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Boost pressure - SLK230

37K views 75 replies 18 participants last post by  sikdogg 
#1 ·
#2 ·
After a lot more driving it gets to 7psi at 2400rpm. A bit better but I always though the boost would be higher. The more intriguing bit is seeing -12 lbs of vacuum at 100kph (62mph) constant going to +7lbs boost when throttle planted and back to Vac on cruise. Certainly different than a turbo car.

Bazzle
 
#3 ·
Boost on the 230K's is rated at 1/2 bar, or about 7 psi. What you show is nominal. Interesting about the vacuum when the blower isn't needed.
 
#4 ·
7psi does seem about right for the standard cars. I moved to the SLK after several turbo cars, all of which I modified. :). Most turbo cars will run anywhere between 12 - 16 psi without problems depending on model.

I'm looking at the pulley upgrade option at the moment. It would seem the upgrade gives 8.5 psi.

Dave
 
#7 ·
I forgot that you had the pulley ..........

In that case you have 1 to 1.5 psi over stock. The SLK is rated at 1/2 bar, but in the past they seldom achieve that. The guys (and there weren't many) that had manifold pressure gauges reported the 1 to 1.5 psi gain.
 
#9 ·
RE: I forgot that you had the pulley ..........

Pressure/vacuum gauges aren't always the most accurate, why not have it dead weight tested, and with the calibration you should get a better idea what you have. Gauges below 4" diameter are seldom used as "test gauges" and anything bigger looks stupid in a car ... [B)][:eek:)]
6 psi would be low for the pulley, but 7 psi is about right, may be slightly low but not much.
In any event you can feel the power, and without a dyno run to show it, that's good enough isn't it? ... [:D][:)][;)]
 
#10 ·
My pullied 230K does 11-12 PSI. 7 PSI is pretty much stock.
 
#11 ·
linh - 12/21/2005 12:58 PM

http:/My pullied 230K does 11-12 PSI. 7 PSI is pretty much stock./
Alright, let stop all this guessing. I'll response when I have time.
Found an earlier post from you LinH[8D]

""The pre-2000 ASP pulley is about 15% bigger then factory pulley and the post-2000 ASP pulley is about 19% bigger then factory pulley. The pre-2000 ASP pulley boosted around 8-8.5 psi and the post-2000 ASP pulley boosted around 10-10.5 psi.""

Now to find my missing 2 psi [}:)]

btw I tried another gauge with same 6 to 7 psi

Bazzle
 
#12 ·
Alright, let stop all this guessing. I'll response when I have time.
Question: If you had time to read this post, and time to respond to it, how much longer would it take to add how many psi the pulley will put out?
I have to wonder why you found time to answer another post, and couldn't spare a few seconds to answer this one properly....
 
#13 ·
OK
Checked gauge against a master from work , same reading, max 7psi.

Originally was picking up reading on "T" fitting on pressure line to fuel regulator. (1998) Red arrow.
Now on aluminium pipe Supercharger side of Intercooler.

New pressure reading of 9lbs, so must be a drop of 2 to 3 across I/C..makes sense.

You other guys, where did you tap into read pressure??

Bazzle
 

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#14 ·
New pressure reading of 9lbs, so must be a drop of 2 to 3 across I/C..makes sense.
A 3 psi drop across the intercooler sounds very high. I'm not saying it isn't possible, but it does sound like a lot... [:0]
You might want to take it off and see if the flow is restricted in some way. There is a side benefit to removing the I/C. You can inspect it, and flush any oil or debris which may eventually get to the MAF sensor.
Just a thought.... [:)]
 
#15 ·
Hello all,

I just purchased a 2000 SLK230 last month. I love it; plenty of torque off the line and at low speeds, but it could use a little more umph at mid+.
I would like to increase PSI a moderate amount and still keep reasonable reliability.

I have owned turbo cars before, so know how to increase pressure on those, but am unfamiliar with superchargers. My old Mercury Capri XR2 (Mazda 323 rally engine) worked fine for 237,000 miles with boost increased from (progressive bleedoff to a max of 6.5 PSI ) to a non-progressive bleed 9 PSI using a checkvalve on the wastegate actuator.

From the little I know, a supercharger gets the easiest increases by using different pulleys to spin it faster. No wastegates.

Does anyone know of/ can reccomend a good source for the pulley and belt for my SLK 230? Any nuances with installation? Any tuning adjustments needed ?

I did improve handling and braking significantly by replacing the old Mich. Pilot Sport AS 205/55, 225/50 X 16 using the same wheels with Yokohama
ES100 225/45 X 16 all around. They give 1" less diameter, so it sits lower, keeps the traction control happy with all the same diam. , and they stick great. (Except the traction control gets a workout in N. California rain; I wouldn't recommend for any snow areas; the car has too much low end torque for minimal traction conditions with the YOKOs)

Thanks for any info, Mark
 
#16 ·
Linh would be the only place to get your pulley. Make sure that the pulley you get is the 2000 model A111 030 09 03, because the spoke is shorter. You're probably going to have to send yours in to be modified.
 
