Any reason not to vent the radiators into the wheel wells (said by Pelican to reduce
12-30-2016, 10:02 PM
#1
Any reason not to vent the radiators into the wheel wells (said by Pelican to reduce
[Edit: the title got cut off - it should say "... (said by Pelican to reduce drag and lift)"]
While the air passing through our radiators is vented down, on 997s, 987s, and 996 GT2s and possibly others, it's vents into the wheel wells. Pelican Parts have an article showing how to get a very similar set up on our cars, and say it cools the brakes and reduces lift and drag. And no, this does not seem to promote the sale of anything in particular:
http://www.pelicanparts.com/techarti...ell_Liners.htm
I first heard of this from a post by The Radium King, here:
https://rennlist.com/forums/996-foru...nd-997s-2.html
He added further info suggesting the lift and drag benefits are real.
But … is it really so simple? While the stock system of venting air down doesn’t seem like a great idea, everything I’ve ever heard suggests you want to get air out of the wheel wells to reduce lift and drag, not into them. That, after all, is why the 991 GT3RS’s wheel well vents are such a huge aero win. And on our cars, the air from the radiators is actually sent out down and towards the outside, not just down, and there is a small spoiler in front of the wheel wells that at least partly deflects that air from entering the wheel wells.
Clearly Porsche thinks it’s a good idea on 9X7s and some other cars. But could it not be that they do this solely for brake cooling? (It occurs to me that all of these cars were available with PCCBs. I’ve no idea if they need more cooling, though I understand PCCBs on 996 Turbos are quickly destroyed on track, whereas 997 PCCBs are not.)
Can anyone help substantiate / confirm / deny the drag and/or lift benefits?
And does anyone know of any other reason not to do this?
Thanks!
While the air passing through our radiators is vented down, on 997s, 987s, and 996 GT2s and possibly others, it's vents into the wheel wells. Pelican Parts have an article showing how to get a very similar set up on our cars, and say it cools the brakes and reduces lift and drag. And no, this does not seem to promote the sale of anything in particular:
http://www.pelicanparts.com/techarti...ell_Liners.htm
I first heard of this from a post by The Radium King, here:
https://rennlist.com/forums/996-foru...nd-997s-2.html
He added further info suggesting the lift and drag benefits are real.
But … is it really so simple? While the stock system of venting air down doesn’t seem like a great idea, everything I’ve ever heard suggests you want to get air out of the wheel wells to reduce lift and drag, not into them. That, after all, is why the 991 GT3RS’s wheel well vents are such a huge aero win. And on our cars, the air from the radiators is actually sent out down and towards the outside, not just down, and there is a small spoiler in front of the wheel wells that at least partly deflects that air from entering the wheel wells.
Clearly Porsche thinks it’s a good idea on 9X7s and some other cars. But could it not be that they do this solely for brake cooling? (It occurs to me that all of these cars were available with PCCBs. I’ve no idea if they need more cooling, though I understand PCCBs on 996 Turbos are quickly destroyed on track, whereas 997 PCCBs are not.)
Can anyone help substantiate / confirm / deny the drag and/or lift benefits?
And does anyone know of any other reason not to do this?
Thanks!
12-31-2016, 12:13 AM
#2
Great thread IMO. I have though about the same thing because once while the speedometer was hitting triple digits and having the gas tank some what near empty. I could feel the front end of the 996 get squirmy.
Yes tire pressure was to specification, tires were properly balanced blah, blah it could be a lot of items but I am open to the front aerodynamics being better vented instead of it feeling like it's generating lift.
Like in one of your links in which it demonstrated how to cutting fins. I though about doing something similar but instead of cutting individual fins. I was going to buy a ready made vent that only need a 4" cut and then can be secured via popfasteners or just snap in place for a nice clean more streamlined look to the mod of venting air out.
Yes tire pressure was to specification, tires were properly balanced blah, blah it could be a lot of items but I am open to the front aerodynamics being better vented instead of it feeling like it's generating lift.
Like in one of your links in which it demonstrated how to cutting fins. I though about doing something similar but instead of cutting individual fins. I was going to buy a ready made vent that only need a 4" cut and then can be secured via popfasteners or just snap in place for a nice clean more streamlined look to the mod of venting air out.
12-31-2016, 09:57 AM
#3
Rennlist Member
I've wondered about this too. I've removed the condensers and fans from my track but have left the ducting that vents the air down. At 142mph on an 8 degree bank it was plenty stable but I also have front and rear aero to assist.
12-31-2016, 01:58 PM
#5
Rennlist Member
12-31-2016, 02:13 PM
#6
Rennlist Member
You can accomplish similar results with a decent data acq system by analyzing speed, g's, and slip. If it had a positive effect it's good, and a negative effect its bad. Not near as scientific as a wind tunnel but a whole lot cheaper.
