custom water-air IC

[brian89gp]

Found out the hard way what too much intake piping will do, horrible throttle lag. Any air-air due to the way the car is built will have a long intake tract and I absolutely hate the lag. I can live with a hotter intake and less boost if I could get rid of the lag.

So, I'm thinking about taking 2 saab 900 IC cores, welding them face to face, and putting end tanks and water end tanks on. The 900 core is about 8x8x2.5, so face to face it would be 8x8x5. It would be a dual pass with air traveling the way it normally does and end takes where the normal cooling air would go.

This would probably be small enough to fit in the fender, so about 1' of intake before the IC, and 2' of 3" pipe to the TB. Think something like this would work efficiently?

[Norm '88 GT]

So did I as I was using a Powerdyne SC, Izusu IC, and 2" tubing. It was cheap and only worth 4 psi @ 5000 rpms. The 90 degree elbows had about a 3" radius. I knew I might have a restriction but the intial(beta) setup would have to do while I was testing most of a kit from a 350 GM truck. I recently increase SC to IC to 2.5" with 5" radius and .4" smaller pulley. The IC to throttle body is still two inch. The boost double through most of the range and I now see 8 psi @ 5000 rpms. Throttle response along with 1 psi @ 2500 rpms is nice.

The article from Autospeed.com below was my motivation.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Autospeed.com

By Julian Edgar


With the use of remote filter airboxes (and intercoolers in all turbo cars), there's plenty of plumbing through which air has to flow before it can become part of the combustion process. Then of course after the burn has happened, the exhaust - again, a long piece of bent pipe - has to be negotiated. The flow through these bends therefore becomes an important part of performance. Sometimes in automotive modification we tend to think that we are inventing something new, but there are plenty of other industries where the flow performance of long pieces of bent tube is critical to the performance outcome.


I recently picked up a book first published in 1960 - the Handbook of Air Conditioning System Design, written by engineers of the Carrier Air Conditioning Company. It's an extremely comprehensive manual of refrigerative air conditioning design, but in addition it has extensive chapters on facilitating the movement of air through pipes - the latter a fundamental of air-conditioning systems. The pressure drop experienced is even more critical in these applications, where pipe runs are much longer than you'll find in any engine bay, and the pressures being dealt with are so much less. So these guys looked long and hard at the restrictions posed by bends, elbows, 180-degree hairpins - and quantified the results.

So let's cut to the chase - what are some of the useful figures? Let's take a 3-inch tube: that's pretty common these days on both high performance exhausts and intakes. A tight 90-degree bend (where 'tight' means a radius about equal to the diameter, ie in this case 3 inches) poses the same restriction as 7.5 feet (2.3 metres) of straight pipe!

A long radius 90-degree bend (a bend radius of 4.5 inches, or 11.4cm) has a flow restriction equal to about 5 feet (about 1.5 metres) of straight pipe.

A 45-degree bend? Well, one with a radius of bend the same as its 3-inch diameter has an equivalent flow restriction of 4 feet, or about 1.2 metres. A 180-degree bend with a 1:1 radius/diameter? It's got the same flow restriction as 12 feet of straight pipe - that's an incredible 3.7 metres!

Get the picture? Those bends - even when they are relatively open - drop flow to a major degree. If the mass of air contained within the pipework isn't critical (eg as it is for intercooler plumbing, where throttle response loss needs to be minimised) it makes a helluva lot of sense to go much longer rather than put in tight bends.

And we've all seen those intercooler plumbing constructions where someone hasn't bothered using a bend at all - instead they've welded a 90-degree mitred join into the plumbing. The Carrier book suggests that in 3-inch tube, such a join has the equivalent flow restriction of nearly 4.6 metres of straight plumbing....

And what about other pipe diameters? Some other data from the book is reproduced here:

Losses in equivalent feet of straight pipe:

SMOOTH BEND ELBOWS
Pipe Size 90-degree standard 90-degree long radius 45-degree standard 180-degree standard
2 inch 5.0 3.3 2.6 8.2
2½ 6.0 4.1 3.2 10
3 7.5 5.0 4.0 12
3½ 9.0 5.9 4.7 15
4 10 6.7 5.2 17
5 13 8.2 6.5 21

'Standard' = radius/diameter ratio of 1. 'Long Radius' = radius/diameter ratio of 1.5.

MITRED ELBOWS
Pipe Size 90-degree 60-degree 45-degree 30-degree
2 inch 10 4.5 2.3 1.3
2½ 12 5.2 2.8 1.7
3 15 6.4 3.2 2.0
3½ 18 7.3 4.0 2.4
4 21 8.5 4.5 2.7
5 25 11 6.0 3.2

[brian89gp]

According to that my intake is simulating 40'ish of straight pipe

[GPXSS]

id hate to have to figure out the nightmarish equation for getting headers tuned according to that article :P

[RacerX11]

You could probably get the homeade air-water IC to work. There is a Yahoo group on making a low-cost air-liquid IC. I don't have the link handy right now, but I can get it to you on Sunday. Or you could search on www.groups.yahoo.com

Marty

[RacerX11]

Here it is (sorry for taking so long, you probably already found it): http://autos.groups.yahoo.com/group/...-Intercoolers/

Marty