Cold air intake question. - Page 2 - PeachParts Mercedes-Benz Forum

Benzmeister · #16 09-14-2003, 09:12 PM

I agree, after I took a good look at the intake horn, it is designed to take in cold air, and if you have a Benz 96 and on you can check the intake air temp at the horn with the climate control system, see the lastest The Star. Only thing I added was a K&N filter and 94 octane and my car runs very well and is "lively" when acceleration is pushed.

My only concern is how hot is the air by the time it reaches the TB in the back of the engines. there's a lot of heat under the hood when I open it from a drive.

psfred · #17 09-14-2003, 11:04 PM

Al:

Why would it matter? You almost never -- or I certainly almost never -- have the throttle wide open demanding all the horsepower the engine can produce. Something about the car in front of me.....

At anything less than wide open throttle and high demand, the temp of the air is pretty much of no interest on a MAS system, the computer has measured the amount of air and is going to add the appropriate amount of fuel. The charge density is pretty light at 17" vac!

On an indirect system like the old D-jectronic, or a carbureted engine, the issue is considerably more complex. Mixture control is only approximate anyway, and temperature has even less influence on operation, except when there is enough water in the air and the temp is low enough to cause ice formation. The carb on my old Dodge Aries froze solid once on the interstate, only had the secondary barrel at full throttle or nothing when the pre-heater broke. Not an issue with FI, the injectors are in the head, or very near it, and icing is never a problem. D-Jets are notorious for going over-lean in hot weather -- no "default" values in a (by modern terms) very stupid computer.

For maximum horsepower, certainly the denser the actual charge (the air and fuel mix compressed in the cylinders) the greater the output (until the engine fails, anyway!), but the cheap and cheerful way to do this is to gently super or turbo charge rather than piddle about with trying to get ambient temp air down the engine. The air heats up on the way, for sure -- the intake is bolted up to the head, and it will be on the order of 70 C or so at operating temp. But how often do you REALLY need the absolute maximum horsepower the engine can produce?

Benz is pretty good at getting very high horsepower out of their engines (remember, the hp ratings are at the tire patch, not the flywheel!) and their engines run and run and run -- my 280 SE has at least 180,000 miles on it, and only uses a quart of oil in 1500 miles or so -- never been apart. It's possible to get more horsepower (AMG certainly does), but reliability will suffer, so will longevity.

Higher octane fuel, so long as it will ignite, will give you more "boot" than colder air in the intake, as it will allow more ignition advance -- the EZL will pull the timing back when it senses knock. More resistance to knock, more advance, more power. There is a limit though -- when you get the octane rating high enough, the fuel won't ignite very well at low charge density, so your idle goes to hell.

Peter

Benzmeister · #18 09-15-2003, 07:58 AM

Yes, what you said is all very true, at higher RPM that is Speed then the addition of cold air would make a difference in performance and the MAS then will calibrate for the difference, also at higher speeds the volume of air would be much higher and the MAS considers that also. Have you seen the air intakes on the DTM Mercedes? the filter span the entire front of the engines compartment, at least in the ones I've seen.

I use a K&N filter because I like them and I think they work, every car I've owned and family members owned have run K&N with no problems. What amazes me about Mercedes engines, at least mine is the torque curve, comes in low and stays there, so you get the feeling of strong acceleration and the 94 octane or 93 also seem to work to there potential in my car. If I had the ambition and the finance these days, I would think very seriously about a supercharger, but, for me, those days of radical mods to a car are over. As I said I and other who have driven or driven in my car are surprise by the acceleration and general good performance and decent gas mileage even during "performance street driving"

psfred · #19 09-15-2003, 07:55 PM

Al:

MB works hard for the low end torque -- most new engines have variable intake valve timing and variable length resonance tube intake manifolds for the sole prupose of making it.

As to "street performance driving" a couple of people got killed today on the Lloyd expressway here in a big pileup, I assume from people driving much to fast (as usual 70-75 in a 50 zone over an overpass to a congested area) -- I would prefer better driving and less "performance" from most of the other drivers on the road......

I love the horsepower in my W108, but I still drive with the traffic flow, not darting in and out and blasting around people. Too dangerous.

If you want a real thrill, go find a 220D and drive IT on the expressway once!

Enjoy that Benz!

