XJ + Torana A9X bonnet bulge pics wanted

[ryanmcsh]

Hey guys,

I am looking at putting some vents in the XJ and i was thinking maybe putting a torana A9X bonnet bulge on there. Im not so sure if i will like the look, has anyone done this and can they post pics up of it???

Cheers,

Ryan

[anthonygubbin]

A bloke put an SLR one on his about 2 years ago but I don't know his name. Someone might know and could search his threads. He has since moved on so the the member himself won't be any help. I reckon the pics were in the XJ forum, what did you do to your XJ today?

Regards A

[anthonygubbin]

Ok bit more info. His name on AJOR was dozer. His last post was 29/9/11 he was only on here for a few weeks. I will let you search the rest to find his picks of his bonnet scoop. BTW his was the only one I have ever seen with a Torana scoop fited.

Regards A

[ryanmcsh]

Thanks for your help Anthony, searching now...

[murray]

hi i have pics of a cowl bonnet in this section

[Mudmonster]

seen one on ebay the other day i think.

i did find this picture on google

59957

you thought of GU patrol scopes??


59958

59959

[anthonygubbin]

seen one on ebay the other day i think.

i did find this picture on google

59957

you thought of GU patrol scopes??


59958

59959

I am thinking of getting one, one day but I am looking at wide Colorado or Patrol scoop and turning it around to face backwards. The issue I have with the Torana ones are they may sit a little too high. Although technically not legal to face them backwards I see little point in drawing in extra air at highways speeds by facing them forwards because an XJ should not normally over heat at those speeds.

Regards A

[junglejuice]

They will still draw air in at highway speeds even facing backwards.....

[anthonygubbin]

They will still draw air in at highway speeds even facing backwards.....

Thats ok then. But when crawling, when you sometimes need extra cooling I assume a front facing vent will make little difference or am a wrong JJ?

Regards A

[Fry92]

My old man put one on his xj and he reckons that it was a noticable difference in temps whilst crawling here are two picks i found if i find more ill throw them up cheers

[Dustbowl]

They were never desingned to force air in, they were made to let the existing hot air out.

[darksidecustoms]

Depends on road speed and position as to what the result will be. Heat will most likely rise out if travelling slowly, regardless of position, unless forced in by a fan.

Vents closest to the leading edge of the bonnet should be best at extracting heat at speed, while vents close to the windscreen should be best at sucking air in (such as the vent/intake for the cabin air) due to the higher air pressure at this location. I understand the A9X style cowls were designed to force air in direct to the air filter on the carb.

However vents directly facing air flow should give a ram effect at speed (think snorkels and pro stock bonnet scoops).

So for extra effectiveness of your radiator, vents closest to the radiator/leading edge of the bonnet should be theoretically the most effective. This is often done in race cars, with many channelling the air directly from the radiator and out these vents.

So in theory A9X style scoops will mainly benefit low speed offroad work and heavy traffic, but actually give worse performance of your radiator at high speeds as the air pressure under the bonnet won't be as low.

[ryanmcsh]

Yeah, thats the theory behind it. And it works. However at speeds i dont see overheating as such an issue, and it could also work to flush the hot air out from under the bonnet. Not as effective, but still contributing.

I was talking to a mate yesterday and he said the trans-am bonnet cowls are much the same shape but smaller in size than the A9X bonnet cowl, so that might be an option because they do look very large on the little xj's by the look of it. However that same mate happens to have an A9X one sitting in his shed to go one someone elses torana, so i can throw it on there for a few seconds to see what it looks like and if i will like it in person.

But i suppose it is interesting, what have other people done, could we perhaps make a thread with just type of scoop/vent and pictures so everyone could see what others have done and decide on what they think looks good?

Save a lot of people like myself asking "What does this look like? What does that look like?" etc.

[darksidecustoms]

I believe Nakkas on here has a similar cowl scoop, there should be pics and a couple of vids in his LS1 swap thread in this section. From memory it's a VK Group A cowl or similar.

