Discussion
I have been meaning to do this for a long time and today i eventually got round to it, i wanted to see exactly what the air scoops were doing, so i got one of those wind measuring things and linked to a P box and put it in different positions all over the car, i did about 5 runs in each position to check accuracy, there was very little fluctuation, i also tested wind speed to try and evaluate the accuracy of the wind speed device, but the results were slightly confusing, hopefully Adrian or Phil ar Paul might be able to shed some light on this.
Travelling at 120kmh air speed going into the front grill was around 87kmh, there was a very slight wind today so driving into the wind produced 90kmh and 85kmh with the wind behind, why is wind speed inside the front grill slower than the speed of the car?
When i measured wind speed around the car it was faster, i.e. travelling at 120kmh it would speed up to 136kmh as it was forced around the body/ sides and over the roof. The only place i got it to measure 120kmh is at the front of the roof i.e top of the windscreen, i think there are alot of negative pressure areas because at the bottoom of the wind screen the wind speed was only 95kmh similar at the front grill location. Holding it out of the window measured 140kmh i assume again this is due to wind speeding up as it gets forced around the car.
Anyway the results were constant over many tests, so i thought i would just log them and move on, hopefully somebody in the know will be able to make sense of them.
So here are the other results which can be related back to the above.
This is for the intercooler, P box V max was 122kmh and wind speed at IC mesh was 40kmh, not sure if this is enough to keep the IC cool, i need to test again at lower speeds.
The below is for the side pods, i have made a few mods to reduce pressure in front wheel arches, mainly that my clam only fixes with a small angle bracket which creates a very big vent at the windscreen.
The P box V max was 130kmh and the wind speed at the IC mesh was 65kmh, so i am pretty impressed with taht result considering you would only get 95kmh to the front radiator
Last i take no pleasure in announcing this
, but the best airflow result came from the top vents in the rear clam, P Box V max 136kmh and wind speed of 94kmh.
I have done aero mods, vented rear wheel arches, vented whale tail etc.. so i do not know if a noble without these mods will pull the same ammount of air into these vents, but at the moment i have some very good air being pushed into the engine bay from the side pods and top vents. I still think i made the right choice moving the air filters into the side pods as they suck in air rather than needing airflow.
Is 40kmh enough for the IC, i do not want to go blocking that airflow with a big fan only to acheive the same airflow, i know it is not getting airflow when stood but it is also doing less when stood. On my Dyno results it showed my intake temperatures were not so good after 3 power runs and that was with a big fan blowing air through it but i have no idea what the airflow was on that fan.
Travelling at 120kmh air speed going into the front grill was around 87kmh, there was a very slight wind today so driving into the wind produced 90kmh and 85kmh with the wind behind, why is wind speed inside the front grill slower than the speed of the car?
When i measured wind speed around the car it was faster, i.e. travelling at 120kmh it would speed up to 136kmh as it was forced around the body/ sides and over the roof. The only place i got it to measure 120kmh is at the front of the roof i.e top of the windscreen, i think there are alot of negative pressure areas because at the bottoom of the wind screen the wind speed was only 95kmh similar at the front grill location. Holding it out of the window measured 140kmh i assume again this is due to wind speeding up as it gets forced around the car.
Anyway the results were constant over many tests, so i thought i would just log them and move on, hopefully somebody in the know will be able to make sense of them.
So here are the other results which can be related back to the above.
This is for the intercooler, P box V max was 122kmh and wind speed at IC mesh was 40kmh, not sure if this is enough to keep the IC cool, i need to test again at lower speeds.
The below is for the side pods, i have made a few mods to reduce pressure in front wheel arches, mainly that my clam only fixes with a small angle bracket which creates a very big vent at the windscreen.
The P box V max was 130kmh and the wind speed at the IC mesh was 65kmh, so i am pretty impressed with taht result considering you would only get 95kmh to the front radiator
Last i take no pleasure in announcing this
, but the best airflow result came from the top vents in the rear clam, P Box V max 136kmh and wind speed of 94kmh.I have done aero mods, vented rear wheel arches, vented whale tail etc.. so i do not know if a noble without these mods will pull the same ammount of air into these vents, but at the moment i have some very good air being pushed into the engine bay from the side pods and top vents. I still think i made the right choice moving the air filters into the side pods as they suck in air rather than needing airflow.
Is 40kmh enough for the IC, i do not want to go blocking that airflow with a big fan only to acheive the same airflow, i know it is not getting airflow when stood but it is also doing less when stood. On my Dyno results it showed my intake temperatures were not so good after 3 power runs and that was with a big fan blowing air through it but i have no idea what the airflow was on that fan.
A couple of pics of the front wheel arch vents which i think is the main reason i am getting good airflow into the side pods, plus the wheel arches are also vented into the sills.
I think if i had also vented the "A" panels same as Simon the airflow to the side pods would have been increased further, and as Andy suggested i think if you put some blades to smooth out airflow on the back of the "A" panels it would increrase airflow into side pods yet again.
The car has potential to say it started off as a brick
i can't take credit for any of this though all the research work was carried out by Adrian, Phil, Paul and company, all i have done is follow there advice and findings, but as can be seen the positive results are there, pressure around wheel arches has gone and airflow around car smoothed out, resulting in good airflow through engine bay, which helps me keep cool and keep power
So i would like to thank everybody who has led the way and also Andy who was patient in explaining how it all worked to me.
It was 35deg today on the road, the fans never came on while driving, and it took at least a minute after i stopped before they came on, i wish i had measured my engine bay temps before so taht i could compare to know.
I think if i had also vented the "A" panels same as Simon the airflow to the side pods would have been increased further, and as Andy suggested i think if you put some blades to smooth out airflow on the back of the "A" panels it would increrase airflow into side pods yet again.
The car has potential to say it started off as a brick
i can't take credit for any of this though all the research work was carried out by Adrian, Phil, Paul and company, all i have done is follow there advice and findings, but as can be seen the positive results are there, pressure around wheel arches has gone and airflow around car smoothed out, resulting in good airflow through engine bay, which helps me keep cool and keep power So i would like to thank everybody who has led the way and also Andy who was patient in explaining how it all worked to me.
It was 35deg today on the road, the fans never came on while driving, and it took at least a minute after i stopped before they came on, i wish i had measured my engine bay temps before so taht i could compare to know.
Hi Chris.
It's good to see that you're giving at least lip service to quantifying your assumptions scientifically.
However.
I can't believe that you're suggesting that Phil's efforts here
Where (IIRC) the conclusion was that the flow into the vents was not particularly good, are to be over ridden by your suggestion that it IS good based on your efforts here
Sheesh Chris.
Mike.
It's good to see that you're giving at least lip service to quantifying your assumptions scientifically.
However.
I can't believe that you're suggesting that Phil's efforts here
Where (IIRC) the conclusion was that the flow into the vents was not particularly good, are to be over ridden by your suggestion that it IS good based on your efforts here
Sheesh Chris.
Mike.
The engine isn't running in a wind tunnel test so there is every chance Chris's efforts may actually be more accurate as an engine consumes a huge amount of air and this alone can change/distort the test results.
Chris... are the fans directional i.e. does it tell you which way the wind is travelling?... i think the biggest problem with your test method is it doesnt tell you what the air is doing, for example is it tumbling or smooth.... the air may be fast but tumbling.
Id be interested in you placing the sensor inside the engine bay in a few key places... for example after the vent in question, lower vents, behind the intercooler etc
Chris... are the fans directional i.e. does it tell you which way the wind is travelling?... i think the biggest problem with your test method is it doesnt tell you what the air is doing, for example is it tumbling or smooth.... the air may be fast but tumbling.
Id be interested in you placing the sensor inside the engine bay in a few key places... for example after the vent in question, lower vents, behind the intercooler etc
It's real world data Mike, and i think that you will find that Phil stated that this vent could have good airflow if the airflow through the engine bay was corrected.
They tested before venting the wheel arches and opening up the back end to improve airflow,opn top of this i ventwed the whale tail which when you look through the mesh you can see a direct line to these same scoops!
That is why i conceded on the last post because i have already carried out aero mods to improve airflow based on the wind tunnel findings, this was the purpose of the wind tunnel and the consequent alterations " to improve airflow!! " and it proves that the modifications really do work.
"It is what it is" Mike, its does not prove you wrong, because your findings may well be correct for a car without aero mods, even though findings were not in a wind tunnel... or on a road... or can be classed as tangible in any way
They tested before venting the wheel arches and opening up the back end to improve airflow,opn top of this i ventwed the whale tail which when you look through the mesh you can see a direct line to these same scoops!
That is why i conceded on the last post because i have already carried out aero mods to improve airflow based on the wind tunnel findings, this was the purpose of the wind tunnel and the consequent alterations " to improve airflow!! " and it proves that the modifications really do work.
"It is what it is" Mike, its does not prove you wrong, because your findings may well be correct for a car without aero mods, even though findings were not in a wind tunnel... or on a road... or can be classed as tangible in any way
some good work there Chris !
god only knows how you find time to rebuild the car and now this stuff
top marks for effort on the whole conversion
you can use something called a manometer to measure pressure around the car and these can easily be placed around the car at the same time so you could view the pressure at different locations and road speeds at the same time
I will email you some info on it
do you think wider side scoops will grab more air ? can you test the air just outside the pod at 1 inch gaps to see how far you have to go to before the velocity jumps up
god only knows how you find time to rebuild the car and now this stuff
top marks for effort on the whole conversion
you can use something called a manometer to measure pressure around the car and these can easily be placed around the car at the same time so you could view the pressure at different locations and road speeds at the same time
I will email you some info on it
do you think wider side scoops will grab more air ? can you test the air just outside the pod at 1 inch gaps to see how far you have to go to before the velocity jumps up
R0162 said:
It's real world data Mike, and i think that you will find that Phil stated that this vent could have good airflow if the airflow through the engine bay was corrected.
Yes, I realise that Chris, and I think you'll find of you look back, that I commented that wherever they are, the filters will guzzle huge volumes of air, I never doubted that.I think you'll find that I also suggested that with additional modifications/alterations that air flow could easily be improved.
What I had said previously was that moving the filters to the bulkhead from the airbox is (IMHO) a downgrade as in that location a very high percentage of the air that they guzzle will be horrendously hot air, (that's bad BTW).
Lovely colour though.
Mike.
Mike Im glad you have expanded on why you were so dismissive above on Chris's findings... I think the point Chris is making is that you actually don't have any data at all to support your view that bulkhead filters mostly get fed hot air rather than cool air, its an assumption based from data gathered in artificial and flawed environments IMHO.
Chris
I think a lot more testing is needed... Im planning an under clip temp sensor on my car... is this something you plan?
Chris
I think a lot more testing is needed... Im planning an under clip temp sensor on my car... is this something you plan?
Only winding you up mike, your findings are most definitely correct as they tally with what phil said, I was arguing results post aero mods which was wrong, all this proves is that the aero mods work, it would be more strange if they did not work as the wind tunnel time would have been wasted.
So moving on, I did further testing, moving the wind device changes the wind speed, I.e. Intercooler, moving it down wind speed slows, moving it up it increases,at 120kmh a few inches further up the wind flow was 47kmh which leads me to believe that putting a lip over the intercooler scoop will improve airflow.
I measured at the bottom of the mesh and at 120kmh wind speed dropped to 34 kmh, I also measured again in the centre but this time at 60kmh and the wind speed into intercooler was 20kmh so the ratio remains at wharves speed, in that you achieve one third of the wind flow of the speed of the car.
The same applies to the side pod, you always achieve half wind flow of what speed the car is travelling.
So moving on, I did further testing, moving the wind device changes the wind speed, I.e. Intercooler, moving it down wind speed slows, moving it up it increases,at 120kmh a few inches further up the wind flow was 47kmh which leads me to believe that putting a lip over the intercooler scoop will improve airflow.
I measured at the bottom of the mesh and at 120kmh wind speed dropped to 34 kmh, I also measured again in the centre but this time at 60kmh and the wind speed into intercooler was 20kmh so the ratio remains at wharves speed, in that you achieve one third of the wind flow of the speed of the car.
The same applies to the side pod, you always achieve half wind flow of what speed the car is travelling.
Mike Tuckwood said:
Yes, I realise that Chris, and I think you'll find of you look back, that I commented that wherever they are, the filters will guzzle huge volumes of air
Depends what you mean by "massive".6000 rpm, 3 litre engine = 1080 m^3 per hour it seems.
A small 7" fan like a SPAL VA07-AP7 shifts that sort of volume of air.....
