Back from the dyno....
4th Gear Member
Joined: Dec 2008
Posts: 1,478
From: Tulsa, OK
Assuming 15% drivetrain loss, at 497 RWHP you are at 585 hp at the crank.
Thread Starter
2nd Gear Member
Joined: Jun 2009
Posts: 386
From: North-Jerzeeee
6th Gear Member
Joined: Apr 2007
Posts: 10,468
From: California
Why does everyone always assume 15%? I guess that number has been thrown out there so often.
Drivetrain loss varries with a whole ton of variables. Higher rpm = more drivetrain loss due to increased friction in the gear clusters and bearings, more power at the crank = more drivetrain loss due to friction from higher pressure at the gear tooth contact points....fluid drag, rotational inertia(which means the FASTER the car accelerates, the higher the drivetrain loss while accelerating)and so on and so forth.
Most production cars cruising down the highway at a steady 65mph have 1% drivetrain loss or LESS. Some newer high performance cars have managed to get losses in manuals down to 10-13% at max power, but that's at the factory power output. Most modified cars are going to be seeing drivetrain losses higher than stock. The more power over stock, the more drivetrain loss increases.
Assuming a stock 3V has a drivetrain loss of around 12-13%, at those kinds of power levels it probably is closer to 15% loss, perhaps as high as 17% or more.
Most people simply assume drivetrain loss stays the same as stock because they never modify a car and chassis dyno it, then yank the engine and engine dyno it and compare. But if you did, you'd see the more power you made and the more rpm you turned, the greater drivetrain losses would become. How much greater depends on the transmission design in part.
Drivetrain loss varries with a whole ton of variables. Higher rpm = more drivetrain loss due to increased friction in the gear clusters and bearings, more power at the crank = more drivetrain loss due to friction from higher pressure at the gear tooth contact points....fluid drag, rotational inertia(which means the FASTER the car accelerates, the higher the drivetrain loss while accelerating)and so on and so forth.
Most production cars cruising down the highway at a steady 65mph have 1% drivetrain loss or LESS. Some newer high performance cars have managed to get losses in manuals down to 10-13% at max power, but that's at the factory power output. Most modified cars are going to be seeing drivetrain losses higher than stock. The more power over stock, the more drivetrain loss increases.
Assuming a stock 3V has a drivetrain loss of around 12-13%, at those kinds of power levels it probably is closer to 15% loss, perhaps as high as 17% or more.
Most people simply assume drivetrain loss stays the same as stock because they never modify a car and chassis dyno it, then yank the engine and engine dyno it and compare. But if you did, you'd see the more power you made and the more rpm you turned, the greater drivetrain losses would become. How much greater depends on the transmission design in part.
Thread Starter
2nd Gear Member
Joined: Jun 2009
Posts: 386
From: North-Jerzeeee
Why does everyone always assume 15%? I guess that number has been thrown out there so often.
Drivetrain loss varries with a whole ton of variables. Higher rpm = more drivetrain loss due to increased friction in the gear clusters and bearings, more power at the crank = more drivetrain loss due to friction from higher pressure at the gear tooth contact points....fluid drag, rotational inertia(which means the FASTER the car accelerates, the higher the drivetrain loss while accelerating)and so on and so forth.
Most production cars cruising down the highway at a steady 65mph have 1% drivetrain loss or LESS. Some newer high performance cars have managed to get losses in manuals down to 10-13% at max power, but that's at the factory power output. Most modified cars are going to be seeing drivetrain losses higher than stock. The more power over stock, the more drivetrain loss increases.
Assuming a stock 3V has a drivetrain loss of around 12-13%, at those kinds of power levels it probably is closer to 15% loss, perhaps as high as 17% or more.
Most people simply assume drivetrain loss stays the same as stock because they never modify a car and chassis dyno it, then yank the engine and engine dyno it and compare. But if you did, you'd see the more power you made and the more rpm you turned, the greater drivetrain losses would become. How much greater depends on the transmission design in part.
Drivetrain loss varries with a whole ton of variables. Higher rpm = more drivetrain loss due to increased friction in the gear clusters and bearings, more power at the crank = more drivetrain loss due to friction from higher pressure at the gear tooth contact points....fluid drag, rotational inertia(which means the FASTER the car accelerates, the higher the drivetrain loss while accelerating)and so on and so forth.
