Bonnet louvre options?

[davekmoore]

Considering louvres above the standard low mount IHI turbo and matching ones on the intake side.
Expecting the ones on the turbo side to help vent some of the heat from the turbo, and expecting both sides to reduce under-bonnet temps.
Also hoping the reduction in under bonnet pressures will allow more air to flow in and through the radiator.

Anyone had experience of simply creating louvres in the bonnet? If you had someone do the work, how much did it cost?

Or can anyone recommend ready made louvres that fit into the obvious shapes on an NB bonnet?

[Magpie]

The issue with doing vents is not only correct placement but cutting through bonnet supports.

http://www.infrastructure.gov.au/roads/vehicle_regulation/bulletin/pdf/NCOP6_Section_LH_Body_and_Chassis_01Jan2011_v3.pdf
From page 13:

If any bonnet reinforcing braces are cut or modified, the design of the modified bonnet must be of equal strength to the original bonnet and any sharp edges created must be suitably treated.

A bonnet scoop manufactured from a plastic or fibreglass material may be fitted, providing that the hole in the original bonnet does not substantially reduce the strength or impact resistance of the bonnet and no rigid component, such as an air cleaner or carburettor, protrudes beyond the original bonnet profile;

Look for NACA ducts as they suck in the boundary layer of air and do not impact on drag. Do some research on NACA ducts because some of the ones sold do not conform and therefore do not perform.

[lightyear]

This was done without cutting the frame.

viewtopic.php?f=44&t=64107&p=800046&hilit=Vented+bonnet#p800046

[Magpie]

Another NA bonnett http://mx5cartalk.com/forum/viewtopic.php?p=691922#p691922

However would not pass inspection in QLD...

[davekmoore]

Thanks. I'm thinking way smaller louvres, more like on a E Type. It's a road car so effective is good. Effective and stealthy is better.

[jimmy_vee]

This kit has been released recently in the US.
http://www.good-win-racing.com/Mazda-Performance-Part/61-1523A.html

Reduces under-hood pressure by 50%
Dramatic Improvement in engine cooling efficiency
Decreases lift on the front of the car
Backed by data developed through pressure and flow testing
Outperforms every hood vent option tested (by a lot)
Specifically designed for the NA and NB Miata hood
Retains hood rigidity and the use of the stock hood latch
Designed and produced in the USA

What you get:

Precision waterjet aluminum louvers
Removeable gurney flaps (can swap them on/off at the track)
Stainless steel mounting hardware
Rubber trim to cover the cut edge for a clean look
Chassis specific vinyl cut template

[bruce]

That is nice.
Skip the middle vent.
Something neater than screws to attach.
You still have to cut the bonnet supports.
I reckon you could make it yourself cheaper...let me copy one.

[forcedfive]

Flying Miata have some and some interesting info on the best placement in the low pressure areas.

http://www.flyinmiata.com/index.php?dep ... r=29-40000

[davekmoore]

Yep, seen them. They looks the best of the add-on options. The research I've seen into pressure zones shows the placement is good too.

A tuner has the car now while I'm away overseas. His brief is to sort the ECU so under bonnet temps don't need to be reduced for it to idle as standard when hot, and for it to start, idle and run correctly at all temps, just as advertised by Haltech and Injector Dynamics.

This will hopefully avoid the need for bonnet vents, because I'd prefer not to spend further money on stuff I don't need to have.