Air Box Design

[jimmy six]

I'm not familiar with 848 but will look. For me it has not come to impounds and I don't remember inspecting it. I did see it at El Mirage but did not look at it.

I do not believe it is required to run a grille insert but if you do it must be stock or fill the entire opening if the shell has been sectioned down to the 530" limit. T's and 28-31's did not have an insert for Fords.

Like I said before. I'm not saying you can not have an air intake but it must meet the rules of 1. radiator must fill the opening, 2 insert if used must fill the the shell.

I'll use a 32 Ford shell for this example. Your air intake could attach to the grille bars and the air goes thru the area alongside the radiator tubes and then into the engine. We don't tell you how many rows your radiator needs to have, only that it fill the area of the shell.. This may not pass tech but, in my opinion only, it meets the definition. It could not be tapered in any way because that would cover part of the opening which is illegal. This would be highly questionable and definately not the best way to go with an air intake. Probably would hinder air flow. but like I said this would possibly be a way to do it....You could also duct the air under the hood to the back of the radiator and just take the air rushing thru the radiator from the speed your going. Nothing to stop you from doing that.

I believe the air intake on the Barbee #357 car was one of the best and it was above the 27 shell.

Gook Luck

[Stan Back]

Tom --

The #1091 Weber/Vanderley Model A D/STR ran at Bonneville with the air ducted thru the whole back side of the radiator and intercooled with ice!  It made it to impounds, as I remember, but couldn't back up their 1st run.

Stan.

(I still don't think cutting a hole in the upper grille shell is going to pass muster, even if you miss the radiator area.)

[Dean Los Angeles]

Here is the grill on the 848 car.

[dwarner]

OK, That is an A shell with an area above the radiator opening that a air scoop can be built. You mentioned a 32 shell. I looked at my street rod with a 32 shell an found that a max. there is maybe 1.5" to build an air scoop.

DW

[jimmy six]

I don't know what shell it is, Could be a T....However if what is shown is legal, a 30-31 has a nice large area above the radiator opening. I think 836 want the "point" of a 32 but with the bars there I don't think it could add any areo advantage....The Vanderly street roadster idea is what I was trying to say only not using the entire area...Good Luck

[Stan Back]

JD, Dan --

The Rule Book says "The body shall not be altered in height, width or contour . . ."

The Radiator Shell is a body part, right?  (It's not a mechanical part.)  And putting a hole in it certainly recontours it.

And its not very "Street Roadstery" in having a hole through your top tank.

Maybe all this will be addressed in the Rules Meeting.

In the mean time, I'd probably make a $100 bet that this is not legal in Street Roadster.

Stan

[dwarner]

Stan,

I don't know about the $100. He claims he spoke with Russ Eyres and got his OK. I'm confused.

DW

[836dstr]

Hi Dan,

I had talked to Russ 3 or 4 months ago about the optimum air intake and he did the calculation on the opening size of 6.6 sq. in. At the time I was considering using a "scoop" that was flush to the hood very much like on the Barbee's 357 car.

After considering the grille shell air intake I made a paper template of the opening and had it with me when I saw the 848 car with the Model T grill shell and air intake. As it happened, Russ came throught the pre-staging lanes at the same time and I showed him the car and my template. My proposed intake is actually a little smaller, but about the same shape with rounded corners.

I am not assumimg that because the 848 is running this type of intake that it is class legal. I had a long talk with them (nice guys !) and the topic never came up other than me saying I was following a similar approach. I guess the benchmake of "legality" is established when a class record is broken and is checked in impound and then possibly protested later. I'm not sure where the 848 guys are in pursuit of a record.

In my case I'm just getting comfortable running the 836 and sorting out the handling and performance. I am currently running 35 MPH off the record (@ El Mirage) and realistically could pick up 15 - 20 MPH with the current engine/trans configuration. My short term goal is to get the most out of the existing combination through tunning and driver technique.

Shortly after Bonneville this year I was talking to a guy that's very much into aerodynamics. I mentioned that I was thinking about removing the hood scoop and making a NACA duct. I had done some research, but not enough. He shot me down in flames stating that to be effecting you need a long flat approach for the air, not exactually what you have with the air bouncing off the nose of a Street Roadster.

