G Tech power graphs (S4 KO3 vs S4 KO4 vs V8 vs G40)

confusionhunter · G Tech power graphs (S4 KO3 vs S4 KO4 vs V8 vs G40)

Afternoon folks,
I thought it was about time that I showed some of the g-tech readings I have taken over the last few years to compare some cars I’ve had the honour of owning/having a shot in etc.
I have a G tech competition performance meter and I find this thing really interesting as it confirms what your bum feels! Combined with VAGcom it can give you a really good idea of the effects of mods and the pros and cons of some modding.

You can also have a virtual race in your mind! For me it allows me to remember just how fast or slow cars actually were rather than just remembering they were rapid when they actually weren’t....

I do realise there are serious flaws in using G performance meters, the main one is any power figures are at the wheel AND are less air resistance which is almost impossible to calculate. To do it properly you need air speed, direction, speed (which isn’t constant anyway!) etc so I’ve just come up with estimates considering size and rolling resistance estimates....and not forgetting transmission loss. However for before and after comparisions its ideal.

So, pressing on, competitors for this compare are:

Main run: (Black line) The control car. This is the car I built for my Brother(VenomAusS4) its an S4 saloon, KO3s, 2.25 dual exhaust, MRC remap, RS4 ICs, APR Bipipe, 18inch wheels, H&R coilies. Approx 350bhp. More here if you are interested: http://www.scottishvag.net/phpBB3/viewtopic.php?f=63&t=25108

Run 1 (Red line) My project S4 Avant, current project Target is 500 but currently running a safe map and a manual boost controller. See main thread for more details. http://audisrs.com/about259.html&highlight=
The target is 500bhp so this will be good to see if this is actually realistic of not.

Run 2: (green line) A6 4.2 V8 Quattro Auto, Custom exhaust otherwise std. Approx 300bhp

Run 3: (Blue line) VW Polo G40, PSD Full blend Charger, dewedged Throttle body, derestricted airbox, Boost return valve bypass. Std IC, std exhaust, 65mm Pulley, 1272cc 8v, 4 cyl, Rolling Roaded at 156bhp at some point...860kg! This run was done some time ago!

On both the S4 runs I didn’t do a ‘proper’ launch through having mechanical sympathy which is why the ¼ mile times might look low and the Avant run was done in the wet too. Not to mention the rubbish shifting times in the Red Avant. Still taking it easy in it...ish. I do need more shifting practise.

So the first Graph is power estimates....ignore the first half of the red line...

So you can see clearly the Avant is ahead of the game, as I would hope!
Max power according to this is 341.5bhp. So lets do a little sum:
341.5 plus 25bhp for Air resistance gives 366.5 times 1.25 for Quattro transmission losses gives 458bhp... nice! And probably about right. It runs around 1.2 bar at red line and MRC tuning say I can run about 1.4 bar at red line so that with a little rev limit rise should take me to the 500 mark.... roll on the new remap!

The Black S4 says 239.2bhp, using the same rule plus 25 times 1.25 give 330bhp! Sounds about right but probably a little low considering the mods, but a head wind could easily account for that.

The V8 says 189 bhp which sounds pitiful but lets work the maths.... 189 plus 35 bhp for the fat lardy A6 shape times 1.35 for the quatto, wide body tyres AND the fact its an auto brings it to just over 302.... actually thats pretty spot on...

Next G40: 125 plus 15bhp as its a tiny car and times only 1.15 as its FWD gives 161bhp.... not bad, not bad at all.....

So it ‘kind of’ makes sense....
Because these power runs are part of a ¼ mile run you don’t get the torque delivery but I might have files that shows those somewhere.... I’ll have a look later on.

More on power this time mapped over time, however this is about power to the floor so gusts of wind and traction loss show up too.....

Well as you would expect the avant takes off but you can see the effect of the wheelspin as the acceleration Gs drop to almost nothing forcing an early change to second which seems to take a while to get going again. S4 saloon line isn’t as bad a change but isn’t ideal. As you would expect the V8 Auto has almost no drop in acceleration G force compared to the manuals.

The Blue G40 line is low and all over the place in 2nd as there simply is bugger all traction in the light 2wd FWD vehicle. So in real terms all the Quattro audi’s have probably pulled a few car lengths already.

