How Are You Getting Cold Air...

[fasterw18s]

With a cowl hood?

This has me perplexed on my truck.

I made a pan, but I lost a little mph.

I really don't want to do the robot arms from the front to the carb setup.

I have a Velocity stack, but its too tall, and I don't want to cut it if its not going to work. I was thinking have it right up against the bottom of the cowl.

Any help will be appreciated.

[Chris Uratchko]

FORGET the cowl hood idea. I've built 3 different air pans for that deal. None ever worked. Some cost as much as 3 tenths and 2 mph.

But, since some folks claim it works, I've come to the conclusion that it all depends on the windshield angle, hood height, position, carb position, and anything else you can throw in there.

I'm down to using nothing, and that works fine.

If my rules allowed it, and they did at one point. I would use a forward facing pan. In other words, turn the cowl type around, lower your radiator, and use the opening above the radiator to pick up air.... at least on my car, with that giant grill, man that worked great. What better place to pick up air than the shovel in my front end. Unfortunately, for a class with many different kinds of cars, that's impractical for a rule as not everyone has the same opportunity to get air like that.... so it's illegal for me.

[fasterw18s]

Frustrating isn't it?

I'm thinking of cutting a hole in the front of the hood, and channeling the air back to the carb, any thoughts?

I would place a blocking piece to keep the air from going past the carb.

I looked but can't find a forward facing hood anywhewre for my truck. I hate the spaceship looking "Aero" scoops!

Or I could just leave it alone and live with what is.......

[BlackBelt]

I have seen more people say that an air pan on a cowl hood slowed the car. I have always wondered if that was because the cowl opening creates a vacuum or if the cowl opening creats a high pressure area that needs to be rejetted for.

Have either of you put a manometer in the pan floor to see what is happening?

[Chris Uratchko]

I did the string thing(cheap way) and it just blew all over the place.. .very turbulant. I spent a lot of time on it... again, the best was the forward facing pan.

[BlackBelt]

Hmmm, interesting. Do you think if the airflow were straightened out a rear pan might work?

I am preparing a car for a cowl opening only class and would like an air pan to isolate the air from underhood temps.

[fasterw18s]

Doesn't sound hopeful John.

Chris, any thoughts on my hole at the front of my cowl scoop?

[Chris Uratchko]

Funny you mention straightening the air out. I actually went as far as to put dividers in the pan, like fins to control the air direction..... I did a lot. I'm not saying your efforts won't work. Maybe it was my hood... maybe it was my windshield angle, distance between my windshield and the edge of the cowl, maybe it was the shape of my pan, maybe it was the carb height to the hood height.... again, I've heard of people having great luck with it.

How hot do you think the air temp is under the hood at even 20+ mph??

[BlackBelt]

Since I am going to have the cowl scoop and a pan is pretty easy to make I think I will screw around with the strings and a manometer before I give up and just take out the pan. Won't be for a while though I am one of those thousands who don't have the car done yet.

If there is still an internet I will come back and report on my folly for the edification of others.

Although reading what you have said I see why a lot of cars are using the raised hood that goes all the way back to the windshield.

[fasterw18s]

I think alot of the hoods are too far from the windshield to be effective, mine included.

[Beyond]

Hey Chris, I've built a deal like what you described to pull it from the front but didn't see much difference with or without.. Didn't really spend time trying to optimize jetting etc. with the setup though so I want to mess with it some more. Was thinking about what you said about lowering the radiator, opening up that path direct to the grill. Did you use a cut down or shorter radiator or lay it back at an angle? I was looking at mine last night and if I switched to a remote water pump I could really lay the radiator over and make a nice path up to the carb.

[BlackBelt]

How hot do you think the air temp is under the hood at even 20+ mph??

I hadn't really thought about it in depth. My last two race cars had no hood so I guess I am a little paranoid about that enclosed engine.

[tom_cowle]

A good spot often times to draw air from is behind the front wheels in your front wheel housing, just think of the wheel opening being a large to draw air in. Pro-stock cars don't concentrate on this area for nothing when it come to being more aero-efficient (as in not letting air in).

tom