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Aero mods and cooling
- Thread starter Siestarider
- Start date
Sure, no problem -- it's in my Project Car thread too.
Unplug the two connectors on the restraint module. Idiot lights abound, but the TVC is off. You need to take out your center console to get to it, and that's a bit of a pain. I don't have an interior or much wiring left, so easy for me. I was afraid to remove that module, but it's getting tossed out now. Beware any CANBUS wiring! Mess with that, and your car may never run again. :/
Unplug the two connectors on the restraint module. Idiot lights abound, but the TVC is off. You need to take out your center console to get to it, and that's a bit of a pain. I don't have an interior or much wiring left, so easy for me. I was afraid to remove that module, but it's getting tossed out now. Beware any CANBUS wiring! Mess with that, and your car may never run again. :/
Thread Starter
#144
Back on the aero cooling mods, this time with better undertray stiffeners to avoid flex, plus put the 2" flexible air dam extension back on. Started to add an aluminum stiffener to air dam but suppressed my enthusiasm just in time to go test again first. Data tomorrow.
Thread Starter
#145
Update: Tested latest version undertray, improved aero per coast down to OEM equal, and cooling pressure drop of 1.4" across radiator vs 1"-1.2"OEM.
Grafted 2" air dam extension back on to modified undertray and lost a little aero, but gained another 0.1" pressure drop across radiator. I.5" is about the empirical optimum for cooling the OEM radiator.
Seems strange that aero performance was better with air dam extension without undertray than air dam extension with undertray. But cooling is the main goal, with least cost to aero.
Overall it calculates to 30% cooling air increase (assuming pressure drop is directly related) and 2% aero improvement vs stock. Fine tuning worth the effort in theory.
I am probably near optimum undertray shape now, could loose air dam extension and keep stealth. But its set up so I can test in stages at track next Sat.
Collect data on track, if not staying cool enough, remove air dam extension first, try again, then remove undertray if temps are are higher than stock. But the theory says I should find better cooling and near same top end as last track day without these aero mods.
I had to stop myself from adding NACA ducts to undertray and playing with hoses grafted to outlets. I am thinking maybe a cool air intake hose to bottom of Mountune air box would be fun. So would a hose to supply air to top back side of engine. And if it turns out oil cooler is necessary for Cyborg, have more options for that too.
Before I forget, all this focus on water and oil cooling ignored the tranny, hope the undertray is not causing too much heat in tranny, I have no way to measure that. Focus RS pics suggest its a worthy thought.
Grafted 2" air dam extension back on to modified undertray and lost a little aero, but gained another 0.1" pressure drop across radiator. I.5" is about the empirical optimum for cooling the OEM radiator.
Seems strange that aero performance was better with air dam extension without undertray than air dam extension with undertray. But cooling is the main goal, with least cost to aero.
Overall it calculates to 30% cooling air increase (assuming pressure drop is directly related) and 2% aero improvement vs stock. Fine tuning worth the effort in theory.
I am probably near optimum undertray shape now, could loose air dam extension and keep stealth. But its set up so I can test in stages at track next Sat.
Collect data on track, if not staying cool enough, remove air dam extension first, try again, then remove undertray if temps are are higher than stock. But the theory says I should find better cooling and near same top end as last track day without these aero mods.
I had to stop myself from adding NACA ducts to undertray and playing with hoses grafted to outlets. I am thinking maybe a cool air intake hose to bottom of Mountune air box would be fun. So would a hose to supply air to top back side of engine. And if it turns out oil cooler is necessary for Cyborg, have more options for that too.
Before I forget, all this focus on water and oil cooling ignored the tranny, hope the undertray is not causing too much heat in tranny, I have no way to measure that. Focus RS pics suggest its a worthy thought.
Thread Starter
#147
For those of us who run them, Quaife is a mechanically controlled split torque differential. Transmission shares fluid with diff. Point is both need cooling via fluid.
Focus RS has one in front and one in back, they do not share fluid, but looks to me like Focus does provide additional cooling for tranny/differential in front, so it is worth thinking about.
Focus RS has one in front and one in back, they do not share fluid, but looks to me like Focus does provide additional cooling for tranny/differential in front, so it is worth thinking about.
