Ford Gt-style Hood On An Elio?

[WilliamH]

Doesn't make a difference for the purpose of a vented hood. GT40 still has it's radiators in the nose.

A vented hood is one thing.
A ducted radiator is a different critter.
The GT40 is a ducted radiator.
So was the Lotus that was done on "Overhaulin'" a couple years ago.

 

[Sethodine]

I was trying to come up with a way to get airflow through the radiator without the drag that the standard configuration causes. The real serious hyper-milers put panels under the engine bay to streamline the airflow, but I would want to make sure the radiator still had proper airflow. Ducted, rather than vented, seems to me to be a solution. I figured it wasn't usually done for front-engine cars simply because the car wasn't designed with that level of performance in mind. Even the Pontiac Fiero doesn't have a ducted hood, even though it is a mid-engined, front-radiator car as well. Although it was sold with L4s and V6s, it was designed and can fit a V8.

 

[Gas-Powered Awesome]

Not unreasonable. People do it on the G1 Insight all the time.

We'll have to wait and see what the actual underside looks like as Elio is going to have to do a damn-good job in the first place to achieve their 84 MPG. If they leave any room for improvement, it's possible a better undertray could be fitted that would still leave plenty of room for venting the hot radiator air underneath. It's only 55 HP, not a lot of waste heat to deal with.

Here's a retrofit undertray on an Insight. Much larger than stock. No cooling problems. No modifications to the hood.

 

[Grumpy Cat]

Both of those links are random, anonymous people merely speculating.

There are actual engineering resources out there if you want to read up on aerodynamics.

See item #3 here: https://www.carthrottle.com/post/engineering-explained-10-aerodynamic-features-of-race-cars/

McBeath's book is a good start: https://www.amazon.com/Competition-Car-Aerodynamics-New-3rd/dp/1845847768

I could have sworn I saw something on Top gear with that hood scoop that actually create downforce, but now I can't find it...

 

[Gas-Powered Awesome]

I think the primary objective is to increase cooling without creating lift. So, yes, it does reduce lift vs. venting underneath the vehicle. The fans do bupkis over 30-40 MPH. There are hood designs specifically for increasing downforce. Look up "time attack" for all kinds of crazy aero devices.

 

[CrimsonEclipse]

Does anybody think the aero on the Elio might be improved by a hood similar to the Ford GT?

no

 

[NSTG8R]

Does anybody think the aero on the Elio might be improved by a hood similar to the Ford GT? By this, I mean the air passing through the radiator exits out the top of the hood and over the windshield, rather than swirling around in the engine compartment and funneling out the bottom of the engine bay.

This would allow for installing a cover plate under the engine bay, to improve the aero (and this is the real aero improvement area, not so much the hood).

I'm not suggesting this as a factory change, but more of an aftermarket kit. It seems there might be enough room in the front to work something like this.

Thoughts?

Beat ya to it, Sethodine! But we're on the same page as far as hood design goes. We had a few conversations about this over the last couple years.

http://elioowners.com/threads/mods-and-accessories-section.6432/page-8#post-117751

and

http://elioowners.com/threads/cooling-drag.3352/

Lots of good points brought up in both threads.

 

[skygazer6033]

I've considered this type of mod myself but discounted it for several reasons. Cars have a high pressure area Foreword of the windshield. You could actually restrict the airflow through the radiator. Without access to a wind tunnel you'd just be guessing. I would guess venting out the side behind the suspension would be a better option. Engines need more cooling airflow than just what comes through the radiator. Without a lot of cooling air plastic sensors and valves get brittle and break up leading to all kinds of problems even fires. I seem to recall Fieros and the Fiat X 1/9 had these problems for this very reason.

 

[Gas-Powered Awesome]

I've considered this type of mod myself but discounted it for several reasons. Cars have a high pressure area Foreword of the windshield. You could actually restrict the airflow through the radiator. Without access to a wind tunnel you'd just be guessing.

This is why vented/ducted hoods have the openings closer to the front than the cowl. This also why "cowl-induction" hoods have the opening at that higher-pressure point where air piles-up against the windshield.

For testing, no wind tunnel needed. Just tape short pieces of yarn all over the area in question. Then stick a video camera in a good location to capture the area (or get a friend to film from another car) and go for a drive.

You can also use a home-made water U-tube manometer to measure pressure differentials. Search the web for "diy manometer" and see results like this: http://www.vansairforce.com/community/showpost.php?p=442886

 

[skygazer6033]

GPA --- Rather than a Manometer I would use a sensitive altimeter for pressure testing (mostly because I have one). With the Elios short nose and steeply raked windshield it may not prove to be a problem but without testing you never know. Cooling drag is always difficult to deal with but can yield real measurable improvements in aerodynamics.