A reasoned discussion on engine location? - Page 2 - 911/Carrera GT - PistonHeads UK

“imagine if……”, has there ever been a question amongst petrol heads that could be more guaranteed to get the arguments flowing? Such thought experiments open up unlimited possibilities; allowing comparisons between the incomparable to be debated and argued over with a ferocity that pays no heed to the temporarily suspended reality from whence the question originally came. For the world of Porsche, the one form of that question that returns as regularly as the tide itself is the “imagine if….” of the Cayman. The unveiling of the GT4 has done nothing to quell such thoughts and discussions, only moving them forwards with a greater sense of certainty added to each argument in the debate. Central to these discussions of course remains the engine location and the need to neuter the car as a result. Mid is surely better than rear so the rest of the debate becomes an apparent home run. Simple right? Except is it that certain? Car and Driver ran an article in June 2011 that attempted to put some numbers to the debate and suggest otherwise (http://www.caranddriver.com/features/the-mid-vs-rear-engine-debate-porsche-cayman-r-vs-911-gt3-feature) but which instead served to only further entrench the dialogue and since then anyone with even a portion of sense has avoided any re-run. This forum, never one to let sense rule, has had a few goes at discussing this topic since that article was published but things played out to the usual script. Some informed posts, lots of subjective opinions trumping said informed posts and the usual unravelling of debate with the champions of the underdog ultimately laying siege to what they perceived to be the battlements of the establishment. Nothing learned and no forward progress. Some of the recent “imagine if” posted on here in the last week or so however got me thinking again about such questions. “Imagine if the GT4 had been given the GT3 engine” is a nice summary of those current themes though NOT the point of this thread. While there is actually an interesting opportunity for intelligent debate surrounding that point too, whether any chooses to take it up remains to be seen. Sparked by those recent thoughts however I wanted to post up something that while not a direct “Cayman what if” topic, can still hopefully prove nuanced and thought provoking nonetheless.. Lofty aims I agree but worth a try right? And to give it any sort of chance at all of succeeding I am not going to involve a Cayman of any sort……

So to the point of this thread. I was once fortunate enough to own a F430 Challenge and a 997 Cup at the same time. While my wallet hurt from the experience; there was certainly something to be said of the Christmas morning like appeal to having such a choice available to me whenever I wanted to head out for a drive. While it was a huge amount of fun – and lets be honest, I am no pro driver so all it is ever about is having fun – it was also a hugely enlightening experience. Two very different cars sharing the same singular purpose. While it is often stated that todays civilisation is the most surveilled in history, the same is also true for todays race cars. With data logging recording everything that happens with an almost unlimited capacity there is very little escaping from what you do in the car. The plus side of this – or the negative perhaps depending on perspective – is that much of the subjectivity involved in the process of using such cars is removed. Everything is distilled down to numbers and measurements to be displayed on a screen in front of you ready to be analysed and compared. The subjective removed, replaced with a detailed objectivity that can at times require a re-calibration of ones own outlook and impressions. Like many others – well at least one, