Question concerning full load curve

engine : L96 6.0L gasoline engine

Hello,

I have a question concerning full load curve. 

I would like to know the RPM when it reaches 75% spot after reaching the max HP.

For better understanding of my question I have upload a picture. please have a look.

Many engines won't go that far for various reasons.

Too many factors to know.  You would actually have to spin it that fast on a dyno to find your number.  360 hp x 0.75 = 270 hp.  You would have to put it on a dyno, spin it to the peak hp, then keep going until the output dropped to 270.  If that happens at 6000 rpms, you're fine.  If that happens at 7500 rpms, make sure you're behind the bulletproof glass.

You can use dyno simulation software to get a vague idea of where it SHOULD happen, but there are way too many factors to know how it will actually work in real life.  Valve seat pressure?  Valve float? pushrod deflection? intake port flow stall?

I think the question is why do you want to know?  What's the reasoning for the 75% and finding that RPM?

This sounds like a homework question for some reason

This must be the most elaborate canoe ever.

I'm thinking EvanB's guess, just because if it was homework it would be a question that had an answer...

That said, it could be an earnest question, in which case it's... already been answered as far as it can be without filling in more blanks?

No way to know without a dyno and the stones to keep revving.

Dyno.  This is one of those engine characteristics that is wildly different depending on all sorts of factors.

A really good engine will carry power for a long time after peak horsepower.   This allows you to keep winding the engine out after peak, so that when you do finally upshift, you drop down to a higher point on the power curve before peak.  In short, you get more average power down, as compared to an engine that falls off of power or hits a rev limiter soon after peak power.

EvanB (Forum Supporter) said:

This must be the most elaborate canoe ever.

Look at OPs other posts on this forum.  An odd duck for sure.

ProDarwin said:

EvanB (Forum Supporter) said:

This must be the most elaborate canoe ever.

Look at OPs other posts on this forum.  An odd duck for sure.

Oh damn, it's that guy.

I'm about 90% convinced he's someone that came to english as a second language and is just trying to fix his stuff.  The phrases don't usually make sense, but if you take them out and spin them around a time or two then put them back in place you can see what was trying to be said.

In reply to ProDarwin :

I've seen them all. They keep getting more odd with each one.

Taking it at face value what the OP needs to know is most likely defined by the cam, heads and valve train they are using. 
 

This is actually an interesting problem that I would have to be aware of when building an engine.  I would build engine to spin put to 8k safely.  To keep this simple I will use some hypothetical numbers but say you were at 75% power at 6k 100 percent at 7k and 75% at 8k. I would tell the user to shift at 8k and have the gear sets set up such that you never went below the 6k on an up shift. This would net you a faster car then if you shifted at 7k and dropped to 5k on the up shift because you would be dropping down to say 60 % power that would have to build back up to the 75% as it tried to accelerate and it would do this slower as you were in a lower part of the power band. Versus never letting the power being applied to the driveline get under 75%. 
 

So yes the OPs question is a very important thing to know and understand when building a motor and is tied to the rest of the vehicles driveline and how it is set up. In some cases I would build the motor to the driveline of the car and in other cases I would build the motor and then make the driveline work optimally with the motor (think quick change rear ends and custom trans gear sets). Tires are also a factor but I figure that is a given.