DIY question: making vents for your bonnet

[trism]

its also defectable.

[miss_motorsport]

i have a vent in my car only because the former owner thought that they would put a vent in a perfectly good crx bonnet... bad move, over time it has caused cracks in the bog & paint. not happy!

the cheapest part of this adventure is the "idea"

the vents may be cheap but the fitment and respraying the bonnet cost you $$$ i would allow a minimum of $500 for this mod

if you are doing this for asthetics and attempt a DIY with no pannel or paint experience you may not be 100% happy with the result.

the only way i could find the vent mod justifiable is if it will improve the performance of the car

good luck

[EK1.6LCIV]

get some celica gt four import vents made to fit on your bonnet (the side vents it has not the middle intake), theyre metal of the same grade as your oem bonnet. Depending on how you attach them will depend on legality.



Wouldn't use washers ethier, they're defectable as it raises the bonnets edges making a sharp surface if you hit a pedestrian (I really still don't understand the needs for sooo many laws in qld and other states when their roads are still very poorly designed, serious make good roads then make laws for cars...)

[redefine]

i would hardly call the edge of the bonnet sharp, especially when the edge is facing away from the front

[geeang]

i would hardly call the edge of the bonnet sharp, especially when the edge is facing away from the front

Regardless, it is still an edge.

If you had a head-on accident with the raised bonnet, it could potentially spear straight through the windscreen and cut you in half.

[trism]

it could potentially spear straight through the windscreen and cut you in half.

this is why spacing bonnets is illegal.

[curtis265]

I rkn you'd be better off trying to make some sort of grille or cut holes in bumper 'grilles' and get a CAI (or use that pipe trick where people run a pipe down to where the foglight goes)

I think hood spacers look like assss too. And you might get water in it

Seriously, looks like the hood doesn't sit properly, and the bodylines are all fuked up

[Alvis]

meh, I don't think bonnet vents don't really do anything too drastic - more for looks than anything IMHO - a raised bonnet however can look pretty good on a civic:

I'm not convinced on vents, maybe do some more homework and let us know... some pics for you anyway


By civica at 2010-05-01


By civica at 2010-05-01


By civica at 2010-05-01

[redefine]

Regardless, it is still an edge.

If you had a head-on accident with the raised bonnet, it could potentially spear straight through the windscreen and cut you in half.

im sorry...but are the 4 mounting bolts, 2 on each side, designed to support much more then the weight of the bonnet itself...going to shear off and fail before the designed crumple points collapse??
on a stock bonnet it wont make a difference. and wont be any more likely then a bonnet with no washers
it only holds where you have a carbon bonnet...and even then, if you have designed weak points, its likely to shatter before it comes through the windshield. cf is not stronger then steel per volume...its only stronger per weight.

and the raised bonnet is less of an edge then an actual scoop which is legal providing that it follows guidelines (that is, if a 165mm disc is rolled up the bonnet, the point of contact with the scoop is on the lower half of the disc)

[curtis265]

The shear force won't be acting on a 'plane' anymore, the bolts are more likely to bendinto an 's' shape, and pull such that the bolt will be in tension. I dont know if bolts are stronger in shear or tension, but my bet is that the plates taht the bolts go through will crush/tear before bolts break

I reckon the bolts will hold, and the bonnet will just crease like so


Carbon will shatter into sharp pieces.. and spear you

[MrMcGinty]

simple fact is that any small car or hatchback looks SOOOO ricey with hood scoops. your better off cutting holes in your bumper where it looks less obvious.

[redefine]

The shear force won't be acting on a 'plane' anymore, the bolts are more likely to bendinto an 's' shape, and pull such that the bolt will be in tension. I dont know if bolts are stronger in shear or tension, but my bet is that the plates taht the bolts go through will crush/tear before bolts break

I reckon the bolts will hold, and the bonnet will just crease like so


Carbon will shatter into sharp pieces.. and spear you

this pic is what WILL happen. raised bonnet or no.
if im correct the bolts will be stronger in tension, being steel, and a shear force is a combination of tension compression. steel is actually quite weak in compression (which is why we use concrete, and not steel for foundations, its the combined tensile strength of steel and compressive strength of concrete that makes reinforced concrete so good, but thats another point)

if the bolts were to shear off you would need an EXTREMELY rigid bonnet. like insanely rigid. considering the length of the bonnet, the cross-sectional area, and the compressive strength

and i rekon the carbon shards would have a better chance of scratching and getting in the eyes of bystanders then spearing you in any way. the firewall/windscreen do a great job of protecting you from shards of material