Discussion
Recent discussions on PH about increasing the Griff’s power has made me think about aerodynamics. The route to more power seems to be pretty well sorted now but when TVR upped the power they wrapped it all up in more aerodynamic shapes – helping to keep the car firmly planted on the road at high speed.
I read in Paul Frere’s book that the front air dam and whale tail spoiler of the (80’s) 911 Turbo still only managed to reduce lift at speed!! (no net downforce!) It just makes me wonder whether having this extra power in the (wing shaped but beautiful Griff) ought to be combined with some aerodynamics to stop you all getting airborne!
Has anyone looked into this? I’m not a fan of whale tail spoilers but how about an under car rear diffuser?
I read in Paul Frere’s book that the front air dam and whale tail spoiler of the (80’s) 911 Turbo still only managed to reduce lift at speed!! (no net downforce!) It just makes me wonder whether having this extra power in the (wing shaped but beautiful Griff) ought to be combined with some aerodynamics to stop you all getting airborne!
Has anyone looked into this? I’m not a fan of whale tail spoilers but how about an under car rear diffuser?
I remember this being brought up before a while back.
Dont think anyone had come up with anything mind.
You could prehaps hang something Under the rear end but not sure of how much effect it would have.
Would be interested to know of any ideas also as the rear can get pretty light at high speeds
Dont think anyone had come up with anything mind.
You could prehaps hang something Under the rear end but not sure of how much effect it would have.
Would be interested to know of any ideas also as the rear can get pretty light at high speeds
when i was doing my college work on aerodynamics in all the research i did it always came back that the first proper series production car to generate actual downforce was the sierra cosworth 3 door (the rs500 was even better).. everything else still produced lift. there were homologation specials that did produce proper downforce (bmw 3.0csl) but not production cars .. as you say, the porsche turbo did still lift at the back with the wing on ..
)I just think that the more power you produce, the faster you get there. Perhaps for road use that isn't too much of an issue, as all it will do it reduce your top speed (already bordering on too much in this country). If you can increase handling and cornering performance even if it means a reduction at the top end, surely that makes a faster car in reality?
Your right. I remember seeing a Griff at Oulton with two metal fixing plates on his boot - at the time I thought they were for a luggage rack! 
Saw his article in Sprint a bit later when he mentioned aerodynamics and the penny dropped! I've not seen any pictures though - he mentioned a rear spoiler and a diffuser being developed.
Saw his article in Sprint a bit later when he mentioned aerodynamics and the penny dropped! I've not seen any pictures though - he mentioned a rear spoiler and a diffuser being developed.I must admit i cant realy understand why nobody has come up with a nice deep front spoiler with a little spliter at the front, the front lift you get at 100 mph + is a bit extreme on the griff, i cant see being able to do much with the back there too high for a diffuser to work and look to nice to put a hidious spoiler on the too, maybe tim should start making some carbon front spoilers??
v8 racing said:
I must admit i cant realy understand why nobody has come up with a nice deep front spoiler with a little spliter at the front, the front lift you get at 100 mph + is a bit extreme on the griff, i cant see being able to do much with the back there too high for a diffuser to work and look to nice to put a hidious spoiler on the too, maybe tim should start making some carbon front spoilers??
The problem is to get it balanced. The rear suffers from worse lift than the front, if you add an air dam and splitter at the front this can reduce the front end lift substantially but by throwing more air over the top of the car it can actually make the rear lift worse. The amount of lift we're talking about isn't hugely significant in terms of lost grip but makes a big big difference to the balance of the car when it starts to slide. Just a few % imbalance can make the difference between being inherently stable in high speed corners, and a car that needs to be actively balanced by the driver.
You don't have to use a front dam & splitter and with the griff's nose I suspect that you'd find the airflow diverted sideways rather than upward anyway.
A flat undertray with a suitable rear diffuser would be much beneficial and would become more effective as you lowered the car. If you can get hold of the latest copy of racecar engineering you'll find an interesting (if a little technical) article on the subject of rear diffusers that should provide some insight on the matter.
Getting rid of lift does not necessarily mean resorting to big wings - those really are a last resort to overcome a fundamental problem elsewhere and as you've already pointed out all they do in the end is reduce lift at the cost of drag. Getting the airflow smoothed out under the car should help enormously without creating drag - if anything it would help to reduce that too!
A flat undertray with a suitable rear diffuser would be much beneficial and would become more effective as you lowered the car. If you can get hold of the latest copy of racecar engineering you'll find an interesting (if a little technical) article on the subject of rear diffusers that should provide some insight on the matter.
Getting rid of lift does not necessarily mean resorting to big wings - those really are a last resort to overcome a fundamental problem elsewhere and as you've already pointed out all they do in the end is reduce lift at the cost of drag. Getting the airflow smoothed out under the car should help enormously without creating drag - if anything it would help to reduce that too!
Although i agree with some parts of what you say i disagree with the front airdam, in my my mind that can only help keep the front of the car from lifting due to the shape of the underneath of the front of the griff, diffusers do work yes but only if the car is low enough to the ground to make them work race car yes i agree but in the real world on the road???
v8 racing said:
Although i agree with some parts of what you say i disagree with the front airdam, in my my mind that can only help keep the front of the car from lifting due to the shape of the underneath of the front of the griff, diffusers do work yes but only if the car is low enough to the ground to make them work race car yes i agree but in the real world on the road???
I beg to differ on that - the air flow seperation at the rear (or anywhere else along the floor) is critical even at relatively high ground clearance. OK 4x4 style clearance is going to minimise the effectiveness but a griff should be low enough that it will make a difference worth the effort.
Slamming it down to 40mm clearance would of course be ideal but not something I would recommend.
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