Grattan National Race, Near Grand Rapids, MI--This weekend!!!! Options

[URY914]

If you're going to do the "sewer" pipe do it right. I've seen air ducts on race cars that look like a 5 year old did it.

1. Use HVAC sheetmetal for the pipe. You can get it a Home Depot but they may not have 7". Try a HVAC/plumbing supply house. It is smooth on the inside and will allow the air to move through it with very little friction.

2. Use as little flex duct as possible. The flex duct isn't smooth on the inside. You can get 45 and 90 degree bends in sheetmetal duct.

3. Use the real HVAC sheetmetal tape not the cloth racer tape or "duct" tape. The real duct tape is silver and has a "AHSE" printed on it. It is much stonger than cloth tape.

4. The sheetmetal duct is made with a crimped end to fit in the next section of pipe and be taped. I would cut the crimped section off and butt the pieces together and tape them. Makes a smoother transistion.

I see a lot of HVAC duct work in my projects (hospital construction). I'm doing a surgery addition to a hospital now that has 7 OR's. You should see the ductwork in the ceilings. It's a shame we have to cover it all up.

Paul

[groot]

Chris,

The ducting outside of the centerlines is not allowed for brake ducting.... That rule is under the brake cooling section.

Paul,

Good input... Can you come up tomorrow to help? Kidding, but I do wish you were closer to help out. I really have a package problem. I'd like to run a hard duct from the front, but I don't know where I can do it. Fuel cell is right next to the shifter, so there's no room to pass the duct.

[ChrisFoley]

Kevin,
You have the stock cooling fan right now?
How about a sheetmetal scoop that lifts air from under the car along the front edge of the engine compartment?

[URY914]

Can you get a duct over to the passenger door through the bars? I ran a NACA scoop in my door for a while. But had to remove it when my bars got in the way.
This is probably not SCCA legal.

How high to the top of your cell?
Got a picture of the inside of the car?

Paul

[groot]

There's certainly room over in the door area, but getting to and fro will required some tight bends....

Chris, neat idea... may try that, too.

[Brett W]

Kevin are you running the sheetmetal that surrounds the perimeter of the engine bay? The Scoop from the underside is a bad idea. It will pick up too much crap from the track and there shouldn't be that much air flowing under your car anyway. How about you just cut the hole in the fire wall and run a duct into the passenger compartment. See if that helps.

[groot]

I'm running no engine tin (except for the stuff around the cylinders). As I understand it, the engine tin is for low speed or no speed conditions, where there's no airflow. I'm not overheating in those conditions. I find it hard to believe that I'm getting hot (exhaust heated) air in the fan inlet when I'm going 100 mph, but there could be some strange flow that I don't know about.

I'll figure out someway to run the stove pipe. I hate to cut the hole and then not use it for Jake's DTM cooling system. I can't just cut the hole to the passenger compartment because the rules state you can use lighting openings to supply air, but do not allow you to make your own.

[Brett W]

We all know airflow doesn't like to make turns but what if you brought the air in from the headlight through both firewalls into teh passenger compartment and then made a custom flattened, oddly shaped duct that would clear the fuel cell and other stuff. Then do a remote fill for the cell. You could effectively create some sort of nozzle to compress and then expand the air tract. Thus creating a super high pressure area at the fan.

[Jake Raby]

Kevin,
You need MOST of the tin to retain the factory pressures inside the shrouding.... What did you kee? this may be your issue.

I have some tricks for you- email me.

[ChrisFoley]

I'm getting ready to do a test day Thursday. My primary objective is to obtain flow-viz and pressure differential measurement in and around the engine compartment. The purpose is to improve engine cooling. I'll let you know what I learn.

[groot]

Thanks, Chris.

I'm "testing" this weekend, too, but at M-O. I'll also pass on what I learn.