Raised Bonnet Effect!

[WLD747]

As you have read the title, i want my r33 to have a lifted / raised bonnet effect. I have heard it lets more heat out of the engine bay and thus leaving the engine at a coolish temp. Well im going nuts working out how these people do it. Ive heard u need washers. Anyone know what washers to purchase and how to fit em.

thanks in advance

ak

[sweetr33]

personally i wouldnt really bother. Its gonna make a nats dick of difference

[ed]

Just buy washers that'll fit over the thread.

[SXCSKY]

hey man

This will help if u wanna do it

cheers

[WLD747]

SXCSKY - thanks for that mate, your a real life saver. Ill give it a go in the weekend.

[dkonig]

I have read that just in front of the windscreen there on pretty well every car is in fact a high pressure region and as such, at speed air gets forced back down in there and doesnt extract any heat at all and can actually interfere with the air that is already flowing into the low pressure region (your engine bay) from the front of the car and then out under the car.

Unless your doing it for "hardcore" look

Daniel Konig

[Amaru]

Not to mention if you have a front end accident, instead of the bonnet going back into just above the firewall and crumpling, its going to miss that section and come straight through the windscreen meaning you have a good chance of decapitating you and your passangers

[(B1) MR_fanny]

i dont see any real benefit from this unless below

Unless your doing it for "hardcore" look

or u fang ur car constantly or do track work to generate enough engine heat that needs to be dissapated.

anyways its ur car and good luck with it. go to the intial drift australia forum to get some ideas. i remember seeing in a thread there people fabricating a bonet hook and anchor cables to prevent decapitation:D:D

[DJ984]

lol.... i did this on my old pulsar..... i ran 'under' the back of a ute and the only way to get the new bonnet to close properly was to do this... I thought of it then and there on the spot, thought i was a genious.... then a year later, i read a heap of people had done it to get that 'drifter' look and i went "Doh! i didn't invent a new and cool idea then"... (even though i thought it was quite silly....) lol...

just my 2c....

[meshmesh]

I have read that just in front of the windscreen there on pretty well every car is in fact a high pressure region and as such, at speed air gets forced back down in there and doesnt extract any heat at all and can actually interfere with the air that is already flowing into the low pressure region (your engine bay) from the front of the car and then out under the car.

Daniel, you're spot on, next time you see a NASCAR they have exactly that, just below the front windscreen.

[cul202]

yes.

the duct behind the NASCAR bonnet actually uses this pressure to feed the engine - the air filter is completely shielded at the front & open at the back where the duct is.

but essentially the shape of the car & the way air flows through the engine bay would determine whether the effect of bonnet lifting would be good or bad.

[Chris32]

surely it would help drop under bonnet temps though?

I raised mine about 2 years ago, and remove the rubber strip as well so there is a pretty big gap there.

Although it was dodgy, I have hung out the window and felt hot air coming out of under the bonnet, so I reckon it works

Just my opinion tho

[HKSgtst]

my car back home had this .. and ppl started doing this like 7 years ago in my country.

its all good, but if you're stopped at the lights and its raining, you can see your mist on your windscreen .. the heat from the engine is the cause, but a flick of the wiper or if you're moving again then its all good ..

[dkonig]

It is likely to have an effect when the car is stationary, but has been suggested to make things WORSE on some cars when moving (especially as speed increases) due to the pressure forcing back in and disturbing the airflow that the designers of your car spent all that R&D money designing.

Daniel Konig

[GTRgeoff]

can easily test by getting some 10cm lengths of wool and taping them down in the region you are interested. Autospeed has some examples. Someone with a digicam wanna try and post the pics?

[funkymonkey]

if you check an aerodynamics test flow image in a wind tunnel you'll notice that air doesn't go anywhere if you have hot air trying to go out and cold air trying to get in. the edge of the bonnet is a high air pressure zone, so raising the back of the bonnet is not gonna help you at low speeds (under 100k's), unless you have a top mount intercooler. Plus it makes it a lot easier to break into your car funnily enough most alarms are mounted on the firewall *lift* *smash* alarm dangling...

[RNS11Z]

i did this just before my car was stolen and noticed a major decrease in under bonnet temps.

[hungry6]

on an r33 with a huge turbo, this is a good way of dissipating heat soak. As for having weird effect on aero, i'm not really sure, i always thought and have been told by knowledgeable ppls that at the base of your windcreens is the lowes presuure zone on most car with a steeply raked screen it would creat a vacumn effect. But i could be wrong.

[trbo32]

The only thing i'd be concerned about, and it was mentioned earlier, is if you smack the front end. Where's the bonnet going to go, straight through the windscreen that's where. Not good.

[xRHETTx]

it makes it a lot easier to break into your car funnily enough most alarms are mounted on the firewall *lift* *smash* alarm dangling...

i did this just before my car was stolen  

Coincidence?

The bottom of the windscreen is definately a high pressure area, i was taught this at Uni in fluid mechanics, so there! Thats why there are intake vents for the air con etc there. Raising the back of the bonnet may cause hot air to escape whilst the car is stationary, but when going along not air would come out that way. Its possibly that cold air would go in that way, but probably not with all the air being forced in through the grill/radiator etc.