Hi Speed Lift

[Tony Hunt]

Another undesirable effect of the half-depth twin nostril is that a lot of the heat which doesn't go out of the nostril gets forced into the cockpit through the numerous holes and apertures in the front firewall.
In tidying up the airflow, fitting a full-depth nostril reduces this heat ingress.

 

[Bill Musarra]

With the mentioning of lift problems, I have a question.
With extending the nostrils down on the radiator, is there a point to which the angle is too great for air to flow or better put, be suctioned, and create an air dam effect. this would seem to create more work for the fans(I have two 12 inchers on my setup). The single nostrils that I have seen look pretty steep. Are the twin nostrils sloped down, or are they pretty much straight down to the base of the radiator?? We are working with my twin setup to make a one piece nostril panel and the angle gets pretty steep.
Bill

 

[Peter Delaney]

Hi Bill, Yes the angle does get steep towards the bottom, but as other have pointed out, that is still has to be better than "pointing an open cup into the wind" with the half-depth nostrils.

My DRB setup looks to be around 45-50deg at the bottom, curving up so that they are nearly parallel to the top of the front clip at the tops of the nostrils.

In a half nostril setup, the air coming through the bottom of the radiator is just going to hit a bunch of hot stalled high pressure air in the front compartment & I would think that would simply reduce the air flow through the lower half of the radiator (and heat up the driver)!

My guess is that the small lips at the front of the nostril openings should generate a low pressure area above the openings, & that should be sufficient to pull the air out (rather than have an air dam situation).

Without the benefit (as yet) of full road testing (still no rego !), I have still managed to do some driving on trade plates & have found that it will stay at around 90degC (no fan) if I keep moving at more than 20kmph.

Back in the 60's, the Ford guys did have access to some wind-tunnel testing & guess that is where the deep single nostril on the MKII came from - better cooling & less lift. The deep twin nostrils are probably not quite as efficient, but in most of our cars, they are just cooling a small block, not the 7 litre monster in the MKII's ! Therefore, probably not a bad compromise between looks & efficiency.

Kind Regards,

Peter D.

 

[ChrisL]

Going back to the original post. I think the use of the word “problem” seems to have been taken out of context. I don’t think that the Ford GT had a “problem” with stability. I would suggest that Ford were simply referring to optimization. The “problem” was more likely that a car that is intended to be a company’s flagship of the modern era, was not good enough. Remember that their target was to out-handle the corresponding Ferrari on the race track.

And as for the GT40 Mk1b replicas creating enough front-end lift to create serious stability concerns (as opposed to quickest lap times), we need to consider what that implies. I assume that the lift we are discussing is not under-car lift, but some sort of aerodynamic lift created by the shape of the upper body (natural aerofoil shape of the wheel arches possibly?). In any case, we are implying that the entire front end is being picked up by the front clip alone. I challenge anyone to attempt to lift their GT40 by the front clip alone. I would expect the latches to break well before the wheels left the ground.

 

[Chris Duncan]

All the originals and the MK V have a curve that transitions into the front clip at the back of the vents. If you make the vent floor straight then you have a sharp angle at that point. Which may or may not be as aerodynamic. Another reason that the orginals are curved is probably to leave room for the spare.

Another thing I've noticed is that depending on which type of radiator you have, either cross flow or upright, the vents have to go down further for the crossflow because the cooling fins go further down. The crossflow goes down almost to the floor pan and the upright is about 3" to above the pan. This makes a difference in the amount of curve necessary in the vent floor.

 

[Bill Musarra]

I have noticed on other gt's that the radiators are all at different angles. DRB's are at a pretty steep angle, making them taller radiators than those that stand more upright. This gives more surface area for cooling, and the base is moved further back which increases the angle. My radiator is only 3"deep and is cross flow. That added to the angle as well.
Bill