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Hood Vents and Under Hood Temps
- Thread starter johnny5
- Start date
Thread Starter
#103
Johnny, what did you use for the aero trim pieces, whatever they're called, around the vents? I've been searching for something suitable to use and can't find anything I like.
I have some grille screen and a grinder ready to go. I just need those air deflector thingies!
I have some grille screen and a grinder ready to go. I just need those air deflector thingies!
@Jonny5, it’s the radiator fan running during these hot sessions?
Is your radiator fan running during these hot sessions?
I think a bypass switch for the radiator fan might be a good idea, and curious if anyone has done this. I have noticed my car runs cooler when the a/c is running because the radiator fan is running on hi pulling fresh air in. I have also noticed my radiator fan does not run as hard when the a/c is off.
Is your radiator fan running during these hot sessions?
I think a bypass switch for the radiator fan might be a good idea, and curious if anyone has done this. I have noticed my car runs cooler when the a/c is running because the radiator fan is running on hi pulling fresh air in. I have also noticed my radiator fan does not run as hard when the a/c is off.
Thread Starter
#105
The a/c was turned off during the track sessions until the cool down lap to avoid parasitic loss.
Talking with some tuners they can modify the temp when the fan turns on, so might try that as well next year. The only thing no one has touched are the 2 solenoids for flow through the t-stat and for flow shut off.
Talking with some tuners they can modify the temp when the fan turns on, so might try that as well next year. The only thing no one has touched are the 2 solenoids for flow through the t-stat and for flow shut off.
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I emailed m-sport directly yesterday and they quoted me £104 (currently $130) EACH for the outer trim pieces and £15 per square meter of screen. No mention of inner trim and there was no picture of it on the exploded diagram he sent.
I'm assuming you can just order them through email or over the phone. Couldn't find them anywhere else to order them.
I'm assuming you can just order them through email or over the phone. Couldn't find them anywhere else to order them.
I want this as well, since during STPR this past weekend, any time the stage captain stopped along the stages to drop off the workers at their marshall/start/finish points, and the car sat idling for a while, the temps started to creep up until I turned on the air to QUICKLY bring them down.
I WISH that I could do this without having the parasitic draw (and rougher idle due to an aftermarket RMM) of having the AC on, or ONLY being able to do this through a tune.![[wink]](/images/smilies/wink.gif "Wink [wink]")
I WISH that I could do this without having the parasitic draw (and rougher idle due to an aftermarket RMM) of having the AC on, or ONLY being able to do this through a tune.
So, as I understand, the low pressure zones are near the front of the hood behind the radiator and high pressure zone is up near the cowl, but what about that middle cowl spot that is right above the hot turbo and crossover? I've blanketed and heat taped my aluminum crossover, but what about cutting a section of lower cowl right below the middle screen area of the upper cowl? I run full recirc and no venting catch cans or anything, and there is already slits there anyway, so I think I'd be safe to try this, so what I'm thinking is with clearance *so* tight there, wouldn't it just *have* to run a little cooler with the heat able to rise away with that section of lower cowl cut out?
The location of these vents (https://cmcomposites.co.uk/shop/fiesta-parts/fiesta-wrc-bonnet-vents ) is where there is a low pressure zone (and the lip on the vent also helps create a low pressure zone).
Awesome, that's good info and kind of what I was visualizing...But isn't there also a low pressure zone behind the behind the radiator towards the front of the hood too right? That's what more forward palced hood vents can help with a bit from what I understand... but going back to the cowl,do you know if the passenger side area is where the protected area is to feed the air to the cabin? That way I can maybe at least cut the lower full cowl on the driver side maybe? Or maybe also even the original center one I was asking about?
I'll add my .02 worth. When I'm sitting still (traffic, stoplight, etc) I can see heat escaping out of the vents on my hood. Does it still do that once I'm moving....?....idk. But my car has never overheated at the track tho, and i am also running a Mountune radiator, fmic, 70/30 water and coolant mixture, and 1 bottle of water wetter. It's never overheated, and never went into limp mode here in Socal summers.....and when I do drive it, I drive it HARD.
I'm just gonna go out on a limb and say the WRC cars have been tested in regards to their aerodynamics more than anything we can come up with and the WRC cars only ever have vents above the headlights such as the ones I have provided a link to.
