Aerodynamic question…

[Daryl]

I feel like “at speed” (ie, 80+) my front end is lifting off! Even with all the suspension upgrades, etc. So, I contacted MM, sent pics of how she sits under load, and the Tech there suggested I RAISE the ride height 1”!??

I was expecting a recommendation of LCA’s, etc . However, I’m now wondering if the lowered height compresses air underneath, causing that “lift” I’m experiencing; and why raising the ride height 1” front & rear, allowing more air underneath might remedy the issue??? Maybe the air flows more easily underneath and doesn’t cause the “lift”?

Suggestions? Recommendations?

 

[cobrajeff96]

A front splitter will take care of that. AJ Hartman Aero. Gonna be $$$ though.

 

[Daryl]

Cobra R style bumper only. :-(

 

[Ponyaddict]

Carters Customs, LLC has a splitter for the stock 95 bumper. I have it on my GT. I did modify it though as it was angled up. Took a router and made a jig to take off 1" off the back edge on the sides.

 

[white95]

Yeah, the splitter seemed to work because the car is definitely faster to 120 mph without it.

 

[shovel]

However, I’m now wondering if the lowered height compresses air underneath, causing that “lift” I’m experiencing; and why raising the ride height 1” front & rear, allowing more air underneath might remedy the issue??? Maybe the air flows more easily underneath and doesn’t cause the “lift”?

Air comes in the front through the grille and radiator, where exactly do you think that air leaves? It pretty much has to join the air coming in under the car which is gonna lead to a traffic jam under the hood & fenders... that's a lot of square inches to push up on.

Also remember when you lower these cars with springs (rather than spindles or tall ball joints) your roll center drops a little over 2x as much as you lowered it leading to increased body lean (the center of mass has a longer lever) , which you then have to combat with stiffer springs and shocks, which makes your car less forgiving when the suspension is disturbed close to the limit so you have to drive further from the limit and leave some speed on the table. You may find it corners faster and communicates better at stock height with softer springs, or lowered only with a spindle drop / tall ball joint - one or the other, both would turn your car into a bulldozer.

 

[joemomma]

I can confirm that my car doesn't exactly feel "planted" at speed (meaning, above typical interstate speed and fast enough to get a nice ticket). I assumed it was a combination of staggered/wide tires and grooved pavement, but it could be certainly be the air buffeting underneath. Makes sense.

 

[Daryl]

Air comes in the front through the grille and radiator, where exactly do you think that air leaves? It pretty much has to join the air coming in under the car which is gonna lead to a traffic jam under the hood & fenders... that's a lot of square inches to push up on.

Also remember when you lower these cars with springs (rather than spindles or tall ball joints) your roll center drops a little over 2x as much as you lowered it leading to increased body lean (the center of mass has a longer lever) , which you then have to combat with stiffer springs and shocks, which makes your car less forgiving when the suspension is disturbed close to the limit so you have to drive further from the limit and leave some speed on the table. You may find it corners faster and communicates better at stock height with softer springs, or lowered only with a spindle drop / tall ball joint - one or the other, both would turn your car into a bulldozer.

Shovel & Joemomma,
You touched on some of the same factors that my contact at Maximum MotorSports did. He wants me to raise the front and rear 1” each, drive it and give him feedback. It DOES make sense about the “floating” feel you and he addressed: all that air occupying a smaller area due to a lowered car. I get it now… ++

Will chime back in in a week or so after I get some miles under the new height.

 

[cobrajeff96]

If you can vent air from the hood like those heat extractor hoods do, it'll make a noticeable difference. I'd like to find a real nice body shop to carefully do that sort of thing to my 96 Cobra hood, we'll see.

The big problem with just about every SRA Mustang prior to 2005 is that Ford made the rear roll center occupy the same height as the spare tire well in the trunk. Makes for a poor handler at all speeds in original stock form.

 

[shovel]

Carter's Customs makes a massive heat extractor / pressure vent hood for SN95's .. it kinda looks cool too if you're doing a full attack sort of cosmetic or don't care about cosmetic as long as the competition's looking at your taillights

https://driftamerican.com/94-98-mustang-and-2016-2020-gt350-heat-extractor-hood-vent/

I should add that while it seems intuitive that a heat extractor/vent hood would relieve that under-car pressure - and it's likely so - some aspects of aerodynamics aren't so straightforward and I don't have first hand experience with those hoods. I would not commit the money or the hood to it without further study.


The nostrils on SN95's are "functional"... in as much as a couple 5/8" diameter holes directly under them can be. But that's not moving real volume, I just find it entertaining that they aren't absolutely fake like New Edge vents