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Discussion Starter #1
Okay, so this is my first E39 M5. I'm coming from a series of E36 M3s and an E46 M3 as well.

Forgive me if this question is ignorant, but I may as well ask.

Are intakes on the E39 M5 worthless or not? I ask this question because the general consensus with on most automotive forums (at least among the wiser members) is that air intakes are pretty much a waste of your money since they do nothing but suck in hot air under the hood.

Now, this doesn't involve BMWs, but I've seen back-to-back dynos on other cars (not BMWs) with an intake and without an intake. On most of the dyno they gained a very negligible amount of horsepower with the intake (if any at all) while sometimes they actually performed slightly worse on the dyno with the intakes.

I am asking this question because intakes for the M5 seem to be rather expensive. The cheapest I've found are the aFe intakes that TMS sells. They claim a 10hp / 10ft/lb gain with those intakes, but I just don't see how in the hell that's possible when essentially all they seem to be is cone filters sitting inside the air boxes.

I don't want to waste money on nothing here, that's why I'm asking in advance! Any input is appreciated.
 

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You're confirming what I already thought to be true. I hear that across all forums that aFe is just snake oil.

I see companies like Evolve and others have $1200+ air intakes. They'll say something along the lines of, "we identified a huge weak point of the S62, the intake system".

I don't know whether the intake system is a weak point or not, but I just can't buy it that an air intake is going to make any power on these cars versus just throwing in a K&N (or similar) panel filter.
 

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AFE is a waste for sure. My car came with afe when I bought it 3 years ago and thankfully the previous owners left the stock stuff in a box in the trunk. I put the stock intake back on. I have no official results for either intake but I felt/heard/noticed no difference.

Unless I missed or am forgetting something I want to say afe even uses half of the stock intake.
 

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Stock intakes are very efficent and anything you would gain from doing the after market such as Dinan or Evolve are very negligible. Im not saying there is not a gain, just that the cost compared to hp is next to nothing and money that could be better spent elsewhere. Just my .01...

You also want to stay away from K&N Filters as the oil on the filters will ruin your MAF's.
 

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I agree with everyone above and will take it a step further to say that it's possible you may see gains with the proper intakes like Dinan and Evolve when combined with headers and a tune to match. Or a step further to add cams and ported throttlebodies.

But a stock engine will not benefit from aftermarket intakes...
 
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Discussion Starter #7
Got it!

I figured such was the case. I'll stay away from intakes and spend my money in other areas. I just can't stand how so many aftermarket companies like to throw out these horsepower claims from air intakes alone.

Anyways, is there a better panel filter to throw in these airboxes than the stock ones or a K&N?

I've read about the MAF sensors and oil from K&N filters so I'm weary of that!
 

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I came from an E36 M3 as well, and I had an intake on it. The situation is a lot simpler there with one intake path and the way to block off the underhood heat was fairly straightforward. I liked it just because of the whomping noise it made under load :). That being said, it looks to me like the E39 M5 stock intake is a well engineered thing. I looked at the aFe as well; it seems worthless to me, and I don't see the benefit in paying huge dollars for minor increases in power.
 

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Discussion Starter #9
Agreed! And for the price of some of these aftermarket intakes it truly is highway robbery. I mean $500 for those aFe intakes that look like nothing more than come filters? Pshhhh, people must just have money to waste.
 

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I'm not even sure Dinan systems offer any real gains

The truth is, the factory system is a true cold air intake. If you open the top of the airbox and look at the bottom you'll see a duct, it pulls air in from essentially right behind the headlight/kidney grill area. It grabs air from here because its a high pressure zone and its cold, ambient air. The Dinan system pulls in air from behind the bumper. In front of the bumper is a high pressure zone, but behind the bumper is a low pressure zone, meaning the Dinan CAI's have less available air to grab.

I'm working on a CAI for these cars right now which will utilize the technology behind the CAI system used on the E46 M3. On the E46 M3 there is a duct which ducts out to the wheel well or under the car somewhere but what happens is there is always air flowing through this duct and because it intakes air from the front, its a relatively high pressure air stream which is also cold, ambient air. When off-throttle the air just flows right through it, but as soon as you tap the throttle you have all this air already flowing, ready to surge into the intake system.

