prodracing.com

Unofficial SCCA Production Car Racing Message Board
It is currently Fri Jul 25, 2014 6:58 am

All times are UTC - 7 hours [ DST ]




Post new topic Reply to topic  [ 44 posts ]  Go to page Previous  1, 2, 3, 4, 5  Next
Author Message
 Post subject: Re: Aero Questions, Especially for MGB racers
PostPosted: Tue Jun 26, 2012 7:44 am 
Offline

Joined: Sat Nov 19, 2011 2:25 pm
Posts: 43
Mike:

In your view, is some panelling right behind the front valance intended to channel air under the crossmember worthwhile?

Don


Top
 Profile  
 
 Post subject: Re: Aero Questions, Especially for MGB racers
PostPosted: Tue Jun 26, 2012 8:45 am 
Offline

Joined: Wed Oct 28, 2009 11:24 am
Posts: 516
Don -

The devil is in the details as it were. The biggest thing you can do to help your aero will be to stop as much unneeded air as you can from coming through or under the nose of the car. This means blocking any air coming through grille or any other front openings that is not needed to feed coolers or air intake (as much as possible under your rules, which are likely fairly free as far as internal ducting etc as long as external appearance is not much affected). And also stopping as much air from going under the nose as possible. Not sure what if anything you can do on a B. A vintage instance of an air dam was the "Spook" on the BRE Datsun roadsters, which I understand was slid in as brake ducting.

If you can keep air away from your underbody crossmembers by blocking it at the front you won't need to think about fairings etc. If you can't and your group will tolerate underbody fairings they could help.

Hope that helps.

PS: But a good data logger system to help measure the effects of your changes! 8)

Al Seim
Race Technology USA


Top
 Profile  
 
 Post subject: Re: Aero Questions, Especially for MGB racers
PostPosted: Tue Jun 26, 2012 10:20 am 
Offline

Joined: Fri Dec 23, 2011 8:59 am
Posts: 492
Location: Spring Hill, FL.
http://www.aerocivic.com/
aero testing stuff, really good IMHO. WTMFT ( way too much free time)*
I treat auto aero with the sq in. of involvement theory. The less square in. of parts that the air hits, the better.
Along that road; reducing piece count under the car is a major area for improvement . IMHO.
So yes, I think that a belly pan , deflecting the air off of ugly parts will go faster.
Keeping air from under the car turns out to be the best .
Some control over the car will show some improvement. The rules play the big part here. reality plays a big part. Will you have any major speed increase ? At long , high gear pull tracks, MAYBE. maybe not.
As far as your bumper goes. if it splits the air above it and under it It will go slower. If it is the splitter and very close top the ground, than maybe.
The flat front with a small splitter, very close to the ground , directing air around the nose and above the car will be the best,IMHO.
Taking the rules to the limit;. you should need a plumb bob as you go around the nose panel/airdam/splitter .
Take a look under the modern VW TDI or some other high fuel MPG car. If the crap did not work, they would not go thru the hassle of putting it on there.

Back to the rules tho, I still have the front end of the HP tapped up and cant tell if it is legal. I guess that the tape is legal but any screen is not. stupid stuff. IMHO.

_________________
Mike Ogren/Protech Racing, http://www.FWDracingguide.com http://www.ogren-engineering.com/ 352.428-8983 mogren@tampabay.rr.com


Top
 Profile  
 
 Post subject: Re: Aero Questions, Especially for MGB racers
PostPosted: Thu Jun 28, 2012 7:24 am 
Offline
User avatar

Joined: Tue Oct 27, 2009 9:26 pm
Posts: 641
Location: Pearland, Texas
The air dam on my #66 Civic was worth 5 mph in the speed trap at RA. The Gauper pistons were worth another 5 mph. The pistons cost ten times as much as the air dam.
We put the black plastic down to about 1 inch off the ground and let the track hone it to the "perfect" height and curvature.

James Rogerson


Top
 Profile  
 
 Post subject: Re: Aero Questions, Especially for MGB racers
PostPosted: Thu Jun 28, 2012 7:55 am 
Offline
User avatar

Joined: Mon Oct 14, 2002 8:08 pm
Posts: 434
Location: Raleigh, NC
James:

Do you have a picture? Thinking about doing the same thing with my FP MGB (letting the track do the final fettling).

