RX8 Dyno
#28
Originally Posted by Maolin34
5) The amazing amount of heat from either engine or exhaust that simply roasts you in the cabin.
Come to think of it the AC in that car wasn't that great either...
Just open the windows and drive really fast you'll stay cool. :D
#29
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Did you guys see that Best Motoring video where they competed 4 RX-8s? They dynoed them and they registered 228, 225, 199, 190+ ps. And I thought the JDM ones were also getting low numbers?
#30
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Originally Posted by pr0ber
you can't accurately dyno this car on a chassis dyno - its been proven how many times now....
Disagree. There's no way to prove this one way or the other, otherwise there'd be lil reason to debate this. It seems most 8's are dynoing around 180-185 whp. This number seems very reasonable to me given what 8 owners are running at the dragstrip. I've argued this before, but for the sake of letting your post mis-inform people, I guess I'll try it again.
In this very forum, most people are running low 15's - high 14's. With very, very few mid 14's. If this car were actually making the suggested 238 hp, it should be pushing about 200 whp , given a 15% drivetrain loss with the manual transmission. A light, 200 whp, RWD, 6 spd car should definitely be running faster than 14.8- 15.0 sec. 1/4 miles.
Most RSX's with 200 whp are running low, low 14's and that's with FWD (significant disadvantage to RWD at the track).
#31
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The RX-8 is not a good dragster but it is a good road racer for the following reasons.
I am sure the RX-8 has much higher drive-train losses than most similar horsepower cars due the high rpms. Remember Horsepower = Torque x RPM. Rear wheel torque is engine torque remaining after engine inertial and friction losses are removed times the gear ratio.
Horsepower created by high rpm will have higher drivetrain losses. This is because rear wheel torque create thru numerically high gear ratios (lower gears) have higher inertial power losses. Inertial losses are proportional to the acceleration. This means when acceleration is high a lot of more power is used to accelerate the rotating machinery.
Car Dyno's measure acceleration of a drum and inertial with friction losses are lost in the measurement. Note how such dynos produce different horsepowers with different gears. This and car weight are good indicators how the car will accelerate of the line. Manufactors engine dyno's measure a steady state Torque at a given rpm so there are no inerital losses. This combined with drag is the indicator for a cars top speed. At track speeds it falls in between the two horsepowers to predict car performance.
Since a average track speeds are higher than the average drag strip speeds the car does very well on a test track but poorly on a drag strip. (When compare to cars with a similar horsepower to weight ratio)
I am sure the RX-8 has much higher drive-train losses than most similar horsepower cars due the high rpms. Remember Horsepower = Torque x RPM. Rear wheel torque is engine torque remaining after engine inertial and friction losses are removed times the gear ratio.
Horsepower created by high rpm will have higher drivetrain losses. This is because rear wheel torque create thru numerically high gear ratios (lower gears) have higher inertial power losses. Inertial losses are proportional to the acceleration. This means when acceleration is high a lot of more power is used to accelerate the rotating machinery.
Car Dyno's measure acceleration of a drum and inertial with friction losses are lost in the measurement. Note how such dynos produce different horsepowers with different gears. This and car weight are good indicators how the car will accelerate of the line. Manufactors engine dyno's measure a steady state Torque at a given rpm so there are no inerital losses. This combined with drag is the indicator for a cars top speed. At track speeds it falls in between the two horsepowers to predict car performance.
Since a average track speeds are higher than the average drag strip speeds the car does very well on a test track but poorly on a drag strip. (When compare to cars with a similar horsepower to weight ratio)
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