[ewh123]

The hood on my gen 2 coupe lifts in the center at the cowl at around 60 mph. I am asking if others have experienced this and what ( if anything ) can be done to correct it.

Thanks
ewh123

 

[LateApex]

There is a high pressure area at the base of the windshield (at speed) Do you remember "cowl induction" on the Chevy Chevelle? There is maybe a wave effect of some sort, where the pressure at the end of the bonnet translates to a low pressure area in the center of the bonnet.

I believe that any solution involves letting the air out of the engine compartment. I have been thinking about this anyway, as there is no forced air into the engine bay to help cool the bits. All air is forced from the nose through the radiator and exists upward through the slot. I am considering some louvers for my particular design.

This may not be your issue. But it has to do with airflow in one way or another methinks. Maybe the flow through the radiator is not exiting the engine bay / bonnet correctly.

FWIW

 

[Gbeck]

I put a couple of louvers in the hood.

 

[LateApex]

Who makes those Glenn?

 

[John Dol]

I made one at the end of the bump on the hood. Made a grate to finish it off.

John

 

[LateApex]

Looks nice !

I am running an eight-stack induction system, and as such, want to keep water out of the stacks This makes it a challenge for me to vent "the bump". Glenn's approach has a bit of a challenge too. There is a double layer of fiberglass under that area of the bonnet for rigidity reinforcement. Making a clean cut there will be ... exciting ...

I've used RunCool Louvers before, and am inclined to their product, as it is very well done. And they have 7" x 23" flavor, which fits perfectly above the heads alongside the bump. Decisions, decisions ...

 

[Gbeck]

Who makes those Glenn?

I bought these from a forum member "SeattleDad" a few years ago. I don't know where he sourced them.
A quick search finds lots of styles in aluminum and ABS, but not much in fiberglass. Somebody on the forums used the hood vents from the Factory Five GTM.
Sorry I couldn't be more helpful.

 

[ewh123]

Thanks for the replies. I have talked to my painter about this and he suggested glassing in a 3/4 conduit near the edge of the hood to strengthen this area to prevent flexing. I am taking it back next week to have this done. It will run across the full width and slightly down the sides. Since the car is already painted with stripes refinishing the underside of the hood should be easier for him. If this does not fix the flexing then the next step will be some kind of vents. I agree that a buildup of pressure under the hood is the problem. The coupe hood looks so nice I would hate to have to cut vents into it.

Thanks again
ewh123

 

[ewh123]

Thanks for the replies. I have talked to my painter about this and he suggested glassing in a 3/4 conduit near the edge of the hood to strengthen this area to prevent flexing. I am taking it back next week to have this done. It will run across the full width and slightly down the sides. Since the car is already painted with stripes refinishing the underside of the hood should be easier for him. If this does not fix the flexing then the next step will be some kind of vents. I agree that a buildup of pressure under the hood is the problem. The coupe hood looks so nice I would hate to have to cut vents into it.

Thanks again
ewh123

I got the coupe back from the painter this past Tuesday. I took it up to 80 mph and the hood stayed flat, didnt bow up at all. He opened up the stiffening rib on the bottom of the hood and bonded in a piece of tubing and then glassed it back closed. I cannot even tell it was done. He did a great job and no venting is needed. Now to put some miles on it. And I am going to have to figure out how to add some pics of it. I will get to that soon.

 

[jingro]

View attachment 367653
I made one at the end of the bump on the hood. Made a grate to finish it off.

John

John, what are the dimensions of the hole you cut in the bubble? I am thinking of doing the same thing. Thanks