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 . 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...
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
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!
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
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!
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
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.
keeping in mind the 75mm SLK32 starts at 14.5psi (6200rpm) but some of the Xfire boys have pulley'd it to 20.
A 65mm pulley gives you 16.7psi
BTW looks like a 62mm SC pulley is the new 65
With already 2 plugs and 2 coils per cylinder, I'd be suprised if you would get that much improvement. Would be interesting for one of us to guinea pig.
I was actually looking at it for my stock 230.
Maybe I'll get it, try it on the 32 and then handme down it to the 230 (which I'm going to sell anyway)
ignition system was designed to handle certain amount of power/pressure. once you change that then you can gain by improving it.
it becomes harder to ignite the spark under higher pressures and if you do the spark wont be very strong which wont promote a full burn. not saying the stock system wont cope but it can be improved
i thought the stock SLK32 boost pressure sits around 10-11psi (consistant) with breif periods of 13psi? have you hooked up a boost gauge to yours?
CS74 has live output on the run - but difficult to do whilst driving.
Havent gotten the dashdaq yet - trying to avoid as it's "old technology" now. It does allow additional inputs and logging.
Just going off the specs around the various places/reviews (2002).
Stock 75mm onto a Stock 157mm crank supposedly yields 14.5psi from the jappy lysholm.
The boys are either doing the Code3 at 65mm or 2 options on the crank - I think its 178 or even more at a 182mm. I think 32Krazy had tried a 65/178.
some have recently run 62mm.
Reportedly, IAT's get really high though and belt slip requires a pulley saver kit and then you go chasing, water circ. seperaton, killer chillers, LET SC air cooler upgrades, water/meth injection and ice buckets....
With my Code3 I'm trying to go with a killer chiller (AC gas/SC water cooler) and cooling water sep.
If you are ordering one of these into the USA do not place your order yet.
My package is stuck at customs and as a typical US Gov agency they say they cant tack it and can not give me any info on it but yet it is sitting in their facility stuck.
I say dont order yet as it may not be deliverable for some stupid US dumb ass reason.
mine went thru in 4 days or so... but then again sometimes your package will get checked. ive had stuff before say in customs for 2weeks then it clears OK. nothing illegal with the product probably a backlog they have to clear..
they will probably x-ray it to see whats inside...
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