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1998 SLK 230
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2,594 Posts
Discussion Starter #1

ive been using this now for a while and now can post back... all i can say is WOW... i can wheelspin from a roll at ~50km/h.... I will have to do 0-100 timed run but still waiting for good weather as its winter here and conditions arent ideal yet.

the biggest difference is from 2000rpm+ when boost kicks in. it kicks in HARD :D. cruising around requires significantly less throttle to get the car to move and throttle response is very snappy.

reason why it makes a big difference is the older pre face lift slk uses TWO coil packs for 4 cylinders which is called a "wasted spark" system. which means the coil fires 2 spark plugs at once. for example cylinder 2 is on the compression cycle (piston near the top) and then it fires. at the same time cylinder 1 is on the exhaust cycle (piston at the bottom) and cylinder 1 fires too (thats why its called wasted spark)... to fire in cylinder 2 requires the coil to work harder as its compressed. so it takes the bulk of the coils voltage. firing in cylinder 1 requires hardly any as its in the exhaust cycle.

thats one disadvantage it chews voltage which could be going to the cylinder which needs it most. the next major disadvantage is the coils dont get sufficient time to "re-charge" for the next firing compared to having a coil for each cylinder.

this device boosts the voltage and makes sure its constant (no drops). it simply plugs into fuse F11 in the engine bay to intercept the voltage going to the coils.

im still running 0.8mm gap on my plugs and will bump it to 1.0mm now as i have enough juice to them...

if anyone wants one i found a seller selling them cheap! pm for details. i got mine $80USD + shipping

in terms of difference to the car where say a pulley kit is 10/10 id put this at a 5-6/10...
 

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R170 SLK 200 Kompressor, W638 Vito 110 2.3 TD
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97 Posts
Hmm... this reminds me of electronic spark ignition enhancers for carburettor engines. My father has built one for his LADA car back in the 80's.

Do you know any long-term possible problems? Of if the face-lifted models are wasted spark systems too?

I believe that my 2002 model had 4 coils, one for each cylinder, but have to check, I don't remember since I changed the spark-plugs.
 

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1998 SLK 230
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2,594 Posts
Discussion Starter #3
Face lift cars have 1 coil for each cylinder which gives it better burn to meet emissions requirements... It will still be noticeable on them too as the car is forced induction.. More so if it's running more boost from a pulley.. Causes no issues to the coils as they have done a fair bit of testing before product came out.. Ups the volts not the amps
 

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1998 SLK 230
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2,594 Posts
Discussion Starter #4
another install pic. plug and play into fuse F11 (igntion coil fuse).

opened up my spark plug gap from 0.8mm to 1.0mm and it works perfectly under high rpm/boost!
 

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1998 SLK 230
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2,594 Posts
Discussion Starter #5
before and after pics
 

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1999 SLK230 Sport 5-Speed Manual, Silver, Subtle Red on Black Interior
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116 Posts
Thanks for all the great threads you've taken time to post over the years - amazingly helpful!!

If you don't change the spark plug gap after installing this mod, what are the drawbacks or how much of the gain are you losing? I have the standard 3 prong plugs and I'm not familiar enough with re-gapping, the re-gapping tools I recall seeing I don't think would fit under the electrode because the other 2 prongs would block the tool? A few pics of the tool on an old spark plug would likely set me straight if you can take some (yes, pretty rookie question)!

Also, while this isn't a top concern for those buying this, what are your insights on whether this mod would actually help improve gas mileage (all else equal that is, since this might alter driving habits with the more powerful throttle response!) due to more complete burn of the gas in the cylinder with the more powerful spark and resulting combustion.

Similarly, it sounds like this should actually help emissions as well, just as you mention the post-facelift versions had this for improved emissions.

Thanks again for all the great threads over the years!
 

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1998 SLK 230
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2,594 Posts
Discussion Starter #7
for a stock car - it would improve throttle response and fuel economy (not sure by how much but a tad). if your car has the 2 coil packs instead of 4 then it makes a bigger difference.

main reason for this mod is for cars running higher than stock boost pressure (mines more than DOUBLE what a stock car has!). as the more boost you push into the cylinder the harder the coil has to work to jump the spark under all that compression. stock coils for stock car is OK. stock coils for non stock car... well they tend to be weak!

the 3 prong ones arent ment to be gapped. they are pre-set to 1.0mm so thats fine. i run 1 step colder spark plugs with single strap (NGKs) and had to gap them to 0.8mm as the stock igntion would missfire, hesitate under full throttle. i noticed this the most on track day.

now that i got more powerful spark i can bring it back to 1.0mm (the stock recomended gap) with NO issues.

i did a test run on a road i usually go test mods and i use to hit ~185km/h in that stretch, yesterday i hit 203-205km/h with nothing else done to my car and the scary thing is the car had more pull post 200km/h to keep pulling more...

i have a few track days planned later this year and will see how we go as i know what i max out on on each of the straights on the track :D
 

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1999 SLK230 Sport 5-Speed Manual, Silver, Subtle Red on Black Interior
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116 Posts
Sweet! Its great how you keep tweaking more performance and reliability out of the car, and not always for lots of cash.

I have a pre-facelift with 2 coil packs, so I plan on doing this mod even without pulley and performance upgrades. Thanks for the thread, and the contact info for firestorm!
 

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1998 SLK 230
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2,594 Posts
Discussion Starter #9
the only "downside" i guess is the spark plug electrode might wear a tad quicker but not sure by how much. theres no way these plugs will last 60,000kms or whatever MB say. i change mine every second oil change anyway. plugs are cheap like $3 so its no big deal.

heres an install the guy did on a lamborghini gallardo LP 560. 2 units. unit 1 does cyls 1-5, unit 2 does cyls 6-10
 

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SLK 230
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1,498 Posts
Got one on the way.

40.00 shipping. Little high.

Thanx Subby
 

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1998 SLK 230
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2,594 Posts
Discussion Starter #11
yeh i know but id did come quickly for me and it was well packaged... still cheap mod!

let us know how you go... when you plug it in it will be immediately noticable. after a week of driving even more so when the ECU adapts
 

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SLK 230
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1,498 Posts
It will be a while before I am back in the states. I am in Brazil till November. But I will follow up on this thread when I get it installed.
 

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1998 SLK 230
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2,594 Posts
Discussion Starter #14
pm sent
 

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2002 SLK320
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22 Posts
Do you think there would be any gain on an '02 V6? If I remember correctly I have a coil pack for each cylinder.

thanks,
Dave
 

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Australia, 99SLK230 R170, 2001SLK32
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1,374 Posts
I think if you read the principal of advantage...you (and Post Facelifts) already have one per cylinder - so me dont thinks so
 

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1998 SLK 230
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2,594 Posts
Discussion Starter #17
from memory the SLK320 has 2 spark plugs per cyl? i think they did that to make a much more complete burn and/or because of cylinder design...

popping this on wont hurt, but it wont be a massive difference as a forced induction car running higher compression. throttle response will improve for sure but power wise looking at few hp at most.
 

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SLK32 red, Chrome roll bars and wheels, custom audio, Custom Grille, HP werks SC pulley, moded intak
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16 Posts
any idea if it would be beneficial for my SLK32 with a smaller pulley for increased boost?
thanks
Mike
 

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1998 SLK 230
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2,594 Posts
Discussion Starter #20
hell yes...!
 
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