Does 65 GTO / Lemans front license plate impede airflow at high speed?

[Jim Doran]

Removing radiator to have it sealed up and improved by a local shop. While draining the coolant and removing lower hose it became obvious that the license plate & bracket hang down a solid 2.5 inches below the front bumper and would be blocking some airflow to the radiator at speed. At a minimum it would create unnecessary turbulence of the airflow.

Anyone ever play around with and without the plate or have a point of view on these topic?

[Goatracer1]

You have to be kidding. The front of your car is shape like a brick I don't think the lic. plate would much matter.

[chrisp]

Originally Posted by Goatracer1

You have to be kidding. The front of your car is shape like a brick I don't think the lic. plate would much matter.

Tough one

[Jim Doran]

Originally Posted by Goatracer1

You have to be kidding. The front of your car is shape like a brick I don't think the lic. plate would much matter.

I agree, diminishing returns, but if you take an actual look, the plate hangs several inches down into what would be a clear airflow into the radiator. I'll try and take a pic.

Trouble is it would be near impossible to measure with and without difference.

[Keith Seymore]

Originally Posted by Jim Doran

I agree, diminishing returns, but if you take an actual look, the plate hangs several inches down into what would be a clear airflow into the radiator. I'll try and take a pic.

Trouble is it would be near impossible to measure with and without difference.

We do this kind of measurement all the time at work; it is directionally incorrect but not measureable (or very insignificant). We generally define the amount of opening in square inches (or square millimeters these days) and quantify how much is being blocked off.

The majority of the air is entering through the upper grille and the bumper slots anyway. The fact that the plate is hanging down in open space (as opposed to a constrained space) also minimizes its effect. When the plate is blocking one of the upper openings then it becomes more of a contributor (like if you mounted it on top of the GTO emblem, for example).

K

[kate`s67gto]

A 65 front bumper looks similar to a 67.
Mounted the front plate with it hanging below the bumper opening.
Two pics with the plate mounted. Red car is mine.

[Hooter]

I've been 135 with my front plate on

[Jim Doran]

Remove the plate and you'll hit 137 !

[John62]

The A/C cars have a radiator that hangs down 2 inchs lower and can be seen hanging below the bumper. In this case I bet it would have some affect on cooling.

[Keith Seymore]

Mine looks pretty much even with the bottom of the bumper:

[Keith Seymore]

Originally Posted by Keith Seymore

Mine looks pretty much even with the bottom of the bumper:

So does Ed Lis's;

Jim - do you suppose you have the wrong bracket?

K

[John62]

Originally Posted by Keith Seymore

So does Ed Lis's;

Jim - do you suppose you have the wrong bracket?

K

As I see it, the bracket in this pic is upside down. I believe if you put the bracket on correctly the plate does hang well below the bumper. Jim's is likely correct. They can and most people do install it upside down because it looks correct but probably blocks more air because it blocks the gap between the top and bottom section of bumper. I hope this comes out the way I think I am saying it.

[John62]

I think this is what Pontiac originally intended.

http://forums.maxperformanceinc.com/...1&d=1452551404

[Chris65LeMans]

Originally Posted by John62

As I see it, the bracket in this pic is upside down. I believe if you put the bracket on correctly the plate does hang well below the bumper. Jim's is likely correct. They can and most people do install it upside down because it looks correct but probably blocks more air because it blocks the gap between the top and bottom section of bumper. I hope this comes out the way I think I am saying it.

This is right, I believe. When I bought a repro bracket, I didn't like the look of the plate hanging down, so I put the bracket on upside down.

[Jim Doran]

John, Chris you are correct. There is a pocket on the bracket that should be mounted at the bottom. The plate then slips into this pocket and is screwed in the lower 2 holes.

Keith, I respectfully suggest your plate might be mounted wrong or with a different bracket. I also remain convinced it disrupts airflow under the bumper.

These pics should help.

[Keith Seymore]

Very interesting.

I don't believe mine has ever been apart. A factory mistake on an early built car, perhap? (My car was built September 18th of 1964, in Pontiac Michigan).

Ed's car has 4200 miles and has never been restored (March built Kansas City car). I can't comment on if any changes have been made to his car beyond that.

K

A couple pics of Ed's car with no plate attached:

[Keith Seymore]

Originally Posted by John62

As I see it, the bracket in this pic is upside down. I believe if you put the bracket on correctly the plate does hang well below the bumper. Jim's is likely correct. They can and most people do install it upside down because it looks correct but probably blocks more air because it blocks the gap between the top and bottom section of bumper. I hope this comes out the way I think I am saying it.

I understand the way you are saying it, and agree, that from an airflow design perspective it is a greater offense to block the area in the opening of the bumper than it would be to allow the plate to hang down into open space.

K

[Keith Seymore]

Originally Posted by Jim Doran

Keith, I respectfully suggest your plate might be mounted wrong or with a different bracket.

Anybody know how the design of the '64 bracket compares?

Looks like there is precedence for mounting it "up high".

K

[HWYSTR455]

An air dam (on the core support, below the radiator) would negate any impact the plate would have on air flow, especially at speed. And it wouldn't have to be very big/much area.

.

[Jeff Hamlin]

While looking through old photo files for something I came across some old shots from a past club cruise and laughed when I saw this pic.
I forgot about this quick change front end treatment and thought it went well with this post
Don has owned his '65 since new so as anyone who has something that long they are bound to personalize it.
He made an air-dam that he easily can put on and take off when he is in the mood for a change.