Have you seen the rear wheel wells on the Cup cars? It was surprising to me.
Attachment 1121405
Have you seen the rear wheel wells on the Cup cars? It was surprising to me.
Attachment 1121405
12-31-2016, 02:32 PM
#7
Rennlist Member
You can accomplish similar results with a decent data acq system by analyzing speed, g's, and slip. If it had a positive effect it's good, and a negative effect its bad. Not near as scientific as a wind tunnel but a whole lot cheaper.
Have you seen the rear wheel wells on the Cup cars? It was surprising to me.
Attachment 1121405
Have you seen the rear wheel wells on the Cup cars? It was surprising to me.
Attachment 1121405
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12-31-2016, 02:48 PM
#8
Rennlist Member
Any better?
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Ratchet1025 (06-05-2022)
12-31-2016, 03:34 PM
#9
Rennlist Member
Much
12-31-2016, 04:37 PM
#10
You can accomplish similar results with a decent data acq system by analyzing speed, g's, and slip. If it had a positive effect it's good, and a negative effect its bad. Not near as scientific as a wind tunnel but a whole lot cheaper.
Have you seen the rear wheel wells on the Cup cars? It was surprising to me.
Attachment 1121405
Have you seen the rear wheel wells on the Cup cars? It was surprising to me.
Attachment 1121405
12-31-2016, 04:57 PM
#11
i think the benefits would be most apparent with entry speed at turn in. with less lift at the front you should be able to brake later and enter faster. all things being equal (tires, suspension setup) a consistant driver should be able to see an improvement in average lap time.
folks talk about overall balance of the car, wind tunnel testing, etc., but as most armchair drivers state, unless you are on the autobahn it isn't going to matter. i agree. i really don't care if my car flutters off like a leaf at 300 kph, because i will never be going that fast. i care about entering corners faster and getting the power down sooner on exit. if i can get more downforce/reduce lift on the front then i'll take it. if the rear now feels lighter (it most likely won't be, but it will FEEL lighter due to the heaver front) i will take it - i can steer out of oversteer but have to lift to correct understeer - slower. further, i can rebalance the car with swaybar adjustments, different brake pad compounds, tire width, etc. - i don't think it is faster to compromise one end of the car in order to balance with the other.
folks talk about overall balance of the car, wind tunnel testing, etc., but as most armchair drivers state, unless you are on the autobahn it isn't going to matter. i agree. i really don't care if my car flutters off like a leaf at 300 kph, because i will never be going that fast. i care about entering corners faster and getting the power down sooner on exit. if i can get more downforce/reduce lift on the front then i'll take it. if the rear now feels lighter (it most likely won't be, but it will FEEL lighter due to the heaver front) i will take it - i can steer out of oversteer but have to lift to correct understeer - slower. further, i can rebalance the car with swaybar adjustments, different brake pad compounds, tire width, etc. - i don't think it is faster to compromise one end of the car in order to balance with the other.
12-31-2016, 07:12 PM
#13
yup. on the 986 and 996 they dumped the air from the rads under the car instead.
porsche is constantly improving their designs (ims anyone) based on failure rates, racing innovation, planned obsolescence, etc. this thread is about trying to incorporate 997 radiator venting into a 996.
really, if a person has an early 9x6, there's lots of stuff to be stolen from later 996 and 997 porsche design and improvement. and you would think that you should have the confidence that, if it made sense for porsche to either change or add to their track cars, then it should be good enough for you. turbo rear brake ducts? oil piston update? gt3 front brake ducts? tensioner and tensioner pad update? 4-channel abs? third radiators? third radiator venting? 997 oil cooler? just do a quick tour though the parts catalog and look for superceded part numbers and ask your self why.
porsche is constantly improving their designs (ims anyone) based on failure rates, racing innovation, planned obsolescence, etc. this thread is about trying to incorporate 997 radiator venting into a 996.
really, if a person has an early 9x6, there's lots of stuff to be stolen from later 996 and 997 porsche design and improvement. and you would think that you should have the confidence that, if it made sense for porsche to either change or add to their track cars, then it should be good enough for you. turbo rear brake ducts? oil piston update? gt3 front brake ducts? tensioner and tensioner pad update? 4-channel abs? third radiators? third radiator venting? 997 oil cooler? just do a quick tour though the parts catalog and look for superceded part numbers and ask your self why.
12-31-2016, 07:23 PM
#15
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Got a different question relating to this mod. I do not track my car (maybe someday since I have several great tracks within 100+ miles) but do live in a climate where it gets hot (over 100 deg) on a daily bases in the summer. I have read on other posts that hot air gets trapped behind the radiators (not sure if this is true)? If so, would venting into wheel wells help with air flow through radiators and cooling of the engine?