J
joust said:
epends what you mean by "massive".
6000 rpm, 3 litre engine = 1080 m^3 per hour it seems.
A small 7" fan like a SPAL VA07-AP7 shifts that sort of volume of air.....
J
Well, I'd say that's quite a lot through a small pipe, then take into account the forced induction element of things?6000 rpm, 3 litre engine = 1080 m^3 per hour it seems.
A small 7" fan like a SPAL VA07-AP7 shifts that sort of volume of air.....
J
Mike.
mgbond said:
Just a guess but can i suggest that the reason the air maybe be slower at the front grill as the little fan on your device is getting slowed down by air bouncing back from the rad (or built up air pressure pushing back)?
Bondy
U got it, I worked it out after, I have sealed the radiator to the clam so air has to go through, I think air slows down as it is being forced through the radiator, the air is not free flowing and I must test again at lower speed.Bondy
Chris, i like what you've done opening up the under edges of the clam and using those new clamping pins, i'll be copying this if you dont mind, need to help the front of my M400 stick to the road better.
i imagine removing the mesh will improve flow through vents and reduce pressure built up at the front of the car allowing higher velocity to pass through the radiator/enter side scoops, (e.g) some outside stairwells on offshore platforms are surrounded by mesh constructed walls to reduce airspeed/stop people being blown down the stairs, at 100ft from sea level winds get to 40/50 knots regularly.
I removed the mesh from behind my intercooler, between exhaust tips and from side pods to get more air in and out the rear but will prob open up the rear arches as you have too.
i imagine removing the mesh will improve flow through vents and reduce pressure built up at the front of the car allowing higher velocity to pass through the radiator/enter side scoops, (e.g) some outside stairwells on offshore platforms are surrounded by mesh constructed walls to reduce airspeed/stop people being blown down the stairs, at 100ft from sea level winds get to 40/50 knots regularly.
I removed the mesh from behind my intercooler, between exhaust tips and from side pods to get more air in and out the rear but will prob open up the rear arches as you have too.
I can't remove the mesh unfortunately, i glued it in strong with sikaflex but i think the air flow through the radiator would not be improved much, i think the restriction is the radiator and air con rad itself, it would be interesting to see if i went faster if the air flow through the rad speeded up or wether it reached its max capacity, i.e anything above may just cause buffeting.
btw another piece of data i collected was that the radiator fan(without air con) pulls air through the front grill(not radiator) at 13kmh, but again i also sealed the fan shroud to the radiator to ensure air has to be pulled/pushed through.
btw another piece of data i collected was that the radiator fan(without air con) pulls air through the front grill(not radiator) at 13kmh, but again i also sealed the fan shroud to the radiator to ensure air has to be pulled/pushed through.
R0162 said:
U got it, I worked it out after, I have sealed the radiator to the clam so air has to go through, I think air slows down as it is being forced through the radiator, the air is not free flowing and I must test again at lower speed.
Unlikely.Mr Bernoulli again, but remember his law proves that as fluid/gas is restricted, flow rate *increases*.
It's more likely that the air is stalling and you have turbulent flow as it can't all get through the radiator core.
J
R0162 said:
btw another piece of data i collected was that the radiator fan(without air con) pulls air through the front grill(not radiator) at 13kmh, but again i also sealed the fan shroud to the radiator to ensure air has to be pulled/pushed through.
Somewhat different principles.As the car goes down the road you are asking the air to stay in laminar flow, enter the grill, go through the core (which will have all sorts of horrible effects) and then come out the other side. This will be tempered by and pressure difference between the front entry and top exit due to the effect of the relative air speeds as they separate and re-join - it's a bit of a mini upside down wing in that just the different distances travelled by the respective air will change things.
When you have fans running and measure the speed at the grill at a standstill, you are just measuring the input of air into the partial low pressure generated just in front of the radiator core caused by the fans effectivly creating a low pressure area by moving air through them. As the fans don't caover the same area as the core, it's going to be very hard to compare a "blow" with a "suck" effect.
Ergo, 13kmph wind speed caused by that low pressure is not the same as 13kmph of air hitting whilst the car is moving. I wouldn't really like to even suggest how they might be related.
If the fans were attached to the grill and "blew" air into it, then you might be able to infer something.
J
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