Personally I plan on running a previous gen Hilux intercooler scoop with a trans cooler and fan, but that's a while off now ;-)

[darksidecustoms]

Here's his build http://www.ausjeepoffroad.com/forum/showthread.php?t=98153
EDIT: couldn't see any pics there but found a decent pic here: http://www.nakkas.org/

[carvesdodo]

They were never desingned to force air in, they were made to let the existing hot air out.


Are you referring to A9X reverse cowl induction scoops ?????


1/.. http://www.camaro-untoldsecrets.com/articles/rpo_zl2.htm

Interesting comment in the article - about forward facing scoops ... and the reason a reverse scoop was preferred.

"The reverse drafting method used on the special ZL2 hood was chosen over forward facing scoops which create greater pressures and increased ram effect but have problems associated with air turbulence at the carburetor air horn. Turbulence causes uneven pressures within the metering bodies and upsets correct air/fuel ratio and delivery. Correcting this type of system is involved and not worth the insignificant power increase the additional pressure affords."

2/.. http://www.a9xclub.org.au/abouta9x.html

"The most noticeable addition to the engine ancillaries was a new rear-facing, bonnet-mounted carburettor induction scoop. This was designed to take advantage of the excellent breathing capabilities provided by the low air pressure zone at the base of the windscreen, and also allowed race teams to fit a cold-air box to further reduce inlet temperatures."



Aftermarket scoops are generally designed to empty wallets and look pretty ... unless they would include any underbonnet, airducting required ... to make them functional and worth the effort to fit.


Proper vents are a whole different kettle of fish ...

https://www.google.com/url?q=http://autospeed.com/cms/title_Undertrays-Spoilers-Bonnet-Vents-Part-1/A_2159/article.html&sa=U&ei=sgccUdyrKMaikQWVsYCgDA&ved=0CAcQFjAA&client=internal-uds-cse&usg=AFQjCNGK8gPfWbwXBTq3L_8dmEgzTQTKeg

https://www.google.com/url?q=http://autospeed.com/cms/title_Undertrays-Spoiler-Bonnet-Vents-Part-2/A_2160/article.html&sa=U&ei=sgccUdyrKMaikQWVsYCgDA&ved=0CAoQFjAB&client=internal-uds-cse&usg=AFQjCNFC_-kJRvBJxD39NXBt3XU6Kfbvyg

https://www.google.com/url?q=http://autospeed.com/cms/title_Undertrays-Spoiler-Bonnet-Vents-Part-3/A_2162/article.html&sa=U&ei=sgccUdyrKMaikQWVsYCgDA&ved=0CA0QFjAC&client=internal-uds-cse&usg=AFQjCNEySJ85IUo5ZEII5AnvgxOd8_yfmg

[Dustbowl]

I stand corrected :hammer:
I'll just stick to my fords now :%

[carvesdodo]

I stand corrected :hammer:
I'll just stick to my fords now :%


mehhhh .... its not your fault ... ;);)


You've just been conned by all the false advertising and the ricer racer fitting of bling ... that has overwhelmed the facts, knowledge and experience of the 70's.


.... finding pics of proper cowl hood setups is also difficult ... as most only show external views ... and few show the ducting that is underneath.

... a fair bit of googling will turn up random pics of a proper cowl hood setup tho - such as the A9X and the VK

... or you can look at one of a Euro, "Orvis" model XJ with fake vents and no holes ... whilst fondling & stroking the jigsaw .. :lol::lol:

[Dustbowl]

Now that you mention it, I do recall seeing duct work in them things... However, unless you ran a filter off the top of your manifold, and then ducted it back for performance purposes.. that style of scoop would only look good, and draw heat out

[ozjeepster]

http://img.tapatalk.com/d/13/02/14/5esy3emy.jpg
http://img.tapatalk.com/d/13/02/14/supehehy.jpg
Is this what your after , I still have the scoop & fit kit. I never got around to cutting the bonnet & fitting it up ;)

[ryanmcsh]

That is all its intended purpose is, to look good and draw hot air out, there are better ways to cold air induct a 4wd... ha ha ha...

[ryanmcsh]

ozjeepster, i could be interested, how much are you asking? pm me? i will know this afternoon after i throw my mates one on the bonnet and see if i like the look...

