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914World.com _ The Paddock _ Chump Car Survival
Posted by: Jetsetsurfshop Aug 5 2014, 03:57 PM
Hey Everyone,
When it comes to my 914 I've always wanted to run it in the Sebring Chump Car race. It's a 14 hours torture fest. That kills car regularly. Hell, Sebring kills new cars all the time in HPDE events!
Heres the rub, I would exit out of the hood except the I would have to exit before my fuel cell. It's even with the back of the headlights. From what I understand about hood exit is that you want to be near or at the highest point of the hood. Way past my fuel cell. 
My first real influence was Kevin Wheeler's red car. That car started me down the rabbit hole and I did the fuel cell shortly after. Always thought that I'd exit the oil cooler as he did (trunk floor). But what about lift? He has some youtube videos of his car at Sebring. It appears to me that lift is not an issue to him. Has anyone done this exit, got into there car, and noticed any lift? Do you think Kevin add that fuel cell to add weight yo the front to plant the car down? 
I like what Brant and Stu has done too. In and out of the fenders. Is that enough cooler for 14 hours. I'm thinking bigger is better. Mocal has a 20" by 6.5" 65 row cooler I can make fit before the cell. Its expensive, and I don't want to do this again and If it works, 
My car current set-up puts the oil temps at 245-260F afters 25 minutes.
All help is welcome.
Thanks
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Posted by: ablesnead Aug 5 2014, 06:49 PM
Shane I faced this same problem running a 3.2 911 in the 12 hours..oil temps at 230 during practice,,,just cut a slot in the hood ( fiberglass slant nose ) oil temps never passed 190 ..thermostat setting...the slot was right about were the forward edge of your cell is..was it at the maximum placement...probably not...but like arguing about if you should paint your push rod tubes...in the real world it amounts to much ado about nothing..I will have another hood if you need to change back after the race..free of charge...I think you would get a better product with a used rx 7 cooler , cleaned and prepared for the fittings of your choice by Pacfic oil coolers....
Posted by: ablesnead Aug 5 2014, 06:49 PM
Shane I faced this same problem running a 3.2 911 in the 12 hours..oil temps at 230 during practice,,,just cut a slot in the hood ( fiberglass slant nose ) oil temps never passed 190 ..thermostat setting...the slot was right about were the forward edge of your cell is..was it at the maximum placement...probably not...but like arguing about if you should paint your push rod tubes...in the real world it amounts to much ado about nothing..I will have another hood if you need to change back after the race..free of charge...I think you would get a better product with a used rx 7 cooler , cleaned and prepared for the fittings of your choice by Pacfic oil coolers....
Posted by: Jetsetsurfshop Aug 5 2014, 09:54 PM
Shane I faced this same problem running a 3.2 911 in the 12 hours..oil temps at 230 during practice,,,just cut a slot in the hood ( fiberglass slant nose ) oil temps never passed 190 ..thermostat setting...the slot was right about were the forward edge of your cell is..was it at the maximum placement...probably not...but like arguing about if you should paint your push rod tubes...in the real world it amounts to much ado about nothing..I will have another hood if you need to change back after the race..free of charge...I think you would get a better product with a used rx 7 cooler , cleaned and prepared for the fittings of your choice by Pacfic oil coolers....
190F, I'd think my gauge was busted
Your right about "maximum placement". I guess there will always be some compromise when engineering this type of stuff. I did a mock up on the hood exit the other day. Didn't hate it.
I have an extra hood, incase I mess up. Thanks though.
Did you think my mocal cooler is a bad choice?
Posted by: Jetsetsurfshop Aug 6 2014, 07:35 AM
Check out this picture I found in Speed News. Exit in yellow is ideal. I guess I'll skirt the edge green and yellow. Take some more pictures today.
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Posted by: wobbletop Aug 6 2014, 08:04 AM
Do you have a front splitter?
I'd think adding one would help with either hood or floor exits. Increases front air pressure and decreases under car pressures.
But I just watch racing. 
Posted by: Seabird Aug 6 2014, 08:28 AM
Shane I take it you skipped the happy hour test the other day.
Posted by: Jetsetsurfshop Aug 6 2014, 09:45 AM
Shane I take it you skipped the happy hour test the other day.
You know it. Do you plan on doing it on the 16th?
Posted by: Jetsetsurfshop Aug 6 2014, 09:51 AM
Do you have a front splitter?
I'd think adding one would help with either hood or floor exits. Increases front air pressure and decreases under car pressures.
But I just watch racing.
