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Old 07-20-2009, 06:16 AM   #21
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Side ducts. It'll give me as much as possible to the radiator.



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I am going to be using sheet aluminum (forgot how thick, like .050ish) and rivets to actually build all this stuff. hardest part will be doing stuff in as few pieces as possible, and getting all the little stuff right (mounting tabs and stuff).
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Old 07-20-2009, 10:14 AM   #22
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IMO that will work as good as it could. This isn't far from what AIM tuning did on their time trial turbo Miata. The only improvement would be in cruves vs. the straight off angles. Harsh angles create a ramp launching the air vs. providing a contoured surface for it follow and encourage expansion. Same stuff you see on all the prototype cars - and stock cars as documented in this article. Graphic from article:


I think there's a reason you see 800hp cars running 24hour races with a full body and not over heating. They focus not on the size of the inlet nearly as much as the exit of the air and what happens to the air after it's passed the inlet. In general, I agree that enlarging the inlet may show improvements over stock, but would arguing that it's not nearly as efficient as improving other aspects - like extracting or sealing up the mouth or reforming the interior of the OE mouth...

Something to consider per your oil cooler feed too- that air will be exiting into the area that contains the high pressure for feeding your rad. So you'll be fighting a pressure differential at that point from the air exiting your oil cooler vs. the air trying to pass through the rad. You might only drill two holes, bring the hold saw to the track and see what happens, drilling more holes as needed. Or devise a means for blocking the oil cooler holes (racers tape?).
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Old 07-20-2009, 11:06 AM   #23
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what is the 3 inch gap under the radiator where all the air goes? did I miss that part?
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Old 07-20-2009, 11:10 AM   #24
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What you are creating is something I have been mulling over for a few weeks as well (no, I'm not turbo'd, but studying and planning still). You have created a Vmount setup in this configuration, just with the IC on the bottom instead of the top where most people's end up. The hot air leaving the IC will not be a factor in your radiator's cooling capability anymore and neither will the restriction of forcing air through the intercooler before allowing it to the radiator. The low pressure area behind the IC and the radiator created by the splitter and your well-sealed ducting will ensure plenty of pull through both heat exchangers. I see it as a win.

If you saw fit, you could move, seal, and duct the oil cooler so that it's hot air exits through the opening between the leading edge of the hood and the top of the core support (where the filler panel is by the hood latch) and goes over the rad, just like the IC's hot air goes under the rad. Just brainstorming on that one. Good luck.
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Old 07-20-2009, 11:20 AM   #25
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god I love a thread with pictures.


I could see a plate in front of the bottom edge of the IC being helpful.
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Old 07-20-2009, 11:23 AM   #26
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Quote:
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It's actually going to end up being like a 30x3 hole...30%.
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Just read through that thread. Pat is 100% correct IMHO. Bigger surface area does not increase pressure. Small in, larger out does.
Corky's rule of thumb is 1:8, inlet to surface area. Anything more ("within reason") is a bonus, provided you maintain positive pressure up front, and negative pressure behind the heat-exchanger.

- L
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Old 07-20-2009, 11:30 AM   #27
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Quote:
Originally Posted by y8s View Post
what is the 3 inch gap under the radiator where all the air goes? did I miss that part?
The way I understand it, the gap under the rad is the exit for the intercooler.
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Old 07-20-2009, 11:30 AM   #28
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Why not cut the bottom support off the facia. Then extend a sheet of aluminum up from the splitter to the bottom edge of the IC, and extended the scoop/shroud out.
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Old 07-20-2009, 11:41 AM   #29
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Quote:
Originally Posted by m2cupcar View Post
The way I understand it, the gap under the rad is the exit for the intercooler.
right, i see it now.

and there will be a barrier between the IC and radiator on the top of the IC?