Thread Starter
#150
Track report: 65 F ambient start of first session running modified undertray and air dam extension. PBIR is a 2 mile track with 10 turns, two straights one 4th, one 5th gear. Report Engine Coolant Temp (ECT)/Oil temp
Start logging: 196 F/ 211
Over 7 minutes into session, ECT hit 220.0 F for first time. Oil 242.
8 minutes in, hit 225 ECT for 2 seconds, Oil 245.
Toward end of session logged 50 sec of ECT above 220 and below 225. Oil running 246-47. Total 5 periods over 220, most lasted 10-15 sec. All at high boost/rpm.
During cool down back straight in 5th 208 ECT and 237 oil.
Hot pit exit ECT 201 oil 234.
Max back straight 120 mph at 5540 rpm in 5th.
I was dragging undertray at pit exit, so removed it completely before next session. Fastener failure. Plan was to remove air dam extension first, then undertray. Oh well, removed undertray first instead.
73 ambient start 2nd session
Start logging: 206/214
Six minutes in 220/230
Hit 225 ECT for two seconds middle of session on back straight in 5th, oil 245. Max speed 121.
Exceeded 220 total of 8 times, most 10-15 sec duration, longest period was 25 secs and included hitting 225/247 in middle.
Hot pit exit 201/234
My plan was to remove 2" air dam extension and log that too, but forgot that part of plan when undertray came off first.
50,000 lines of data in spreadsheets, logged fine grain mainly to try to understand TVC action with LSD. But that is another day.
My main takeaway from this track day is do not try to run BFG SC2's for a new personal best when they are already at wear bars. They still stopped well, but lateral grip was lacking. At the end of my last session I spun in exit of turn 9, easiest exit on track, overpowered and lost front traction, and around we went, gracefully if ignominiously.
Start logging: 196 F/ 211
Over 7 minutes into session, ECT hit 220.0 F for first time. Oil 242.
8 minutes in, hit 225 ECT for 2 seconds, Oil 245.
Toward end of session logged 50 sec of ECT above 220 and below 225. Oil running 246-47. Total 5 periods over 220, most lasted 10-15 sec. All at high boost/rpm.
During cool down back straight in 5th 208 ECT and 237 oil.
Hot pit exit ECT 201 oil 234.
Max back straight 120 mph at 5540 rpm in 5th.
I was dragging undertray at pit exit, so removed it completely before next session. Fastener failure. Plan was to remove air dam extension first, then undertray. Oh well, removed undertray first instead.
73 ambient start 2nd session
Start logging: 206/214
Six minutes in 220/230
Hit 225 ECT for two seconds middle of session on back straight in 5th, oil 245. Max speed 121.
Exceeded 220 total of 8 times, most 10-15 sec duration, longest period was 25 secs and included hitting 225/247 in middle.
Hot pit exit 201/234
My plan was to remove 2" air dam extension and log that too, but forgot that part of plan when undertray came off first.
50,000 lines of data in spreadsheets, logged fine grain mainly to try to understand TVC action with LSD. But that is another day.
My main takeaway from this track day is do not try to run BFG SC2's for a new personal best when they are already at wear bars. They still stopped well, but lateral grip was lacking. At the end of my last session I spun in exit of turn 9, easiest exit on track, overpowered and lost front traction, and around we went, gracefully if ignominiously.
That is interesting.
I wonder what the differential is above and below the under tray.
The air dam should create a low pressure zone behind it, high pressure in front with some spilling forward in to the grill creating more pressure in front of the radiator.
The under tray should mostly smooth out the air under the engine but the air dam might be creating a differential that's trying to tear the tray down away from the chassis.
What a full splitter does is keep the high pressure zone in front of the grill from spilling under the car by extending forward to a point where the pressure gradient is close to ambient.
When I get my WRC style hood vents in I expect that I can install a sturdy splitter/under tray that will improve cooling and add downforce. I expect drag to be worse because I will be pushing more air through an opened up grill, a bigger intercooler, maybe an oil cooler and a more restrictive thicker radiator core. That is probably the price of cooling and some down force.