I don't want to run a splitter for chump. With all the cars there and the curbing, it will get broken. I already marked up the 916 bumper from turn 4 curb running side by side with a GT3RS.
He disappeared shortly after that.
Posted by: Jetsetsurfshop Aug 6 2014, 10:10 AM
Mock up. Pic 1.
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Posted by: Jetsetsurfshop Aug 6 2014, 10:11 AM
Pic 2.
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Posted by: Jetsetsurfshop Aug 6 2014, 10:15 AM
Thinking this will work with a louvered hood exit. I also plan on really modifying the 916 bumper so I can get air to the cooler. The lower hoses will stay for the brakes. Any thoughts?
Posted by: andrew15 Aug 6 2014, 10:16 AM
We had a bit of a cooling issue at WG in May
On the fly, we used a section of garden hose to space the rear mounting of the front trunk pins up about 1.5"
Basically, it allowed for a 1.5" gap all along the rear of the front trunk / cowl joint and it worked fine to cut the rad temps down.
I can't remember where I heard it, but apparently you want the exit area to be about 1.5 times bigger than the entry area to facilitate a steady flow of air.
Posted by: Seabird Aug 6 2014, 11:19 AM
We had a bit of a cooling issue at WG in May
On the fly, we used a section of garden hose to space the rear mounting of the front trunk pins up about 1.5"
Basically, it allowed for a 1.5" gap all along the rear of the front trunk / cowl joint and it worked fine to cut the rad temps down.
I can't remember where I heard it, but apparently you want the exit area to be about 1.5 times bigger than the entry area to facilitate a steady flow of air.
Thats actually a pretty cool idea, pun not intended
little bit of guessing here... 20x6.5x1.5=195 195/64=3" gap at the rear of the trunk would suffice without chopping anything. I am assuming the back of the trunk lid is about 64 inches and not counting any exhaust out the sides of the trunk.
Your certainly not raising the frontal area of the car as the hood has the windshield behind it..... I wonder what fluid dynamics would look like there.
Posted by: Seabird Aug 6 2014, 01:42 PM
Shane I take it you skipped the happy hour test the other day.
You know it. Do you plan on doing it on the 16th?
Only if the car stays running....
I am about to wire up the lights and drive it on the street for a few days.... I wonder how long it will take to get a noise violation.
Posted by: ablesnead Aug 6 2014, 03:28 PM
I GUARANTEE that set up will solve your problem...remember in this case the frontal ducting to your cooler is of more importance than the exhaust ducting .try to funnel it down if you have the room..should but a a small amount of head pressure on the cooler face
Posted by: Jetsetsurfshop Aug 6 2014, 05:29 PM
I GUARANTEE that set up will solve your problem...remember in this case the frontal ducting to your cooler is of more importance than the exhaust ducting .try to funnel it down if you have the room..should but a a small amount of head pressure on the cooler face
This was "plan 1". Exit under the before and under the fuel cell. Just thinking about if it causes to much lift.
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Posted by: Jetsetsurfshop Aug 6 2014, 05:33 PM
Found this to add to the debate. My hood exit would be a little bit more forward. I don't know where I found this pic. Have no info if this works well or not?
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Posted by: carr914 Aug 6 2014, 05:34 PM
I GUARANTEE that set up will solve your problem...remember in this case the frontal ducting to your cooler is of more importance than the exhaust ducting .try to funnel it down if you have the room..should but a a small amount of head pressure on the cooler face
This was "plan 1". Exit under the before and under the fuel cell. Just thinking about if it causes to much lift.
I never thought that my down & under created lift at Sebring. I always had the back end of the car lifting @ 14 & 17 due to the High Speed (I did not have a Rear Spoiler)
Posted by: ablesnead Aug 6 2014, 06:31 PM
remember the air in front of your cooler is stalled to about 15 mph....really how much lift can you have...the volume in my estimation is insignificant to lift..again you maximize everything on a clean sheet of paper..but you improvise within the parameters of reason on a retro fit to solve a problem.
Posted by: stownsen914 Aug 11 2014, 12:00 PM
remember the air in front of your cooler is stalled to about 15 mph....really how much lift can you have...the volume in my estimation is insignificant to lift..again you maximize everything on a clean sheet of paper..but you improvise within the parameters of reason on a retro fit to solve a problem.
Just what I was about to write ...
Also, the rear of the trunk isn't ideal as an air exit. It probably is better than nothing, but the base of the windshield is a high pressure area, so air will want to enter there. A hood exit can be a low pressure area if you put a lip at the leading edge. Wheel well exits can work too (cut a hole in the sides of the trunk).
Scott
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