Yes they do look better with a valance, but for me the biggest benefit is it makes the car much more stable causing around 70mph or in strong winds. It seems to direct the air flow towards the rear car and stops lift under the bonnet. Well worth doing. Have look at Cain's offerings, he will also make bespoke.
Adrian , I am slightly surprised by your comment about stopping lift under the bonnet. In the 1960s most of the competition +4s and 4/4s used a similar valence under the front of the car , it was explained as being used to decrease drag and therefore gain top speed on long high speed circuits. In the 1970s several of the competition +4 copied this, but we didn't have have any wind tunnel data, we just liked the look of it, and the theory seemed good. One +4 even tried to put a "floor" under the engine bay to aid the "flat bottom" but this proved to be a disaster as the under bonnet air could not escape, it forced the under tray off its mountings and driver started at the back of the grid as he didn't get his 3 qualifying laps completed. We ditched that idea pretty quickly.
In the mid 70s John Macdonald produced a supercharged +8 lightweight, which had a one piece bonnet which pivoted at the front , and was held down with rubber clips at the rear. We clipped on a curved valence, the results were quite unexpected . The bonnet was wrenched off its rear catches and left flapping in the breeze! We asked around a few aero engineers and they took one look at it and all laughed like drain at us . They were adamant that we needed a vertical air dam, or nothing at all , the curved one was generating lift in the under bonnet area. We fabricated a few different designs from aluminium and fibreglass and eventually settled on full width one , that was about 6 inches deep. The transformation was instant. The bonnet now stayed in place even without the rear catches being done up.
In fact if you look at the Class A & B cars competing in the Morgan Aero Challenge series you can observe that all the serious competitors use some sort of a vertical air dam/spoiler on the front in preference to the curved back design. Now I agree that this look is perhaps not the prettiest addition to a Mog , but it works in practice. The curved design does look better, but will promote lift under the bonnet.
Just my two pennyworth.
Andy G 1999 +8 , Indigo Blue. Ex-John McKecknie/Mike Duncan 1955 +4 racer.
Graham Bell advocates a small flat airdam in his book. " Modern Engine Tuning". It helps create an area of lower air pressure to allow under bonnet air to escape and not fight against under car air. Anyone tried an extraction fan? Remember the Brabham " fan car" ! Gordon Murray genius!
Graham Bell advocates a small flat airdam in his book. " Modern Engine Tuning". It helps create an area of lower air pressure to allow under bonnet air to escape and not fight against under car air. Anyone tried an extraction fan? Remember the Brabham " fan car" ! Gordon Murray genius!
I've got an air dam. Something like the attached.
Original article I got the idea from is here. Note that this is the Google Chache version as the original is no longer online.
I thought about the rubber mat but eventually after a bit of t&e settled on this which is made from three separate pieces of aluminum. It was cheap to buy (theres something in France as they don't do cheap) and easy to do. The centre panel is fixed at the front of the chassis rails. Are you thinking then Andy that this shouldn't work? It does seem to aid cooling though because I would have thought that warm engine air would have been sucked out as the car moved forward.
2015 Roadster 3.7
