swoope

iTrader: (5)

i have managed to put 40k miles on it in 2 years, so i think i could have mileage figures real quick.

beers

Sephiroth

You need to find an exclusive tuner to tune the fcon. the interceptor can be tuned by any rotary tuner

colin204

I have the F Con working on my street car, so it is very possible if you have a good pro dealer. There are only a few that are experienced with the RX8.

rotarygod

$1600 plus a few hundred more to get it tuned? Plug it in and drive off. It's easy and no you wouldn't have to go get it tuned by anyone.

rotary crazy

247hp x 17%= 41.99

247-41.99= 205.01 rwhp

thats the # scott got, the rx-8 its capable of this hp, the only thing that dont allow the car to get this #'s is the cars ecu tune to save the cat.

TeamRX8

iTrader: (25)

there's no way that a mechanically proper, broken-in RX-8 drivetrain registers a 17% efficiency loss

trying to take a drum roller dyno number and work it backwards to engine output is a load of bullcrap

epitrochoid

http://www.ls1tech.com/forums/archiv.../t-154395.html

good read. but really, who cares what your crank numbers are? the engine doesn't accelerate the car, the wheels do.

Nemesis8

iTrader: (3)

Scott, did you hold the timing to 30 degrees from 6K to redline?

rotary crazy

15% to 20% its whats normally use by allmost every tuner, so 17%.

when the rx-8 was lauch the question of how much rwhp the rx-8 put out was ask to a mazda exc I belive by the guys at rotarynews.com and his answer was 205 rwhp.

the s2000 puts out 205 to 207 rwhp so this means the car does't have 247/250 hp ?

I understand what you are saing if you increase the engine power the % loss most go down, but the only figure I know of to calculate drive train loss is 15 to 20 %.

rkostolni

I think 15% gives a very rough estimate, but really drive train loss is a constant plus a percentage related to the square of the acceleration of the parts.

carbonRX8

iTrader: (1)

Team's post is what I intended, but I would also point out that to say that the car manufacturer made a car that makes x hp because someone mods a car to make x hp is rather nosensical.

epitrochoid

if you guys read the link i posted, you'll see that the percentage figure is more or less static, while the actual number of horsepower lost changes. as the force applied to a gear increases so do the bad forces that generate power robbing heat. if there are more calories of heat being lost in the gears of the transmission and differential, there is less power coming out. if there is 247hp worth of energy going into a series of gears and only 205 coming out, you've lost 42hp to heat. the energy has to go somewhere (some can even be lost to light, but i hope our transmissions don't get that hot)

i think everyone can agree that the drivetrain heats up considerably under spirited driving. in normal driving, when maybe only 80hp is sent through the drivetrain, everything stays pretty cool. when 247hp is sent through the drivetrain, more heat is generated, thus more power is lost. the relationship (ie - percentage effeciency) is constant (at least within a relavent range as at extreme power levels the heat generated cannot be dissapated quickly enough and the gears can bind), and the number of HP lost is increased. if you took your entire drivetrain and melted it into a block, and calculated the power required to accelerate it to a given velocity you'd have a constant value. you have to accelerate X amount of mass at a moment of Y and that does not change regardless of BHP of the motor. however this number is small in comparison to the power lost to heat.

but back on topic...

TeamRX8

iTrader: (25)

it's been proven that the drum dyno drivetrain losses method is highly unreliable, the only accurate way to measure drivetrain loss on a chassis dyno is to install a torque transducer in the drivetrain and measure the actual efficiency

unfortunately drum roller dynos dominate the market, but if you can then at all costs you need to be on a low-inertia Dynapack or Rototest setup that bolts on in place of the drive wheels if you want good chassis dyno info

some info (Adobe PDF file)

r0tor

iTrader: (1)

umm... NO

you don't loose the vast majority of power to heat. Most well lubricated gear sets (excluding worm drives) are about 98% efficient at delivering power - meaning you are losing 2% to friction which will cause heat. Then throw in another percent or two to account for frictional loses in bearings.

The other say 10% of your power is being lost before it hits the wheels because everything in your drivetrain has mass - and all that mass needs to be accelerated. It takes power to accomplish this. Also guess what - the dyno can control the rate at which all this rotating mass is accelerating by controlling the load on the dyno and how fast it lets the tires accelerate... meaning the percentage of drivetrain loses can vary depending on how the dyno is opporated.

MazsportScott

Yes I did, I was doing pulls running between 10 and 38 deg. advance, I also was adjusting the split.

MazsportScott

Not at this point, the unit will need to be returned for internal mods. The turnaround will be quick, If I know in advance 24 hours.

Nemesis8

iTrader: (3)

Thanks

FlyingLeggs

I'm going to have to agree with Epitrochoid (dude I had to look at your sign-on like three times to spell that. Why can't you be Sam or Mack?) Anyway, hp to the wheels is all that matters. Who gives a flip if you crank out 500 if you only lay down 200. Slight embellishment to prove a point.
Epi....didn't you order a plug-in from Scott also? Did you get it yet?

FlyingLeggs

Scott, sorry for not knowing, but I assume that you have a dyno at your shop or you have easy acces to one. How much do you charge to dyno?

MazsportScott

I do not have an in house dyno for sound/fume reasons but I use one about ten minutes from my shop. The dyno charge is 125 per hour and my rate is 100 per hour.

Nemesis8

iTrader: (3)

I think you need one in your home also - that way you could burn the midnight oil

FlyingLeggs

If I wanted to get enough pulls for an accurate reading (3 or 4)? on a stock 8 how long would it take? I would like to get a good base number now before I add a few mods. Is there any tuning at all that you can do without adding a plug-in? Last question guys, no hijacking here.

davefzr

So whats the latest on this project? Is Scott continuing to perfect the drivability of the car in different situations?

Nemesis8

iTrader: (3)

He told me he is ready to ship at the end of the month, so must be done I guess.

MazsportScott

About a hour total time, and the dyno would probably be about $75. With the stock ECU there is no tuning that I can do.