Heavily modded cossie engine with standard 2wd bonnet
16-08-2017 | 10:52 PM
#81
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From: Sutton
It was just before he mapped to 701 bhp (which I saw) but he dropped 40 lbft torque on that run to previous. He said it was a super bike so assumed 1000 as dont know of any 600cc super bikes,. It was a story told at a rolling road so could have been a 125cc but I do know that it is a very fast car as any 4wd 700 bhp car at 1400 kg will be, it is in Veyron worrying territory power to weight and a whole lot of sticky contact patch compared to a bike tyre.
When people say 'superbikes' I usually take it as either 600 or 1000cc bikes, i.e. Gsxr600, gsxr1000 and so on...
Cheers Paul
16-08-2017 | 11:12 PM
#82
Agreed with Paul, either pushed out by hot air or pulled out by cool air passing over and will raising the bonnet do similar?
I am tempted to add some air sensors for what it is worth, closed and then vented. Measure air under bonnet constant and air at back of raised bonnet and air at vent. If air at vent or back of bonnet is higher than under bonnet the surely heat energy is escaping somehow for the benefit of heat loss and if under bonnet temps do not alter then all is a waste of time?
Measure water and oil temps throughout
Does that cover all option?
I am tempted to add some air sensors for what it is worth, closed and then vented. Measure air under bonnet constant and air at back of raised bonnet and air at vent. If air at vent or back of bonnet is higher than under bonnet the surely heat energy is escaping somehow for the benefit of heat loss and if under bonnet temps do not alter then all is a waste of time?
Measure water and oil temps throughout
Does that cover all option?
But they are not.
Well not on my car anyway......one is over where the air filter box was
Marc's diagram is a little misleading, with respect to it looking like any significant amount of hot air coming from the rad then exits through the vents.
You can see vent locations on my sig pic below.
Last edited by Ridgey; 16-08-2017 at 11:14 PM.
16-08-2017 | 11:20 PM
#83
............
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From: West Mids
This is becoming quite painful
Yes vents make a difference
Yes hot air escapes from them
Yes more cooling happens
BUT
The extra cooling comes from the rad and intercooler being able to work harder as there is more air passed across them as there is a larger pressure differential each side of them not because the heat is escaping from the vents
Yes vents make a difference
Yes hot air escapes from them
Yes more cooling happens
BUT
The extra cooling comes from the rad and intercooler being able to work harder as there is more air passed across them as there is a larger pressure differential each side of them not because the heat is escaping from the vents
17-08-2017 | 06:43 PM
#85
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From: Guildford
I too get what you are saying, my point being that ford decided to put bonnet vents on the 3dr, saph 4x4 and escos, yes a lot was styling but from what you all are saying (even if it is painful) the general consensus is that bonnet vents help the rad and intercooler work better leading to cooler temps ergo if the car is running hot bonnet vents may help it run cooler if in the right place.
18-08-2017 | 09:15 PM
#87
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From: Devon
I was always under the impression from various wind tunnel tests I've seen on similar things, but things like raised bonnets cause a turbulent void of low pressure behind the bonnet and it renders them almost pointless, even giving negative effects.
As well as lifting the bonnet off its firewall rubber seal so the heater blower sucks in fumes from the engine bay. Be a pretty good way to kill yourself with open breathers
Ford designed the vents to work and probably spent a good while doing so. I don't think Fred in a shed with a bit of bent tin has the same testing facilities to check the way these things operate, or if they work at all.
As well as lifting the bonnet off its firewall rubber seal so the heater blower sucks in fumes from the engine bay. Be a pretty good way to kill yourself with open breathers
Ford designed the vents to work and probably spent a good while doing so. I don't think Fred in a shed with a bit of bent tin has the same testing facilities to check the way these things operate, or if they work at all.
Last edited by Loomer; 18-08-2017 at 09:28 PM.
18-08-2017 | 09:24 PM
#88
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From: God knows!
I was under the impression that bonnet vents can be useless at speed as the air rushing over them forms a kind of high pressure shield keeping the air in the bonnet space. I seem to remember reading that a small flat vertical lip should be placed in front, this spoils the high speed flow over the vent and allows air to escape, making the vent more effective. Can't remember where I read it but it makes sense to me.
Last edited by jonfoc; 18-08-2017 at 09:26 PM.
18-08-2017 | 10:31 PM
#91
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From: Holbury,Southampton
This thread has tried to get very technical but at the end of the day its simple. If some people dont like the vented bonnet and dont think it helps keeping engine bay temperatures down dont use it. For others they do like and prefer it so stick with it and every one is happy!
19-08-2017 | 12:26 AM
#93
cossie fan (unluckerly)
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From: hampshire
This thread has tried to get very technical but at the end of the day its simple. If some people dont like the vented bonnet and dont think it helps keeping engine bay temperatures down dont use it. For others they do like and prefer it so stick with it and every one is happy!
But we all have different views and opinions so each to there own
19-08-2017 | 09:10 AM
#94
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From: Sutton
I was under the impression that bonnet vents can be useless at speed as the air rushing over them forms a kind of high pressure shield keeping the air in the bonnet space. I seem to remember reading that a small flat vertical lip should be placed in front, this spoils the high speed flow over the vent and allows air to escape, making the vent more effective. Can't remember where I read it but it makes sense to me.
Small carbon lips placed infront of the vents...
Cheers Paul
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