Home  
Site Partners: SpotterGuides Veloce Books  
Related Sites: Your Link Here  

Go Back   TenTenths Motorsport Forum > Saloon & Sportscar Racing > Sportscar & GT Racing > ACO Regulated Series

Reply
 
Thread Tools Display Modes
Old 10 Jul 2003, 16:08 (Ref:658013)   #1
Dauntless
Racer
 
Dauntless's Avatar
 
Join Date: Dec 2002
United States
San Francisco Bay Area
Posts: 386
Dauntless should be qualifying in the top 10 on the grid
ACO 2004 Rear Diffuser vs. Toyota Eagle MkIII GTP Rear Diffuser

I was drooling over the photos of Toyota's GTP on MulsanneMike's website this morning when it struck me that the ACO 2004 rules would seem to produce a rear diffuser strikingly similar to the very effective diffuser employed on the all-conquering MkIII.

From the 2004 ACO rules on Mike's website:

3.5.2 - Rear diffuser
An inclined surface (rear diffuser), flat, continuous and rigid is mandatory underneath the car and at the rear.
a/ It must be inclined relative to the reference surface and it must comply with the maximum volume defined by
drawing nĀ°1 ;
b/ No part of the diffuser must be more than 200 mm above the reference surface and its rear end must be plumb
with the perimeter of the bodywork ;
c/ The panels joining the rear diffuser to the reference surface must be vertical. In addition, from the rear axle
centreline to the rearmost edge of the diffuser, the outer panels joining the rear diffuser to the reference surface
must remain parallel to the longitudinal centreline of the car ;
d/ A maximum radius of 10 mm is authorised to connect the rear diffuser to the vertical panels ;
e/ A maximum of two vertical fins may be added to the rear diffuser, but their surfaces must :
e.1 ā€“ be at right angles to the diffuser ;
e.2 ā€“ be flat and parallel to one another and to the longitudinal centreline of the car ;
e.3 ā€“ be positioned symmetrically about the longitudinal centreline of the car.


Now, having read that, check out this photo of the rear diffuser on the Toyota...

http://www.mulsannescorner.com/toymkiii-5.html

Notice that there is a full width flat reference plane ahead of the diffuser, then the diffuser rises to what appears to be no more than 200 mm. And there is one rules-compliant fin per side.

The Toyota was an exceptionally grippy car. Perhaps I underestimated the down force potential of the new rules...
Dauntless is offline  
Quote
Old 10 Jul 2003, 18:24 (Ref:658108)   #2
pirenzo
Veteran
 
pirenzo's Avatar
 
Join Date: Dec 2002
United Kingdom
London, UK
Posts: 10,241
pirenzo should be qualifying in the top 5 on the gridpirenzo should be qualifying in the top 5 on the gridpirenzo should be qualifying in the top 5 on the grid
the Toyota still wasn't as grippy as modern cars i don't think however...
pirenzo is offline  
Quote
Old 10 Jul 2003, 18:33 (Ref:658114)   #3
gttouring
Veteran
 
gttouring's Avatar
 
Join Date: Jan 2003
Location:
USB 3.0
Posts: 4,536
gttouring should be qualifying in the top 10 on the grid
the toyota may not have had modern cars rubber development...and wing developments, but the undertray is a fresh air bit isn't it.
From flat bottom to this ahh it feels good
gttouring is offline  
__________________
SuperTrucks rule- end of story.
Listen to my ramblings! Follow my twitter @davidAET
I am shameless ...
Quote
Old 10 Jul 2003, 18:41 (Ref:658118)   #4
JAG
Veteran
 
JAG's Avatar
 
Join Date: Aug 2002
England
Posts: 10,500
JAG should be qualifying in the top 3 on the gridJAG should be qualifying in the top 3 on the gridJAG should be qualifying in the top 3 on the grid
The main thing is we won't have to worry about top speed/humps etc. anymore as the more air gets under the car the more downforce is created , whereas currently if any air gets under the car at high speed it is likely to flip.

With the extra drag a 2004 cars creates top speed may be reduced despite having more power.

Sounds like the ideal compromise to me.


Powerful cars without the top speed problems. Afterall whats the difference between 200mph and 215+mph as the cars were doing in 1999 despite only lapping at the speed of the current cars.
JAG is offline  
Quote
Old 10 Jul 2003, 19:27 (Ref:658171)   #5
Dauntless
Racer
 
Dauntless's Avatar
 
Join Date: Dec 2002
United States
San Francisco Bay Area
Posts: 386
Dauntless should be qualifying in the top 10 on the grid
The Toyota wasn't as grippy as full-tunneled cars of the era, but I suspect that it is comparable in downforce to today's cars due to its length and width, plus the semi-tunnels. The best of today's cars have better suspensions and especially better dampers and tires than cars of 12-15 years ago. I think that goes a long ways towards explaining the fast lap times of today's cars, in spite of their lower horsepower.
Dauntless is offline  
__________________
Stan Clayton
Dauntless Racing
Quote
Old 10 Jul 2003, 21:34 (Ref:658282)   #6
MulsanneMike
Veteran
 
MulsanneMike's Avatar
 
Join Date: Jun 2001
United States
Posts: 1,831
MulsanneMike has a real shot at the podium!MulsanneMike has a real shot at the podium!MulsanneMike has a real shot at the podium!MulsanneMike has a real shot at the podium!
I'll go out on a limb and say there is little difference between the Toyota's underfloor and the ACO spec. For starters the Toyota's wasn't simply an flat plane as mandated by the ACO for next season. It's a graceful arc. The MkIII's rear exit height is well above 200 mm. Also, the strakes are arcs, not parrallal to the centerline (as would need to be per ACO'04), that's a very large difference as they are generating a nice vortex because of their arc relative to the centerline. I haven't checked their forward leading edge compared to ACO'04, but I suspect they are well forward of that.

