MattyB
Member
Registered: 13th Nov 01
Location: 118.5bhp :D
User status: Offline
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quote:
Originally posted by Evisu
I think they look better than a vent anyway
they do look smoother in their traditional "vacuum" layout, but i wanted functionality rather than just looks alone.
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MatthewR
Member
Registered: 21st Oct 02
Location: Rickmansworth
User status: Offline
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Yeah definatly, effective lookswise and performance
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Gambit
Member
Registered: 5th Jun 00
Location: Common Sense HQ
User status: Offline
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quote:
Originally posted by MattyB
quote:
Originally posted by Gambit
born_upsideout do some reading into things before putting stupid comments - u only make yourself look daft
when the car is moving, the lourves work by the air passing over it creating a small vacuum just behind the top of the louvres this then draws the hot air from the engine bay to fill this vacuum, hence sucking more cold air from the front to replace the hot air that has just been extracted
if they didnt work why do most turbo cars have loveres in the bonnet??
[Edited on 12-03-2004 by Gambit]
turbo cars gain more power via cooler boost temps, which is achieve by scoops/vents above the I/C. slightly cooler ambient under bonnet temps dont make too much of a difference to power.
yes Matt i do know what scoops and vents do, but they still need to get rid of the under bonnet heat generated by turbo engines to help keep the engine run that bit cooler
hence why rs turbo's cossie's etc had louvres, and why Impreza's and Evo's 4/5/6 have them
[Edited on 12-03-2004 by Gambit]
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TRL
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Registered: 24th Mar 01
Location: planet tharg
User status: Offline
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Most cars don't have a problem getting air into the engine bay. They have a problem getting it out. Trying to force more air under the bonnet might work, but I'd say it needs to be done together with some sort of extraction.
Also, reversed louvres will create drag, slowing you down. That's why racers use NACA ducts to get air in:
http://www.quickcar.net/cooling/cp_nacaduct.html
They leave the outline of the bonnet pretty well unchanged.
Tony
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vibrio
Banned
Registered: 28th Feb 01
Location: POAH
User status: Offline
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quote:
Originally posted by MattyB
quote:
Originally posted by vibrio
quote:
Originally posted by MattyB
quote:
Originally posted by born_upsideout
wow helpful comments as usual!!  IMO louvres dont really help all that much, more of a cosmetic mod
depends how they are laid out and on what car.
largest sized reversed louvres pressed over intercooler/TBs etc =
pretty patterns on a NA engine = No effect at all, but look smart!
Matt
hot air rises. holes in the bonnet means the hot air can escape.
yep ur right there ............but the reduction in ambient underbonnet temperatures?? I few degrees if anything. The difference made would be sod all, unelss u owned a racing car and were caning it round on a hot day.
Matt
you'd besuprised how much of a diffence a few degrees make Matt
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TRL
Member
Registered: 24th Mar 01
Location: planet tharg
User status: Offline
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Yep, take a look at this:
http://www.auto-amd.com/technical_2.asp
Tony
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MattyB
Member
Registered: 13th Nov 01
Location: 118.5bhp :D
User status: Offline
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quote:
Originally posted by TRL
Most cars don't have a problem getting air into the engine bay. They have a problem getting it out. Trying to force more air under the bonnet might work, but I'd say it needs to be done together with some sort of extraction.
Also, reversed louvres will create drag, slowing you down. That's why racers use NACA ducts to get air in:
http://www.quickcar.net/cooling/cp_nacaduct.html
They leave the outline of the bonnet pretty well unchanged.
Tony
10mm high louvres make sod all difference. The front of a ph1 306 is like a brick anyway, and i never do more than 100mph. 
Matt
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MattyB
Member
Registered: 13th Nov 01
Location: 118.5bhp :D
User status: Offline
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quote:
Originally posted by Gambit
quote:
Originally posted by MattyB
quote:
Originally posted by Gambit
born_upsideout do some reading into things before putting stupid comments - u only make yourself look daft
when the car is moving, the lourves work by the air passing over it creating a small vacuum just behind the top of the louvres this then draws the hot air from the engine bay to fill this vacuum, hence sucking more cold air from the front to replace the hot air that has just been extracted
if they didnt work why do most turbo cars have loveres in the bonnet??
[Edited on 12-03-2004 by Gambit]
turbo cars gain more power via cooler boost temps, which is achieve by scoops/vents above the I/C. slightly cooler ambient under bonnet temps dont make too much of a difference to power.
yes Matt i do know what scoops and vents do, but they still need to get rid of the under bonnet heat generated by turbo engines to help keep the engine run that bit cooler
hence why rs turbo's cossie's etc had louvres, and why Impreza's and Evo's 4/5/6 have them
[Edited on 12-03-2004 by Gambit]
yep sorry me gettin at wrong end stick i think.......i was more angled towards induction temps for some reason  silly me.
as for those performance cars having louvres.........yep......they need em. shame my TD dont! 
Matt
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MattyB
Member
Registered: 13th Nov 01
Location: 118.5bhp :D
User status: Offline
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quote:
Originally posted by vibrio
quote:
Originally posted by MattyB
quote:
Originally posted by vibrio
quote:
Originally posted by MattyB
quote:
Originally posted by born_upsideout
wow helpful comments as usual!! IMO louvres dont really help all that much, more of a cosmetic mod
depends how they are laid out and on what car.
largest sized reversed louvres pressed over intercooler/TBs etc =
pretty patterns on a NA engine = No effect at all, but look smart!
Matt
hot air rises. holes in the bonnet means the hot air can escape.
yep ur right there ............but the reduction in ambient underbonnet temperatures?? I few degrees if anything. The difference made would be sod all, unelss u owned a racing car and were caning it round on a hot day.
Matt
you'd besuprised how much of a diffence a few degrees make Matt
i was very suprized at the difference the louvres above my i/c made. Imagine the difference the scoop wud have made!!!!!!! (apart from ruining the look of my car that is)
Matt
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Andy
Member
Registered: 28th Dec 99
Location: Cumbria, UK
User status: Offline
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All depends where the vent/louvres are on the bonnet. With most cars moving forwards through air, there is positive pressure at the very front of the bonnet and also at the very rear, near the windscreen. In the middle of the bonnet, there's negative pressure. Louvres in the middle will therefore help suck air up from the engine bay and out. At the very front and rear, they'll not do much. Conversely, a vent or scoop placed at the front or rear will force cold air into the bay, but in the middle, will be pretty ineffective.
Square, I will have a bonnet with rear scoop for sale very soon. I found it to be quite effective for directing cold air over the throttle body intakes. U2U me if you want more info
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Matt H
Member
Registered: 11th Sep 01
Location: South Yorkshire
User status: Offline
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do you have a pic of this bonnet andy?
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