STILLEN 370Z Supercharger System - Announcement!!!

Phimosis

'An off-road only car owned by someone I know' was sent to Stillen to have them do a pre-CARB supercharger install. The sales department at Stillen said that the first kits they produced were making 8 lbs of boost on the dyno, but were making more when being driven on the street. Now they are shipping their kits with a re-sized pully to keep boost at 8 lbs while being street driven. This particular car was installed with the new pulley. It already had Stillen high flow catalytic convertors, Stillen headers, Stillen cat back exhaust and Stillen G3 intakes on it. Previously it was tuned with an 8,000 rpm redline and made almost 15hp more, but was reverted to the factory tune for the baseline prior to supercharger install.

Here are the dyno results:



Here are my observations/impressions:

1) Based on previous dyno's results on this car the combination of headers, cats, intakes and exhaust netted 27 hp over stock, with the 8,000 rpm tune, it was 40hp above stock. Using that data; this car without ANY mods on Stillen's dyno should have dyno'd at 287 whp (314-27). This gives a decent indication of how optimistic Stillen's dyno is.

2) If you estimate that this car would have dyno'd an additional 13 whp for the previous 8,000 rpm tune, it would be around 327 whp for an "all bolt on setup." If you also guesstimate that this car would have dyno'd at least 10 whp less if it had stock cats and headers, that would be 412 whp with S/C. So, for those comparing S/C with exhaust vs N/A with intake, headers, cats, exhaust, and tuning, the S/C route only has about an 85 whp advantage.

3) When Stillen released this product and advertised 515 hp, they used a 15% frictional loss in their hp estimate from their dyno numbers (515 x .85 = 438). Using the same 15% estimate, this car would be making 497 hp.

4) Based on Stillen's advertisement of 515 hp on a car with cat back exhaust and otherwise stock, I was expecting to see at least 525 hp with the cats and headers. So the pulley change to keep boost down is costing (educated guess) around 30 hp.

5) On the dyno chart, the torque curve post supercharger is 18 lb/foot lower than the baseline at 2,800 rpm. LOOK CLOSELY HERE. This is not artifact. On the baseline setup, the torque progressively goes up at throttle tip in and peaks once the throttle is open. Then the VVEL keeps the torque curve nearly flat. After supercharging, the torque goes down at throttle tip in, then comes back once the computer has sorted things out. It happens every time you abruptly open the throttle. It takes about 500 milliseconds to do this, but it's annoying as hell. The driving impression: you get is good torque until half throttle, then bog if you go to full throttle. It's really annoying to have to remeber to squeeze the throttle open rather than whack it open, especialy at 60 mph in high gear (like if wanted to pass someone, although I doubt this 'off-road only' car would ever see that kind of manouvre). This phenominon would happen on big Holly double pumper 4 barrel carbs on a small displacement V8's. When you whack the throttle open, the A/F ratio goes too rich and power drops. Also, I had the first year ('98) Suzuki TL1000R, which had fuel injection, and about 10% of the times that you whack the throttle open, it would bog. Most times it worked fine. A/F ratio? Ignition advance? Interestingly, the A/F ratio after supercharging is much richer than the stock program on throttle tip in. Could this be the culprit? Regardless, I think this can be fixed with some tinkering and an ECU update.

6) Using the old addage that it takes about a 30 hp upgrade before you can notice a difference in power, that 30 hp difference doesn't occur until 5,000 rpm. Realistically, I notice a difference at 4,000 rpm. But don't be fooled, opening the throttle at 3,000 rpm doesnt produce torque like an american V-8.

7) In a racing situations, keeping this engine wound as tightly as possible, 7,500 rpm shifts will drop you back to 6,000 rpm. At 6,000 rpm it's making 340 whp. Comparing this to a Nissan GTR, which dyno's about 10 whp higher (430 whp average of 3 runs, motortrend 2009), you only need 4750 rpm to get 350 whp. What does this mean to you? A gtr is going to have a wider useable power band (4,750 to 7,000) vs (6,000 to 7,500).