Rick

_________________
FP MGB (getting ready for paint)


Top
 Profile  
 
 Post subject: Re: Aero Questions, Especially for MGB racers
PostPosted: Fri Jun 29, 2012 6:16 am 
Offline

Joined: Sat Nov 19, 2011 2:25 pm
Posts: 43
A vintage B is limited regarding air dams. It is inevitable that air will get underneath.

One possible device for dealing with this is hood vents like louvers or similar. If these are placed in the proper place, i.e a few lateral rows right behind the radiator, some of that disturbed air can be drawn out, which adds negative lift. And, under-hood temps lowered (11 degrees =1% power, allegedly).

Does anyone disagree with that?

The next issue is the certain negative effect of these vents/ louvers on Cd: Disturbance of laminar flow from the device itself and any hot air emerging into the air stream. Of course, this is more of an issue at higher-speed tracks like Road America.

Given the above, does anyone have an opinion on the net gain or loss of hood venting in a production race car, especially an MGB?

One direction I seeks to have two bonnets: A vented one for the bullrings like Blackhawk, another unvented one for Road America. Another is to somehow try to make the venting adjustable. This could involve use of flat vents (nothing protruding into the airstream) with some kind of attachable cap which could seal it.

Any observations would be appreciated.


Top
 Profile  
 
 Post subject: Re: Aero Questions, Especially for MGB racers
PostPosted: Fri Jun 29, 2012 6:35 am 
Offline
User avatar

Joined: Fri Oct 01, 2010 11:21 am
Posts: 568
dcharnet wrote:
Given the above, does anyone have an opinion on the net gain or loss of hood venting in a production race car, especially an MGB?


There is no rule allowing vents in a production car hood, unless those vents came with the base model, stock.


Top
 Profile  
 
 Post subject: Re: Aero Questions, Especially for MGB racers
PostPosted: Fri Jun 29, 2012 6:45 am 
Offline

Joined: Sat Nov 19, 2011 2:25 pm
Posts: 43
blamkin86 wrote:
dcharnet wrote:
Given the above, does anyone have an opinion on the net gain or loss of hood venting in a production race car, especially an MGB?


There is no rule allowing vents in a production car hood, unless those vents came with the base model, stock.


Aha, thanks.

That fundamental point established, does anyone have any comment on the questions? Maybe for this dispositive reason, no one in production gets into these areas.


Top
 Profile  
 
 Post subject: Re: Aero Questions, Especially for MGB racers
PostPosted: Fri Jun 29, 2012 6:46 am 
Offline
User avatar

Joined: Mon Oct 14, 2002 8:08 pm
Posts: 434
Location: Raleigh, NC
Don:

One problem... (Mr. Lamkin and I are on the same wavelength apparently...)

Per SVRA General Rules and Regulations:

A. Body: The body configuration should be as raced "in period". All body parts must be of the same material and design as those supplied by the manufacturer as standard or optional.

1. Undocumented supplemental aerodynamic devices such as spoilers, air dams and wings are not permitted.


Rick

_________________
FP MGB (getting ready for paint)


Top
 Profile  
 
 Post subject: Re: Aero Questions, Especially for MGB racers
PostPosted: Fri Jun 29, 2012 6:58 am 
Offline

Joined: Sat Nov 19, 2011 2:25 pm
Posts: 43
Rick Starkweather wrote:
Don:

One problem... (Mr. Lamkin and I are on the same wavelength apparently...)

Per SVRA General Rules and Regulations:

A. Body: The body configuration should be as raced "in period". All body parts must be of the same material and design as those supplied by the manufacturer as standard or optional.

1. Undocumented supplemental aerodynamic devices such as spoilers, air dams and wings are not permitted.


Rick


Hi, Rick, I know. Sebring-style valances are OK with SVRA, and there are many cars racing vintage nationally with louvers. This is no issue ith VSCDA. I accept this regulatory framework, and am trying to get to the merits.

Hope you Flying Circus guys are coming to Grattan to show us What For.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 44 posts ]  Go to page Previous  1, 2, 3, 4, 5  Next



All times are UTC - 7 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group