I wonder what the differential is above and below the under tray.
The air dam should create a low pressure zone behind it, high pressure in front with some spilling forward in to the grill creating more pressure in front of the radiator.
The under tray should mostly smooth out the air under the engine but the air dam might be creating a differential that's trying to tear the tray down away from the chassis.
What a full splitter does is keep the high pressure zone in front of the grill from spilling under the car by extending forward to a point where the pressure gradient is close to ambient.
When I get my WRC style hood vents in I expect that I can install a sturdy splitter/under tray that will improve cooling and add downforce. I expect drag to be worse because I will be pushing more air through an opened up grill, a bigger intercooler, maybe an oil cooler and a more restrictive thicker radiator core. That is probably the price of cooling and some down force.
Thread Starter
#152
Data interpretation time. First, I have lots of logs from that particular track with stock air dam and no undertray. My main concern was that undertray would not perform on track as well as on mexican road tests. So that concern is alleviated (except for fastener failure, which is on me).
Stock maximum speeds 118 on back straight. 2" air dam extension + undertray solid 120 mph. Air dam only 121 mph. Right at the same % aero improvements measured in coast down tests. So that is good verification of test data transfer to track.
Main interest was and is cooling. I still have stock coolant in the car, have added water several times, so probably 60% water by now. I have also experienced overheating on track, which I determine by when the idiot light comes on, not by absolute ECT or oil temps. My rationale is Ford knows when to say "back off".
My idiot light does not come on until ECT is 235+ and oil is 250+. So goal of all this messing around was to see if I could alter aero and improve cooling enough to prevent overheating light. Data say yes, you can.
The air dam is the easiest method to improve radiator heat flow, but 1" of street clearance is not really practical for a DD. Undertray performed a little better on track with regard to cooling, but cannot say how it will perform without air dam extension on track. My goal is to get enough cooling with undertray to stay with stock cooling equipment.
Maybe the most impressive data to me were: 1. Only four seconds total logged over 225 F ECT. 2. Very rapid recovery from full race mode to ECT below 212 once backed off. These are significant improvements vs stock logs from last year.
As a reminder, I did start plugging little gaps around radiator last year, and found a couple more last time I had nose off, so that is certainly part of this process. But undertray has more potential for cooling than I would have thought, and its stealthy for street, so I will be testing that option further.
Stock maximum speeds 118 on back straight. 2" air dam extension + undertray solid 120 mph. Air dam only 121 mph. Right at the same % aero improvements measured in coast down tests. So that is good verification of test data transfer to track.
Main interest was and is cooling. I still have stock coolant in the car, have added water several times, so probably 60% water by now. I have also experienced overheating on track, which I determine by when the idiot light comes on, not by absolute ECT or oil temps. My rationale is Ford knows when to say "back off".
My idiot light does not come on until ECT is 235+ and oil is 250+. So goal of all this messing around was to see if I could alter aero and improve cooling enough to prevent overheating light. Data say yes, you can.
The air dam is the easiest method to improve radiator heat flow, but 1" of street clearance is not really practical for a DD. Undertray performed a little better on track with regard to cooling, but cannot say how it will perform without air dam extension on track. My goal is to get enough cooling with undertray to stay with stock cooling equipment.
Maybe the most impressive data to me were: 1. Only four seconds total logged over 225 F ECT. 2. Very rapid recovery from full race mode to ECT below 212 once backed off. These are significant improvements vs stock logs from last year.
As a reminder, I did start plugging little gaps around radiator last year, and found a couple more last time I had nose off, so that is certainly part of this process. But undertray has more potential for cooling than I would have thought, and its stealthy for street, so I will be testing that option further.
Something I found the other day which may help with cooling is a lower temp thermostat sold by Mishimoto. I know it wouldn't help in the higher temps but if you are starting at a lower temperature it would take longer for the coolant to reach that 235+ rate. Also instead of an air dam have you tried with a front splitter in conjunction with the undertray? I haven't gone into detail as you have with my cooling effects but I have not overheated on track or canyons with my splitter and undertray set up. I do run 80% water and 2 bottle of purple ice with the rest being coolant (benefits of living in So Cal).
