[zx9rmal]

So, being a CPA, I like fu***ing with numbers.

The SS is rated at 455 hp and dynos at around 400 hp. The ZL1 is rated at 650 hp and dynos at around 550. That's a drivetrain loss of 12% for the SS and 15% for the ZL1. Let's assume both are manuals.

Why the difference?

[SSDan]

Part of it would probably be parasitic power loss to spin the supercharger.

[zx9rmal]

Originally Posted by SSDan

Part of it would probably be parasitic power loss to spin the supercharger.

Good point, but wouldn't that already be part of the 650 hp crank rating, which is being put through the drivetrain?

[CW3SF]

In my experience manuals have less drivetrain loss than autos. Usually 11-12% for manual and 14-15% for an auto. Are you sure you comparing manual to manual?

The difference would not be due to the supercharger. The flywheel horsepower rating has already accounted for the parasitic loss of the belt drive.

[minn19]

Originally Posted by zx9rmal

So, being a CPA, I like fu***ing with numbers.

The SS is rated at 455 hp and dynos at around 400 hp. The ZL1 is rated at 650 hp and dynos at around 550. That's a drivetrain loss of 12% for the SS and 15% for the ZL1. Let's assume both are manuals.

Why the difference?

I'll still take the extra 150 at the wheels. I like numbers to.

[SSDan]

Originally Posted by zx9rmal

Good point, but wouldn't that already be part of the 650 hp crank rating, which is being put through the drivetrain?

Yeah - you're right - my pandemic "stay at home" addled brain isn't firing on all cylinders.

[Crushed 1LE]

eLSD?

[LT4Greg]

I would think the engineers factored in the driveline hp loss in the final hp numbers.

[Stephen12ZL1]

It's just like the numbers you report to the IRS...certain unfounded numbers look better than others. 650/650 sounds better than 640/640

[CW3SF]

Originally Posted by LT4Greg

I would think the engineers factored in the driveline hp loss in the final hp numbers.

Actually they don’t. The rated hp numbers are for the engine at the flywheel. Which driveline the engine goes into (auto or manual) is not considered and does not affect the rated number.

[rdrfronty]

Also most ZL1 manual cars running 93 octane are closer to the 565-570whp average range. So that puts your drivetrain losses closer.
91 octane cars are closer to the 550whp you mention.
The 93 vs 91 octane makes more difference on LT4's than LT1's.

[zx9rmal]

Originally Posted by Stephen12ZL1

It's just like the numbers you report to the IRS...certain unfounded numbers look better than others. 650/650 sounds better than 640/640

Ahhhh. You know how I play that game. And notice what's more important to me. THIS rather than doing tax returns. Of course, the tax returns enable THIS.

[zx9rmal]

Originally Posted by rdrfronty

Also most ZL1 manual cars running 93 octane are closer to the 565-570whp average range. So that puts your drivetrain losses closer.
91 octane cars are closer to the 550whp you mention.
The 93 vs 91 octane makes more difference on LT4's than LT1's.

Good point. I need to go back to the dyno charts I've looked at and see if they indicate the fuel octane.

[Stephen12ZL1]

My 2017 high performance supplement incorrectly shows the horsepower of the LT4 as "640 hp" which may be closer to reality. Most dynos put the ZL1 in the 560rwhp range. Now the numbers seem to work...