Postby Magpie » Mon Dec 22, 2014 12:30 pm
My motor makes more power than yours (however naturaly aspirated) and the exhaust temps get upto 800 degs for sustained periods on the track, I have no overheating issues. Yes I have a NACA vent in the bonnet but it is to get cool air to the ITB's not to draw hot air out.
Goodwin racing have a reasonably cheap and proven bonnet venting system do you know how this was proven? I thought it was designed to fit within the reinforcement of the bonnet not taking into account any aerodynamics.
I guess I have posted enough on this but you need to understand the air flow both above and below the bonnet. Adding vents could make the problem worse. If the air pressure inside the engine bay is increased less air will flow through the engine bay making your heat issues worse. Do some pressure differential testing where you plan to install the vents to see if they will work as planned, you will be suprised or I will be! However you can install a reverse NACA duct and this will 'suck' air out simply because of its design.
The louvers ship flat (unbent), you bend the fins when you receive them, and the finish work is up to you. Powdercoat will have great longevity, but even simple Rustoleum flat black looks fantastic. This is the problem, what angle did they test the fins at too steep oe shallow and the effect could be undesirable. If they are too steep drag will also increase and the air will stall, but that is another issue
Other thoughts are you could wrap/ceramic coat the exhaust, however if it is stainless like mine wrapping is not an available option.