Peter

Benzmeister · #20 09-15-2003, 09:16 PM

Thanks for the information, the low end torque is very nice,

But I want to get one thing straight, when I say performance driving I don't mean reckless driving, I drive the speed limit and stay in my lane most of the time, unless someone is driving 40 in a 65. I have a couple of secluded places, one an old Air Force base, that I can performance drive. I'm 57 years old and drive safely on public streets. Also, I had a lot of experience when I was young, started drag racing at Highstown NJ, then did some road racing with an MGA and AH 3000 all sanctioned and I've owned a few High Performance cars over the years, everything from muscle cars in the 60's and two Porsches a 911 and a 944. I have been driving since I was 17 and have gotten 2 speeding tickets and I warning, I've had 2 traffic accidents, neither my fault.

Just to keep the record straight.

Peter Fearing · #21 09-15-2003, 09:22 PM

RE: K & N filters. Keep in mind, more air, moredust/dirt and more engine wear. If that is your goal that is a good thing. If you want to keep your car a long time, that is a bad thing.

Benzmeister · #22 09-15-2003, 09:28 PM

More air, dust, engine wear, I suppose you don't like my K&N filter? and did you read my last post, I'm not a speed demon but like to nail the throttle once na while, on one of my secluded roads or the old airports, helps blow out all that dust, and carbon build up.

#23 10-31-2003, 03:59 PM

When it comes to CAI i thing that I have had a lot of experience in this area. I have added CAI to Jeeps, blazers, xterra's, Mustangs ect. and I can attest that they do add power in the whole range.

The biggest thing that a CAI does is it usually replaces the factory Airbox setup which is very restrictive. The reason for this restriction is to muffle the noise that an engine makes. Every time that the cylinder fires you have a explosion which is very loud(just listing to NASCAR and Drag Racers). Most of the air intakes have the box with a secondary "muffler" in the fender or by the radiator. So a car manufactures goal is to have a quite ride and not a fuel effiecent car. Any time you add a CAI you will notice more engine noise than with the factory airbox.

If you look at most intake systems you will see a tube the size of a baseball running from the airbox to the engine but when you look at the size of the inlet into the airbox you will see it is the size of a golfball. This translates to a sprinter breathing through a straw. These CAI usually have a connical filter which has a larger surface area to get air into and no restriction. So even i you have a connical filter in the engine bay and you do not have a heat shield your engine will not have to work as hard to get the air into the engine. Now you will get even more benefit if you can draw cold air from another sourch such as a fender well or by the back side of a bumper cover.

omegabenz · #24 10-31-2003, 10:05 PM

My feeling is that mercedes already have cold air intake. Most of them have pretty decient size piping. If you can run an extra tube going to the air cleaner that really helps.

Benzmeister · #25 11-01-2003, 09:17 AM

Quote:

Originally posted by omegabenz
My feeling is that mercedes already have cold air intake. Most of them have pretty decient size piping. If you can run an extra tube going to the air cleaner that really helps.

I agree, at least with my C280, however I thing the shortcoming of the system is the air box, it allows a lot of air to sit, I feel with the K&N replacement filter, the intake is sucking in more air as the K&N is not as restrictive as the stock. My mechanic agrees with me, if that means anything, but he and his son build a lot of street racers. Also, I said in a post a while back I disconnected the battery for 10 minutes, which reset the CPU, of course I had to reprogram the windows, sun roof, esp and radio, but afer about a week of driving the car is more responsive and uses less gas and in my opinion faster.

Jackd · #26 11-01-2003, 11:45 AM

It looks like a lot of people are kidding themselves with what they think is a miracle happening with a revised air induction system and K&N filters.
Test reproduced in several serious magazines have proven again and again the a K&N filter has no positive effect in most cars. MotorTrend recently testes a Nissan 350Z with and without the K&N: Result: More HP with the stock system. Some slights benefits are barely measurable at very high RPM at the cost of letting in more contaminants in the engine.
Mercedes (W124) intake systems flow up to 620CFM without any restriction (Ref:http;//www.rndperform/test/mbz124) which is about what is required for a 103/104 engine to run at 7,200RPM.
The ''feeling'' of having more performance with a modified intake system comes much more from the added intake system noise and the gratifying feeling of having spent $$$ (thus expected positive results)
jackd

Benzmeister · #27 11-01-2003, 02:53 PM

Quote:

