2871R goes rather nicely...

[Rusty]

Ah, 100Hz then so 20 times more data than my GPS... will get on it today sometime.

[S2central.net]

Well - you wanted data...........

[Rusty]

it's not a problem was more of an observation, should give better results as the acceleration is measured not calculated for speed.

[EspenW]

That temp and pressure gives a SAE correction factor of 0.966, so adjusted net hp is354hp.

It seems to be geared ridiculously long? Peak power in 3rd gear at approx 5900rpm is 98.77mph. An RS2 (and S6+) is barely doing 80mph at that rpm in 3rd.
Assuming Cd and frontal area pretty similar to the RS2, power loss to aero drag will be approx 47hp at 98.7mph.
What kind of gearbox ratios and wheel size?

Seems that 034 is rating their 2871kits (boosting 1.8bar) at approx 330hp at the wheels:

http://www.034motorsport.com/product_info.php?products_id=17600

[S2central.net]

Stock UrS4 gearbox circa 1993 on this thing. Nothing unusual about wheels.

I'd be OK with a Cd similar to RS2 but the UrS4 most definitely has a bigger frontal area than RS2.

We didn't go as aggressive as 1.8bar midrange on this (stock internals and 95RON aren't the best mixture) but I'd imagine 034 are into 1.5bar territory (maybe lower) on the redline with this turbo.

I've seen other posts claiming ~360bhp on this setup at the wheels so I think thats on the money.

So how much you think at the flywheel on this Espen ?

PS - pls post a reminder of how you do those SAE conversions and the aero losses for a given speed & Cd & Fa... I can't seem to find my spreadsheets on that stuff.

[A80Avant]

Espen,can you give me the correction factor for the temp and mbar in general? Maybe i can add that as info on the excel and manipulate that as well when measuring hp

[A80Avant]

Im afraid i cannot use the excel on the g-tech data.
apparently it calculates time every 0,01sec and even if i get the figures averaged,it still gives very low accel. in (g) so it cannot calculate the numbers accuratelly.
I tried to use the G values from the g-tech plot area and got some numbers,but are far from the ones that g-tech provided.

SO i decided to use all info from g-tech instead,and just put them on the excel file to actually see if there is any way to get some losses calculated.
Unfortunatelly the excel file is too big,so Paul,would you like me to send it via email?

[EspenW]

Stock UrS4 gearbox circa 1993 on this thing. Nothing unusual about wheels.
I've seen other posts claiming ~360bhp on this setup at the wheels so I think thats on the money.

So how much you think at the flywheel on this Espen ?
PS - pls post a reminder of how you do those SAE conversions and the aero losses for a given speed & Cd & Fa... I can't seem to find my spreadsheets on that stuff.

SAE conversions: http://www.csgnetwork.com/relhumhpcalc.html
Aero drag: http://www.gtechprosupport.com/support/AeroDragCalc.php

I wonder about the gear ratios, since max power is reached at a wild 98.7mph. Adding the 47+hp aero loss to SAE adjusted 354hp net gives us 411whp, that seems too high...

I think about 20% drivetrain loss when measured on the road is approx. correct.

[EspenW]

Espen,can you give me the correction factor for the temp and mbar in general? Maybe i can add that as info on the excel and manipulate that as well when measuring hp

This is the equation:
PCF = ((1.18 * ((PressStd / PressAct) * Sqrt(TempActAbs / TempStdAbs))) – 1.18)

Search for SAE J1349 for more info

[A80Avant]

from the graph i get,the car seems to be producing all this power figures @ crankg mainly from the weight input.Again,im not saying that the weight aint so,but it seems to me a bit strange that the 2871R is almost producing same torge as my 3071R and the power is pretty much the same when i have vastly higher boost levels and 98octane gas always in the car!

[A80Avant]

here is the excel which i use for the perfomance box.

Paul,i will send you the modified through email for the g-tech

If i were able to actually calculate the g-forces through the time/speed only,i would have been able to get a different result as far as power is concerned to compare.Now im merely copying whatever the g-tech measures and just adding the losses.

[DJones]

Well I just did the nominal 15% drivetrain losses on that 367bhp to arrive at ~430bhp. For crappy 95RON fuel I think the result is pretty good at the wheels ...

With more time and emptier roads I'm sure we could get some better power runs in 4th.

We'll maybe get a dyno day setup over here soon and then we'll see what its doing on the rollers.

The calc i was told to use to get crank hp with a GTech is:

Gtech measured hp +10/.82

In the case of my car that equates to 358 + 10 = 368 / .82 = 448 at the crank. which sounds about right given my turbo is rated at 450 and i am using an RS2 ex manifold.

I have also tried this on my new A8 and a A5 that i borrowed both were weighed on my neighbours weigh bridge prior to the run and both came within 2% of the manufacturers figures... good enough for me..

To be honest i only use it for for and after runs, in my opinion its a perfect bit of kit for that.

By the way some good figures there Paul well done.

[diesel des]

I would like to thank Paul The car goes great! It is heavy as it has a extra gas tank etc. Will Get it on a rolling road to measure power but i think the Gtec is close enough.

Thanks again Paul!

[EspenW]

I would like to thank Paul The car goes great! It is heavy as it has a extra gas tank etc. Will Get it on a rolling road to measure power but i think the Gtec is close enough.

Thanks again Paul!

It shall be interesting to see what kind of numbers that you get on a rolling road, just remember that the numbers will vary greatly (easily 10%) between different brands of dynos.

[S2central.net]

The calc i was told to use to get crank hp with a GTech is:

Gtech measured hp +10/.82

By the way some good figures there Paul well done.

Going by that rule of thumb, this puppy is 460bhp... Seems a bit OTT - I dunno. This subject is so contraversial with so much conjecture and opinions.

I really should GTech my own car with stock airbox and factory chips to get a reference point as baseline for a healthy S2 Coupe... Been so many years since I drove a stock setup you just forget...