A simple fix I used is to cut the intake cowl at the end of the intake hose by the radiator. Not only is the cowl restrictive, it also opens in front of the auxillary fan on the driver's side. The cowl faces backward into the aux fan, meaning that the fan is sucking air AWAY from the intake. I cut the cowl flush with the radiator so the hose opens straight forward. I have not changed the filter yet, but I feel a difference in acceleration. No change in sound, and haven't measured gas mileage. Just a thought.

Don

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Don Drake

1990 300E 125k Miles
1994 S420 100k Miles

The downside to that modification is having large particles enter ing the airbox. The solution would to actually clean the airbox every week.

I wish you can dyno your car to actually see the increase in HP.

Hey there. Yea, I agree, I had posted about that earler... and I got laughed at no, not really. But I went ahead and cut the intake scoop off, and boy can I notice a difference. The high-speed acceleration is a LOT better, pulling up past 110 is not a problem anymore. So yea... its a good deal all around!

I would add that I don't think there's going to be much of a problem with large objects going up the intake, given that the opening is still small, and shielded by the grill. Driving on normal roads in Texas, all I would expect to see would be a few more bugs in the housing, all of whom are easily removed with the shop vac. I'll be taking my car on an extended drive this thanksgiving, and may have more to report then. I'll try to benchmark mpg as well.

Don

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Don Drake

1990 300E 125k Miles
1994 S420 100k Miles

you could also keep the stock intake and add a secondary one like don swinford did to his car.

http://home.earthlink.net/~asherson/Don

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

I've seen Don's ram air. There's a big problem with it in that it is not actually a ram air. That fact alone would not be a problem except for the fact that his system, while increasing the volumetric efficiency of the engine (see my post on theoretical intake of 300E, this forum), the additional air it does intake is extremely heated. Since the engine compartment is so well sealed on these vehicles, it gets extremely hot under the hood. I know the intake box is down low, but its hot down there too. Just stand next to an idling 300 E and feel the heat blasting out from under the car, especially in summer. Not only that, but the box is directly behind the cooling fan so it sucks in all the hot air from the radiator to the front, and the manifold (1000 F plus on gas engines). Hot air is 1) much less dense than cold air (so you could actually decrease the actual amount of air that is taken in) and 2) increases the tendency to knock or pre-detonate since air is heated when compressed in the cylinder; hot air just gets that much hotter than cold air. The result is that the engine knocks that much sooner, which the car (even with the omni pack) compensates for by retarding the spark which, again, reduces power, increases emmisions, and reduces fuel economy. That is why ALL cars' intake hoses take in air from outside the engine compartment. (Any other Mech. Engineers out there will also agree that maximum thermodynamic efficiency results from the greatest temperature differential between processes.) It's also why superchargers and turbos have intercoolers-- to cool the air the compressor heats up!
I am working on a new design that will draw all air from outside the engine compartment. The cooler, the better. When complete, will advise. In the mean time, I have a request in to mercedes to find out how much air the stock setup passes. Stay tuned; I welcome your comments!!

Don Drake

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Don Drake

1990 300E 125k Miles
1994 S420 100k Miles

Don:

A couple of threads in the past talked about removing the headlight wiper/washer trim strip and drawing air in from under the headlights. The downside discussed was the posibility of sucking water into the engine during rain storms or splashes from the street.

I have wondered about re-routing the air intake back into the windshield cowling area to pick up cooler air at the base of the windshield, but don't understand enough about the flow dynamics and pressure variations in this area to know if they would help or hinder. Any ideas?

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John

2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)

Click to see 87 300E

I also remember I believe that Don had modified it since those pictures...

I would route it right to the front airdam if possible, but I would think a route to the windshield area would work nicely.

How about the diesel front fender idea with the vents? Use those to intake air but have them on both sides?

It would probably work nicely as an alternative to just cutting the hose off...

And it would look pretty cool too.

Some hood slits might work as well if incorporated to be near invisible, but only a black car could hide them well....

Personally I'm happy with my car's resposiveness, I would love to improve low end to make it quicker without changing the engine design.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

I have found that trimming the cowl just in front of the aux fans does just that -- adds low end torque. My ideas so far are to utilize the tow hook area (passenger side front bumper, or both sides of the grille.

The idea for putting the scoop at the back of the hood by the windshield is a good one, but JCE's insight is very astute. Placing an intake back there, due to the aerodynamics of the car and due to the "wing effect" of air moving rapidly over the hood and proposed intake, will probably create a low pressure (vaccum) area in that region, reducing intake.

