Translator

Every dyno sheet on a stock cam/heads C7 with a supercharger appears to have a redline/cut-off around 6200 - 6300 RPM's? Why is that? Someone said that there was no more power to be made above that, so might as well not go all of the way until redline? Are the tuners moving down the actual redline; or are the cars redlining at OEM factory RPM's, but the tuners are not going all of the way on the dyno? Even so, wouldn't it benefit to go until redline in each gear, in order to maximize power in each gear while driving out in the streets? I remember that for the LS2/LS3, the power would also remain flat and not gain much from around 6200 RPM's to a redline of around 6500 RPM's; but the dyno's for supercharged LS2/LS3's would wind out at OEM redline. The LT1 appears like a strong engine, and is holding boost at enormous power levels, so I do not think that the engine longevity is the case for the lower RPM cut out. Or is it a case that the cam and heads on the LT1 just does not flow well above 6200 - 6300 RPM's? I would think that one would want to wind it out to redline, in order to maximize boost and efficiency in each particular gear. Now, I understand for example why some would lower the redline on boosted LS7's from 7K to 6400 - 6600 or so; due to the weaker block and thinner walls and such.

Theta

I've seen plenty here with 6550 maxes, but the power just drops past 6000 anyway.

Look back at the initial SC runs (threads from 1-2 months ago), and you'll see everyone pulling to redline. I'm guessing everybody knows now that there's no sense in going higher for no reason.

Translator

Sean, on the dyno sheets that I have seen, the HP does not seem to drop off past 6K, but remains about the same until redline. Look at that dyno sheet from Corvette Connection for the ProCharger system. If this were the case, the TQ starts falling off at the point where it crosses with the HP line at around 5250 RPM's for most vehicles on a dyno. Given that, you do not see anyone shutting the run down at 5250 RPM's. Wouldn't it be advantageous to stay on the same gear until redline making max boost; as opposed to having to shift to a taller gear earlier at a lower RPM with less boost? I must go back to the LS2/LS3's. Most dyno sheets for supercharged applications that I have seen for LS2/LS3's, wind it out until redline; and you also did not see any gains past 6K or so anyways on a stock cam/heads car. So if the previous was the case, why should with the LT1 be any different?

Theta

Not sure, was honestly just a guess. I can grab a bunch of sheets showing them going all the way out, but I see what you mean with the latest batch of dyno sheets.

Using your analogy of 5250, though, the max wtq would have been found, but not the max whp. In the case here, 6200 is already showing max whp and we already saw max wtq BY 5250.

Translator

Sean, on the dyno sheet below from the ProCharger system, it appears like the HP was still climbing above 6K. This one seems to have been shut down at 6400 RPM or so; but even then, the HP was still not falling.

Higgs Boson

rev limiter is 6600....what's 200 or 300 rpm going to tell you? probably better not to bang the rev limiter on every pull on a supercharged engine that has kits available for a matter of weeks, not years.....

Translator

The above dyno is the highest pull that i have seen at 6400 rpm. Most shut down around 6200 to 6300 rpm. In the above example, power is still climbing above 6k though. Some shops and tuners have throw a lot of boost and put out crazy numbers with the lt1 for a few months now.

Theta

Nearly every sheet I've seen has a massive dip between 6000 and 6200. This is an exception, but of course there will always be strange results out there.

There's no reason to risk taking it to redline (especially on a customer car) on pump gas to dyno queen it unless it's cammed and forged. The 1000+whp cars are taking it all the way to redline, but they're beefed up.

Even on meth, I'm going to be shifting at or before 6000 - no reason to risk it.

Skunkworks

First;
HP = Torque * RPM / 5252
http://en.wikipedia.org/wiki/Horsepower
Not sure where this hang-up with 5252 came from? Peak torque occurs at highest volumetric efficiency, on a highly tuned/optimized 1000cc motorcycle engine that will be around the 10,000 RPM range, on a large stationary diesel can be as low as 1200 RPM.

