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Luke

Bonnet vents

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I’ve seen a few cars with bonnet vents especially on the track day cars. Do they provide a benefit for the GT86? Or are they more for show? Also does it stop the bonnet flexing at speed? 

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Yes they provide a benefit, most noticeably with oil temps. However I wasn't concerned with this, I had them installed to reduce the engine bay temps around the coilpack area. What I should have done was have my exhaust manifold thermally shielded (google thermo met).

I probably wouldn't bother if I was to do it again. 

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2 hours ago, Luke said:

I’ve seen a few cars with bonnet vents especially on the track day cars. Do they provide a benefit for the GT86? Or are they more for show? Also does it stop the bonnet flexing at speed? 

I saw an approx 10° reduction in oil temps with the vents. Vents also add a little aero as they allow pressurised air to escape. Mines a carbon replacement so can't comment on the effects on the standard bonnet but I don't see bonnet flex now with a vented bonnet.

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The vents do stop the standard bonnet from flexing. I've got a turbo located at the front of the engine bay and it definitely helps with the under-bonnet temperatures. I'm not going by the oil temperature, more when I open the bonnet I don't melt with the heat wave.

The vents and oil cooler have been on so long I can't remember if it's helping the oil temperature.

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So they definitely serve a purpose in keeping the temps down when out on track but it depends on your cars setup as to whether you really need them.

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3 hours ago, Luke said:

So they definitely serve a purpose in keeping the temps down when out on track but it depends on your cars setup as to whether you really need them.

A good summary.

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There were tests/data by CSG. They do obviously reduce underbonnet temps. In addition to that vents also reduce front-end lift, which also seems beneficial, as imho is similar to rear diffuser, adding a bit downforce to front w/o much extra drag, and w/o having to compromise ground and front's geometrical clearance, that lowering/splitters and alikes do.

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