Heat Extractor For 2011+

[JimC]

Interesting - need to keep watching your progress on this.

 

[Department Of Boost]

Here's a side view using a 60 m/s flow stream of air over the top surface, and a high pressure region at the vent mouth:

http://www.leanangle.us/guest/sidevel.avi

Well that's cool!

 

[CCS86]

^that....

If its recessed then I misunderstood.

*subscribed!!

Yeah, that sketch is sloppy enough to hide it, but it is recessed

 

[CCS86]

Here's a different fluid study on the design. It's still very simplified versus reality, but this version is probably more realistic...

http://www.youtube.com/watch?v=RkKxE0a9W2g&hd=1

 

[bmaxwell]

Sick!

 

[ArizonaGT]

So when do you start to fab?

 

[CCS86]

I'm going to try to get access to the rapid prototyping printer to get a mocked up flange first.

 

[CCS86]

It's about 107* here today and after installing a pair of GT500 mufflers and romping around a little, I am reassured that this project is worthwhile in a functional way. The car feels like a dog in the heat compared to a nice cool night and it is kicking off heat.

My hope is that I will be able to pull enough heat out of the coolant, intake, and fuel rail area that the ECU either allows more timing advance, removes less due to knock, intake air is simply more dense, the commanded AFR is slightly leaner, or some combination of these. I'm confident that at the worst, the AC will cool down quicker.

I did a quick datalog with my Bluetooth OBD2 adapter and the Torque Android app. This is a 2nd gear pull in the mid day heat and it didn't feel very impressive. I would ignore the first data point as I was rolling into the throttle at less than 1000 rpm. The fueling is very nice (obviously on the safe side). Does anyone know how to get faster than 1 hz logging? I only had a few parameters selected. On the realtime display, they refresh much more quickly than when logging.

 

[Department Of Boost]

It's about 107* here today and after installing a pair of GT500 mufflers and romping around a little, I am reassured that this project is worthwhile in a functional way. The car feels like a dog in the heat compared to a nice cool night and it is kicking off heat.

Holy smokes! Those IAT’s are crazy for a NA car!

My stupid Kenne Bell “lava maker” at 19.5psi doesn’t seem quite so bad now, LOL!

Your underhood temps must be really high to create heat soak that induces IAT’s like that. Your extractor will help out tremendously with that. I’m running a full splitter (nose to back of rad support) which helps pull air out of the bottom and the GT500 hood which has the small heat extractors and my underhood temps aren’t too bad all things considered. Between my LT’s and that stupid KB throwing off dumb levels of heat I’m seeing underhood temps (my AIM data system samples them) about 25-30deg over ambient as long as the car is moving.

If I can keep underhood temps at 25-30deg above with heat extraction that isn’t nearly effective as yours you should be looking pretty good.

For more heat extraction and better aero I’m going with a Tiger Racing hood in a few weeks. But it’s a “race car”. Your setup is much more suited to a DD. I’ve been looking for a spare hood for my 2012 on the cheap and have my fingers crossed that you may decide to make more than one of those extractors.

 

[CCS86]

Agreed! And a white car too. After some cruising those IAT's will drop, but anytime it sits idling, they creep up quickly in this 100*+ weather.

 

[CCS86]

It's a nice balmy evening here so I decided to log another 2nd gear pull to compare data. I made a chart that plots spark advance vs rpm for that smoking hot day run vs tonight. It's no real surprise, but the ECU adds a significant amount of spark advance when IAT's are lower.

Now I need to get this vent built so I can see if it nets a real improvement during a blazing hot day.

 

[Department Of Boost]

It's a nice balmy evening here so I decided to log another 2nd gear pull to compare data. I made a chart that plots spark advance vs rpm for that smoking hot day run vs tonight. It's no real surprise, but the ECU adds a significant amount of spark advance when IAT's are lower.

Now I need to get this vent built so I can see if it nets a real improvement during a blazing hot day.

It's interesting that the delta between ambient and IAT is so much different on the two days.

 

[CCS86]

It's interesting that the delta between ambient and IAT is so much different on the two days.

Scenarios were a little different. The 'hot' run was done after a little romping around, then sitting at a red light and heat soaking. The cooler run (besides being like 20* cooler ambient), was after driving around until it was warm, then hitting it.

