Bonnet vents S3
Discussion
Hi,
I'm looking into adding some bonnet vents to let some hot air out on my S3. On the S4 and the SV8 TVR incorporated hot air exhaust in the bonnet but in the S1-S3 the only way out for the air is beneath the car. There is the smallish scoop but I’m not sure that is of any use at all…
I have reduced the seal beneath the bonnet towards the windshield to just some support points, but that only helps stationary or at low speed as that area is a high pressure zone at speed. -No use to cut holes under the bonnet above the seals for the same reason I think.
My solution would be to introduce two small vents in the bonnet to let air out but not “destroy” the bonnet design. The S4 bonnet design is the best alternative but being stuck with an S3 bonnet what would be the next best alternative?
These are from an RS Turbo and are rather neat. They would of course be painted red as the car to be less visible.
Do you think they would evacuate enough air to make it worthwhile? One mounted over each header.
My car runs with a twin screw supercharger and hence the extra need to evacuate heat. Radiator is new and so is the fan (and upgraded). The cars cooling system works fine but the forced induction does create some extra heat.
Sorry for the picture being sideways but I don't know how to prevent the forum program to rotate it.
All input appreciated
Kind regards
//Rob
I'm looking into adding some bonnet vents to let some hot air out on my S3. On the S4 and the SV8 TVR incorporated hot air exhaust in the bonnet but in the S1-S3 the only way out for the air is beneath the car. There is the smallish scoop but I’m not sure that is of any use at all…
I have reduced the seal beneath the bonnet towards the windshield to just some support points, but that only helps stationary or at low speed as that area is a high pressure zone at speed. -No use to cut holes under the bonnet above the seals for the same reason I think.
My solution would be to introduce two small vents in the bonnet to let air out but not “destroy” the bonnet design. The S4 bonnet design is the best alternative but being stuck with an S3 bonnet what would be the next best alternative?
These are from an RS Turbo and are rather neat. They would of course be painted red as the car to be less visible.
Do you think they would evacuate enough air to make it worthwhile? One mounted over each header.
My car runs with a twin screw supercharger and hence the extra need to evacuate heat. Radiator is new and so is the fan (and upgraded). The cars cooling system works fine but the forced induction does create some extra heat.
Sorry for the picture being sideways but I don't know how to prevent the forum program to rotate it.
All input appreciated
Kind regards
//Rob
Tuscan challenge race car vents keep mine cool.. mainly for expelling air that's been through the rad.
Also for letting water in lols..
If you want a pair higher up, above the exhaust I like the jaguar supercharged style ones you can get them with or without "supercharged" embossed..
Thanks
Damian
Also for letting water in lols..
If you want a pair higher up, above the exhaust I like the jaguar supercharged style ones you can get them with or without "supercharged" embossed..
Thanks
Damian
Removal of the bonnet seal does make quite a difference, as does removing the gauze from the two openings at the front of the bonnet and also the scoop.
This is noticeable to such an extent that the plenum will run cold during a long journey only to heat up from the engine for half an hour or more after use.
some provision for protection of the rad is probably wise.
This is noticeable to such an extent that the plenum will run cold during a long journey only to heat up from the engine for half an hour or more after use.
some provision for protection of the rad is probably wise.
Mine just has holes cut in the bonnet, arranged in a line that is roughly over the headers, with black mesh behind them. Not as pretty as those mass produced vent trims, but looks OK to me and a lot easier and cheaper to do. They are at the low pressure point of the bonnet and extremely effective at pulling air out of the engine bay at speed - weird to see wool tufts standing straight up six inches into the air flow at motorway speeds. It also lets out a hell of a lot of heat when stationary. Jag increase this further with ducts acting as chimneys between the exhaust headers and the vents, but I didn't bother with that.
Thank you for feedback.
Can you please upload some pictures from your bonnets, both from top and from the engine side.
I like your Tuscan race style louvres Damian, but that also means a total bonnet rebuild and respray. Would be great to see how it's done on the inside.
I've also toyed with cutting slits along the sides and it would be great to see how it turned out. Pictures please
I saw the Jag ventilator and the only drawback I saw is that it gives less ventilation per visible “bonnet area” compared to the RS Turbo one. I also looked at other Ford vents (including carbon Cosworth) but they are too big/wide and would be a bit do dominant in the bonnet.
If anyone does have pictures of other vents in “S” bonnets it would be much appreciated if you could share them here.
Kind regards
//Rob
Can you please upload some pictures from your bonnets, both from top and from the engine side.
I like your Tuscan race style louvres Damian, but that also means a total bonnet rebuild and respray. Would be great to see how it's done on the inside.
I've also toyed with cutting slits along the sides and it would be great to see how it turned out. Pictures please
I saw the Jag ventilator and the only drawback I saw is that it gives less ventilation per visible “bonnet area” compared to the RS Turbo one. I also looked at other Ford vents (including carbon Cosworth) but they are too big/wide and would be a bit do dominant in the bonnet.
