The stacked ASP 178mm and EC 65mm pulleys are installed and tuned!

I won't withold the results: 403 RWHp & 415 RWFT-LB.

I took her to the drag strip Sunday and ran in the Import Faceoff event. My best time was 11.85 at 116.8 mph. Welcome me to the 11 second club!! WOOHOO!!
Timeslip scan is at end of post.

We were discussing the fuel mods required in this thread. I posted an update. I can say for sure that 550cc/min injectors are definitely required for 178/65 stacked pulleys. I have a completely upgraded fuel system now including:

• Walbro 255 L/hr HP pump
• 8AN check valve
• Regulator-less fuel-filter
• 8AN line to rail
• "Ultimate Fuel Rail": 168% larger inlet, dual outlets
• Bosch 550 cc/min injectors
• Adjustable FPR
• Fuel pressure controlled AFTER the rail rather than before
• 6AN return lines

Other mods include

• Custom dual 3" intake
• Custom 3" exhaust
• Custom IC reservoir / ice tank
• Dual Johnson CM30 IC pumps
• Dual IC heat exchangers
• Insulated intercooler
• Wavetrac differential
• MikeR rear camber arms
• Mickey Thompson 16" ET Street Radial drag radials (only at drag strip)
• Innovate Motorsports WBO2
• NGK iridium spark plugs, 1 heat range colder
• Needswings pulley saver kit
• Tuning by Eurocharged with dyno operation by IPS Motorsports

Below is the dyno graph.

SLK32Dyno4-22-2014stackedpulleys_zps6de4ebf7.jpg

The dyno graph doesn't look quite right. In my prior dyno graphs the torque has been flat like a plateau. See below. With the new pulleys and tune, the low-rpm torque feels MUCH higher than before. It is incredible in fact! I am guessing that on the dyno graph above they were rolling into the throttle to keep the automatic trans from down shifting.

dyno6-7-13timmayfest_zps55410f83.jpg

I am very impressed from driving it on the street. The car has a LOT of power and is very responsive. From idle to redline, it is an animal! I am going to have to relearn how to launch the car!

1185timeslip4-27-14_zps7b4cf964.jpg

UPDATE 6/10/2014:

I got a new (better) dyno graph. 409 RWHP and still 415 RWTQ, but they were WOT for much more of the run, so the torque curve is more accurate, and more awesome. See this post.

 

My impressions of running stacked. Thrilled and scared. (disclaimer, stock injectors and fuel rail with Pierburg SL55 pump) The boost and instant power in the midrange was impressive. Then I noticed the 14.7 AFR's at part throttle along with that huge boost. Danger Will Robinson! At the track the car pulled crazy hard until 3rd. gear then it laid down. Don't know why. AFR's were around 13 in 3rd. which may be the answer. If you got the fuel figured out, as it appears you have, you should be golden. (11.8 IMO) Good luck with getting traction. (my problem)

I haven't run stacked since. Only did it once. Perhaps I'll do it again and put my car on the dyno.

I'm really interested in the mph in the 1/4 for your car. The most relevant number of them all for me.

Les

 

matt are you getting any supercharger surge at part throttle? watch for it it will put you thru the windshield if your not ready for it

nice # btw

 

How many psi is this making?

 

Good guess! I updated the first post with the 1/4 results. 11.85 @ 116.8. Zero problems with running lean. I will post a datalog.

Thanks Steve! No problems like you are describing yet. It runs GREAT in fact.

21 psi.

 

great times....looks like you figured it out. Stacked and not lien....

 

I have attached a datalog that shows some interesting data. This is the log from the 11.85 pass. The line to the LEFT of each data points box shows the locaiton on the graphs where the reading are taken.

RPM is in green in the center. I launched at 1360 rpm, let off at 4680 in 4th. Nothing to see here other than getting our bearings.

AFR is in magenta. The leanest it got was 11.66 in 2nd gear, and 11.38 in 3rd, getting as rich as 11.0 in those gears. It goes rich after shifting and in the upper RPMs. When it shifts to 4th, the AFR drops to 10.4! So, no shortage of fuel.

Boost is black. 21 psi.

Timing Advance is blue. The deep valleys are the shifts. It starts higher, 19 degrees in 3rd and 4th, and drops as the RPMs climb. The timing advance is somewhat inversely proportional to boost between the shifts. As boost climbs, timing drops.

IAT is red. I was running ice, thus the starting line IAT of 57 degrees F. I dumped a 10 lb bag of ice in before each run. With the volume of water in the system the ice would melt very quickly, before the run even. But it left very cold water. I could fit up to approimately 25 lb of ice in the reservoir. The IAT climbs through 1st and 2nd and actually levels out somewhat in 3rd around 102 F, before climbing again between 5700 RPM and redline to a maximum of 118 F. The supercharger is working hard here. Interesting, when the RPMs drop back down to 4600 after the shift to 4th, the IATs drop also, down to 113 F before I let off the gas.