[carvesdodo]

That is all its intended purpose is, to look good and draw hot air out, there are better ways to cold air induct a 4wd... ha ha ha...

Now that you mention it, I do recall seeing duct work in them things... However, unless you ran a filter off the top of your manifold, and then ducted it back for performance purposes.. that style of scoop would only look good, and draw heat out


Cowl scoops drawing air out is a myth ...

1/. When the vehicle is stopped and engine off ... hot air will naturally rise up and waft out the opening ... same as it will waft up and out from any opening - located anywhere in the bonnet.

2/. Once the engine is started ... Its the fan/fans blowing air out the opening.

3/. And when the vehicle is moving ... Its the fan/fans/vehicle momentum, radiator intake that blows air out the opening ..... Until vehicle speed causes that air to be prevented from exiting the cowl scoop ... or forced back in the cowl ... and some woollen telltails will show thats a possibility from about 20kph upwards.


Cowl Scoops on an XJ are a great "vent" ... for trailered rigs with big ratio diffs and low/low ratio transfer cases .. ;);)



If you're after looks ... dont waste a jigsaw blade cutting holes ... Thats what I learnt back when you could buy an A9X new .. but a torana, paint and a fake scoop was cheaper ;)

[ryanmcsh]

Ok, i think it is a time for a bit of clarification on the theory, the cowl will act as a cold air induction if it is isolated from the extremely high pressure area in the engine bay cause by the fans and the speed of the vehicle, however, if you havent seperated the air intake from the rest of the engine bay, you will get a larger high pressure area in the engine bay than you do in front of the windscreen, so even at speeds, it will force the air out of the cowl. If you look at a proper cowl arrangement as per an A9X Torana, and look at the under bonnet area, you will see the amount of effort that went into separating the 2 areas. However, that is not the purpose of this, it is just to be used as a stylish vent.

I agree, nothing does look better, however, it really does get hot in that engine bay when i am wheeling, and i am a big fan of something useful looking good as well, so i am just looking at ideas...

I hope that can clarify some of the theoretical points. It will only draw air in, if it can get a higher pressure infront of the windscreen than below the bonnet, which by laws of effective areas, it cant as the effective area is constant, and the speed increases by the same amount in both of the zones causing an equal increase in air pressure in both zones, you then add the fans and the heat rises theory in, and you get a really good vent, but nothing going the other way.

[Dustbowl]

Carves, not to start a flame war, the Bernoulli's principle states the faster air creates a low pressure system... and the static (fanforced air) is a relatively high pressure system, Pascals principle states that the force will be exerted evenly upon the container... until a weakness or lower pressure system is found, this lower pressure system created by the movement of air over the cowl will draw the air out....
I did study mechanical engineering...

Open to correction.


Ryan, yes you are correct, if it is enclosed it will create a high pressure system instead :)

[carvesdodo]

Carves, not to start a flame war, the Bernoulli's principle states the faster air creates a low pressure system... and the static (fanforced air) is a relatively high pressure system, Pascals principle states that the force will be exerted evenly upon the container... until a weakness or lower pressure system is found, this lower pressure system created by the movement of air over the cowl will draw the air out....
I did study mechanical engineering...

Open to correction.


Ryan, yes you are correct, if it is enclosed it will create a high pressure system instead :)


hey ... all good ... Its a bit hard to have a flame war when we are saying the same basic things ... just coming at them from different directions ;)

A mix match of ...
Bernoulli,
Woollen telltails stuck on the bonnet and around the cowl opening,
Overheating kingswoods after raping the bonnet to fit a bodgy, repco, scoop - but not overheating with a bit of tin pop rivetted over the hole ...
And this piccy of veh, high and low, pressure areas ....


http://i1143.photobucket.com/albums/n629/carves-oz/Vehicle%20Bits/Cooling%20Bits/JaguarExahighres15cropped.jpg


all suggest ... "venting" is better done some other way .. other than a cowl induction scoop. ;)

.