More to come later.....

Gunzero

^can you put an rb engine in my z

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RCZ

Someone needs to fix this immediately... it is annoying as hell when you "whack" the throttle. My ECU seems to be doing the same thing.

shumby

Mines not.

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Originally Posted by SAM@GTM
Engine detonation is not normal and it should never never happen, and whoever told that need to do something else for living .
Sam

NewYorkJon34

So is this throttle issue going to be the first "problem" of buying the supercharger? Or will there be a fix in the tune?

RCZ

Stock cars do this too, there's a whole thread about it.

Shumby: If you would please record a video of you mashing the gas so we can see what happens.

Phimosis

Some stock cars may do it, just like my Suz TL100R did it, but MY car didn't do it until after the supercharger.

On a side note, I'm pretty sure it's not the supercharger, it's the tuning. Also, that issue isn't real appearant if you tune a car on the dyno and take it to an off road course and flog it. It's only when driving it mildy in low rpm situations that it's a problem.

JB-370z

Sorry to hear that, I hope Stillen gets this all squared away. Maybe looking into so mods to help responsiveness. Either way im sure there will be a fix

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ll Baker Tuning ll GTM ll Powerhouse Amuse ll HKS ll Up-Rev ll iForged ll AP Racing ll Pioneer ll SPL ll Bride ll Top Secret ll OS Giken ll
GTM Stage 2 Twin Turboed 370z (First in Texas, Thanks To Baker Tuning)

shumby

will do it will be on or around the 25th of july wheni get back to Canada. I was not tying to be a smart *** but mine really does not do this.

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Originally Posted by SAM@GTM
Engine detonation is not normal and it should never never happen, and whoever told that need to do something else for living .
Sam

Jordo!

Lag on tip in probably just means they need more inj and/or ign correction... it's easily tunable after a little street time.

The torque curve looks nice and flat... that said, it'll take a roots blower to give it significant grunt off the line. For a centrifigul blower, looks pretty good to me.

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Enjoy it. Destroy it.

LateralG'z

This is looking great, definitely sounds like a tune issue, would agree it sounds like a rich condition

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2010 Mag Black, 6MT,

Jordo!

Actually, if they didn't mess with accel enrichment, but added boost, my guess is it's probably skewing very lean on tip in...

Although ideally you want it to quickly arrive at the target AFR for the next map cell, as a general rule of thumb, skewing rich will tend to feel less laggy than skewing lean.

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Enjoy it. Destroy it.

Chris@FsP

There is no acceleration enrichment adjustment on Osiris. Enrichment / enleanment is all controlled by the ECU in the background. If your K value is adjusted correctly, throttle tip in should not really be affected when going to larger injectors on a boosted setup.

Phimosis

You can see on the graph it is rich on tip in (sorry its hard to read, I snapped a photo of the dyno sheet with my iphone)....Around 11.0:1 then quickly leans to around 11.6:1 and hangs there throughout the rev range. At 5,000 rpm this tune is only making 30 hp more than my baseline run. How rich does it really need to be at those low rpms? The supercharger is not making much boost yet.

The stock curve (which makes great power) is at 15:1 at tip in and then quickly goes to 13.5:1, then trends down to 13:1 by 5,000 rpm, then 12.15 at redline. 14:1 is going to make the most power, but runs hot. Most sports cars run around 12.5:1 for power and economy. Tuners go into the 11:1 range for quench and to keep cylinder temps down. They use it for safety, but it hurts power output, fuel economy and emissions. Having an 11:1 A/F ratio at 3,000 rpm when the S/C is making 1-2 pounds boost is counter productive. Having 11:1 A/F ratio at 8,000 rpm and 10 pounds of boost is a really smart idea.

RCZ

right, but is that tuner controlled or is it the ECU doing something beyond our control?

Sounds to me like it would happen at tip in even if the target was AFR was leaner...