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Don Drake

1990 300E 125k Miles
1994 S420 100k Miles

I still like the vented fender direct to dual intakes on the airbox.. hehe one vented fender on each side to extra intakes would work quite well I think.. Just probably expensive to either gett he fenders cut for it and redone just to add some extra air intake..

New BMW M3 has slits on the sides of the fenders for air intake I believe...

Looks cool if ya ask me...

Can you explain the cowl, you mean making it so it is not curved in but rather more open tot he front?

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

Hey there Alon,

Thanks for all the replies. I am getting more and more addicted the more I come to this site. By the way... Killer looking Benz you have!
I really like your idea about the bumper scoops... If I understand your idea, we are thinking along the same lines. I can't tell from the pics of your car, but on mine (1990 124 3.0E) on the passenger front left, there is a removable plastic plate on the bumper which covers a tow hook. My original idea was to use that in combination with the existing hose for a dual intake system. However, I really think you're on to something with your idea, and it would really look good. I think I could remove the bumper and do the cutout myself on the drivers side. Then, add some sort of cool screen covering, and wow (Ala BMW M series). I think that is the avenue I will persue. I will keep you updated. I plan to use insulated flexible home air conditioning duct for my intake hose. The ducting is shiny on the exterior, which will reflect a good deal of the radiant heat from the engine. It is also fiber glass insulated which will keep out the convection heat. I think I will also keep the stock hose, for 3 intakes. As time (and money) permits, I will do this and post pics and results.

To answer your question about the cowl, you are precisely correct. You will notice the stock cowl curves around to the front of the radiator, with its opening to the rear, facing the auxillary fan. Not only is the cowl restrictive, but it is in competition with the aux and main fans for the same air. What I did is to cut the cowl where it begins to curve around, so that now, the opening faces directly forward in the direction of travel. I am not exagerating when I say I can feel the difference. I have a degree in Mechanical (Automotive) Engineering, so I feel qualified in my opinion that I am not just imagining the benefits. Thanks for the replies. My 1990 has 140K miles and counting. I have just begun efforts to restore it to its original glory. Next come the headlights. If you know where to get cheap euros, please let me know. Both of my headlights are broken so I have to aim them by hand.

Two final questions, for now. 1) how do you achieve senior member status, 2) My wife drives a 94 s420. Do you know of a factory service manual for it? Thanks!!

Best Regards,

Don Drake

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Don Drake

1990 300E 125k Miles
1994 S420 100k Miles

Hey guys. Guido here. I'm the one who did away with my wiper motors. Installed a solid filler panel . So now its a forced induction. I have no problem with rain or debris. I check my K&N's regularly there ok. You might want to try that. You guys made alot of valid observations. There is alot of what we should call dirty air. The hot air from the RAD or heat rising from the exhaust.


Anyone from the calif area attending the euro tuner fest put on by CEC its going to be a great turn out


Later guys.

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500E Sold
2006 Mini Cooper S
Modified,pulley,injectors,suspension
2009 E350 Sport AMG package

Here's an update after my trip. Though I haven't had to refill the gas tank yet, given current consumption and current trip odometer readings, I am projecting 24-25 MPG on a 1990 300E with 130000 miles and otherwise bone stock except for the modified cowl. Car was moderately to above moderately loaded and had a/c running the whole 300 mile trip. Improved acceleration at low and high speed. Improved torque available seemed to help downshifting as well.

Don

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Don Drake

1990 300E 125k Miles
1994 S420 100k Miles

Well... here is an idea. I noticed that there is some interest in putting the air intakes down from the bottom of the front air dam. Now.. sure this would look really really cool. But im not sure if you would still get the "ram air" effect from those. They way I understand it... ram air uses the speed of the car to compress air into the air box... giving you more air to work with. If you put the intakes down in the air dam... you would be using really long hosing to duct the air from the air dam to the airbox. I think that the tube will just be too long... and any "ram air" benefits would be lost. This mod would however a.)look cool and b.)give you more airflow... just not "rammed" air. So... if you are going to go that route... I suggest using the 3 intake setup that was mentioned earlier...(or get a big supercharger )

I believe that the rear of area of the hood is a high pressure area, rather than a vacuum. Chevrolet muscle cars of the late 60's offered a rear facing intake to take advantage of this. Later aftermarket hoods for these types of vehicles feature rearward facing scoops. I believe it may be the result of a downward swirl producing down force in that area.