Thread Starter
#155
I looked into just removing the thermostat for tracking but its not very accessible in our cars. In fact, I recall deciding it was so inaccessible that it was not worth fooling with. Do you recall how much work was involved in changing it out?
I use the cheapest stuff available for experiments, Home Depot 4" vinyl base for air dam, 1/8" ABS for undertray. Have not figured out how to make a really cheap splitter for testing. But your experience is encouraging, and a real splitter is less visible than 2" air dam extension, so that sounds like a plausible street friendly test option.
I am going to keep running stock coolant this year until the aero mods fail to keep the idiot light off. Then try straight water with an additive next.
Whole 'nother thread could be started regarding how hot is too hot, and whether running on track with 230/250 temps is "bad". Lots of water temp theories, but oil is pretty easy. Our oil at 260 is still good to go, but I have no idea what pressures are doing at that oil temp.
Good to know that another stock cooling system can cope with heat along with aero mods. I am seriously wanting this to work. Hate the idea of adding weight for more cooling.
I use the cheapest stuff available for experiments, Home Depot 4" vinyl base for air dam, 1/8" ABS for undertray. Have not figured out how to make a really cheap splitter for testing. But your experience is encouraging, and a real splitter is less visible than 2" air dam extension, so that sounds like a plausible street friendly test option.
I am going to keep running stock coolant this year until the aero mods fail to keep the idiot light off. Then try straight water with an additive next.
Whole 'nother thread could be started regarding how hot is too hot, and whether running on track with 230/250 temps is "bad". Lots of water temp theories, but oil is pretty easy. Our oil at 260 is still good to go, but I have no idea what pressures are doing at that oil temp.
Good to know that another stock cooling system can cope with heat along with aero mods. I am seriously wanting this to work. Hate the idea of adding weight for more cooling.
Wimp - where did you order your hood vents from?
I'd like to know how hot is too hot as well. On my 1.0 the fans don't kick on until 215F and it'll cruise down the highway at 210F if the grill shutters are closed. That's a little uncomfortable for me. ...but I've never had a car with the water cooled exhaust manifold (same as all of your ST's, right?). So hearing you guys running 230+ is... ...interesting.
Has anyone pressure tested the cowl area at the base of the windshield? The windshield angle isnt that different from the hood angle (compared to most cars). So if there isn't really any pressure build up there, that might be an area to vent engine bay heat if you don't want hood vents.
I'd like to know how hot is too hot as well. On my 1.0 the fans don't kick on until 215F and it'll cruise down the highway at 210F if the grill shutters are closed. That's a little uncomfortable for me. ...but I've never had a car with the water cooled exhaust manifold (same as all of your ST's, right?). So hearing you guys running 230+ is... ...interesting.
Has anyone pressure tested the cowl area at the base of the windshield? The windshield angle isnt that different from the hood angle (compared to most cars). So if there isn't really any pressure build up there, that might be an area to vent engine bay heat if you don't want hood vents.
Thread Starter
#159
I have posted manometer results as they were obtained, probably earlier in this thread. Short version: underside hood -0.4" H2O, base of windsheild over +2", top corners hood where WRC vents are roughly -2.5", so even though underside of hood is negative, those particular areas of hood are more negative on top side and with some "lip" should pull hot air out of rear top sides engine compartment.
Same opportunity does not exist at windshield base.
Manometer data are mostly about aero mods and cooling, trying to obtain optimum pressure gradients across heat exchangers while minimizing adverse aero, or even improving aero and cooling both, which is where I am with undertray mods at present.
Maybe Wimp will report on WRC vent effectiveness, I will use undertray as long as I can keep improving it. If I can reliably track with 230/250 maximums for water/oil it will be successful.
Same opportunity does not exist at windshield base.
Manometer data are mostly about aero mods and cooling, trying to obtain optimum pressure gradients across heat exchangers while minimizing adverse aero, or even improving aero and cooling both, which is where I am with undertray mods at present.
Maybe Wimp will report on WRC vent effectiveness, I will use undertray as long as I can keep improving it. If I can reliably track with 230/250 maximums for water/oil it will be successful.
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