Managing heat with a flat underbody
#41
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A small stream of exhaust can make havoc when it has nowhere to go. Heating the tank from below is not a good idea.
V-bands and some flex units could never hurt I guess. Routine inspections are more difficult but also more important...
My friend (who's aero I've posted pictures of somewhere) managed to ignite one of the exh hangers due to flange bolts getting loose.
A small fire just below the tank is not a nice thing.
His face turned a bit pale when I made him feel the temp of the tank (20 minutes after the fire was put out)...
#42
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For what it's worth (and that's approximately what you have paid me for it), we were constantly having to repair or replace Dzus fasteners when I was an assistant crew member with the old spec Barber Dodge formula team. Granted, the body work came off a lot more frequently than an undertray might.
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^ Of course, extra fluid will have to be added to make up for the coolers and line sets. Were your cooler feeds in the upright position? When I assemble mine, the feed fittings will be upright to help prevent that. I would *think* the pump would do a good job of acting like a check valve from it all flowing back in the units, causing your over-filled situation. Close?
#45
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It had to do with where I aimed the discharge line. I don't remember now if I had the oil stream landing right on the gearset, which caused misting; or if it was some other issue. Tech support at Jerico helped me sort this out; apparently, there is a "preferred" placement for the incoming oil line.
#46
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On the rear, I cutout the coroplast around the midpipe, less than 1/2" between, and it showed no signs of being close to melting-- this was for over a year of DD and a few track days. It's still on the car as we speak.
I got an IR reading of the differential from a 30 minute daily drive, it was about 170 degrees... I was sure it was the diff casing because if the IR beam hits the exhaust pipe, it was much hotter (obv)-- but my IR reader reads to 220~230 degrees and on exhaust pipe it just reads "HOT."
I never remember to check diff casing temps after a session, let alone tire and brake times.
#48
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I talked to Brian Goodwin today at SEMA about his MX-5 flat bottom and cooling, and he said he's got venting to the transmission and the differential, and he's had no apparent heat problems with either. He has revers NACA's (if I recall correctly), and runs hoses that direct air at the pumpkin.
#50
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This also happened recently in my miata. The downpipe came loose and melted my dipstick pull-handle off. The resultant oil spray collected on my heat-shield wrap for my water lines and caused a small fire. I've learned my lessons: Metal shielding only in a race car!
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Last edited by gtred; 10-31-2012 at 01:43 PM.
#51
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I talked to Brian Goodwin today at SEMA about his MX-5 flat bottom and cooling, and he said he's got venting to the transmission and the differential, and he's had no apparent heat problems with either. He has revers NACA's (if I recall correctly), and runs hoses that direct air at the pumpkin.
-Ryan
#52
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Well, just finished fabricating the flat underbody and new diffuser. I'm going to put a NACA duct in to feed air to the differential before Auto Club Speedway in a week and a half and we will see how it goes!
![](https://www.miataturbo.net/attachments/race-prep-75/59318-managing-heat-flat-underbody-finishedbare5.jpg?dateline=1352328703)
-Ryan
![](https://www.miataturbo.net/attachments/race-prep-75/59318-managing-heat-flat-underbody-finishedbare5.jpg?dateline=1352328703)
-Ryan
#56
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Well, just finished fabricating the flat underbody and new diffuser. I'm going to put a NACA duct in to feed air to the differential before Auto Club Speedway in a week and a half and we will see how it goes!
[IMG]https://www.miataturbo.net/attachment.php?attachmentid=59318&dateline=1352328 703
-Ryan
[IMG]https://www.miataturbo.net/attachment.php?attachmentid=59318&dateline=1352328 703
-Ryan
#60
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Sorry--If your car is drag limited or not. I think it was a NB1 engine in an NA, but it was getting stuck at 130s on the banking... only til drafting a Del Sol did it reach 140s. I know you've a turbo so it might be moot.
You'd be surprised at what you might see tufts doing at the gap between the bumper and diffuser.
You'd be surprised at what you might see tufts doing at the gap between the bumper and diffuser.