Sav: I wouldn't worry about taking air from under the bumper. it's all going to exit the engine bay under the car anyway.
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Old 07-20-2009, 12:12 PM   #30
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That's how I understand it. And here's a pic that applies the theory from that stockcar article discussing contours past the entrance.
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Old 07-20-2009, 12:16 PM   #31
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now just stretch that contour across the entire bottom edge of the radiator.
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Old 07-20-2009, 12:25 PM   #32
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Quote:
Originally Posted by m2cupcar View Post
That's how I understand it. And here's a pic that applies the theory from that stockcar article discussing contours past the entrance.
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now just stretch that contour across the entire bottom edge of the radiator.
+1 each.

curves mean attached flow and attached flow means flow to the bottom of your radiator.
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Old 07-20-2009, 02:27 PM   #33
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Quote:
Originally Posted by m2cupcar View Post
Something to consider per your oil cooler feed too- that air will be exiting into the area that contains the high pressure for feeding your rad. So you'll be fighting a pressure differential at that point from the air exiting your oil cooler vs. the air trying to pass through the rad. You might only drill two holes, bring the hold saw to the track and see what happens, drilling more holes as needed. Or devise a means for blocking the oil cooler holes (racers tape?).
The plan is to seal the bottom of the mouth to the top of the radiator, creating a separate chamber for the oil cooler. It'll exit above the radiator.
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Old 07-20-2009, 02:31 PM   #34
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Quote:
Originally Posted by Braineack View Post
god I love a thread with pictures.


I could see a plate in front of the bottom edge of the IC being helpful.
I have plans for one as well, as well as extending the plate on top across the radiator. I like the idea of cutting the bumper down, though.

I also like the curves. Straight lines are about a thousand times easier to assemble and build, though. Any ideas for attaching the side ducts to the bottom ducts? I was going to just have little bent tabs on the sides and rivet them to the bottom, but I can't do that with curves.
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Old 07-20-2009, 02:52 PM   #35
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Quote:
Originally Posted by Savington View Post
The plan is to seal the bottom of the mouth to the top of the radiator, creating a separate chamber for the oil cooler. It'll exit above the radiator.
Into the engine bay, or through the hood (hole/extractor)? I wonder in this situation if it did go into the engine bay, what kind of impact it's going to have on the pressure differential there since it has a separate entry from the mouth (rad/IC feed).
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Old 07-20-2009, 03:02 PM   #36
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The oil cooler dumps into the engine bay, but there is a hole in the hood.

I will have to cover/uncover that hole when I do the magnehelic tests.
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Old 07-20-2009, 05:18 PM   #37
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Just be careful with cutting all this aluminum, that stuff can be sharp as a razor blade!
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Old 07-20-2009, 06:49 PM   #38
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Sav, have you instrumented if your problem is lack of airflow or poor heat transfer from the coolant to the radiator? My guess though, is lack of airflow.

I think the reason why V mounts help, without increasing the frontal hole area, is akin to impedance matching in electronics. When you have a very high airflow velocity the high resistance of the radiator core + i/c core just makes the air pile up in front of the radiator.

I have a theory that during road testing this problem manifests as significantly higher coolant temps at higher cruise speeds (e.g. 75-85 mph) vs. at lower speeds (55-65). This is as opposed to setups which overheat in stop and go traffic.

With V mounting the air spreads out over a larger area, plus the resistance the cores present is reduced (the rad and ic aren't stacked).

This theory is probably also why my AG Bell book "4 stroke performance tuning" suggests that a lower fin density radiator is better for high speed cooling.

As patsmx5 alluded to before, enlarging the frontal hole area of the car is not good, but my theory is not so much because it doesn't improve cooling (it will somewhat), but because the cooling to drag penalty is poor. (big increase for marginal improvement in cooling).

BTW the TDR ic has plastic panels which bend airflow smoothly towards the radiator, along the same lines as m2cupcar's drawing in post #30.
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Old 07-20-2009, 07:00 PM   #39
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I have a v-mount that I am finishing up right now. I was planning on waiting until I had some road testing in place so I could have some data to back up the design. But, if y'all want to see it I'll post up the picts beforehand.

It is a top-mount v-mount using the stock NB nose. Minimal cutting required for the body, and the framework was easy to fab as well. It is all boxed in (splitter and undertray) so all of the flow coming in the nose is forced through the radiator and IC (and a/c condenser).
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Old 07-20-2009, 07:51 PM   #40
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Quote:
Originally Posted by Savington View Post
I also like the curves. Straight lines are about a thousand times easier to assemble and build, though. Any ideas for attaching the side ducts to the bottom ducts? I was going to just have little bent tabs on the sides and rivet them to the bottom, but I can't do that with curves.
Sure you can. Use a metal shrinker. What kind of aluminum are you using? If it's the hardened 6061-T6 stuff i see widely available, you'll want to anneal it first before bending.
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