Bonnet popped open......
Discussion
Hi Twisty, had the lights and the splitters done oop north! at a place I will not publicise as I got screwed by them, the light pods are Fibreon and i believe the splitters are too, they are attached using two bolts either side, I love them!
Must get round to painting them soon! only been on 2 years.
Must get round to painting them soon! only been on 2 years.
Gaffer taped the darn thing shut for today's session and had no problems other than not being able to check the oil and water.
I will have a muse and decide what to do next. Obviously it is only a track day issue, as I wouldn't be speeding on the pubic highway.
Pins or splitters, that is the question. I too like the look of the splitters on the black Chimaera, and not all bonnet pins look too horrendous.
Or I can just carry a roll of black gaffer tape with me to track days.
Thanks everyone for your contributions
I will have a muse and decide what to do next. Obviously it is only a track day issue, as I wouldn't be speeding on the pubic highway.
Pins or splitters, that is the question. I too like the look of the splitters on the black Chimaera, and not all bonnet pins look too horrendous.
Or I can just carry a roll of black gaffer tape with me to track days.
Thanks everyone for your contributions
The reason the bonnet flaps is due to several things, bouncing as the car moves over undulations in the road, poor alignment and structural weakening of the bonnet frame and under bonnet pressure, the latter appears to be a major reason. Fitting a splitter will reduce under bonnet pressure and will also reduce air cooling which should help the engine reach working temperature quicker.
I must add though that fitting the splitter backwards will not reduce under bonnet pressure and may actually increase it at speed because it will create lift by way of increased under car pressure. Fitted the right way round the splitter prevents air getting under the car and thereby creates a partial vacuum which should serve to hold the bonnet down. That was never the intent of the splitter, its purpose is to reduce understeer at speed, less bonnet flapping is a welcome by-product
I must add though that fitting the splitter backwards will not reduce under bonnet pressure and may actually increase it at speed because it will create lift by way of increased under car pressure. Fitted the right way round the splitter prevents air getting under the car and thereby creates a partial vacuum which should serve to hold the bonnet down. That was never the intent of the splitter, its purpose is to reduce understeer at speed, less bonnet flapping is a welcome by-product
Thanks Bobfather, that is a great analysis of all the factors.
All bonnet movements occurred on a dead smooth operational RAF base runway. Tornado GR4s will be flying out of there tomorrow morning.
In my case, I had the passenger side flapping fairly wildly from about 90-100 mph, so taped that down
Then at 135 mph I had so much force on the bonnet that it not only detached the gaffer tape, it also pulled the bonnet catch peg out of the closed bonnet catch, meaning that the bonnet must have bulged enough for the peg to pull right out without the catch opening. Have a look at your own bonnet catch if you don't know what I mean.
I need as much under bonnet cooling as possible on hot, high revving, hard working track days. Most of today was spent between 4000 and 6000 rpm, but the car was always between 70 and 92 degrees C.
So the solution for me is I guess not splitters, it is better fixing of the bonnet to the car. Pins (or gaffer tape) is probably the answer to my issue.
Unless the cool air passing over the engine will still be adequate with a splitter fitted.
Now I know what the vents in the bonnet are for.
Thanks everyone - do you all agree?
All bonnet movements occurred on a dead smooth operational RAF base runway. Tornado GR4s will be flying out of there tomorrow morning.
In my case, I had the passenger side flapping fairly wildly from about 90-100 mph, so taped that down
Then at 135 mph I had so much force on the bonnet that it not only detached the gaffer tape, it also pulled the bonnet catch peg out of the closed bonnet catch, meaning that the bonnet must have bulged enough for the peg to pull right out without the catch opening. Have a look at your own bonnet catch if you don't know what I mean.
I need as much under bonnet cooling as possible on hot, high revving, hard working track days. Most of today was spent between 4000 and 6000 rpm, but the car was always between 70 and 92 degrees C.
So the solution for me is I guess not splitters, it is better fixing of the bonnet to the car. Pins (or gaffer tape) is probably the answer to my issue.
Unless the cool air passing over the engine will still be adequate with a splitter fitted.
Now I know what the vents in the bonnet are for.
Thanks everyone - do you all agree?
there is also a Griffith with a Custom Tuscan racer inspired vented bonnet...
and here I guess for guiding the air out?
I guess it also helps a little bit to get more air out.
http://www.classiccarsforsale.co.uk/classic-car-pa...
and here I guess for guiding the air out?
I guess it also helps a little bit to get more air out.
http://www.classiccarsforsale.co.uk/classic-car-pa...
bobfather said:
The reason the bonnet flaps is due to several things, bouncing as the car moves over undulations in the road, poor alignment and structural weakening of the bonnet frame and under bonnet pressure, the latter appears to be a major reason.
I must add though that fitting the splitter backwards will not reduce under bonnet pressure and may actually increase it at speed because it will create lift by way of increased under car pressure.
Main reason is surely because the catch is way off-centre ?I must add though that fitting the splitter backwards will not reduce under bonnet pressure and may actually increase it at speed because it will create lift by way of increased under car pressure.
whether my little "splitter" was the right or the wrong way round it certainly reduced the some what disconcerting bonnet flap at high speed and with no detrimental side effects.
Theory is one thing, in practice is another
phillpot said:
Main reason is surely because the catch is way off-centre ?
whether my little "splitter" was the right or the wrong way round it certainly reduced the some what disconcerting bonnet flap at high speed and with no detrimental side effects.
