Would you modify the front fascia?
If it was a no points / no penalty / permitted modification, would you make any changes to the front fascia / bumper cover?
I am thinking in terms of opening up the oil cooler or grill openings to promote better cooling. |
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That's what I was thinking; it appears to have better cooling openings.
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It’d be better if you could cope out the bottom of the 5 mph crash bar to match the radiator shroud opening (just in front of the radiator).
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Originally Posted by TeamRX8
(Post 4845418)
It’d be better if you could cope out the bottom of the 5 mph crash bar to match the radiator shroud opening (just in front of the radiator).
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It’s kind of an arch shape; higher in the center and then arcing down at the front chassis rails. Ideally you’d cut the matching shape into the lower half of the crash bar and then weld in a piece of thin sheet metal to seal it back up. I’m not sure if the rules you’re using allow that or even complete removal. Other countries don’t have it.
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Originally Posted by TeamRX8
(Post 4845399)
Pretty much duplicate the Mazdaspeed fascia.
I'm not certain mine was a genuine Mazdaspeed part, but it was surprisingly stiff and brittle. Also, the hardware used to attach the screens in front of the radiator and oil coolers was...crappy. I ended up drilling holes and riveting little brackets I made out of aluminum stock. And i made new, very light screen out of metal lath I spray-painted black. |
Originally Posted by TeamRX8
(Post 4845421)
It’s kind of an arch shape; higher in the center and then arcing down at the front chassis rails. Ideally you’d cut the matching shape into the lower half of the crash bar and then weld in a piece of thin sheet metal to seal it back up. I’m not sure if the rules you’re using allow that or even complete removal. Other countries don’t have it.
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It’s heavier that I remembered; approx. 15 lbs. total
https://www.rx8club.com/series-i-tec...8/#post4067144 Whacking or torching the front center bar section only would be fairly easy too and save you from purchasing and fabbing the rest of it. I suppose it just depends on the person and what they can or want to do. If there are limitations like it has to dimensionally meet the OE part in either size or weight then modding it is probably the way to go. No limitations; then some 20 Ga small dia cross-braced tubes, flanges, and strips meet the bare min expectation is what I’d do since that’s way out at the farthest point out past the wheelbase. |
it just have to meet similar crash protection as the oem, i don't know how they would measure that. does the stock bumper cross beam support the front bumper? if that's the case, they yeah probably better to notch out the cross beam and box it in.
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I wouldn't modify anything on the bumper, where you need to modify is how to get the air out?
The easy part is getting the air in through the holes of the stock bumper, duct it all up, but to make everything a lot more effective you need to find how to duct the rear of the openings to a low pressure area. Almost everyone focuses on the ducts to the inlets, but rarely the outlet ducting. If you can duct to a low pressure area you actually suck air through the heat exchanger. You also typically only need about 1/3 the square area of the heat exchanger for it to work exceptionally well. you also want thinner heat exchangers, not super thick ones that most people go after. thin with many rows that aren't super wide. Most people get super thick and super long rows, which is opposite of what you want. http://cdn.speednik.com/files/2016/0...6_10-42-40.jpg http://cdn.bmwblog.com/wp-content/up...rbo-900-hp.jpg |
Originally Posted by lOOkatme
(Post 4846257)
I wouldn't modify anything on the bumper, where you need to modify is how to get the air out?
The easy part is getting the air in through the holes of the stock bumper, duct it all up, but to make everything a lot more effective you need to find how to duct the rear of the openings to a low pressure area. Almost everyone focuses on the ducts to the inlets, but rarely the outlet ducting. If you can duct to a low pressure area you actually suck air through the heat exchanger. You also typically only need about 1/3 the square area of the heat exchanger for it to work exceptionally well. you also want thinner heat exchangers, not super thick ones that most people go after. thin with many rows that aren't super wide. Most people get super thick and super long rows, which is opposite of what you want. A "quick and easy" is to add hood vents, which (if executed properly) can reduce underhood temps, improve air flow out of the radiator, and reduce front end lift. There's a kit from singular motorsports, but it seems to me they may be positioned a tad too far back from optimal?: Singular Motorsports Hood Louvers: Mazda RX-8 | Singular Motorsports http://www.racingbeateurope.com/ekmp...1-b-2261-p.jpg Good discussion on the forum: https://www.rx8club.com/rx-8-racing-...s-pics-259352/ https://www.flyinmiata.com/tech/imag...-pressures.gif NC, not an RX-8, but... Some other DIY ideas (the S2000 on MotoIQ seemed the benefit most from the front center vent at lower speeds, probably the lowest above-hood pressure in that region: S2000 DIY Vented Hood Project S2000: Part 23. Testing Air Temps Through Coolers and Vents they also talk about the OEM airbox restricting airflow out of the vents, and this forum has talked about relocating the battery and using a CAI to reduce restriction behind the radiator. Do you guys have any other practical ideas for reducing pressure behind the radiator? |
You’d be better served to increase and control airflow; what’s needed to the radiator and what’s needed into the engine bay. Blocking everything through the radiator only is a great way to reduce both performance and engine life.
