EricRyan

iTrader: (4)

http://dave.newbern.org/gallery/album11

Kento

That was basically my point.

The PURPOSE behind the design of the side vent is that it creates a low pressure area which helps "pull" the airflow through the oil cooler. But to not have it directly connected to the oil cooler sort of defeats its purpose, because it REDUCES its EFFICIENCY.
Check out the radiator ducting (as well as the actual size of the radiators) on an F1 car. The "entrance" ducts are actually much smaller than the face of the radiator, as are the "exit" ducts. They don't just duct airflow INTO the radiator and then forget about it; they ensure that airflow through the radiator is high by creating major pressure differences between both sides of the radiator, and that means carefully ducting the exit side.
Right, and think how much more EFFICIENT your IC or radiator would be if a properly designed vent WAS sealed to the back of the IC or radiator?

FDNewbie

iTrader: (10)

So Kento, you're suggesting a very small entrance surface area...but shouldn't it still open up immediately before the core (be it a radiator, IC, oil cooler etc) to close to (if not) the same size as the core to utilize the entire core's surface area? I understand the larger the duct's surface area, the slower the speed the air will travel...but on the backside, again the duct would be as wide as the core, then narrow back down to evacuate the air quickly. Yes/no? If not, could you describe how the duct should be shaped from start to finish?

Thanks
~Ramy

silverTRD

iTrader: (37)

http://www.negative-camber.org/crispyrx7/cwrcoolers.htm

there is a pic of a inner fender liner vent at the bottom of the page, its the last pic so just go all the way down. you can see the oil cooler through it. i might try this but not sure, kinda following this thread on this one. lol

Kento

The ducting shape basically depends entirely upon the design (and requirements) of the heat exchanger, as well as external aerodynamics and internal space concerns. And yes, the ducting must open up where the heat exchanger is located in order to expose the surface area to the airflow.

Basically, the size of the intake and exhaust duct doesn't matter as long as they provide enough of a pressure differential to promote airflow.

EricRyan

iTrader: (4)

Excellent find silverTRD, this gives me a much better insight at things.

silverTRD

iTrader: (37)

my fd is a touring model, does it have a functional side vent like the driver's side?

ptrhahn

iTrader: (9)

I guarantee you that if you were to somewhow create a duct that would seal to the back of the oil cooler like the duct in front of it, and then connect EXCLUSIVELY to that tiny little duct that goes over the fender and connects to the fender vent, you'd be SORELY dissappointed with the result.

It's very true (in F1 and everywhere else) that the inlet and outlet ducting to heat exchanger can be smaller than the exchanger itself, but they shouldn't be severely mismatched. Blocking the backside of an exchanger is nearly as bad as blocking the front side. The opening in the bumper will let in a far larger volume of air than that punky little vent could evacuate all by itself.

Not having it sealed to the backside of the cooler would only "reduce efficiency" if it was actually able to evacuate all of the air it needed to, and I rather doubt it is.

OF COURSE your IC would work better with a real nice dedicated and sealed exit duct...(per your question Ramy. This was actually part of the original design scheme for the CWR IC, and why it sits at an angle. Duane K. had grand plans of bulding a vented hood that sealed to the back of it, like many racecars do) but not if that exit duct was a McDonald's straw. It would need to be sufficiently sized to match the inlet... otherwise, you're better off blowing into open space.

and MY POINT still holds that the fender vent is indeed functional, even if it is or isn't as good as it COULD be.

Kento

Ehh, we're reading a bit too far into my words here. I never said that everything would have to be exactly as it is stock except hooking up to the exit side of the oil cooler. If you look at my original post, I was only refuting the statement that the side vents were "very effective"-- not that they weren't functional at all. So basically to reiterate MY POINT, the way the setup is stock, you'd be just as effective (if not better) by having the exit side of the cooler vent into the wheel well (like was shown in the one photo, where there is somewhat of a low pressure area). Better than depending on the "punky little" stock vent (and any holes and leaks in the interior area of the fender well liner). But if you were to take advantage of the side vent's design with properly designed ducting (and yes, maybe some tweaking on the side vents), then you would have a "very effective" side vent setup, instead of what is not much more than a styling exercise as it sits stock.

DamonB

Sure, and a proper duct does.

A typical duct often expands between the inlet and core as well. The speed of the vehicle and the size of the inlet are going to determine how many air molecules enter the inlet in a certain period of time. Once air enters the duct an expanding duct in front of the core insists the air molecules slow down. This makes the duct more efficient. Once air enters the core energy (in the form of heat) is added to it. The exit after the core then constricts to speed the airflow back up. This ensures good airflow through the duct and core and good attachment of the airstream to the vehicle at the duct exit. The exit to the duct doesn't have to be near as large as the inlet if the exit uses it smaller cross section and the added heat energy to increase the airspeed. Aircraft and many racecars use this technique to actually create thrust from the duct, adding (usually small amounts) of power to the vehicle. The best example of this is the SR-71. At its Mach 3 cruising speeds it's thrust comes nearly entirely from energy captured within the inlets rather than from the thrust of the engines themselves.

In the case of the FD I can't be certain but I would expect the ducts to be highly functional. Everything on a mass produced car is limited by bean counters and I find it hard to accept that Mazda would go through the expense in including an unseen duct above the fenderliner if it didn't work better than merely venting the oil cooler into the wheel well. Another possible consideration could be that they didn't want to dump hot air from the oil coolers right into the R1 brake scoops on the uprights.

It would be cheaper to have made the fender vent cosmetic only and vent the cooler into the wheel well, given that they didn't do that I have to assume the vent over the fender to be a better solution in the FD's case.

Kento

I'm thinking that they were originally going to have a dedicated duct leading to the cooler, but cost overruns led them to scratch the project midway into production. The resulting duct pop-riveted to the liner and stopping at the top of the liner was probably the best the supplier could do at that point.

The way it sits doesn't make a whole lot of engineering sense. There is no real difference between pulling the air from the top of the liner, or just doing away with the duct and pulling air from the area inside the liner area.

DamonB

The front wheel well is typically a high pressure area whereas the fender vent would be in a low pressure area. I think the theory of keeping the hot oil cooler air out of the brake ducts makes some sense as to why they'd bother with a duct over the fender.

EricRyan

iTrader: (4)

I give up

Kento

I think you misinterpreted my statement. What real difference (in stock form) does it make whether they grab the air from the top of the liner or whether they grab it from the rear where the side vent is? Or in-between? This is with the liner in place, no vents or holes in it.

DamonB

OK, I think I got it now. You mean if the cooler is sealed to the area above the liner and the liner is sealed to the exit duct why do you also need a second duct over the top of the liner? You could do without that second duct and the area enclosed by the liner would function as a plenum?

In that case I have no idea!

Kento

Heh, now everybody's really going to give up!

silverTRD

iTrader: (37)

so for a dual oil cooler setup, its probably not the best idea to have the hot air exit through the front of the fender liner because it would lead the hot air to the brakes?