Theory is one thing, in practice is another
Sorry, I'm not picking on you; I'm just trying to help the OP understand how splitters work. With the deflector facing backwards it becomes a wind deflector which produce body lift by increasing pressure behind it. Splitters are always forward facing, this isn't a TVR thing, it is fundamental aerodynamic design used throughout the auto industry. A splitter works by blocking the air from the front of the car so that it doesn't get under the car. The forward motion of the car causes air to be drawn out from under the car, the splitter blocks the incoming air so that the overall effect is a partial vacuum pulling the car into the road thereby improving road holding. whether my little "splitter" was the right or the wrong way round it certainly reduced the some what disconcerting bonnet flap at high speed and with no detrimental side effects.
Theory is one thing, in practice is another
haircutmike said:
Er, no!
Gutter spiitter pointing forward pulls bonnet down so bonnet won't pop up.
Nearside corner flaps because of poor design, fit pins.
Pack bonnet catch forward a couple of washers and ensure that you have the plasticsleeve on your bonnet pin.
All imho, of course.
Still jealous!
Thanks Peter - I will look out for next year's track weekends and see if we can get a bit of a TVR weekend going. They normally do two of them, but occasionally they have to cancel at short notice due to needing the track back to fly their Tornados off the main straight. The chance to spin the car at high speed and know you aren't going to hit anything was actually a real boon for muppets like me. In the mean time I will have a think about how to sort out the bonnet, and thanks everyone for your great contributions.Gutter spiitter pointing forward pulls bonnet down so bonnet won't pop up.
Nearside corner flaps because of poor design, fit pins.
Pack bonnet catch forward a couple of washers and ensure that you have the plasticsleeve on your bonnet pin.
All imho, of course.
Still jealous!
Stuart the test driver pronounced my car very nice to drive, his only suggestions being less sticky tyres to loosen the back end a bit (
errr, I don't think so!!) and a longer gear lever or greasing the linkage, to make the gear change a bit slicker. As the box was only out last Monday to have reverse sorted, and I cannot imagine that Mat didn't grease the linkage before he re-inserted the box, the gear-change must now be as good as it gets. To be fair, it was getting a bit sticky towards the end of the day. He did like the standard TVR aircon - I did the entire weekend with the roof right down, to avoid overheating......me, not the car.
haircutmike said:
Er, no!
Gutter spiitter pointing forward pulls bonnet down so bonnet won't pop up.
Nearside corner flaps because of poor design, fit pins.
Pack bonnet catch forward a couple of washers and ensure that you have the plasticsleeve on your bonnet pin.
All imho, of course.
Still jealous!
Thanks Peter - I will look out for next year's track weekends and see if we can get a bit of a TVR weekend going. They normally do two of them, but occasionally they have to cancel at short notice due to needing the track back to fly their Tornados off the main straight. The chance to spin the car at high speed and know you aren't going to hit anything was actually a real boon for muppets like me. In the mean time I will have a think about how to sort out the bonnet, and thanks everyone for your great contributions.Gutter spiitter pointing forward pulls bonnet down so bonnet won't pop up.
Nearside corner flaps because of poor design, fit pins.
Pack bonnet catch forward a couple of washers and ensure that you have the plasticsleeve on your bonnet pin.
All imho, of course.
Still jealous!
Stuart the test driver pronounced my car very nice to drive, his only suggestions being less sticky tyres to loosen the back end a bit (
errr, I don't think so!!) and a longer gear lever or greasing the linkage, to make the gear change a bit slicker. As the box was only out last Monday to have reverse sorted, and I cannot imagine that Mat didn't grease the linkage before he re-inserted the box, the gear-change must now be as good as it gets. To be fair, it was getting a bit sticky towards the end of the day. He did like the standard TVR aircon - I did the entire weekend with the roof right down, to avoid overheating......me, not the car.phillpot said:
Ok , your right, I'm making it all up, bonnet flapped around like a flag, engine overheated and car nearly took off at anything over 50mph ! 
Same old discussion.... splitter
Relax, I was replying to QBs post but the reception in The Highlands is crap and it posted half an hour after sending!Same old discussion.... splitter
phillpot said:
I got the idea from a thread some time ago, it's made from a piece of plastic rain guttering. Back then there were two schools of thought as to which way round it should go.
All I can say is it definately reduced bonnet lift and car felt stable and steering positive at high speed.
To test the "which way round theory" this is my S Series....
With such crude aerodynamics my opinion is that as long as you have something deflecting air from under the bonnet it's gotta be better than nothing
This All I can say is it definately reduced bonnet lift and car felt stable and steering positive at high speed.
To test the "which way round theory" this is my S Series....
With such crude aerodynamics my opinion is that as long as you have something deflecting air from under the bonnet it's gotta be better than nothing
And in the pic above it is fitted the right way round, although for a chim that is a little big.It needs to be forward facing and a bit smaller so it wont catch on something and rip itself off.Here is a pic of one i had on my chim.
I have either lost or destroyed 3 of them up to now but they do work. I drove the car for a couple of weeks without one, and at speed on the motorway, the bonnet would flap and lift on the offside. With a splitter fitted this never happened.
Apparently with being forward facing it creates negative pressure behind itself, and this has the effect of actually drawing air down from the engine bay, and thus helps keep the bonnet in place.
I believe it can also aid under bonnet temps a little as well.
Whatever the theory behind it all, IT DOES WORK!
Edited by TJC46 on Monday 20th August 19:48
Gassing Station | Chimaera | Top of Page | What's New | My Stuff