G-Tech Pro RR newbie

[S2central.net]

LOL - that'll be 3750lbs of course - lil typo there

The RS2 airbox I have already has a big hole in the underside... I'm worried it will suck up more hot air than anything so I'm thinking of riveting a plate over it. I don't want that chavvy 'pshhh' sound on gear-changes either.

As to exhausts - my original item must be on its last legs - no leaks, but looks rubbish. The NI emissions test will let me legally run without CATs so thats a bonus. Might save some weight too when I get rid of those and something like a Milltek system coupled to a new downpipe - no Y junctions for me

PS - Hoping for more runs on the 'T stream' for you tonight / tomorrow. I'm pretty sure I have defeated the ABYs compensation for air temp in regards boost pressure, but its consistently boosting too high - when I tame that it will be fantastic... Same boost in Summer and Winter - which means LOTS more torque on colder days - the ones when you have less grip I know why Audi did it their way being incredibly safe, logical and dare I say 'German' but the Porsche guys injected a bit more 'fun' into their boost chip brew !

[Rusty]

Good work there Andy - as ever...

Cheers Paul, had a lot of fun doing it although there's always that initial apprehension that the car will last

Its about 210 at the wheels on the runs so far at 3750kg.

WOW! that's one heavy S2!

RS2 IC and a different airbox will help, exhaust is a must too, still got my DP and sports cat to go on and the 7A inlet cam to defy convention for a change My airbox is completely Swissed now with a myriad of 16mm holes along the cold side. The noise is great and gets a lot of looks on medium to WOT, just need some exhaust noise to help things along now.

16" Avus alloys are the way backwards, they weigh about the same as my lightweight 17s and with some 225/50R16s you'll have all the grip you need. Only issue with 16s is that the most modern tyres are all for 17" + rims. Why not reat yourself to some track tyres in a smaller diameter such as 225/45R16 for summer and track use. Acceleration would be

There are a few makes of lightweight 17s that I've been looking at, Lenso have released some nice ones at 7.5Kg ea., Team Dynamics Pro Race are a bit heavier at 9Kg each but are developed from BTCC so are tough too. OZs are sweet, BBS RKs are light too

Be interesting to see the results from the newer blend of GTech and see whether it's a bit less fickle. The problem with the old clunker is that you need to know what you're looking to achieve to confirm the mass

I can assure you that a nice and efficient k24 is a great setup, what it lacks in out-and-out grun it more than makes up for in cost effectiveness and driveability due to low lag

[S2central.net]

Good work there Andy - as ever...

I'm going to get a few more power runs in mine... Its about 210 at the wheels on the runs so far at 3750kg. Your additional oomf is believable. However I am one step closer to catching up with the arrival of one slightly used RS2 airbox that I acquired... Will try that on same brew to quantify the gains.

Then maybe I'll get the energy to fit the RS2 IC that has been quietly boxed away for ~3 yrs (jees dont ask).

Oh and I've bit the bullet on a 2nd set of Avii ;-) - be REALLY funny if the lower drivetrain losses (and mass) give more gain than the RS2 parts !!!!


Paul

[Rusty]

I'm very happy with unit as I paid 5/8ths of FA for it . I understand that spikes are a problem but my car is standard and well understood so I'm happy to combine the figure with my gut instinct and come to a logical conclusion, I've driven it every day for many years so know every little input that it gives and can tell if there is a boost leak, heat soak or even what fuel it's got in it now.

The reason for multiple runs is to remove the spike factor, as is the mean, median and modal analysis.

With the little k24 there's almost no such thing as lag or off-boost problems so I'm happy to chase power figures and get the maximum rev-a-bility out of it at this time

[EspenW]

The original G-Tech is a great tool, but the newer ones with logging and graphing capabilities are in a totally different league, and still cost less than a few trips to a dyno. I cannot praise the now discontinued Mr. Dyno unit high enough (developed by the former head of software development at Mustang Dynos).
A tweak that might put out an extra peak horsepower, but destroys the mid range will look like a gain on the Mk1 G-tech, but a graphing one will tell the truth. I have both types of G-Meters, BTW. Also, by only reporting the peak number, the Mk1 is susceptible to spikes. Nice for timed runs and max g's in gear, though, although it seems that 0-60 runs are a few tenths lower on the original G-tech (not sure of that one has 12" of roll out built in, like the newer ones). 12" of roll out equals approx 0.3seconds. With a granny launch (all I dare to do) with the engine bogging down, I run 0-60 in 5.2 secs, with a 0-30 time of 2.8 secs. A stock RS2 will run to 30 in 1.5 secs with a 7K launch, so a nice 0-60 time is just a brutal launch away I have rollout set to 0 on my unit, so drag strip times would be 0.3 secs lower at the track.

