Exhaust?

Originally posted by oanglade:
(Removing the top) won't help the SM's much (they already could in 2004), but it will help the IT Miatas drop an easy and quick 40+ pounds if needed to get to min. weight.
Click to expand...

Any estimates whether the 40 pound weight reduction will make up for the additional aerodynamic drag? I've heard rumors that a topless Miata loses about 1.5 seconds at Roebling (2.02 mile course) compared to the same car with the top on.

------------------
Doug "Lefty" Franklin
NutDriver Racing
 
I don't know if the weight reduction will make up for the higher drag, but 1.5 seconds on a 2 mile track sounds like a lot to me.

The times that I've run a Miata without a hardtop at a track it has been pretty similar in terms of lap times to Miatas with hardtop, but I've never tried a before and after on the same car.


------------------
Ony Anglade
ITA Miata
Sugar Hill, GA
 
No testing was done with a Miata, but we did test an MG Midget with and without the factory hardtop. At Road Atlanta, the top end was 7 MPH slower without the hardtop, and removing it added 3 seconds per lap.
Sadly for us, SCCA rules prohibited using the hardtop on the Midget.

------------------
Bill
 
Originally posted by wbp:
... did test an MG Midget with and without the factory hardtop. At Road Atlanta, the top end was 7 MPH slower without the hardtop, and removing it added 3 seconds per lap.
...
Click to expand...

Well, since that's 3 seconds in 2.54 miles, it makes the 1.5 seconds in 2.02 miles more believable, at least to me.

------------------
Doug "Lefty" Franklin
NutDriver Racing
 
So the CRB has put out a Technical Bulletin on the Spec Miata exhaust:

Check it out:
http://www.scca.com/_Filelibrary/File/TB04-08a.pdf


They say that the intent of having the exhaust come out of the bodywork is to make sure that there are no trapped gases under the car and possibly drawn into the driver's compartment.

So, how long do you guys think it will be before the exhaust rules for IT are changed also?



------------------
Ony Anglade
ITA Miata
Sugar Hill, GA
 
I was speaking with a comp board member asking about this and there seems to an be honest difference of opinion on what was allowed with the old rules.
"exhaust shall exit behind the driver, and shall be directed away from the car body."
now I would think that a turn down in front of the rear axel would be legal. some thought that it has to exit out the side or rear. I know this will be addressed again. In a GT car exiting under the car would not be good with there lack of body work, but the question is does it create a problem in an unibody car like we race.
I think this is a case of unitended consequences and will be more thoughly thought thru soon.
dick
 
boy am i a friggin pyscic. there is a tech tech bulletin on the scca garage site dated 6/21 backing off the rule change. they say they will reconsider the implication for the future.
dick
 
I think that any current SM's or IT Miata cages won't be very legal without the top. They SHOULD have to follow prod-style cage rules for open-top cars...and will need to be a lot taller to be legal...and won't fit inside factory tops.

AN

------------------
Andy Bettencourt
ITS RX-7 & Spec Miata 1.6
New England Region R188967
www.flatout-motorsports.com
 
Andy,

I looked all over the GCR and ITCS and all I could find was that the top of the helmet would have to be 2 inches below the top of the main hoop. I bet I can already pass that with the cage and hardtop and the seat bolted to the floor.

But I really doubt that I'll race without the top.

------------------
Ony Anglade
ITA Miata
Sugar Hill, GA
 
You must log in or register to reply here.
Back
Top