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1999 SLK230 turbo
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Discussion Starter · #1 ·
I'm sure this may have already been covered before on here but couldn't see it with a quick search.

Quick spoiler: there's free Throttle response to be had馃槈

So anyone with a 230k car whether Slk or any other variant maybe interested in this, I thought I would do a little video on the design of these airboxes because anyone who hasn't pulled their car apart might want to see just how flawed the stock intake is.


When I started the video I didn't have any intention of doing what I actually did and I did know these clipped apart, especially as I have had so many of these cars and engines but always assumed that it would be difficult and damage parts.... I was wrong with barely any effort at all it all pops apart, the only tough bit is the metal ring that holds the main retaining clips in place that has to be deformed to release it.

After doing this I popped the airbox back together and back on and after I realized I didn't plug the Bypass valve back in 馃ぃ, I took the car for a spin it had improved the throttle response so much. The top end is so much better to aswell as my idle speed had picked up.

Reason? Well due to the silencer in the intake for the bypass valve the actual intake is restricted to about 50mm 馃槷. Imagine a 50mm intake on a 2.3 Supercharged engine, all I can think is mercedes maybe deliberately did this? Either way it's easy to undo and don't worry if you don't like the Supercharger howling, it still sounds stock you can hear it but it's far from overwhelming.

Some of you may already know this trick there's got to be no way on the planet I'm the first person to do this. But I wanted to show and explain it to anyone who may not know.

So once again I hope this is useful to some of you 馃槂

Thanks for reading and watching
Alex
 

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1999 SLK230 turbo
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690 Posts
Discussion Starter · #3 ·
So presumably they wanted a venturi effect, but shoved it so it hits the pipe wall and sets up turbulence?
Could this be to mix air that is at two different temperatures?

I have very vague memories of such from when we wore cloth caps and shorts.
Well I can understand the Venturi effect but not the 50mm intake 馃ぃ.

One reason I can understand for them doing it is so that all the charge pressure is lost so it doesn't cause run on when off throttle.

I am coming up with a free flow quiet performance intake, I'm halfway there with the design and I actually have most of the stuff to fabricate it already. I want to keep the stock bypass valve but I think I'm going to have to baffle where the valve vents to avoid run on. But the concept will have to be made of steel to start with nothing like using a performance lightweight material like that 馃ぃ.
 

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1999 SLK230 turbo
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Discussion Starter · #5 ·
(y)
Just throwing it out there, as it was using space in the dark recess of my mind.
Haha what else is floating round in there 馃槈 I tell you what though the Clk is even more happy to light up the rear tyres now so far I haven't even gone near an overdrive pulley, it really is quite impressive.
 

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2000 SLK230
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35 Posts
Alex, now that it's been a few weeks, any problems with this mod? Did you keep it or revert to stock?

Thanks
 

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1999 SLK230 turbo
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690 Posts
Discussion Starter · #7 ·
Hey @Solchris so far no issues at all, very faintly you can hear the Supercharger but it's only very slight. Performance is still good even with the engine being a bit poorly (unrelated issue) throttle still nice and sharp. The good thing about this mod if your careful it can easily all be refitted into the airbox, but so far I think it's absolutely fine 馃槂
 

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2000 SLK230
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I had an airbox lid in my hand at the wrecking yard a few days ago but I got distracted and didn't buy it. If I get back down there again I'm going to grab it and pull all the baffles out so I can do back to back runs.
 

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1999 SLK230 turbo
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Discussion Starter · #9 ·
I had an airbox lid in my hand at the wrecking yard a few days ago but I got distracted and didn't buy it. If I get back down there again I'm going to grab it and pull all the baffles out so I can do back to back runs.
That's a good idea I noticed definitely sharper throttle I also am missing a muffler though, so my exhaust is straight through flow wise other than cats. Im not sure if it's that or the air box mod that's helped the top end so much. But I'm sure you will notice similar gains to me.
 

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1997 SLK230
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That's a good idea I noticed definitely sharper throttle I also am missing a muffler though, so my exhaust is straight through flow wise other than cats. Im not sure if it's that or the air box mod that's helped the top end so much. But I'm sure you will notice similar gains to me.
Thanks to your video I've also removed the "clutter" from the air box and noticed a smoother pick up and increase in the revs, it's also ironed out a slight lumpiness that was present at idle. I have however left the rubber intake from the bypass valve in place to direct the pressure towards the supercharger outlet rather than let it swirl within the airbox. A question I have is: how much of a vacuum is created in there as the rubber intake tube doesn't appear to have much holding in place once the plastic baffle is removed and could there be a chance of it working loose?
 

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1999 SLK230 turbo
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Discussion Starter · #11 ·
Thanks to your video I've also removed the "clutter" from the air box and noticed a smoother pick up and increase in the revs, it's also ironed out a slight lumpiness that was present at idle. I have however left the rubber intake from the bypass valve in place to direct the pressure towards the supercharger outlet rather than let it swirl within the airbox. A question I have is: how much of a vacuum is created in there as the rubber intake tube doesn't appear to have much holding in place once the plastic baffle is removed and could there be a chance of it working loose?
No worries I'm glad it helped and you are seeing positive results 馃槂. My advice would be to take away the rubber aswell, you have the right thought process with keeping it to redirect the air that makes perfect sense. The reason I say is the answer to you question there is a LOT of vacuum in there and there is a very real chance that the rubber tube could be sucked into the intake, now it may not get all the way to the charger if it did but there's that possibility it could. Basically if it did get to the charger it will destroy it. Although yes there is turbulence when the bypass vents I've not noticed it be detrimental to performance so far馃檪.
 

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1997 SLK230
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No worries I'm glad it helped and you are seeing positive results 馃槂. My advice would be to take away the rubber aswell, you have the right thought process with keeping it to redirect the air that makes perfect sense. The reason I say is the answer to you question there is a LOT of vacuum in there and there is a very real chance that the rubber tube could be sucked into the intake, now it may not get all the way to the charger if it did but there's that possibility it could. Basically if it did get to the charger it will destroy it. Although yes there is turbulence when the bypass vents I've not noticed it be detrimental to performance so far馃檪.
Thanks for the confirmation, better a small amount of turbulence than a stuffed supercharger! ;)
 

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1999 SLK230 turbo
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Discussion Starter · #13 ·
Thanks for the confirmation, better a small amount of turbulence than a stuffed supercharger! ;)
Definitely especially with the price people ask for M62 Superchargers here in the UK, I may update this thread with some more ideas I have for the intake but they will be a custom intake trying to go high flow but still quiet.
 

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1999 SLK230 turbo
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690 Posts
Discussion Starter · #14 ·
For anyone else interested I have also made a second airbox modification, this modification I may have even already seen on here at some point but I believe my way is a slightly more effective method.


Now don't expect miracles from this mod but it really helped the top end instead of choking the now pulls all the way to the red line.
 
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