Originally posted by Jackd
It looks like a lot of people are kidding themselves with what they think is a miracle happening with a revised air induction system and K&N filters.
Test reproduced in several serious magazines have proven again and again the a K&N filter has no positive effect in most cars. MotorTrend recently testes a Nissan 350Z with and without the K&N: Result: More HP with the stock system. Some slights benefits are barely measurable at very high RPM at the cost of letting in more contaminants in the engine.
Mercedes (W124) intake systems flow up to 620CFM without any restriction (Ref:http;//www.rndperform/test/mbz124) which is about what is required for a 103/104 engine to run at 7,200RPM.
The ''feeling'' of having more performance with a modified intake system comes much more from the added intake system noise and the gratifying feeling of having spent $$$ (thus expected positive results)
jackd

I disagree with your last sentence completely, for me spending $$ is not gratifying, I'm cheap, that being said, I've read several article on K&N type filters and most of them have produced mixed results. But why does Mercedes use this type of filter in the German touring car races? Like our SCCA, the german touring cars have to be basically stock. I'm watching the Rolex racing on SPEED and I'll bet that all if not most of these cars have "free flow filtering of some type" Have an nice day, I got to finish waxing the spouses car for Winter.

#28 11-01-2003, 03:01 PM

I just want to get this straight.

Quote:

The ''feeling'' of having more performance with a modified intake system comes much more from the added intake system noise and the gratifying feeling of having spent $$$ (thus expected positive results)

I am sorry that you have fooled your self into believing this quote. If this is true, then how come every car that I have added a CAI has gotten a 2-3 mpg gas increase and has also provide horsepower that is verified by a dyno. I am not going to start posting scans of dyno results and get into a debate on if the dyno person knows how to conduct a dyno test. CIA work and are not just noise. Just search some forums out there and search on the FIPK kit and see what this noise only kit does to everyones cars.

Now I AM NOT saying that mercedes cars can benifit from a CAI because like my SL500 it already has one. I was responding to the idea behind a CAI.

Also I believe that you mentioned the 350Z car from R&T. First of all Nissan has done a lot of work to squeeze all the HP out of that little 6cyl block that they can. So you are not going to get much HP gains from something that is already optimize to get the max horsepower. Since you are quoting R&T I guess that I should to. There was an article ZOUNDS! the tuners let loose on the 350Z. Well these tuners got about 50 extra horse power form 1. blower 2. CAI, flywheel, cam and exhaust. So the tunning company that R&T is tesing uses a CAI for there car. Stupid tuners, they wasted lots of money to add a CAI to there car when they should have just keep the stock one. But I forgot, What ever R&T says is the final word and they are never wrong........

psfred · #29 11-01-2003, 06:49 PM

Every car I've seen with fuel injection has a cold air intake, period. Heated air intakes have a system for maintaining the intake air substantially above ambient (usually 100F) so that the carburetor doesn't freeze up in humid conditions. Quite an experience if you've not had it, by the way...

Please don't confuse cold air intake systems with low restriction systems -- all the discussion I see here is about low restriction intakes, not cold air intakes.

Beware backyard engineering, and all claims should be backed up with controlled condition dynamometer testing, not drag race results -- ambient conditions have a BIG effect on peformance, and the strip won't be the same from hour to hour, let alone day to day.

Less restrictive filters allow bigger dust particles through, this is the nature of physics.

Be careful with ANY oiled foam filter to avoid getting oil on the platinum wire of the mass air flow sensor, it will carbonize during "cleaning" cycles and clobber the MAS. Gets expensive.

Peter

Benzmeister · #30 11-01-2003, 08:06 PM

We aren't necessarily talking about CAI but as you said less restrictive filters. Your correct most FI engines have a different setup for intake air, carbs needed some warm air to keep carbs from freezing, I remember those days also. Most FI cars have a "cold air" type system. My wife's 94 Audi draws air from behine the headlights inside the fender, my C280 thru the grille. I also know a backyard engineer who took a very nice 97 Z3 and made a homemade CAI, it was OK for a while until he hit a deep puddle of water and guess what happened? Hydrolocked the engine. He had ran a tube from the stock air box down to the back of the fog lights, installed screens for water, but apparently that didn't work too well, he even drilled some extra holes in the bottom of the stock air box to let water out, turns out this was not a good idea, the holes created more suction and really drew the H20 into the engine, he followed directions he picked up on the internet, long story short, he bought a new Z3 at the time and just put a K&N filter in it.