GT Redline

[Hack]

Do any of the current tuners raise the fuel cut off points? Have dyno data on the power curve past the stock cutoff point?

There was a video posted earlier in this thread that addresses your questions.

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[Hack]

OK...making that statement is your right...so far. Now, prove to us that we're wrong.

Are you using the royal "we" here? ;)

You said it...MAX hp with 93 fuel is made at 6500....power is made, but, at what price? For what reason going any farther?

Let me start with asking this: Are you serious with these questions?

 

[DivineStrike]

Grintch, at those rpm levels valve float shouldn't be an issue

 

[Grintch]

Vorslag's TT3 car rev'ed to 7500 with stock internals and valve train. I also reran the numbers based on those dyno results and got higher optimum values, suggesting my power roll off assumptions for your data were conservative.

I will post the file whan I get home.

 

[Katastrophe]

These are the results from the Steeda power pack for the 11-14 5.0's. FYI, it includes a CAI, Boss manifold and tune. Note that they provide a tune up to 7500 RPM...and if you know Steeda, they don't really do aggressive tunes...they are all about safely providing increased performance.

http://www.steeda.com/images/thumbnails/902/650/detailed/6/555-3939-1.jpg

Other companies with Boss manifold packages had tunes higher...7700+ RPM and now on the 2015 5.0's, up to 8000 RPM as was the case with the video I previously posted. On the stock manifold however, these types of RPM's aren't typically used as the car will fall on it's face a bit...11-14 5.0's more so than the 15 5.0 with it's revised manifold.

 

[Grimace427]

Vorslag's TT3 car rev'ed to 7500 with stock internals and valve train. I also reran the numbers based on those dyno results and got higher optimum values, suggesting my power roll off assumptions for your data were conservative.

I will post the file whan I get home.

Vorshlag actually reved to 7,800rpm for over 4 years of competition with their 2011 5.0, and it didn't even have the Boss intake manifold.

These are the results from the Steeda power pack for the 11-14 5.0's. FYI, it includes a CAI, Boss manifold and tune. Note that they provide a tune up to 7500 RPM...and if you know Steeda, they don't really do aggressive tunes...they are all about safely providing increased performance.

http://www.steeda.com/images/thumbnails/902/650/detailed/6/555-3939-1.jpg

Other companies with Boss manifold packages had tunes higher...7700+ RPM and now on the 2015 5.0's, up to 8000 RPM as was the case with the video I previously posted. On the stock manifold however, these types of RPM's aren't typically used as the car will fall on it's face a bit...11-14 5.0's more so than the 15 5.0 with it's revised manifold.

My current Steeda tune is set to 7,600rpm in my 2011 and I have a Boss intake manifold to match.

 

[Hack]

OH MY GOD, the power has dropped off 5 hp. I need to shift now where the engine will have 70 less hp in the new gear [with less torque multiplication].

Per your chart HP at ~6750 - 375
HP at ~ 4600 - 305 (RPM after a 1-2 shift)

Do I need to explian why having 305hp is slower than having 375? Basicly you don't want to shift until you will have the same or more horspower at the new rpm point in the next gear. This is why shifting at your power peak is stupid, because it guarantees that this will not be the case.

Another approach for determining optimum shift points is to calculate the torque x the gear ratio, and shift when the that value in the next gear is the same or greater than in the current gear. I have to do some extrapolating of the 6500+ drop off and will do that tommorow.

Well said.

You can also just experiment at the drag strip to learn what works best for you, but the math is a helpful guide.

 

[Katastrophe]

Vorshlag actually reved to 7,800rpm for over 4 years of competition with their 2011 5.0, and it didn't even have the Boss intake manifold.




My current Steeda tune is set to 7,600rpm in my 2011 and I have a Boss intake manifold to match.

Was that on request by you, or does Steeda have their basic Boss manifold tunes set at that RPM? Either way, thanks for putting a few cents in here. The misinformation floating around these forums is getting ridiculous at times.

What did Vorshlag have done to their engine? I'd be interested in seeing what kind of power they made along the rev range, considering the stock manifold has a tendency to drop off at high RPM's. I guess a better question would be: at what RPM did they actually shift the car?