#17 ·
markw - 12/22/2005 8:03 AM

Hello all,

I just purchased a 2000 SLK230 last month. I love it; plenty of torque off the line and at low speeds, but it could use a little more umph at mid+.
I


http://www.benzworld.org/forums/search/query.asp?keywords=pulley&searchforumid=26&author=&days=&action=search

Hijacked my thread [:0][:0][:0][:0]

Bazzle
 
#18 ·
my pullied pre-fl 230 only shows 0.5 bar. the boost was tapped from the pressure line to the fuel regulator. is this normal? my pullied c200 yr2001 is showing 0.6bar upon redline.

is 225 rear tyre size good enough to counter the massive pullied low end torque if i were to upgrade to 17" since 17" would be heavier?
 
#19 ·
Bazzle@
Why do you think that boost reading (measured from the line of the FPR) is max 0,6 BAR (O.K. sometimes 0,7-0,8, but for very short time) at 2000 rpm and the same (0,6 BAR) at 6000 rpm? It would have to be 3 times more (1,8 bar), because kompressor have 3x more revs at 6000 rpm than at 2000 rpm. But the boost is always 0,6 BAR??? I know that engine is using this kompressed air, but it can not be that linear (the same pressure between 2000 and 6000 rpm)?
 
#20 ·
Snogard said:
Bazzle@
Why do you think that boost reading (measured from the line of the FPR) is max 0,6 BAR (O.K. sometimes 0,7-0,8, but for very short time) at 2000 rpm and the same (0,6 BAR) at 6000 rpm? It would have to be 3 times more (1,8 bar), because kompressor have 3x more revs at 6000 rpm than at 2000 rpm. But the boost is always 0,6 BAR??? I know that engine is using this kompressed air, but it can not be that linear (the same pressure between 2000 and 6000 rpm)?

Bypass keeps pressure regulated to some extent.
Boost is lower on the FPR compared to end of IC.

Bazzle
 
#21 ·
And how in the world can bypass valve know when and how much shoul it bleed out when full throttle is pressed? For example at full throttle at 4000 rpm (on the autobahn) the bypass valve is FULLY closed as far as i know. So why there is not at least 1,4 BAR pressure (doesnt matter if measure at FPR or at the ALU kompresor outlet, because difference is only 0,1-0,2 BAR and we are missing almost 1 bar)?
 
#22 ·
Snogard said:
And how in the world can bypass valve know when and how much shoul it bleed out when full throttle is pressed?
Bypass valve

Position
At top part of air cleaner

Task
Operating recirculated air flap steplessly between 0 - 90°for boost pressure control

Design/function
The recirculating air flap actuator is operated by means of a PWM signal supplied by the engine control module.
 
#23 ·
DickB said:
Bypass valve

Position
At top part of air cleaner

Task
Operating recirculated air flap steplessly between 0 - 90°for boost pressure control

Design/function
The recirculating air flap actuator is operated by means of a PWM signal supplied by the engine control module.

I know all of that what you did written, but i am telling you that at full throttle is air bypass valve FULLY CLOSED (90% PWM signal), and we still get only 10,5 PSI at 4000 rpm, instead 21 PSI (if i get 10,5 PSI at 2000 rpm at full throttle, then logicaly we should get 21 PSI at 4000 rpm at full throtttle, but WE DONT!!). Why? Where is that pressure lost (remember bypass is closed at full throttle)?
 
#25 · (Edited)
Bazzle said:
So Snogard, how much boost can the Supercharger make??

Bazzle
Close down pipe to bypass and make test drive and read pressure. You will be surprised what boost can our SC make....:thumbsup:

On German SLK forum we are exploring at the time what makes pressure lost.... If i have 1 BAR at ALU outlet write after the SC at 2000 rpm at full throttle, then why i have still only 1 BAR at 6000 rpm at full throttle meassure at the same place (write after the SC at the ALU outlet)? Because engine is using so much air and so lineary? Wrong. B ecause air pressure IS LOST somewhere. And we think that bypass (even if its fully closed at full throttle) doesnt alloud more than cca 0,9-1 BAR. Maybe spring in the bypass is not hard enough or there is pressure sensor who is telling to open the bypasss when pressure is larger then 1 BAR....It seems that nobody knows that one or nobody wont to share that little secret with us....
 
#26 ·
silberpfeil1234 said:
My pullied 230K does 11-12 PSI. 7 PSI is pretty much stock.
And where exactly do you meassure boost?
 
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