Virtual Dyno Room-Dyno Simulator
Look for test results with power curves of engines on an engine dyno, then installed in a car on a chassis dyno. The power curves are almost identical except the chassis dyno's #'s are lower obviously. This shows that the drivetrain losses are generally consistent throughout the power curve. The higher the HP output, the larger the difference between the engine dyno and the chassis dyno....so you can't just add or subtract a specific #. It's a PERCENTAGE of power loss, not a set amount.
The argument that it's a percentage loss doesn't make sense to me, because basically you're saying:
1) Say it takes 75 hp to operate your drivetrain on a 300 bhp motor
2) Swap a big turbo to make 600 bhp
3) That same exact drivetrain now somehow requires 150 hp to operate?
It doesn't make sense. In the real world and not the paper world, drivetrain loss is not EXACTLY a static percentage NOR EXACTLY a static number, but personally, I think using a static number is much more accurate, especially when you're talking about highly modded, big horsepower cars. It's absurd to think that a 600 whp Evo is losing 200 hp due to drivetrain losses.
Last edited by recompile; Oct 12, 2009 at 05:53 AM.
Evolving Member
Joined: Aug 2007
Posts: 104
Likes: 0
From: wales
If the entire curve stays the same, only moves down -60 hp, how does that prove it's a percentage? It doesn't, it just means the curve has shifted due to drivetrain loss... a loss that could just as easily be described as a static number of -60 hp (throughout) instead of -25% (throughout)
The argument that it's a percentage loss doesn't make sense to me, because basically you're saying:
1) Say it takes 75 hp to operate your drivetrain on a 300 bhp motor
2) Swap a big turbo to make 600 bhp
3) That same exact drivetrain now somehow requires 150 hp to operate?
It doesn't make sense. In the real world and not the paper world, drivetrain loss is not EXACTLY a static percentage NOR EXACTLY a static number, but personally, I think using a static number is much more accurate, especially when you're talking about highly modded, big horsepower cars. It's absurd to think that a 600 whp Evo is losing 200 hp due to drivetrain losses.
The argument that it's a percentage loss doesn't make sense to me, because basically you're saying:
1) Say it takes 75 hp to operate your drivetrain on a 300 bhp motor
2) Swap a big turbo to make 600 bhp
3) That same exact drivetrain now somehow requires 150 hp to operate?
It doesn't make sense. In the real world and not the paper world, drivetrain loss is not EXACTLY a static percentage NOR EXACTLY a static number, but personally, I think using a static number is much more accurate, especially when you're talking about highly modded, big horsepower cars. It's absurd to think that a 600 whp Evo is losing 200 hp due to drivetrain losses.
The more force that is applied to bearings, components, tyres etc the more energy gets sapped up by them.
so it is definately not a fixed hp number.
Newbie
Joined: Oct 2009
Posts: 4
Likes: 0
From: Louisville, Kentucky
Agreed, but it's not a set percentage either. Imagine bolting a 10,000 hp motor to the same drive train. It'll take a smarter person than me to figure out what the fomula is to solve this, but I'm sure it's do-able.
Guys, don't try to hurt your brains here. It's been proven decades and DECADES ago that it IS 10000% in FACT a PERCENTAGE!!!!!! People have taken a stock engine and dyno'd it, then tossed in in a car and had a specific PERCENTAGE loss. Then took ANOTHER super high HP engine off a engine dyno and bolted it up to the EXACT same drivetrain and had the exact same drivetrain percentage loss. Period. The percentage amount may change throughout the power curve but the percentage 'curve' is a constant. Do some research here, don't just argue your theory blindly just because you don't believe it.
Start with Supra's, definitely a good example. a 1400hp built engine only does about 1100-1150hp to the wheels, the same percentage the stock engine does through the same drivetrain basically.
Start with Supra's, definitely a good example. a 1400hp built engine only does about 1100-1150hp to the wheels, the same percentage the stock engine does through the same drivetrain basically.
Last edited by Jack_of_Trades; Oct 12, 2009 at 12:00 PM.
Evolved Member
Joined: Jul 2005
Posts: 619
Likes: 0
From: Istanbul
well if you disagree with my comments / observation, I would appreciate your input instead of making a useless post. I for certain know that dastek and vamag dynos used in Europe do not have constant multipliers. Now, the same might not be true for DD, Mustang or DJ but I have no idea. Maybe this is where you can enlighten us 
If you guys don't mind, I would rather that you start a new thread for this discussion because I can see this taking up a lot of pages and I want to keep things on topic for this thread. Thanks fellas.
Mr BNeat Track guy here that's taken his car to the track 1 time in 9 years of owning it
Open your 3rd gear pull datalog (or 4th gear) with Microsoft Excel (or OpenOffice Calc), copy the 'LogEntrySeconds' and 'RPM' data and paste it into the appropriate sections in VDR. Be sure to only copy/paste the data while you were at 100% throttle, nothing else. Then just fill out all of the info for your particular vehicle.
ok now i understand the concept and using the excel file. my concern is, i do have saved logs but i think their just shortcuts instead of the actual file. in evoscan i think its only save into a temporary file in which evoscan can open with. i tried opening them with the excel but they're giving me an error saying my log"xxx" does not exist. i have the sample logs that came with evoscan. those open up with the VD file...i dont get it?