 

[DivineStrike]

Well said.

You can also just experiment at the drag strip to learn what works best for you, but the math is a helpful guide.

Just throwing this out there that my talk about shift points are in reference to a Stock tune. However I will admit I hadn't thought about there being a better shift point, and never thought about the actual math either.

That said it seems most engine builders try not to waste power on usable rpm just to benefit a shift point. I don't see any real reason for them to either. I see it being much more beneficial for them to eek out as much peak power towards the end of the rev range as they can by using the appropriate tune, intake, or cams. Obviously not quite the case with mass produced cars.

 

[Norm Peterson]

That said it seems most engine builders try not to waste power on usable rpm just to benefit a shift point. I don't see any real reason for them to either. I see it being much more beneficial for them to eek out as much peak power towards the end of the rev range as they can by using the appropriate tune, intake, or cams.

Crudely, an engine tries to be a constant-torque device, so building in more power requires higher rpm (HP = T x RPM / 5252). The fact that torque curves all drop off once you pass the torque peak only makes RPM more important for achieving peak power increases. As your build-up requires rpms that approach the mechanical limits of your engine, you don't get to use much (or possibly any) of the back side of the power curve, even though there would be something useful out there if only you could get at it. Using some of RPMs on the far side of peak power would still provide more "area under the curve" than you get from shifting precisely at peak power rpm. Keep in mind that "area under the curve", with the low RPM end defined by upshift rpm and gear spacing, will provide a more complete picture of acceleration than any single power & rpm data point.

Exactly how far past peak power rpm still provides a benefit depends on gear spacing, the engine's actual power curve, and several other smaller things.


Norm

 

[DivineStrike]

I understand the usefulness of the power after peak... It just seems that most of the time an engine builder tries to maximize its peak power as close as it can to the rpm limits of the engine. Obviously not the case with some production cars, like our coyote which is really only limited due to the intake manifold

 

[Grimace427]

Was that on request by you, or does Steeda have their basic Boss manifold tunes set at that RPM? Either way, thanks for putting a few cents in here. The misinformation floating around these forums is getting ridiculous at times.

What did Vorshlag have done to their engine? I'd be interested in seeing what kind of power they made along the rev range, considering the stock manifold has a tendency to drop off at high RPM's. I guess a better question would be: at what RPM did they actually shift the car?

Yes I told Steeda where I want my rev limiter to be set to. Before the Boss intake my limiter was set to 7,300rpm. I have my original dyno sheet from way back showing over 400rwhp from 6,000-7,300rpm with a peak right at 6,600rpm so I was definitely not wasting any power by shifting higher than stock.


Vorshlag has very little done to their engine. I think they finally replaced their oil pump gears but not 100% sure on that. Otherwise they have a full exhaust and custom tune. Their reason for shifting so high was very specific in that they wanted to extend 2nd gear for Auto-X competition.

 

[15GTBEN]

People saying the 5.0 can't safely be revved to 7200 rpm with the stock manifold are obviously new to the coyote platform...

 

[Grimace427]

People saying the 5.0 can't safely be revved to 7200 rpm with the stock manifold are obviously new to the coyote platform...

Yup, I think a lot of people forget that the Coyote has been out since 2010 and that people have been racing them since then.

 

[Katastrophe]

Yes I told Steeda where I want my rev limiter to be set to. Before the Boss intake my limiter was set to 7,300rpm. I have my original dyno sheet from way back showing over 400rwhp from 6,000-7,300rpm with a peak right at 6,600rpm so I was definitely not wasting any power by shifting higher than stock.


Vorshlag has very little done to their engine. I think they finally replaced their oil pump gears but not 100% sure on that. Otherwise they have a full exhaust and custom tune. Their reason for shifting so high was very specific in that they wanted to extend 2nd gear for Auto-X competition.

I kind of figured that. Staying in one gear longer and revving it out is easier/faster than trying not to waste time managing a fast upshift and downshift. Kind of a similar situation to you and the Texas Mile right? Had better success staying in 5th.

All this talk of revs, though...makes me miss my 2010 Civic SI and that 8,300 RPM K20. Then again...a certain 5.2 could also solve all of my problems...

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