Whats also interesting is that the Avant gets MORE power to the ground as it gets faster rather than less like all the others.... clearly showing the big power advantages as speeds get higher. Really obvious in 4th.

Considering the vast differences in power output you wouldn’t think you could even compare the some of them! However..... lets look further...

This is estimated speed over time:

As you would expect the Avant buggers off without too much bother, with the S4 Saloon following a similar pattern behind. The Saloon spends over 2 seconds longer in 3rd gear than the avant. You can see I'm shifting slightly earlier in the Ko3d car in 1st and second, as the power tends to die off at the higher revs. That is made even more obvious by the curve in the black third gear line and looking at the area between the black and red. 80mph plus the Avant just starts to bugger off...

Some interesting lines in the V8/G40 race too.....The V8 auto has no dips in Gs as there’s little shifting time. Despite the traction issues the G40 has a significant weight advantage so in actual fact the 1st gear acceleration is pretty much identical until the first change. Then the V8 gets ahead, g40 comes back till the change to third gear. Then the little g40 gets rid of its traction issues and shows its strength in mid range acceleration and starts pulling back on the big V8. In fact , looking at the angle of the lines its now accelerating slightly harder than the S4 saloon! You've got to admit you'd be pretty surprised to be out accelerated from 50mph by a standard looking early 90s polo if you were driving a modded S4 or V8! Loved that car!

This graph also Highlights the effects of diminishing returns. If you imagine a std S4 is similar to the V8 green line, a simple MRC remap and exhaust would get you close to the black line. But to get to the red line which has less of an advantage over the black than the black has over the green, it would take several thousand pounds and a lot of messing about!

I personally think the sweet spot is taking the KO3s to their limits, OR perhaps KO4s with Rs4 injectors if you are forces to do a turbo change engine pull. That’s another debate altogether!.

Lets have a look at the actual G readings, theres no arguing with these....

Well you can see my ‘sympathetic starts’ in the S4s signified by the double humps as I bring up the clutch until fully engaged before I bury the throttle, hardly dropping the clutch at 4500revs...

You can also see the effect of the wheelspin has on the Avant and it takes several seconds to get back up to power in second as the change drops the revs to below the turbo spool sweet spot. That really highlights the difference in spool up time between the KO3s and KO4s. Clearly I need more practise in changing in the Avant as Im capable of better changes like in the saloon. Both had Tanoga shifters and the Avant has the ESP Gearbox brace.

Again the V8 plants it down with little interruption from the tiptronic and the G40 lines are up and down like a yo yo for 1st and 2nd. Ah... suspicions confirmed. The G40 does pull harder in third gear than both the V8 and S4 saloon. Amazing machines, thats why I loved em! However in real terms the S4 would be miles ahead in a standing start race, just look at the area between the black and blue lines in 1st and 2nd. There not chance the third gear advantage would pull that back.

Also after 8 seconds all cars start to drop off in power delivery except the Avant which still has a reasonably constant pull throughout third gear and then again in 4th. Look at the general angle of the lines. Hmmm interesting stuff.

Anyway, I think I am pleased with the results of the Avant and after I learn to drive it better and another remap, the difference should hopefully justify the effort thats been put in!!! Then I’ll go Ferrari hunting... ;o)
Hope you enjoyed the blurb....
Cheers.
Mark.

confusionhunter

hi guys, I found some comparible logs in terms of power curves and torque delivery between the KO3'd saloon and the KO4'd Avant....

I commented driving the both cars back to back a while ago. I was unsure on the power delivery of the avant as from memory it didnt seem as 'urgent' coming out of corners as the saloon and it was only when my brother visited it was put in context. Yes the KO3s give you better punch out of the roundabouts but once at the high revs the avant felt significantly faster and for it to feel significantly faster than an est 350bhp car it would need to have another 100ish bhp! I felt a lot better about it!

However... this graph portrays the camparison perfectly! Ignore the power figures as I had to do a FATS style run to get the full torque curve.......

Does no one else find this stuff interesting?
Or have I just gone into waaaaay too much detail!?!
Constructive critisism welcome.

DJones

Nice work, they are great for before and after comparison runs.

I love the G graphs as you say no disputing it...

This is my MRC stage 1 against my ur quattro.. as you can see the ur is a tad more aggressive...