Most production cars cruising down the highway at a steady 65mph have 1% drivetrain loss or LESS. Some newer high performance cars have managed to get losses in manuals down to 10-13% at max power, but that's at the factory power output. Most modified cars are going to be seeing drivetrain losses higher than stock. The more power over stock, the more drivetrain loss increases.
Assuming a stock 3V has a drivetrain loss of around 12-13%, at those kinds of power levels it probably is closer to 15% loss, perhaps as high as 17% or more.
Most people simply assume drivetrain loss stays the same as stock because they never modify a car and chassis dyno it, then yank the engine and engine dyno it and compare. But if you did, you'd see the more power you made and the more rpm you turned, the greater drivetrain losses would become. How much greater depends on the transmission design in part.
6th Gear Member
Joined: Feb 2007
Posts: 11,302
From: North Carolina
67 knows too much, lol! Just kidding, very informative as usual. Now if I could just retain that info for more than 5 minutes.
NJ, those are some impressive numbers, man. Just be easy on her and try not to rev it too high too often until you get the build finished. I bet that thing pulls pretty hard.
NJ, those are some impressive numbers, man. Just be easy on her and try not to rev it too high too often until you get the build finished. I bet that thing pulls pretty hard.
Thread Starter
2nd Gear Member
Joined: Jun 2009
Posts: 386
From: North-Jerzeeee
67 knows too much, lol! Just kidding, very informative as usual. Now if I could just retain that info for more than 5 minutes.
NJ, those are some impressive numbers, man. Just be easy on her and try not to rev it too high too often until you get the build finished. I bet that thing pulls pretty hard.
NJ, those are some impressive numbers, man. Just be easy on her and try not to rev it too high too often until you get the build finished. I bet that thing pulls pretty hard.
6th Gear Member
Joined: Apr 2007
Posts: 10,468
From: California
Could always give it a really conservative tune, reduce power and makes sure it lives. I don't know if I'd have the discipline enough to not lay into it. Or I would do it to blow it up as a justification for getting a new shortblock 
Mish-ogynist
Joined: Nov 2007
Posts: 3,784
From: Helena, MT
welll.. there are people holding at 500whp.. and people who have blown under 400whp.. infact, i think it was JDM who had someone blow up under 400whp on their dyno.. they hadn't touched the car yet though. there is more to it, but.. I agree you are playing with fire.. and an alluminator block is a hell of a lot cheaper than any alternatives ive seen.. and can hold a lot of power... you'd need a big turbo setup to run beyond the power that block can hold.
@ctgreddy, the problem is with the rods.. they are regularly compared to toothbrushes..
@ctgreddy, the problem is with the rods.. they are regularly compared to toothbrushes..
Thread Starter
2nd Gear Member
Joined: Jun 2009
Posts: 386
From: North-Jerzeeee
welll.. there are people holding at 500whp.. and people who have blown under 400whp.. infact, i think it was JDM who had someone blow up under 400whp on their dyno.. they hadn't touched the car yet though. there is more to it, but.. I agree you are playing with fire.. and an alluminator block is a hell of a lot cheaper than any alternatives ive seen.. and can hold a lot of power... you'd need a big turbo setup to run beyond the power that block can hold.
@ctgreddy, the problem is with the rods.. they are regularly compared to toothbrushes..
@ctgreddy, the problem is with the rods.. they are regularly compared to toothbrushes..
5th Gear Member
Joined: Dec 2006
Posts: 4,552
From: Redding, CA
welll.. there are people holding at 500whp.. and people who have blown under 400whp.. infact, i think it was JDM who had someone blow up under 400whp on their dyno.. they hadn't touched the car yet though. there is more to it, but.. I agree you are playing with fire.. and an alluminator block is a hell of a lot cheaper than any alternatives ive seen.. and can hold a lot of power... you'd need a big turbo setup to run beyond the power that block can hold.
@ctgreddy, the problem is with the rods.. they are regularly compared to toothbrushes..
@ctgreddy, the problem is with the rods.. they are regularly compared to toothbrushes..
and
If you are concerned about popping themotor, some cheap insurance is a little bit of race fuel when you go to the track. It would help fight off any unforeseen detonation.
If you are really that concerned, just pull a few degrees of timing.