RWHP vs. Crank HP Conversion...
05-11-2011, 01:37 PM
#4
Safety Car
normally people go with a 20% loss threw a auto and 15% threw manual trans. also everyone feels mustang dyno record about 15% lower than a dynojet or other brands of dynomometers.
what motor,trans and mods do you have?
what motor,trans and mods do you have?
05-11-2011, 01:40 PM
#5
Melting Slicks
I'll use my car for example. I didn't have a stock dyno, but lets say it made around 385 RWHP (typical for a stock LS3 stick car).
436-385 = 51 HP or roughly 11.6% drivetrain loss....
Apply that same % of drivetrain loss to the 562 RWHP I have after adding the blower and you get roughly 635 hp at the crank.
635 - 562 = 73 hp lost.
How did the IDENTICAL drivetrain, which used to cost 51 horses in parasitic loss now somehow siphon off 73 hp just because the enigne in front of it got more powerful?
05-11-2011, 01:42 PM
#6
Safety Car
15% loss at the tranny was always the general rule I've heard to go by. Keep in mind every dyno reads differently. And every dyno operator can make their dyno read differently.
Last edited by Daekwan06; 05-11-2011 at 01:48 PM.
05-11-2011, 01:49 PM
#7
Burning Brakes
Thread Starter
I have an LS3, 6-speed, headers, cai, thermostat, custom dyno tune
05-11-2011, 01:52 PM
#8
Le Mans Master
Parasitic loss is not a static number. The more HP you have,the less the percentage.
If not,a 6000HP dragster would have a 900HP drivetrain loss.
If not,a 6000HP dragster would have a 900HP drivetrain loss.
05-11-2011, 02:07 PM
#9
Safety Car
sounds just about right.
true its just knida a rule of thumb to help figure crank hp. its defantly not constant figure and sure not from car to car each manufactors drivetrains have different losses.
true its just knida a rule of thumb to help figure crank hp. its defantly not constant figure and sure not from car to car each manufactors drivetrains have different losses.
05-12-2011, 04:02 AM
#11
Myth Buster
This topic is heavily debated in many formats, but all are really moot. The whole idea behind a Dyno is to use it as a tunning aid and to measure gains and losses. None of them are consistent. Some users dont factor SAE correction yada yada. FWHP is useless, RWHP is what counts, well torque helps to but thats another topic. But to your original question, I doubt youll get a real figure unless you pull the engine, take to a test cell, and optimise the run environment in order to get the most out of your FWHP results
05-12-2011, 08:34 AM
#13
Team Owner
Member Since: Jun 2005
Location: Northern, VA
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St. Jude Donor '15
"In honor of jpee"
If you look in C6 Tech, Katech (kind of a known quantity) is being criticized for testing ported intakes (major brand that they found to be best of 3 tested, they don't sell. thus, no reason to claim it's best). The way they tested is to use it in the most controlled situation: an engine dyno vs. a chassis dyno. You may want to read the thread. It's interesting. Rules of thumb are used all the time, but they're not really rules at all.