Second;
The E92 ECM is not anywhere near completely cracked (reverse engineered) or understood for that fact. The E92 is holding engine back, VVT may also be a small contributing factor. GM is using a torque based driver demand model in ECM which is new to Corvette. As mention above, it’s barely cracked and just starting to be understood, could even be a hardcoded limit that is being bounced of off.

My experience with E92 is limited at this point, but will say it’s a different beast.

Theta

Sorry Skunk - caught that typo after reading it again. Should have been BY 5250, not AT 5250.

3 Z06ZR1

Why beat the car. I noticed my tuner does the same thing.
maybe 1 run to run line the rest are short of red line on purpose.
one reason is heat rdline equal a lot of heat.
Then he treats it like it's his car! A lot of tuning stuff is done way below redline. Finished dyno show 5800 rpm and 585 rwhp on a Mustang. Added a bigger blower left the tune alone because In watched him all fuel was Maxed after a point.
Then just read the plugs. Ran hard with more then the 585 the sheet said.

Theta

Another explanation is the 'safety zone' of the HPFP - I wouldn't want to go lean with boost @ 6500rpm when it starts to sputter.

That's the nice part about using meth for fueling is not having to worry about that.

But I'll stick with the opinion of babying customer cars now that these are no longer shop-owned examples as we've seen go to redline in the past!

MitchAlsup

The 50 MegaWatt (power generating) engines run at 105 RPMs, but they do get 50% thermal efficiency out of the #2 fuel oil used.

0ProChargerTech

HOPE THIS CLEARS THIS UP

We likely have hundreds of dyno pulls under our BETA and R&D program with C7's, and can shed some light on this.

With the stock cam shaft, boost, and the limits of middle of the road pump fuel, we have seen no significant gains in HP going past where you all are seeing these dyno pulls stopping.

GM did a very good job with the camshaft and VVT settings to create a very efficient power and tq producing engine. Sure you can play with them a little hear and there, but no real "shatter the world" results were had.

Plus keeping the rev-limiter in the stock setting, helps ensure that rods and other rotational parts are happy, since we all know how much stress of more RPM puts on a motor vs. more power.

Also on some dynos its better to cut the run a couple hundred RPM early, to ensure proper data collection. Otherwise that weird spike can happen at the end, which not only looks silly, but skews readings like average power, and tq.

Translator

Thanks for all of the input guys. That is much appreciated. For most of the times, I would be driving my supercharged C7 in a docile manner; but it would be fun at times to do some highway pull's shifting just before redline.

@ ProCharger. By no means would I ever want to increase the OEM redline (unless if I did heads and cam with the supporting valve train modifications with no boost). With the tunes that you all supply, is the OEM redline maintained, or decreased?

0ProChargerTech

We leave the revlimter stock on this application.

Some applications such as the 5.0L Mustang we raise them, because of the power gains to be had, and proven reliability of the motor at elevated rpm levels.

Translator

Duly noted. We have to give props to Ford, as the 5.0 is a beast of a "breathing" motor; and to think that it is used on a car such as the Mustang GT at a really attainable price point. I have seen some videos of ProCharged 5.0's; and they are beasts.

0ProChargerTech

We have four of them that "live here" full time at the company.

2011 GT, stock motor, stick car, 7.5psi from an i-1
Goes 10.87@131 on 91 octane tipping the scales at 3850lbs
(Company Track Car)

2013 GT, stock motor, stock auto, stock down to the mufflers. 10psi from D1SC
Goes 10.72@131 on E85.
(Engineers Daily Driver)

2014 GT, stock motor, stock auto, convertible, on stock 19" tires. 7.5psi i-1
Goes 11.65@don't remember (spins through first 2 gears), daily driver/kid hauler.
(Company Car)

1989 Fox Body Coupe, stock GT motor, 10psi from D-1SC
Makes 700.3rwhp on 91, plus a little meth. No track times yet, car is very light though, should fly.
(Blower Assembly Technician)