As far as im concerned, its all about the wheel hp figures, no point having massive numbers if the drivetrain eat them all. Bhp is a theoretical number derived from torque and thats whats measured on a dyno........I think

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FN2 Civic Type R w/Mugen Parts
Toyota Celica GT4 ST205
Toyota Celica GT4 ST185

I've split this discussion out of Mixer's thread to keep Mixers on topic.

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GT4DC Events Co-ordinator
1996 ST205 UK

I was looking and thinking "how did he do that to the thread?"

Mike, you have some crazy powers and seem rather wise to split it, I can see a can of worms being opened!

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FN2 Civic Type R w/Mugen Parts
Toyota Celica GT4 ST205
Toyota Celica GT4 ST185

good to have a seperat thread, be good to see what others have go and compaire differnt dynos

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Sorry Dale if I have offended you it's not intended, it's just that I've been to several rolling road sessions with lots of GT4s present and I've never seen anything get that close to that whp at that boost on a stock turbo, and all the ones that have made that ballpark at the wheels were calculated at a good 350 at the fly.

I have recently had mine dyno'd twice with extensive mods, forged, cams, motec etc, S148 at 1.5bar, the first time it made 261bhp at the wheels which they calculated as 392bhp at the fly and 367lbft. The second time they recorded 271bhp at the wheels which they make 411bhp at the fly and 375lbft. So those transmission losses are huge compared to yours. The engine was also dyno'd up north in the car it came out of at 386bhp with a smaller exhaust so I'm fairly confident the figures are about right as its been on 3 sets of rollers that I know of. Also it was pretty much a dead heat against a new Carerra 4S which are similar stats which means I'm pretty confident on it. If anything it must be my at the wheels figures that are wrong as the transmission losses are pretty huge?

Last weekend there was about a dozen of us on the rollers at Interpro and a dozen more over somewhere in the midlands and all the transmission losses where shown as pretty hefty in both locations.

Also if you look at mixers examples above they are coming up at about 100bhp loss, apart from the last one which only shows a 47bhp loss, seems very strange on the same rollers each time?

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GT4 no 10 - I must be mad :help:

^^^Click the banner for my Black Treacle project thread ^^^

Now back home and mapped to 531bhp & 411lb/ft - that's enough power for now!

thats certainly an interesting loss as my brothers makes around 305-310 at the wheels and dave calculated that to be 404 at the fly.

as above, flywheels isnt really too much of an interest to be fair as there are so many different calculations as everyone knows that people love big numbers, hence why i only pay attention to the whp.

previous to the chart above mine made 234.9 wheel horsepower on the same dyno with a 304.7bhp flywheel.

I have no idea how similar these are but at the same time as the above run it was for banzai magazine and our friends r32 made 642 bhp which was near the same as the power that it ran on mgt's run.

But all i know is its quick, really quick for a stock unit, and its nowhere near 100bhp slower than my brothers and its more than held its own against a 400bhp mapped evo 8 at Cadwell the other month too so make what we will out of that like.


If you go on Dave Rowes mapping stats on their Dyno Dynamics rollers it works at around the 25% loss

Calcuation is made by say 305 / .75 (25% loss) = 406 atf

my 256 / .75 = 341atf

Yes I would generally expect, and have always been told, to see around a 25% loss on a GT4. My Interpro figures come out at around 34% which does seem too much, but as I said the bhp has been calculated in 3 different locations at roughly the same output, (plus I've owned enough of these cars to get an idea of horsepower by butt dyno) so it makes me wonder whether different rollers measure at the wheels figures differently? This would obviously mean that ATW figures are not very accurate either as a comparison between cars unless they are on the same dyno in the same conditions.

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GT4 no 10 - I must be mad :help:

^^^Click the banner for my Black Treacle project thread ^^^

Now back home and mapped to 531bhp & 411lb/ft - that's enough power for now!

the dyno should go theory be calculated and setup correctly, this i would imagine is especially important in the mapping i imagine.


i have owned this one for 8years now so only know how quick mine feels and goes in comparison to my brothers monster and also how it easily does my friends supra which made 338 on the fly on same dyno as mine.

All these numbers are only ever going to mean anything when used as a comparison under the same conditions.

There are so many variables that will affect the actual reading from the wheels and then a whole number of variables and corrections that are applied to derive the flywheel figures.

One thing I noticed was that the Interpro readouts had an ambient temperature of 20degC listed - seems a bit warm given the weather we've had recently, most garages tend to be a bit chilly in the winter.

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GT4DC Events Co-ordinator
1996 ST205 UK

indeed my main motto was always if it feels fun to the driver, win cares like, last time i went on war mainly just to see how my fuel pump was doing as its 137,000 miles now!

all good though still.

I used to think that horses were getting smaller seeing some of the power figures reported
Now I think that dyno operator noses are getting longer too

When I was mapping the black car it made 246 at the wheels according to dataloglab. Using some of the corrections here that would be somewhere around 360 at the flywheel which would be complete horse potatoes given it was a stock engine with a S148@1.2bar

I've never understood a fixed percentage ratio even over the same cars. Rotational friction doesn't increase with power
I think it was Dave Walker who told me 25hp + 15% was a more realistic estimate

Hmm, dyno at crank power !

Look at it this way. 110 bhp is 80kW. Now I know if you put 80 kw into a gt4 transmission it would melt it !

Gearboxes don't loose that much power, period. These crank figures are baloney.

Treacle, you still live near Stur ? One evening we could meet up and use streetdyno software and a g-tech pro thingy, both of them if you e got an accurate weight of your vehicle will tell you the real power at the wheels.



Sent from my HTC One X using Tapatalk 2

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Darryl

160 bhp transmission loss is about 120 ka, which is an insane amount of power to dissipate in a 12 inch by 6 cooler. Doesn't seem possible to me.

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If at first you don't suck seed, try drier grain.

Exactly, I've seenn lots of standard engines, show 150 to 160 at the wheels from a approx 200 bhp ( Toyota engine quoted bhp ) and not many cars still produce the factory spec power .

You loose about 45 bhp, not a percentage from crank to wheels,

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Darryl

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Darryl

Of course a small percentage of the power lost in the transmission is based on the input power, but its from the cross cut gears and only a few percent.


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Darryl

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Darryl