042714-1111471185_zps4fb1ae5b.jpg

 

Success! Way to go. Observations: I'm running more timing than you are so your safe there. What your seeing at the shifts is normal for our cars. Timing is pulled, the throttle body closes partially, the supercharger disengages for a moment etc. I'm really liking the 11.85 but expected a bit more mph. Perhaps it's the extra weight of the SLK? Where's your redline? Stock? If you dare (I've only done it on the dyno) you'll find 20 hp going from 6100 to 6400 rpms.

Les

 

Love your work!
Great Times.
Excellent results from the ice tank - I don't think many could better that 118F (49C)!
So can we glean from this - that it doesn't matter how cold your IC is - at these demanding stages - there's not enough "air time" in the IC to cool it down much more than what you are seeing.
Can you guestimate from the isentropic chart what your IC inlet temps are... 120C (250F)???
And you're still pulling them way down to 120F!

 

Very nice work.

 

Fantastic run man. I wish I could've gotten mine dialed in like that.

 

Great job Boost, It has been a pleasure watching and learning from all y'all (you know who you are, lol). Congrat.'s on dialing it in. As I've learned, it's not an easy path. Good luck on your pushing the envelope.

 

Thank you for the compliments guys! This really is a great forum of people.

Steve, are there any symptoms I should be looking for? I am familiar with the compressor surge phenomenon for centrifugal compressors, but not with positive displacement superchargers. If I have problems I always have the option of bakcing down the boost by swapping the EC 65mm pulley for a machined down stock pulley. A 178/68 combo would fall right between the 62mm I had before and the 178/65 combo I have now. According to info Grip Grip has posted, 66mm is the absolute minumum the stock pulley can be machined down to.


That is good to know, thanks Les.

I believe the SLK32 is actuallly lighter than either the SRT6 coupe or roadster. I have always seen the curb weight listed as 3220 lb. I actually weighed my car last week. 3215 lb without me and low fuel. The total race weight should be right at 3400.

I do not want to increase the redline or the shift points. The supercharger really is out of its efficiency range by redline already with the 178/65 stacked pulleys. Running the RPMs higher would push it even farther out. I am intentionally building a TORQUE monster. I <3 torque. I really, really, do.

 

very very good runs ,,,great job of setting every thing up, were you running 100 oct unleaded fuel?,, they have that at PBIR hope they have it close to you ,it helps a little and every little bit helps. keep up the great job,,Oh are you running 327 gears? jim

just a note,,,I got rid of all heat exchangers and am running a killer chiller ,,my IAT's Sunday in 89 degree weather,,( the track was 104) IAT"S were 66 at burn out and 72 at the tree and 107 at the end of the 1/4 mile run,, by the time i got back to the pits mt IAT's were back to 79 to 82,

 

Yes, yes I can guesstimate. You know I am a sucker for graphs and numbers. I try not to bore everyone though.

Below is my estimate of the airflow/pressure ratio points on the compressor map for these stacked pulleys. As you can see, at low and mid RPMs the supercharger is operating right in it's sweet spot. Over 5000 RPMs, it is out of it's efficiency range.

178amp65AMGS105IHKIsentropicADEFFampHPampTEMPampRPMampNUMBERSADDED_zps9596f07d.jpg

The worst case scenario is at redline obviously, where I estimate that 96 HP is required to turn the supercharger, the efficiency has dropped to 40%, and the discharge temp is 356 degrees F!

Here is a chart of supercharger efficiency, discharge temp, and drive HP based on the above plotted compressor map:

178amp65calculatedcurves_zpsdc06cb6a.jpg

If my calculations are close than it appears that the intercooler is doing an excellent job!

 

Congrats on 11's and great dyno numbers.

I'm suspect we'll see some 11.5's from your car before the end of the year based on the dyno numbers.

 

nice work matt. ill see you and beth in june. not sure if the pcar will make it, I'm not holding my breath at this point. i have 31 days to get the car finished but I'm doubtful

 

That's what I wanted to hear Steve! It will be fun even without the Pcar. I can loan you a Mercedes M-class so you fit in at Timmayfest if you need. Lord knows Beth will drive her Corvette to the GERMAN CAR SHOW just because she wants to.

 

11.8x at 116.xx for a SLK is strong. Believe it or not, your car is 100 lbs heavier than a "Chrysler". Mine weighs 3300 with me in the drivers seat. Grip proved a 3:27 is worth at least .2. I'm looking, patiently, for a cheap one and you should too. I ran stacked one day and one day only. That day I improved from a best of 12.01 to 11.992. (117.xx) But I iced the engine for the first and only time too. So I can't give the credit to the extra boost. I may be wrong but my opinion is a well tuned 178 is equal to running stacked because of the horsepower required to spin the supercharger outside it's efficiency range. Guran says otherwise. Please keep pushing, that's how we all learn and understand how to get the most out of our cars.

Les

 

Boostmonkey. Are you just using the stock intake manifolds?