Now lets look at the MkIII's aero performance, these numbers come directly from Hiro Fujimori:

Downforce:
4061 lbs. @ 150 mph, with 929 lbs. of drag
5848 lbs. @ 180 mph, with 1338 lbs. of drag
7220 lbs. @ 200 mph, with 1652 lbs. of drag

Peak downforce: 9,000+ lbs. at 200 mph

Lift-to-drag ratio: 4.37:1 (the comparative L/D is decieving to below as GTP cars were pretty dirty at high downforce levels as they had prodigous hp to move them through the air and were less constrained by drag than say contemporary Group C cars)

So that puts the MkIII's downforce easily 4500 lbs. (at peak) more than any contemporary LMP/LMGTP. Consider that the ACO'04 rules are aimed at a 25% downforce reduction with a 10% drag increase. So if a top LMP generates 4500 lbs. for 1000 lbs. drag (4.5:1), you'll be looking at 3375 lbs. downforce for 1100 lbs. drag (3.06:1). I'm pretty confident we'll see similar reductions for '04 cars despite the designers best efforts. Give then a few years. Suffice to say, the ACO'04 rules will not be producing 9000+ downforce monsters, ever.

Last edited by MulsanneMike; 10 Jul 2003 at 21:38.
MulsanneMike is offline  
Quote
Old 10 Jul 2003, 21:39 (Ref:658286)   #7
cybersdorf
Veteran
 
Join Date: Oct 2001
Austria
Vienna, Austria
Posts: 3,580
cybersdorf should be qualifying in the top 10 on the gridcybersdorf should be qualifying in the top 10 on the grid
Pity.
cybersdorf is offline  
__________________
Oops
Quote
Old 10 Jul 2003, 22:08 (Ref:658302)   #8
Dauntless
Racer
 
Dauntless's Avatar
 
Join Date: Dec 2002
United States
San Francisco Bay Area
Posts: 386
Dauntless should be qualifying in the top 10 on the grid
Indeed...
Dauntless is offline  
__________________
Stan Clayton
Dauntless Racing
Quote
Old 10 Jul 2003, 23:20 (Ref:658353)   #9
Dauntless
Racer
 
Dauntless's Avatar
 
Join Date: Dec 2002
United States
San Francisco Bay Area
Posts: 386
Dauntless should be qualifying in the top 10 on the grid
Quote:
Originally posted by MulsanneMike
I'll go out on a limb and say there is little difference between the Toyota's underfloor and the ACO spec.
Mike, just to clarify, did you mean to write that "there is a little difference"...?

Last edited by Dauntless; 10 Jul 2003 at 23:22.
Dauntless is offline  
Quote
Old 16 Jul 2003, 20:53 (Ref:663295)   #10
C_g
Racer
 
Join Date: Dec 2002
Location:
Baltimore, USA
Posts: 204
C_g should be qualifying in the top 10 on the grid
Also remember that the 2004 cars will not have sidepods that extend all the way down to the reference plane. Instead they will be bevelled, much like keel on a boat. Imagine a rowboat with wheels, and that will give you (an exaggerated) idea of what the car's underfloors will be like.
C_g is offline  
Quote
Old 16 Jul 2003, 21:21 (Ref:663318)   #11
MulsanneMike
Veteran
 
MulsanneMike's Avatar
 
Join Date: Jun 2001
United States
Posts: 1,831
MulsanneMike has a real shot at the podium!MulsanneMike has a real shot at the podium!MulsanneMike has a real shot at the podium!MulsanneMike has a real shot at the podium!
Oopps, should read "little similarity..."
MulsanneMike is offline  
Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
V8 supercars- front diffuser? lemanfan Australasian Touring Cars. 10 15 Jun 2005 21:45
Ferrari F1-2000 Diffuser desmo Racing Technology 5 10 Feb 2005 21:45
Was rear and front nose diffuser allowed lemanfan Sportscar & GT Racing 2 2 Aug 2004 11:18
2004 rear wing regs Dan_Lowe Sportscar & GT Racing 32 30 Apr 2004 14:58
What actually was illegal with the pre-Imola Williams 2001 rear diffuser? Sodemo Formula One 14 23 Sep 2003 09:45


All times are GMT. The time now is 13:09.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Original Website Copyright © 1998-2003 Craig Antil. All Rights Reserved.
Ten-Tenths Motorsport Forums Copyright © 2004-2021 Royalridge Computing. All Rights Reserved.
Ten-Tenths Motorsport Forums Copyright © 2021-2022 Grant MacDonald. All Rights Reserved.