Questions, Air Ducts, etc

[Bob Danielson]

Haven't made much progress on the project of late but will be working in earnest this week as my wife and kids are on vacation and I'm home with the pets.
Going to concentrate on getting the air ducts done for cylinder cooling, carb intake and oil cooler. I would appreciate any thoughts on how best to build. I would like to do it right the first time.
Cylinder Cooling: There are seems to be a lot of variation here. Cruising the pits at Grattan I noticed no one was using the simple scoop that bolts to the original tin and sticks out the side. (available here from Dan and another version from SR) Is it folks opinion that they don't flow enough air? Seems to be the simple solution so I was surprised I did not see any on FST cars. I assume they are some what "draggy" compared to more flush ducts.
Also I saw a couple of different concepts on cylinder tin. Some cars had boxes built to replace the original tin and flowed air directly from the side instead of the top. It would seem to me that this would be less efficient, any thoughts?
Can anyone tell me if the Evolution uses stock tin? The car seems to have a very efficient system.
Finally, can anyone give me the height of the carb including the restrictor plate. I don't have one yet and need to get some idea of how high above the intake manifold to build the air duct.
Thanks for any help and ideas.
Bob

[dd46637]

Bob,

It is 9 3/4" from the top of the case (center rib) to the top of the carb inlet on my car.

Evolutions use the stock tin. And don't forget to use the deflector on the bottom side of the heads. If you leave it out the air won't get directed around the jugs.

AFIK the scoops you refer to work just fine. If I remember correctly it takes about 20-25sq. inches of inlet per side to get enough air flow to keep things cool.

Dave

[problemchild]

The EZ way is to use VW tins and use Dans scoops or Evo type scoops.
However, they are extremely high drag and probably makes any bodywork aft of the scoop simply cosmetic.
Cooling from lower on the side is much more difficult, particularily with the bulky 1600 manifold, but will be cleaner from an aero standpoint.
Bob, your car previously had an Evo type arrangement. I would think the Caracal scoops and VW tin would be a good start ..... although may require bigger ears on the body.
IMO, the RGU Mysterian has the best system. If I was copying somebody, I would be looking there.
Err on the too much cooling side ....if that is possible

[Bob Danielson]

Thanks guys!
The original Caracal ducts are now somewhat obstructed due to the widening of the cage. The down struts from the hoop are now slightly in the air flow so I am going to use them for intake and oil cooler air which leaves only the engine cooling air to figure out.
I'm thinking about expanding the current ducts and using a spitter or going with the Dan's.

[Bill Bonow]

Bob,

The Blackhole scoops (aka Dan's or SR's) are a great choice. Bolt them on and your heads will be cool. I must say I haven't seen any wind tunnel figures that would rank the Blackhole (or any other type scoop) as "extremely high drag". The only thing I could add is that Jim Smalley had head temp problems when using the Caracal scoops. Which ever route you go, measuring head temp for your first few outings would be a good idea.

[Bob Danielson]

Thanks Bill. That's the info I got from Jim also. I understand that when he went to the large side scoops, ala heater register boots, things improved considerably. May play with that a bit but will probably go with the "Blackhole" units just to simplify things for the near term.