Picking up the air in back of the radiator as JD and Stan mentioned is a possibility I had not considered. Obviously the straighter the air flow path the better. I'm guessing the intake would have to be sized larger because of the restriction of the radiator tubes and fins, grille shell insert vains, etc. Also picking up the air in the middle of the radiatior would be best to minimize the turbulance cause by the air stacking up in front of the radiator and rolling around and over the grille sheel. Running a Moon tank on the front would probably also give the air flow a double wave effect so maybe higher is better?

I haven't decided which way to go yet. Is it better to ask forgiveness rather that permission as Jack Dolan would advocate, or formally submit the question to the rules committee. If so, how do I do that?

Either way I go, I still have the same basic question, is the air gap of 4" from carb to underside of the hood sufficient?

I do appreciate all the comments.

Tom

[JackD]

I don't advocate "Forgiveness is easier to get than permission."
but that is often how the system seems to work.

[836dstr]

Hi Jack,

Just yanking on your chain a little ! Maybe "advocate"  was the wrong word, but you know what I meant. Do you think Rick Y.'s trailing engine in is Streamliner would have passed muster if the "Tech" guys had been advised in advance.

In the long run I want to be running "Legal". In the short term I just want to go faster.

Tom

[836dstr]

Larry ("Hotrod")

On the 7th post you gave this link:

http://www.profblairandassociates.com/pdfs/RET_Bellmouth_Sept.pdf

I finally read the article and while not fully  understanding all of the technical discussions I did get the major points that you did well in summarizing in your post.

I was kind of amazed at the varitions of air inlets/scoops I saw at Bonneville this year. It's clear that a round bellmouth with a half radius would be the optimum design.

Thanks for the info  ! Now all I need to do is to figure out how to interject "vena contracta" into a casual conversation.

Tom

[interested bystander]

Hey, everyone- what about the SPIRIT of the rules, maybe a Nebulous term (sorry Jack) but , we all know that MOST Land Speed street roadsters are purpose built for speed trials, but the idea is, they're supposed to LOOK like a street driven hot rod.

How ' bout making competitors DRIVE them to the events?

[JackD]

Hey, everyone- what about the SPIRIT of the rules, maybe a Nebulous term (sorry Jack) but , we all know that MOST Land Speed street roadsters are purpose built for speed trials, but the idea is, they're supposed to LOOK like a street driven hot rod.

How ' bout making competitors DRIVE them to the events?

The rules for Street Roadster evolved from the LA Roadster Club wanting
 a suitable class for their Street Rods that were driven around So Cal. long ago.
They are mostly gone but not forgotten and the class remains.

[836dstr]

We have seen that the spirit of the rules does not mean much. Should we have 185 MPH vehicles running single hoop roll bars, no fire systems, no fire suits, chutes, no AIR INTAKES, and leather helmets. So much for the good old days where a Street Roadster looks like it could be street driven.

Kudos to Jim Kitchen, and the So Cal Speed Shop group that have taken a true street roadster and made them competitive in class with bolt it roll cages.

The Class rules are in place so let's work with them.

I started this thread with a very simple question about an air box question. This Forum is for technical questions. Not conjecture. I have probably brought some of this on myself. I had asked a very simple question about hood clearance and have asked 3 or 4 times for this question to be addressed to no avail.

Jack, I'm sorry I brought you into this in jest. You've "been there and done that" and I respect you for that !

Stan, Dan, JD, Larry, let me thank you for the "technical" discussion that's taken place here.

If I sound a little frustrated, maybe I am, or it could be 2 glasses of wine. I'm glad it's 6 months until the next meet, I may have a definative answer by then.

Tom

[JackD]

The rules are whatever comes on the wind.
As for the original question, the best result we ever had with a carb on a
 V motor was with a Moroso/ aftermarket air cleaner top and bottom.
The shape of the base directed the air into the carb better than any of the
inserts we tested on a Dyno.
The top was about 4 inches up and helped a bunch to gather air from all
sides and down the hatch.
Important to the scheme was to get the heat generated by the motor away from the intake air.
We did it with flat panels the went to the sides of the engine bay at the height of the carb base.
That put all the heat down and out and used the whole hood space above as a plenum.
We did not use an air cleaner element but spaced the top from the bottom
the same distance.