Aero mods and cooling

[Chuckable]

Based on your experience with the air dam, do you think that the Mountune splitter would be of any benefit to cooling?

I called Mountune to ask about functionality, and they said it's mainly a cosmetic piece. However, I didn't specify what functionality I was asking about. I should've asked if it helped with aero or cooling.

 

[Siestarider]

I got a good peek at the Focus RS undertray at Ford tent Sebring, its more complicated than pics can show. Some parts are definitely not intuitively functional. One of the articles on the RS claimed it the first production car with no lift front or rear at speed.

I have not inspected the Mountune splitter on a car to see how it is integrated with the flat tray beneath IC. All my undertray experiments have been behind the stock air dam, which is behind the flat tray under the IC and also lower.

Rick may be a better source of ideas, he used his splitter as an integrated part of a full undertray, but I have not heard any cooling reports, probably because he upgraded his radiator and put on an oil cooler two years ago. Or maybe because he changes turbos like I change underwear, lol.

 

[Wimp Lo]

He took his turbocharger off a long time ago and I don't think it is back on yet...

 

[RAAMaudio]

Turbo, waiting for the GT2560R change parts to come from DHM.

Splitter/undertray, I need to fab up a new rear mount then get it welded up, sucks having my really nice Miller in storage 700 miles away.

Tweaked my back a bit yesterday during the final adjustment of the BBK caliper mounts to fit the new 15x8 wheels over the brakes I hope to get that done in the AM so I can have the new mounts made and move on to the rest of the car mods, lots of them going on

 

[Siestarider]

Made some hood vents today, going to bolt extended air dam back on and do some coast-down testing. I think it was Dusty who reported hood vents improved coast time as well as cooling, I have forgotten which thread that was. Undertray shelved for now, it just was not paying off with big effects on either aero or cooling.

I put the vents where previous pressure testing showed the greatest negative value on outer surface, actually had -2" at 80 mph, with -.3" on inner surface at that location. A 1.7" pressure drop should pull some air.

Before I forget, when modding both sides always do your passenger side first so if you refine your methods the side you look at every day will be the better one.

Hoping the combination of extended air dam and hood vents will improve aero and cooling both. I will try for data tomorrow weather permitting.

 

[Siestarider]

New vent

From under

Close up

Modified air dam with aluminum stiffener behind it.

Too windy today to take data, so I completed brake duct cooling system, added drivers side CMB Racing duct, added a slight modification to direct more air into rotor hub, built new air boxes to feed ducts. Getting ready for Sebring in two weeks.

 

[Wimp Lo]

That looks nice.

Still, with air able to exit upward in to the low pressure area, the under tray might start working better and the best configuration would be a true splitter mounted low (and forward) enough to create a low pressure area under the car.

 

[Chuckable]

One of the few underside shots of a hood vent on a FiST I've seen. Thanks for posting. Not sure I have the guts to cut up my hood

 

[Siestarider]

Once other members' reports suggested cooling and aero benefits might be had with hood vents, I had to try. These are quick and dirty, if I like them, I will go back and reshape slightly to look better. I also found some weather strip I can place around upper side to replicate the WRC air flap, assuming the rubber molding I used for trim does not extract enough air. And if they have to expand over top edge into upper surface, still room to do that. So lots of room to experiment. Have enough aluminum bug screen and rubber molding to try several more iterations.

I wanted to stay as stealthy as possible for first attempt, so stuck to hood sides. Pressure data are strong for this location, hoping it works. Probably take tracking to really find out.

I thought about it for a lot longer than it took to cut the holes. It was a relief to just do it. Now the hood is experimental, so going back to stock just means buying a stock hood. Probably less costly than buying vents and having a pro install them.

 

[Levi1.0]

...Before I forget, when modding both sides always do your passenger side first so if you refine your methods the side you look at every day will be the better one...

That is great advice.

Looks good. Look forward to seeing any data you can get.

You know the vents on the sides of the F-series truck hoods (they usually have the "F-350" or whatever logo on them)? I wonder if any of those vents would be the right size for the sides of our hoods. I like the side vents because less water can get all over the important bits. Convenient that it's a good Aero spot too.

Keep up the good work.

 

[LT Berzerker]

I was thinking the shape that best fits our hoods isn't really something you typically see on cars... (Talking WRC fiesta)... So I did a little looking and found that snowmobiles might actually have something a little more akin to what best fits for shape... Just an idea and a lot cheaper... IE:

https://www.rmproducts.net/content/polaris_proride_upper_pipe_side_vent_panel

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[Levi1.0]

Those bottom ones look like the right shape. And the tight mesh screens might do a good job of shedding water as well.

Good find.

 

[Dustys318]

One of the few underside shots of a hood vent on a FiST I've seen. Thanks for posting. Not sure I have the guts to cut up my hood

Another one for you to see...

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[jayrod1980]

Dusty those look so nice! Are the raised portions glued on or snapped in?


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[Dustys318]

3M pro tape.. I've been through car washes and up to 155mph, no issues...

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[jayrod1980]

I would love doing this! How did you cut the hood again?


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[Siestarider]

Just downloaded coast down data. Big disappointment. Maybe still to windy, but average 2 ways 4 reps, more than 10% less coast time than stock. Then again, I am now running BFG Rival S instead of stock Bridgestones, so maybe the gumballs don't coast well. Either that or I have bricked my aerodynamics.

I did stick my hand out the window and easily felt the hot air stream at 60 mph. Did one hard pull in 3rd, compressed air temp, boost, timing and mass air look normal. Time from 2500 to 6500 was 7.9, slower than my usual 7.6 secs, but against wind and with larger diameter and width tires, hard to conclude anything.

On to Sebring in 2 weeks, a new PB will make me happy. At least I will get enough data to see how cooling behaves with these mods. No canyons around here to challenge cooling.

Love the snowmobile vents, that is really out of the box.

 

[Chuckable]

Another one for you to see...

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Nice pics! Looks like a clean install. I've never done any body work so I'm afraid to attempt this, especially when it's something you literally see everyday.

 

[meFiSTo]

Another one for you to see...

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I've got these ordered. I think I might pull the insulation/sound deadening off for track days and not cut it -- rather than cut the material away under the vents. It might provide a little bit of shield from heavy rain. I'm not too concerned about water intrusion (car is garaged so does not sit out in the rain usually). However, in the winter, it does rain most days, so a little bit of cover should be enough.

 

[Levi1.0]

Just downloaded coast down data. Big disappointment. Maybe still to windy, but average 2 ways 4 reps, more than 10% less coast time than stock. Then again, I am now running BFG Rival S instead of stock Bridgestones, so maybe the gumballs don't coast well. Either that or I have bricked my aerodynamics.

I did stick my hand out the window and easily felt the hot air stream at 60 mph. Did one hard pull in 3rd, compressed air temp, boost, timing and mass air look normal. Time from 2500 to 6500 was 7.9, slower than my usual 7.6 secs, but against wind and with larger diameter and width tires, hard to conclude anything...

You could put painters tape over the vents and do the coast down tests again, with and without the tape. That would minimize any variables that have changed since you did the original tests.