaply secondhand. There seems to plenty of instructions on the internet about how to build an eductor. The bloke I know who built one found that having a slight venturi-type taper on the outlet pipe made it much more efficient - most people don't worry about the taper for simplicity. Unless the whole eductor is underwater (at least initially) they are very hard to prime and get started.

[PiperPa42]

I'm pretty sure compressed gas cylinders run at about 150bar (or the ones I have seen at least).

You are not going to fill up that cylinder with your workshop compressor. They usually run at 7-8 bar.

[Greg Locock]

150 bar is diveshop stuff. 

[ray b]

That's a big fishpond. Now that amateur gold suction dredging is illegal in Oz you should be able to find one fairly cheaply secondhand. There seems to plenty of instructions on the internet about how to build an eductor. The bloke I know who built one found that having a slight venturi-type taper on the outlet pipe made it much more efficient - most people don't worry about the taper for simplicity. Unless the whole eductor is underwater (at least initially) they are very hard to prime and get started.

I am the other ray b not ray bell and not down-under  but in s fla

[Kelpiecross]

I am the other ray b not ray bell and not down-under  but in s fla

You are right - I didn't know there was two.