[Rusty]

Right kids, done a few runs today in about 20deg ambient on nice level ground. Here are my results.

The unit was set to 3750lbs (1704.5Kg @ 2.2lbs/Kg).
The unit was at 0.00g +/- 0.01
The runs were not always done over the same ground but it's a flood plain so pretty level.
My launch was firm but not harsh.
All runs were done in 2nd or 3rd gear, first was not used with WOT.

Results (hp ATW):-

235 ... 254 ... 236
221 ... 238 ... 250
240 ... 238

Mean was 239, Mode 238.

So this compares favourably with my guestimate of 240whp and gives me a baseline setup that I can use in the future.

As can be seen the variation is approx +11 / -18bhp or near as dammit 5% in nice whole numbers. The lower power run felt a little impared, more than likely heatsoak from stopping and then resetting the unit and then heading off again, this was remedied with increased experience of what was what. I have to admit that the 3rd gear runs resulted in tunnel vision and I felt pretty hard on the old girl wanging here round to 7.5k 8 times in a row She never missed a beat though. I've yet to check for niggly boost leaks and the passenger side wheel bearing is on it's way out. Other than that the car is healthy and running 225/45R17s.

I then tried a 0-60 with a bogged down start and slow gear change in the heat she posted 5.7s. With a slightly more aggressive start and again a quite slow gear change I posted 5.5 with a 1/4 of 14.5 @ 101.

Finally, car pulls 0.45g in second at WOT.

HTH

[Rusty]

Almost forgot, having the power meter running in real time is hilarious, at what I think is a small amount of throttle / acceleration I'm producing well over 100bhp, more than a lot of cars ever will

[Rusty]

Did another couple of runs today with a bit more load in the car so at 3800lbs. Got a believable 225bhp ATW with a hot engine from traffic pulling onto the motorway. An interestingly I got 199bhp going down a gentle slope although there might not have been full turbo boost. Need to get some petrol tomorrow as I'm low enough to hve hiccups and then get some energy up to go play GTech on the test route. Going to use 3700lbs as a baseline and do a few runs. I think 10 should give an indication of repeatability. Then I can compare new chips, zorst, cam as and when they get fitted, in the same manner. Sweet

[Rusty]

And using constant acceleration equations means that you're getting average power for the run.

[EspenW]

I think these equations assume constant power. Easy with a CVT, not so easy without.
Not sure if they take into account the time that it takes to shift gears

[S2central.net]

These seem to work meaningfully - say 14 seconds ET for 1/4 mile (402m) and exit speed of 100mph (44.7 m/s) for a 1650kg mass gives us approx 150kW at the wheels which is approx 203hp at the wheels. Then use various rules of thumb to estimate drivetrain loss for something like 250-270bhp at flywheel in round numbers. Totally ignoring aero effects here...

[S2central.net]

We are missing a step here...

Force, F = M x A (Newtons)

Torque or Work W = Force x Distance (Nm)

Power, P = Work / Time (Watts)

Thats what we need for paper exercises

[EspenW]

Paul: would be interesting if you could generate some graphs with the same setup, but made at different temperatures, in order to see how these turbo cars compare to the SAE correction factors (which all dynos use, but the equations are developed for NA engines..). If doing testing during the day in sunlight, use real temp, in the sun, not official temperature (shade).

[S2central.net]

Here's a find

http://www.stealth316.com/misc/performance_fox_equations.doc

[Rusty]

Oh well

Hoping to get back to my test route this weekend and do a few runs, see how I get on. Need to get to understand the equipment betterer and adjust the weight a little. I want a repeatable 240bhp ATW (I'll need to get it on the RR after the rest of the mods are sorted to know what it's actually doing as I'm guessing the weight )