 

[CCS86]

Still haven't heard back from the shop yet, so I'm going to stop by today.

I modeled a simplified version of the front half of a mustang. It's still pretty simple, and assumes the engine bay to be totally sealed (which it obviously isn't). But, it really shows that even with the vent installed, the high pressure region under the hood can reject quite a bit of incoming air, not allowing it to flow through the grill.


http://www.youtube.com/watch?v=72hyr-GueBo&hd=1

 

[JesseW.]

Still haven't heard back from the shop yet, so I'm going to stop by today.

I modeled a simplified version of the front half of a mustang. It's still pretty simple, and assumes the engine bay to be totally sealed (which it obviously isn't). But, it really shows that even with the vent installed, the high pressure region under the hood can reject quite a bit of incoming air, not allowing it to flow through the grill.


http://www.youtube.com/watch?v=72hyr-GueBo&hd=1

what if you moved the heat extractor closer to the front of the car where the high pressure is?

 

[CCS86]

what if you moved the heat extractor closer to the front of the car where the high pressure is?

Well, that would defeat the purpose. You already have upper and lower grille openings in the high pressure, near the bumper. Like the latest CFD animation shows, at higher speeds the whole under-hood region becomes pressurized (which starts rejecting air from passing through the radiator).

By putting the vent where I intend, you use the low pressure (exterior) region along with the higher pressure under the hood to drive flow.

 

[JesseW.]

Well, that would defeat the purpose. You already have upper and lower grille openings in the high pressure, near the bumper. Like the latest CFD animation shows, at higher speeds the whole under-hood region becomes pressurized (which starts rejecting air from passing through the radiator).

By putting the vent where I intend, you use the low pressure (exterior) region along with the higher pressure under the hood to drive flow.

ok, i understand that, i know you said it was a quick mock up and the dimensions do not look to scale either.

it just seemed like the vent was a little too far back on the hood. i was thinking if it were placed behind the radiator over the throttle body where it looks as if the air is coming to a zero velocity (high pressure) that it may help it reduce the high pressure under the hood and take advantage of the fast velocity air (low pressure) to pull the pressurized air out from the engine bay.

going too far back on the hood you come to another high pressure point where the hood meets the windshield that would make it not work as well, but i am not sure at what distance back on the hood that would begin.

i guess what i'm trying to say is to model without the vent, then put the hood vent where the delta P is greatest from the inside to outside for it to work the best. the air in the simulation is at its highest velocity on the outside (where the pressure is lowest by looking at the darkest blue dots) closer to the front of the hood.

a bonus of this is it will also reduce front end lift at higher speed.

 

[CCS86]

ok, i understand that, i know you said it was a quick mock up and the dimensions do not look to scale either.

it just seemed like the vent was a little too far back on the hood. i was thinking if it were placed behind the radiator over the throttle body where it looks as if the air is coming to a zero velocity (high pressure) that it may help it reduce the high pressure under the hood and take advantage of the fast velocity air (low pressure) to pull the pressurized air out from the engine bay.

going too far back on the hood you come to another high pressure point where the hood meets the windshield that would make it not work as well, but i am not sure at what distance back on the hood that would begin.

i guess what i'm trying to say is to model without the vent, then put the hood vent where the delta P is greatest from the inside to outside for it to work the best. the air in the simulation is at its highest velocity on the outside (where the pressure is lowest by looking at the darkest blue dots) closer to the front of the hood.

a bonus of this is it will also reduce front end lift at higher speed.

If you look at the first post in this thread, you can see where I intended to located the vent (quite far from the windshield). But the leading edge (which is the actual opening) is just barely behind the rear edge of the fan shroud. This gives a pretty convoluted flow path, so I'm going to push it back a few inches.

 

[CCS86]

Arg...

It looks like I have clearance to use the CNC mill, so I stopped by the metal supply place today. The stock for the top flange ( 0.5" x 12" x 24", 6061 Al) is $76. Then another $30 or so for the .090" sheet to make the rest. I don't really have the cash to drop at the moment so I left empty handed.

 

[JesseW.]

ahh, i forgot about that, i read it when you first posted then checked back yesterday. can't wait to see the finished project when you get the funds