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OK,Guys and Girls......I've had several vehicles dynoed ...and my GS done for a second time this week because of a cam package I had done on top of the SC.......
Step 1...Lets take a stock LS-3 Motor which from the factory is 430 hp...
All motors,NHRA,NASCAR and most engine builders Dyno their motors in a controlled environment,68 degrees,no transmission,water pump,alternator,power steering pump etc....
GM did the same thing and came up with the 430 hp for the LS-3 Right??
What is this Hp?...With no tranny it should be RWHP (brake hp) right??
If it's 430 hp and after you put it in car and add transmission you need to subtract 15% for standard tranny or 20 % for automatic and another 15 hp +\- for the drag from belts to A/C,Alternator,water pump and power steering etc Right???
430 rwhp-GM Dyno
64.5 Minus 15 %for standard tranny
15.0 minus for drag from belt driven accessories
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350.5=true hp correct?
This is what a Dynojet should be reading on a base Dyno run with minus 10% on a mustang Dyno.......
Help me out....What is the crank hp for a 430 hp LS-3....autos and standard are going to be different But GM calls them both 430 hp on sticker price.....
How are autos and manuals going to be different hp at the CRANK?
You're assuming GM removes water pump, alternator, etc. That isn't true and hasn't been for a long time
You're also assuming 15-20% loss. That has been proven wrong many times as well
430 rwhp-GM Dyno
No. If GM advertises is as 430HP then that is at the motor WITH accessories and exhaust. That is NOT a RWHP rating. Transmission doesn't matter for this rating.
How are autos and manuals going to be different hp at the CRANK?
You're assuming GM removes water pump, alternator, etc. That isn't true and hasn't been for a long time
You're also assuming 15-20% loss. That has been proven wrong many times as well
No. If GM advertises is as 430HP then that is at the motor WITH accessories and exhaust. That is NOT a RWHP rating. Transmission doesn't matter for this rating.
So your saying when you add a transmission to the motor and put it in the car there is no loss for transmission and it should Dyno 430 rwhp on a Dynojet...Not trying to be an ***,just trying to find answers,left a message for call back from a GM rep in engines...we will see if he calls me back.
Thanks
I'm not sure if you aren't understanding what power at the "crank" means or something else? Your response is pretty much the opposite of what I said.
The rating GM gives is based on measurements AT THE MOTOR. Period. No transmission. No wheels. No rear end. AT. THE. MOTOR.
Put the motor on an engine dyno, all accessories/exhaust on it (no transmission) and 430hp is what you should get. Or at least very close. This is what the GM numbers are based on.
It doesn't matter what transmission they get because GM rates them based on how much power they are making AT THE ENGINE only. They don't advertise what they make at the wheels.
If you measure the power at the wheels it WILL BE LOWER than 430hp due to drivetrain losses.
I'm not sure if you aren't understanding what power at the "crank" means or something else? Your response is pretty much the opposite of what I said.
The rating GM gives is based on measurements AT THE MOTOR. Period. No transmission. No wheels. No rear end. AT. THE. MOTOR.
Put the motor on an engine dyno, all accessories/exhaust on it (no transmission) and 430hp is what you should get. Or at least very close. This is what the GM numbers are based on.
It doesn't matter what transmission they get because GM rates them based on how much power they are making AT THE ENGINE only. They don't advertise what they make at the wheels.
If you measure the power at the wheels it WILL BE LOWER than 430hp due to drivetrain losses.
Thanks,that's what I'm looking for......Do you agree when the motor is put in vehicle and dynoed it will be reading 12 to 15% less with a standard transmission and 18 to 20% less with an automatic?
All motors,NHRA,NASCAR and most engine builders Dyno their motors in a controlled environment,68 degrees,no transmission,water pump,alternator,power steering pump etc....
The SAE J1349 standard is 77 degrees inlet air at 29.31 inHg.
I think those percentages are high, and that drivetrain losses aren't really a "percentage" of total power (though the internet tends to always act like it is..). I would say it takes a certain amount of power to spin the drivetrain. Having a higher or lower output engine doesn't change how difficult it is to spin the transmission/rear end and wheels.
The power at the wheels as measured by whatever dyno you want to use will be lower than the output measured on the same engine on an engine dyno. That is for sure... the question comes down to how much different should it be?
So.. the short answer is yes, the power at the wheel will be less. Will it be 12 to 20% less? I don't know.
But there have been enough dyno pulls on stock cars done that you can do some searching and do the math to see what other people are seeing for stock'ish power levels.
What I prefer with a dyno is consistent repeatable results, the same dyno. If you are doing before/after runs you know have numbers that make sense.
Dyno's also measure different ways such as load bearing vs inertia. Load bearing generally is calibrated by weight of the vehicle & load @ 50 mph, inertia by spinning of weighted drums. Both will display differently & both are correct, the internet likes to try & compare the two.
It's gains & loses that matter, comparing different measurement's by percentages is in my mind a guess. Possibly a ball park estimate to see if your in that particular game should you be trying to play.
I see a lot of variation from model to model same dyno never mind comparing load bearing to inertia. That can be from lack of calibration or individual's manipulating results. I've first hand experienced manipulation of displayed numbers.
The same applies to engine only dyno's, if you wanted to verify your LS3 you need to know how GM is doing it. Results may vary form different dyno manufactures & procedure's. My guess would be that if you verified your LS3 @ the crank your results would be higher than GM published numbers.
Here is a pic of a ls3 getting tuned at the GM factory....and what I'm reading is they are getting around 492 hp with headers no tranny and other belt accessories...When installed in car with tranny and accessories it is getting the advertised 430 rwhp.....I was hoping with 200,000.00 members on here that one worked on the engines at GM......
Until one of those guys gets on here we still don't know...
Here is a pic of a ls3 getting tuned at the GM factory....and what I'm reading is they are getting around 492 hp with headers no tranny and other belt accessories...When installed in car with tranny and accessories it is getting the advertised 430 rwhp.....I was hoping with 200,000.00 members on here that one worked on the engines at GM......
Until one of those guys gets on here we still don't know...
That is not a stock LS3. The throttle body is an MSD 103mm, and it has an electric waterpump.
Pull the sae standard they are tested with if you want the details. It is full accessories in set test conditions. Percentages for drivetrain has been proven wrong time and time again.
Pull the sae standard they are tested with if you want the details. It is full accessories in set test conditions. Percentages for drivetrain has been proven wrong time and time again.
So your saying there is no drivetrain loss?....or how much loss do you think there is?
He's saying it isn't a percentage, i.e. the power needed to turn the drivetrain doesn't increase with engine power. That doesn't mean there aren't losses from the drivetrain. Of course there are losses from the drivetrain.
06-25-2016, 06:44 PM
Anybody mind answering a few Dyno questions?
