How does the design of the M-Tech bumper work to provide air to the stock M5 intakes?
When I put my brake ducts in I took a long hard look at the way that air gets into the engine. The two main snorkels open into the enclosed space behind the front bumper. On the right side (looking from the driver's position and facing forward), there's a second branch to the snorkel that goes to an opening in the fender well, presumably to fetch cold air from there. On the left side, the row of holes at the top of the lower grill provides what appears to be the only cold-air inlet to the space where the snorkel is.
That's it - there's no magic and no access from the snorkels to the outside air, except for that little row of holes on the left side. Of course the space is not sealed, although it is baffled, so apparently enough air gets in there to make 400 horsepower. At speed of course, that row of half-inch holes lets lots of cold air in, I'm sure.
When I installed my factory M-Sport grill insert (with the splitter) I drilled a row of holes across the top of both brake duct tubes (left and right) to fulfil the function of the lost holes in the stock grill insert. I'm not sure that breathing would be inhibited without the row of holes, but it's the only source of outside air for the intake snorkels.
Cheers
JJ
Well I'm not sure that resurrecting a 3 year old thread is the best way to join the party, buy what the heck. Hello everyone!
I started visiting here to learn more about the E39 M5, which I guess I consider to be the big brother of my "baby beast" '03 540i M Sport. While there are certainly a world of differences between the two models, there's still enough that the two have in common to make it worthwhile to know more about the M5.
With the front bumper cover of my 540 being painted, I've also recently had the opportunity to contemplate the design reasoning behind the placement of the intake trumpets on the M5 and how they might be fed by the air flow that may (or may not) occur inside the bumper cover and behind the bumper support. As has been covered many times in other threads here, the 525, 530 and 540 all take their air from a rear-facing duct that attaches to the cover on the front side of the air-conditioner condenser coil, the radiator looking thing in-front of the actual main cooling radiator. On the other hand, the M5 utilizes open horns that pull their supply from any air that could reach them through the back of the metal bumper support as directed by the shape of the inside of the bumper cover and the insides of the wheel wells, behind the foglamps. The ports on the condenser cover that supply the intakes of the other models are blocked by covers.
So with the understanding that the 540 functioned as designed well before the cosmetic addition of the M technic bumper (which had been primary to the M5 during the entire run of the e39 platform), and after looking long and hard at the design of the bumper cover and the placement of the intakes on the M5, I started to think that maybe one of the design considerations for the M bumper cover was to provide a distribution channel for cooler air intake air flow to the trumpet openings.
But, the more I look at the component and the design, I'm starting to think that I'm either crazy or that my theory may have been true at one part of the design and development, but then became obsolete due to other design or mechanical considerations that superseded the air flow issue.
Take a look at the large rectangular holes in the bumper support just inside and under the high beams. This is exactly where the openings of the trumpets are, which also happen to be directly above the brake ducts/intake ports on the the euro M5 and the 540i lower grill. Yes, this is where the PDC sensors go, but they're pretty large for just a sensor. Was this for put here for a reason that went away? A bumper intake? Maybe some venting from the ducts in the lower grill?
So in addition to the 6 holes in the blocked portion of left side only of the lower grill, the only sources of fresh air I can find on the US M5 are the few vent slots in bottom of the left side wheel well liner (which are being replaced by the way). Here's a shot. I wonder if these function to remove water or to introduce air into the enclosed area behind the bumper?
JJ, I also had the idea of providing a little air by punching through the brake duct, but I thought I'd just cut a flap and fold it into the duct to force a little air up toward the right side M5 horn I'll be installing in my 540.
Anyway, I'd love some other opinions on this if anybody has any... or if anybody cares. Thanks for letting me ramble!
Ti
