So why did my hood suck up?

[vette#128]

" but remember I'm running GT -  so I can't mess with the OEM aeropackage -  and the car is pretty low right now."

Carl, Coil-over front springs are legal in GT and will drop your vette in the dirt (or salt) if you wish. In addition, they will  keep the front end planted at speed....The transverse composite leaf WILL allow the front end to lift, as you know, not a good thing. I have my springs (550#) adjusted to near coil-bind so it is almost a solid front end.  At B'Ville, the rubber front spoiler just barely scrapes the ground...... I know this because I have to wash the salt out of the radiator after every run.  Oh, by the way.... I had a transverse front spring break (in 2 places) at about 220 mph once and got a pretty wild ride out of it .... I recommend coil-overs.

[Unkl Ian]

The angle of the windshield influences the pressure at the back of the hood.

In the '60s,windshields were vertical enough to create a high pressure area.
Now that they are all layed down,the effect is reduced,or eliminated.

It would be interesting to play around with some differential pressure gauges
to see what is really happening.

[Harold Bettes]

Howdy All,
The only thing that is super important is that the driver needs to drive and not get fixated on the pressure diff gage(s).  Generally best to leave this task to a passenger or a camera!

The Magnahelic gages are very good and they can typically be had very inexpensively at surplus houses that deal in instrumentation.

Although that this one is full scale at only 2"H2O, it seems to work well enough.

The deflection from zero is because the gage is laying on its back smiling for the camera. 

Regards to All,
HB2

[Carl Johansson]

" but remember I'm running GT -  so I can't mess with the OEM aeropackage -  and the car is pretty low right now."

Carl, Coil-over front springs are legal in GT and will drop your vette in the dirt (or salt) if you wish. In addition, they will  keep the front end planted at speed....The transverse composite leaf WILL allow the front end to lift, as you know, not a good thing. I have my springs (550#) adjusted to near coil-bind so it is almost a solid front end.  At B'Ville, the rubber front spoiler just barely scrapes the ground...... I know this because I have to wash the salt out of the radiator after every run.  Oh, by the way.... I had a transverse front spring break (in 2 places) at about 220 mph once and got a pretty wild ride out of it .... I recommend coil-overs.

Ed,
 Any Idea what caused that front transverse spring to break?    The thought of that gives me the willies -  yikes!  I am considering coil overs -  right now it seems pretty pricey for what I would be gaining -  but I'm still researching and thinking about it.  I have also thought about just "chaining" down the front suspension -  like they do in some of the hot rods -  but I can't figure out a safe and effective way to do it.  Right now I have about 1.5 inches of travel in the front end -  made up some rubber stops -  as far as I can tell the front end lowers I assume due to pressure -  and just sits on the stops at high speed -  at least thats what it looks and feels like is happening in videos and in the car.
 Next year -  when we put in the big block -  we will take a long hard look at what to do with the front suspension etc -

Carl