It felt fine, bit more wind noise than I'm used to though!

I would think the Cab's roof line would be a big help, but imagine a Cab' with a rear wing, yuk, i think Ritchie runs one? think ive seen him drag with the top down, so thats a guide Rich',, someone needs to be brave and re profile the saloon roof to a NACA duct shape between the gutters from about the mid point back to the rear window, i cant do it for falling foul of the silhouette rules, but i have back filled the normal low pressure area behind the decklid by venting it, gaping it, and venting the rear apron, another plus for water cooled motors is they need no ducting or fan housing so are more versatile for bringing air up and over it or around them, did it work? i have to say it did, thats why sports racers run 'open deck' engine bays, its well known to reduce drag, now tho, ive gone a different rout with the engine paneled in by 'aero panels' and have made a solid GRP decklid, this will feature a spoiler when i get time next winter, Wally is on the right track with his whale tail but many poo poo these, mine will be similar but different;) lol, ok, not as bragging right
friendly as a wing, but we are getting good anti wing evidence coming good now, apart from a personal dislike for the B&D work mate, the spoiler is miss understood and its full function is not well documented, what they do if properly positioned is work wonders for the airflow UNDER the car, tho you need to work that area and de clutter and smooth it all to exploit it to its fullest, it smooths the turbulence behind the car and causes up flow from ground level to a height above the spoiler depending on its design and angle of attack, this then pulls yet more air out from under the car, icing on the cake if its already flowing well underneath, but most old design stock cars with busy underbodys just roll along on stagnant air, dragging the air along with it, it can then turn on a viscous effect with lift and drag thrown in for good measure, it all take work to get going, and a little understanding, the trouble starts again when flat bottomed cars get down Below the magic 40mm, which just happens to be the MSA lowest ride height rule, below 40mm, the viscous problem with drag and lift comes back to haunt you and it needs a special shaped underbody to perform, the 40mm rule is accidently the ultimate, im sure it is just an arbitrary figure to stop special needs in club racing, again, look at NASCAR for aero advantage, tho they dont cross over to well for anything else, they have skirts but they also get huge spins at 200 mph, i see those helping to stop air lifting them when side ways at huge speeds, but their spoilers work exactly as ive outlined above, the airflow so smooth and high riding it allows bumber to bumber 40 strong packs at 200 mph. :cool: what do we know?

,

I had plans to build a NACA duct piece that fits down into the ragtop section, initial thoughts were intercooler intake cooling, but at this point I might stay naturally aspirated for awhile and then I don't need the volume of air a big NACA would create. What shape do you guys think might help with aero using the ragtop hole?

Jason

http://www.rjvolksperformance.com/gallery.html
Hi Jason, big question you asked! Expensive roof too! So It's probably best left alone, but here you can see Ritchie running his Cab with the roof down, this is giving aero advantage to his folded DOWN top!! Which now looks more like a well developed spoiler to me...very clever, it will be doing much of what I mentioned above, and pulling air out from under the car to help with down force, this car has run an 8 sec, pass at 150 mph, no workmate bolted on the back either, there is always a way for the clever guys to exploit ANYTHING, the good bit is those without the instinct never Suss how the quick guys do it, we are left with the starting point for efficient high speed stability being the front, mechanically sound and with a minimum of 6* castor and air flow control to kill front lift is my recommendation, oh! and it must be fun at all times! regards, Johnny.

IIRC Richie's car is basically a cab body draped over a tube chassis (or semi-tube chassis) and the "folded top" is basically a canvas covered wing. You can hardly call it a sleeper but it is a great looking car.

A super cabrio with a canvas cover over a folded top would probably be much more stable at speed than it's hardtop counterpart but going 100+with an open top would be a bit noisy :)

the main reason richie runs with the roof down is he had a few rear windows blow out. if the roof is down the window cant blow out.