Run # 1 - WITH SL55 Y-Pipe (004.drf)
274.45 hp / 284.13 tq

Run # 2 - WITH SL55 Y-Pipe (005.drf)
273.47 hp / 282.60 tq

Run # 3 - W/OUT SL55 Y-Pipe, stock (007.drf)
283.29 hp / 289.30 tq

Run # 4 - W/OUT SL55 Y-Pipe, stock (008.drf)
280.77 hp / 283.83 tq

-All runs were on a Dynojet dyno, 80* air temp / 95% humidity.
-All runs were done in 4th gear
-Fuse #17 & #18 were removed for dynoing
-Car would hit a 'rev-limiter' at 5,600 rpm. The guy said there is probably another 10 hp if it would hit redline or closer.
-The graph looks 'odd' because you couldn't MASH the throttle without it kicking down to 3rd gear.

I'm anxious to see if anyone dynos their car with the SL55 Y-Pipe AND the SL55 inlet tubes, or even the whole SL55 airbox setup (complete system).

So, in conclusion, with K&N Filters - the SL55 Y-Pipe HURT the car. Remember, I do not have the SL55 Inlet tubes...I made the stock inlet tubes fit (which could defeat the purpose of the SL55 Y-Pipe).



SQ

 

Very interesting, soo its worse with sl55 y-pipe. Are you going with the needswings intake now? Already ordered mine.

 

That's really strange. I was betting on a ~10 HP increase. I bet those factory inlet tubes are to blame for the decrease, but I can't see the SL55 ones making up 20+ HP to get to the 10 HP increase predicted. At this point I'm going to bet that the SL55 Inlet tubes will show numbers close to stock...

 

After talking with the shop owner (who has a few turbocharged stangs, a 9sec blown 05 stang, and experience with several supercharged cars), he says that the shape of the stock Y-Pipe points the air into the blower better than the SL55 setup. He did say that the SL55 Y-Pipe has more volume - so it will possibly help on a car with a pulley setup.

He also said that, obviously, the Y-Pipe is not the major restriction on these cars (which is hard to believe by looking at it).

For the record - I ran the SL55 Y-Pipe first, so the engine/IC temps should've been cooler. Still made less power.

Interesting either way! But, I posted honest results, at least!

I also plan to try it at the track, both ways.

Without being able to open the throttle up through the whole dyno run because it would down shift...we could be missing a low-end gain over the stock pipe. Although the peak power is less, the low end may be what makes it 'feel' faster out of the hole and around town. The track should show this in the 1,000 ft and times/speed, 1/8mile, etc.

Otherwise, I could've been mistaken about the 'noticeable' gain due to the fact that you can hear the supercharger much more and you can hear the intake better.

SQ

 

I plan to order the Needswings kit when the budget allows.

My co-worker also has an SRT-6, and he is actually funding me to do a little 'testing' to try and come up with a decent option to the NeedsWings intake. He doesn't like the look of the NeedsWings intake and wants to keep the car's factory look, or somewhat.

I only spent ~ $40 on the Y-Pipe and parts to make it fit...no big loss. But, it didn't help the car. So, we'll have to come up with a different idea to make more power with the factory look, or just talk him into the NeedsWings kit.

The dyno was $60, but I wanted to do that anyway to get a baseline (he split the cost with me though).

SQ

 

Just my semi-educated opinion (and that of the Bosch Engineers) as mentioned in other threads... In laymans terms, you can dump more gas or more air, or both into this engine and it will not produce noticable HP gains because the Bosch ECU / PCM and sensors are programmed to maintain stociometric AFR... So, the timing will be retarded, fuel will be trimmed to keep it there...

Until you manipulate (tune) the ECU to override the OEM programming, you'll be pissing in the wind...

I'm surprised you guys haven't been searching the earlier threads regarding this issue...

That's why I bust ***** when people start talking about intakes, exhaust, etc. to make more HP in this car, without thinking about the Engine Management Systems that control it...

 

I have to commend you on taking the time, and posting the results! I do like the stock look, it makes the motor look bigger for some reason. I dont think I'll keep the supercharger cover on either, when I put on the NeedsWings intake. So when I pop the hood everyone will see the little monster.

 

Well I guess dumb luck (all on my part) might just work out to my advantage. I choose to wait until I could purchase all the mods at one time with the last mod being the ECU tune.

I hope that my dumb luck (and a set of headers I found will arrive before the Thanksgiving weekend) will work out for optimum performance gains.

So many 3.2L Supercharged owners on the other MB forums including a few I have spoke with on the phone with this week said the stock SL55 AMG V8 intake system has helped with this engine's performance.

Thanks Shawn for your effort posting your results.

HDDP - what shop do you recommend for Engine Tuning?

 

Weren't you saying that the stock A/F on these cars was 14.x? Not sure how that would work on a boosted car...mine is hanging right around 12.

SQ

 

I think this ECU does a GREAT job of adjusting to mods. Check out my ASP pulleys thread and it is odvious this ECU is more than capable to adapt and overcome mods. I was told by several tuners familiar with the car that the ECU can adjust for up to 20%.

Shawn,

Did you give your car time to adjust to the new mods? How many miles did you drive on the new setup before dyno'ing? I noticed more improvement with my intake and pulleys after several hundred miles was driven with them on the car.

BTW don't let the dyno do the talking...take her to the track and do some before and after runs. My car dyno's really low IMO but my track times tell another story.