They don't have slats in the middle of the hood, they don't have openings at the front of the hood, or the top of the hood - consistently in one spot
https://www.google.com/search?q=fie...0.0l7j69i60.1961j0j7&sourceid=chrome&ie=UTF-8
They don't have slats in the middle of the hood, they don't have openings at the front of the hood, or the top of the hood - consistently in one spot
https://www.google.com/search?q=fie...0.0l7j69i60.1961j0j7&sourceid=chrome&ie=UTF-8
I feel like I can add a bit from my racing experience after reading this thread.
for track days / road racing you want to seal the rear cowl area because this creates lift (see any wind tunnel stuff). When at low speeds heat will come out of there and anywhere really that it can escape, but at speed the air comes off the windshield and lifts the hood up.
in champcar, where I've raced for years, it costs me points to upgrade radiator so while I would run a nice aluminum one in a second if I could, I'm running ebay specials of the factory radiator. We are able to keep the car cool with shrouding, water wetter, and no coolant. This strategy would not work on a street car that idles often, we have an electric fan on a switch for sitting under red flag or in pits.
things that matter for cooling system -
1. a lower thermostat really helps on a race car because when the car does get a chance to cool it will go to a lower temp giving headroom to expand from. it's buying more time under load / on the back of another car's bumper before temps get too high.
2. shrouding is everything. if you can force as much air as possible through the radiator with no chance of escaping then you'll keep temps down
3. more fluid volume will mean the whole system can absorb heat better
4. under-hood temps don't matter as much when moving fast, but do matter a lot when at low speeds / sitting still. cutting holes to prevent pressure build up will help at low speeds and high speeds, but we still have a solid hood on the racecar and its going wide open for 8-24 hours.
what does this all mean for the street /+ trackday fiesta st?
1. upgraded radiators will increase capacity which should really help.
2. lower thermostat will help a bit, but it's a compromise for a street car, you don't want to drive around at lower than t-stat temps in general use.
3. less coolant concentration and water wetter will help a bit
4. venting hood in right places can also help a bit, but shouldn't be needed to run without overheating
5. shroud and seal with tape as much as you can
for track days / road racing you want to seal the rear cowl area because this creates lift (see any wind tunnel stuff). When at low speeds heat will come out of there and anywhere really that it can escape, but at speed the air comes off the windshield and lifts the hood up.
in champcar, where I've raced for years, it costs me points to upgrade radiator so while I would run a nice aluminum one in a second if I could, I'm running ebay specials of the factory radiator. We are able to keep the car cool with shrouding, water wetter, and no coolant. This strategy would not work on a street car that idles often, we have an electric fan on a switch for sitting under red flag or in pits.
things that matter for cooling system -
1. a lower thermostat really helps on a race car because when the car does get a chance to cool it will go to a lower temp giving headroom to expand from. it's buying more time under load / on the back of another car's bumper before temps get too high.
2. shrouding is everything. if you can force as much air as possible through the radiator with no chance of escaping then you'll keep temps down
3. more fluid volume will mean the whole system can absorb heat better
4. under-hood temps don't matter as much when moving fast, but do matter a lot when at low speeds / sitting still. cutting holes to prevent pressure build up will help at low speeds and high speeds, but we still have a solid hood on the racecar and its going wide open for 8-24 hours.
what does this all mean for the street /+ trackday fiesta st?
1. upgraded radiators will increase capacity which should really help.
2. lower thermostat will help a bit, but it's a compromise for a street car, you don't want to drive around at lower than t-stat temps in general use.
3. less coolant concentration and water wetter will help a bit
4. venting hood in right places can also help a bit, but shouldn't be needed to run without overheating
5. shroud and seal with tape as much as you can
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Unlike the people open tracking their cars here, the WRC cars also run HUGE, full coverage skid/bash plates under the whole front clip of the car, right up into the front bumper attachment points..
That confined engine/turbo heat has to have some place to escape, so I disagree with you on the brake vent theory.
Also, when looking down into those vents on the R5, and open class Fiestas at ARA events, there is NO ducting down to the front brakes at all, it is open enough to see turbos (depending on the configuration, and whether or not it is a 'hybrid' car like MCKenna's open class ex-S2000,Fiesta with a 2 liter,'old school', Focus WRC engine in it) and engine components.
That confined engine/turbo heat has to have some place to escape, so I disagree with you on the brake vent theory.
Also, when looking down into those vents on the R5, and open class Fiestas at ARA events, there is NO ducting down to the front brakes at all, it is open enough to see turbos (depending on the configuration, and whether or not it is a 'hybrid' car like MCKenna's open class ex-S2000,Fiesta with a 2 liter,'old school', Focus WRC engine in it) and engine components.
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McKenna has his rally car equipped with lots of aero bits and guess where his hood vents are??
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