If anyone does have pictures of other vents in “S” bonnets it would be much appreciated if you could share them here.
Kind regards
//Rob
Alan Whitaker said:
I was thinking of a Pr of these at the rear of the bonnet
If you want cooling at high speed then keep them far enough forward to avoid the high pressure zone in front of the windscreen. The middle third of the bonnet is a low pressure zone so anywhere in that area is likely to work well.ETA: My profile has a pic showing the bonnet vents.
High pressure in the middle of the screen sucks air downwards. On the outer corners you'll extract upwards. Both at speed. If you duct after the radiator you'll extract loads of hot air but otherwise I wouldn't bother as most air goes down the transmission tunnel.
What are your heat issues? High speed, low speed or what?. If high speed sort out the radiator issues. If low speed fit some bonnet fans or a viscous fan to the crank. that's an awesome mod :-) At low speed it's a heat soak issue.
What are your heat issues? High speed, low speed or what?. If high speed sort out the radiator issues. If low speed fit some bonnet fans or a viscous fan to the crank. that's an awesome mod :-) At low speed it's a heat soak issue.
Edited by Boosted LS1 on Saturday 19th August 23:29
I have 2 turbos right up front between the rad and the engine, Just not sure where the hot spots are going to be, so I don't want to cut the bonnet and put vents in if they are not going to do anything. Have a larger grill area than normal so I was hoping most of the air would just run through the intercooler rad and down the side of the engine. I do like the look of the Tuscan race vents, a bit of thought on this me thinks
Just my two 'penneth but anything "borrowed" from a modern car is going to look "stuck on" , not at all right..............
How about some Naca ducts or some good old fashioned loovres...........
How about some Naca ducts or some good old fashioned loovres...........
Alan Whitaker said:
I have 2 turbos right up front between the rad and the engine, Just not sure where the hot spots are going to be, so I don't want to cut the bonnet and put vents in if they are not going to do anything. Have a larger grill area than normal so I was hoping most of the air would just run through the intercooler rad and down the side of the engine. I do like the look of the Tuscan race vents, a bit of thought on this me thinks
Your downpipes and turbine housings will get very hot but that's quite normal. Air will transfer the heat away. You could put heat shields around the turbo's that stand maybe 1" away from the exhaust housings. They can be bolted directly to the turbo's with a couple of brackets. I've made stainless shields before and they polish up nicely. They will act as an air break especially when the car's stationary. It will also protect other components from heat damage. At speed you'll have air flow through the engine bay.
I don't know but on my TR8 turbo I tried all sorts. First i wrapped the turbines only to find that they rusted badly because of the wrap. I wrapped the headers and didn't like that either. In the end I found that heat shields were the best solution and they could be made to look really nice when highly polished.
If I were you I'd leave the bonnet alone and wait until you get any issues, you may be fine. Shields are easy to fit and remove. You can also buy a cheap temperature probe with a guage that's on a long wire. That way you could monitor engine bay temps. I bought something from Maplins iirc.
If I were you I'd leave the bonnet alone and wait until you get any issues, you may be fine. Shields are easy to fit and remove. You can also buy a cheap temperature probe with a guage that's on a long wire. That way you could monitor engine bay temps. I bought something from Maplins iirc.
Hi,
I don't think the blower gets as hot as the turbos, luckely for me. But the headers sure does.
The problem is that since there are no hot air exhausts in the bonnet or the fenders the air does not circulate arround the headers and/or the top of the engine. Not even at speed as the air has nowhere to go except down.
The pressure in front of the wind screen probably prevents air to get out that way so we get some kind of air lock.
In my case the engine block gets ample cooling by the radiator but the top of the Engine, the headers and the blower & intake probably see very litte fresh air circulating.
The air comming in to the car is probably more than enough but it needs to pass trough the engine bay and cool thing on its way out.
The vent I pictured is from a 90's Ford RS Turbo. Maybe with some fantasy one can envision TVR using something like that if they had not come up with the S4/SV8 design.
Or I just cut vents like greenv8s to mirror a S4 bonnet.
Kind regards
//Rob
I don't think the blower gets as hot as the turbos, luckely for me. But the headers sure does.
The problem is that since there are no hot air exhausts in the bonnet or the fenders the air does not circulate arround the headers and/or the top of the engine. Not even at speed as the air has nowhere to go except down.
The pressure in front of the wind screen probably prevents air to get out that way so we get some kind of air lock.
In my case the engine block gets ample cooling by the radiator but the top of the Engine, the headers and the blower & intake probably see very litte fresh air circulating.
The air comming in to the car is probably more than enough but it needs to pass trough the engine bay and cool thing on its way out.
The vent I pictured is from a 90's Ford RS Turbo. Maybe with some fantasy one can envision TVR using something like that if they had not come up with the S4/SV8 design.
Or I just cut vents like greenv8s to mirror a S4 bonnet.
Kind regards
//Rob
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