 

at low rpm the A/F is in the high 14's low 15's and at redline on a stock ECU it should be in the mid 11's.

 

I probably only put about 100 miles on it since I put the Y-Pipe on it. My main goal for the dyno was to get a baseline reading. I got that.

My car still isn't at 2,400 miles either - if they actually 'do' wake up.

And, I DEFINITELY will swap it out at the track next time I go to see if it helps.

For the record - your car was on a mustang dyno (which actually puts resistance on the car)...they always dyno lower. Like you said, the actual 1/4 and street performance is all that matters to me. Some people's cars are 'dyno queens'...I really don't care HOW MUCH it makes, but I like to know how much benefit I get from each mod (if any).

SQ

 

Are you saying that an increase in air will not result in the computer adding fuel to maintain A/F ratio? But instead will just read a lean condition retard the timing?

 

That's the way I read it...and I'm not disagreeing with him (HDDP) at all, just curious if that is how he meant it.

It seems like the car would adjust to minor air increases...it definitely feels like it runs much better when it is colder (dense air = more of it).

SQ

 

Shawn,

Put some miles on that thang!

 

I feel the same as Chi-Town. I bet that once the ECU has time to adjust, the results could be different. My thought is to disconnect the battery for 30 minutes, reconnect and once driving the car for a couple tank fulls - I just can't believe that t stock Y makes more power. It seems that the velocity would be greater with the SL55 especially with a supercharged motor needing to breathe... I could see where it would be too much volume for a N/A motor. I am installing mine when it arrives and I hope my thoughts are correct.

Shawn, thanks for a great write up. I was wondering if you were going to leave it on for a while then take it to the track?

Steve

 

No, That's not quite what I meant, but that's probably because of the way I wrote it... What I meant is that the ECU will do everything in it's power to a maintain stoichiometric state... Which is 14.7:1...

As everbody knows, an internal combustion engine should produce its maximum / optimum HP betwween 12.5:1 to 13.2:1 AFR with a lambda of 0.85... But since the OEM ECU will always try to force this engine to maintain 14.7:1, even if you introduce more air, or more gas into the system, your HP gains will probably be much less than if you just adjusted (tuned) the ECU to optimize the air / fuel to the stock set-up...

Please don't get me wrong guys... this engine WILL benfit from various mods, but it won't develop the HP expected unless you tune it to specific changes... And keep the AFR somewhere in the 13 range...

As far as the previous post stating that the AFR was running at 11:1 under full throttle, I can't discount that fact... (running very rich) I've done many dyno's before and they are usually done full RPM for only a few seconds , which means you MASH the pedal for a few seconds to get a reading at redline... This usually produces a "rich" AFR like 11:1 because you've just stuffed a ton of gas into the cylinders without adding the approriate air... My guess is that if you had maintained that RPM for a minute or so, you would have rapidly seen the AFR go back to the mid 14 range as the ECU adjusted the injectors, timing, etc...

I know I have belabored this point to death, but if you really want to see what happens with this OEM engine when fuel or air is added, you have to monitor the AFR and timing simultaneously... You'll be surprised to see how the ECU adjust things...

 

Oh Dear...I take delivery of my SL55 Y pipe and intake pipes on Tuesday and as I do not have access to a rolloing road, dont think it is worth fitting now. Oh well, I will sit on it for a while (store it for later use, maybe) and see if anyone is able to Dyno with "full Throttle" and some Qtr mile times. If it does show an improvement I will fit it straight away.

I must say I am very supprised by the results. Does the ECU retard timing until the engine is up to temp ? My Subaru used to and it also cut Boost until the car was warmed up. This may account for lower readings.

I am really keen on hearing the supercharger a bit more, but don't want the "non stock" appearance of the "Needs Wings" set up (I would like some gain though).

Does the SL55 Y pipe keep the air/fuel mix in "safe" limits?


Also I would be very supprised if the SL55 Y pipe flowed more air than the "Needs Wings" set up........it's so bizarre.

 

At high load and 14.7, you will hole a piston, lift a ring land or pop a head gasket! Most ECUs stop takeing input from the O2 sensors at around 75% throttle and stop trying to acheive 14.7 way before that. At WOT on a N/A engine , best (and safe) power is acheived at around 13.5-13.7. On a forced induction engine it is around 12.5-12.7. The reason these things run so darn rich is becuase rich is safe.

As far as showing a rich condition on the dyno because "You just stuffed a ton of gas in the cylinders" is kinda true. The first 1-2 hundred RPM of the pull will show a slightly over-rich condition from the ECU's " accelerator pump" just trying to get the engine going. After that, it is just the fuel map.

I'm not a Bosch engineer, but I am a race engine builder by trade. After 14 years it is the only career I've everknown, so I know it pretty well (but learn new things everyday). An engine is an engine, no matter what manufacturer is on the valve covers. Engine managment systems (ecu) will need to keep the fueling in certain parameters or bad thing will happen.

-Jeremy

 

This is basically what the dyno-operator told me. He said at 14.7, the engine would self-destruct (supercharged). He said an N/A engine would be OK...but boosted would blow, if I remember correctly.

I'm not very knowledgeable in A/F and its effects. I know lean is bad, but fast...too lean is fatal.

He did say my A/F was right where it needed to be.

Interesting discussion regardless.

HDDP, how much of your research has been on the SRT engine you have now, vs. the N/A stocker you had?

SQ