I'm going to be using my open lower grill and brake ducts (complete system out to fender liners) to make this happen. The brake duct will always have air flowing through it when moving so I'm going to tap into this air stream and route it right up to the lower intake box. Everything from the intake plenum to the upper intake box will be stock, but the lower box will utilize the stock ducting plus additional ducting pulling from the brake duct. Theoretically I see no way losses could be developed from this system as it is the stock system with additional parts to facilitate more air flow, as opposed to replacing the entire system.

When I finish it, if it works I may think about reproducing it. But for right now, as far as I can tell, any CAI on the market is either just for sound (induction noise is pretty cool so IMO thats fair enough) or looks. The intake on these cars really doesn't need help, but with headers or something an improved intake system wouldn't hurt. A true, beneficial CAI needs to take in air from OUTSIDE the bumper. Its a low pressure zone where most CAIs intake air from and this is not desirable. There is a high pressure zone immediately in front of the car, and thats where air needs to be taken in on a true CAI.

Another idea I had was to duct the intakes right into a sink drain grill. I decided against ONLY taking air from there though, as turbulence and air volume and flow rates all would be much more important if you change the entire system like that. By just modifying the lower intake box these things are less of a consideration. Using brake ducts + tapping into that air stream utilizes that idea but in a more conservative and OEM way. I think active autowerks makes a CAI like that though (its over $1k iirc)
 

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You basically replicating Active Autowerke intake from what I understood. I made this intake myself for under $200 and even though AA claims 25hp increase, I did not notice any difference. Did this mainly to have functional "sink drains" and brake cooling.
 

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You basically replicating Active Autowerke intake from what I understood. I made this intake myself for under $200 and even though AA claims 25hp increase, I did not notice any difference. Did this mainly to have functional "sink drains" and brake cooling.
A 25hp increase from an intake? What a joke... See, claims like this bother the crap out of me.

Sure, a 25hp intake in combination with software, I believe that 100%. However, from an intake alone? Pshhhh
 

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I personally think intakes are more than for pure function but its interesting to see how beautiful some of them can be, such as the Gruppe M intake, and evolve's carbon CAI looks amazing! the stock boxes are not very pleasing to look at IMO but they work!
 

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You basically replicating Active Autowerke intake from what I understood. I made this intake myself for under $200 and even though AA claims 25hp increase, I did not notice any difference. Did this mainly to have functional "sink drains" and brake cooling.
Very similar yes but the AA intake routes ONLY from the sink drains (at least as far as I can tell), using their duct tube to the sink drains in leiu of the OEM duct that goes behind headlights. To install the AA you remove the OEM duct and attach their piece in place of it. Mine will not replace the OEM duct, I will be adding a slot for a second duct to the lower air box and then routing that to the brake ducts. So it will have two paths for air to enter - the stock ducting behind headlight and from the brake duct; whereas the AA only takes in air from the brake duct.

I'll make a DIY on how to do it once I get it done. May not help, but I don't see it hurting either. I'd love to design a full system, particularly for Alpha N cars there are some improvements that could be made in the upper intake system. I'm going to look into it once I have more free time.
 

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The weak point in the S62 is certainly not the intake, it is the exhaust headers. They are quite restrictive in stock form, a good proper (probably expensive) set of headers has shown good results. Don't quote me on this but I want to say in the range of a 40 hp increase.
 

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The weak point in the S62 is certainly not the intake, it is the exhaust headers. They are quite restrictive in stock form, a good proper (probably expensive) set of headers has shown good results. Don't quote me on this but I want to say in the range of a 40 hp increase.
Yes, the exhaust headers, then the intake, cylinder heads, then cams, then lastly throttle bodies IIRC
 

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Yes, I'm aware of the headers. That seems to be the weakest point in the design of this engine. I'm planning on getting some Evolve stepped headers to remedy that. I'll probably pair that with some cams and a good tune and call it good.
 

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Yes, I'm aware of the headers. That seems to be the weakest point in the design of this engine. I'm planning on getting some Evolve stepped headers to remedy that. I'll probably pair that with some cams and a good tune and call it good.
Not to split hairs here, since you're not definitive, but cams are not worth it without porting the heads first.

Should progress like this: Headers --> heads --> cams. Or all at once with a good tune.
 
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