[Dustbowl]

Hahahaha riiiiiight, this all makes sense now we are all on the same page :p

[ryanmcsh]

So, it is agreed that this is an inefficent vent at high speeds because the 2 pressure systems fight each other, however, it will still work. But this is more aimed at keeping the low speed cool, and looking clean. So i think i am going to have to see what it looks like this arvo and see if i like the look of it or if it is too big... im currently thinking that it will look too big, however, if i can get one at the right price and modify it, could be an interesting thing. But we will see...

Damn reflexxion for not continuing to make the bonnets for XJ's... lol.

[kj69]

Damn reflexxion for not continuing to make the bonnets for XJ's... lol.

not wrong there my idea was to add therno fan to the cowl area and suck the hot air out when wheeling , the reflexxion is the only cowl i would ever put on my jeep.

[anthonygubbin]

Ok I am totally confused. Will my idea of a wide & low Colorado vent facing backwards help to remove some of the hot air when I am crawlling? If not I will not bother as I could spend the money on more useful upgrades.

Regards A

[murray]

guys this has been flogged like a dead horse before and it cuased a lot of friction
i had 2 xjs att 1 stage 1 with a cowl bonnet (petrol) and a deisel with out i the put bleed air vents in the deisel it lowered the temp i suggest that search should be used on this subject

[SeaComms]

Or if its more for looks, my brother in law melded an XC falcon bonnet skin onto his patol rebuild:

https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-ash4/197718_1770990168740_5502906_n.jpg

https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-snc6/165128_1706837044952_2424860_n.jpg

[Mitch]

I,ve had two plastic nissan 260z bonnet vents in me XJ for yrs now.When crawling the heat haze pours out of these.I have the thermo on a manual switch if i eva wanna pump a bit more cool in.I have had an ADRAD radiator fitted for 1 month so most of my low range was with a stock one.Never had an overheat issue offroad.

[darksidecustoms]

Ok I am totally confused. Will my idea of a wide & low Colorado vent facing backwards help to remove some of the hot air when I am crawlling? If not I will not bother as I could spend the money on more useful upgrades.

Regards A

If I was to do that it would be as close to the radiator as possible. Possibly even use some Aluminium sheet to channel the flow of air from the radiator directly out it.

[ryanmcsh]

Anthony, yes it will work.

I tried searching before putting up this thread, but i couldnt find any pictures of how it would look.

I was after the function with the looks, not pure looks, if i was after that, there wouldnt be any holes going in the bonnet at all, and no cowls going on.

I tried the cowl off an SLR 5000 my mate has at his place, and while it did look good on there, i lost a lot more sight than i thought i would, so i have decided to go sunken vents.

If i could find a decent set of 260z vents for the right price, i would go for it, but they are not easily available these days, however, you can get the ford cosworth style vents pretty cheap, and they do look nice on these cars, so that is probably what i will go with.

I was trying to keep theory out of this thread and just go something along the lines of: this car has this vent/cowl/scoop and this is what it looks like (add picture) because it is hard when you are trying to find something that looks good on these things without spending the money first. That is something that hasnt been done to death, the theory has.

[junglejuice]

Ok to help those wondering what a Torana scoop will look like on an Xj then look at the pics below...

I had a guy visit me today to buy some parts and he has the Torana scoop fitted so with his permission I present a pru-update with a Torana scoop....

http://i1182.photobucket.com/albums/x451/junglejuice72/Mods/Bonnet%20Scoops/20130216_141540_resize_zpsecdb4a18.jpg
http://i1182.photobucket.com/albums/x451/junglejuice72/Mods/Bonnet%20Scoops/20130216_141545_resize_zps0010caf8.jpg
http://i1182.photobucket.com/albums/x451/junglejuice72/Mods/Bonnet%20Scoops/20130216_141552_resize_zpse7580aa0.jpg
http://i1182.photobucket.com/albums/x451/junglejuice72/Mods/Bonnet%20Scoops/20130216_141654_resize_zps507d857a.jpg

[iwanajeep]

how about a something like a plymouth superbee scoop fitted in reverse. open it for crawling close it for cruising on the road. I doubt a scoop like this would be hard to make.