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Originally Posted by TeamRX8
(Post 4846304)
You’d be better served to increase and control airflow; what’s needed to the radiator and what’s needed into the engine bay. Blocking everything through the radiator only is a great way to reduce both performance and engine life.
For sure. I currently have an LRB solid undertray, and high density foam around all sides of the radiator except the passenger side. i'm letting a small amount of air to bypass the passenger radiator side to enter the engine bay in the vicinity of the exhaust manifold for engine bay cooling; made a big difference when I pop the hood. RIWWP had some really good DIY hood vents in his Mazdaspeed build thread, I think I will try to copy something like that. I wish we had pressure data on the RX-8 hood, or else i'll just be looking at NB/NC/ND miata hood vent placement and making an educated guess. |
I think I'll bite the bullet and buy a device to get the data. Although top surface pressure is only half the equation. Engine bay pressure and flow/obstructions plays a role, as does practical constraints of hood strength when cutting away material.
https://www.amazon.com/dp/B01680C4C2/ref=sspa_mw_detail_0?psc=1 |
Understand as you change the front openings those points will likely change as well. Don’t try to overthink it. The general layout is low pressure near the front where air is cresting over the top and high pressure at the rear as it hits the windshield and bleeds to the sides.
I’d suggest that you needs some air on the other side of the engine as well. Combustion occurs on that side, coils need cooling, the intake, and so on. Make sure your radiator fan runs on temp only without a speed cutoff point and you don’t have to worry so much about trying to force feed it. Fwiw, getting a better radiator/fan/shroud system should be a higher priority imo. |
Out of curiosity, do you guys think this BMI 4 rotor rx8 is using a modified OEM hood, or aftermarket? The vents look too be in about the right place..
https://cimg3.ibsrv.net/gimg/www.rx8...9872e408ca.jpg |
The aluminum OE hood is the lightest one and you already have it ...
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Originally Posted by TeamRX8
(Post 4846458)
The aluminum OE hood is the lightest one and you already have it ...
But it looks like that hood has had the underside bracing completely removed... or it's aftermarket. I'm just curious as to whether I might be about to achieve the same effect with my OEM hood without compromising it's strength too much. The OEM hood for the most part appears to experience lift rather than downforce, which would be reduced with proper venting. |
If I ever did that it was always my intention to do just that; pull the center bracing off and use the framed skin. If it needs reinforcement then some bent aluminum angle formed with some extra curvature running fore/aft with the ends pressed down into place and welded to the opposing frame ends is how I envisioned it. This way the curvature stress of the angles is pushing outward to reinforce the skin against the aero forces. You could always add dual side tape (some serious strong structural types out there now) or glue/sealant between the angle and hood skin for guaranteed strength.
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2 Attachment(s)
Originally Posted by lOOkatme
(Post 4846257)
I wouldn't modify anything on the bumper, where you need to modify is how to get the air out?
The easy part is getting the air in through the holes of the stock bumper, duct it all up, but to make everything a lot more effective you need to find how to duct the rear of the openings to a low pressure area. Almost everyone focuses on the ducts to the inlets, but rarely the outlet ducting. Attachment 286348 Attachment 286349 |
very nice. imma have to copy that :D
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You get an -A- for originality and effort for sure, but I’d hate to have to dig through all that on a race car everytime to access the engine, etc.
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It's just two bolt on each duct that hold the to the orange bracket. It's very secure under the hood with the upper flanges so there's no need for too many fasteners.
Much easier than dealing with the battery and OE Airbox. |
Good job!
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What's your theory behind your placement of the air intake and filter? It doesn't appear to line up with any vents in the hood, but looks to be relatively sealed to it.
Neat work, by the way. |
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I fit the vent out of a C7 Corvette into my hood, which is the exit for the radiator ducting in my car.
Radiator entry is through the grille, with the radiator leaning on a fairly steep forward angle and ducting exits the hood. The oil coolers are mounted on angles under neath and use the center lower opening in the bumper and vent into the wheel wells/brake ducts, as I have a triple heat exchanger setup for the water/air intercoolers and the outboard coolers are in the old oil cooler locations Attachment 286347 |
Originally Posted by Mr. Pockets
(Post 4846752)
What's your theory behind your placement of the air intake and filter? It doesn't appear to line up with any vents in the hood, but looks to be relatively sealed to it.
Neat work, by the way. The air filter was moved there mostly to just get it out of the way. There is about a 6cm gap between the filter box and the underside of the hood, and the plan is to run a duct from the upper passenger side vent (it's forward facing as an inlet), I just haven't gotten around to it (and there's enough airflow that there hasn't been any real change in IATs with that placement). |
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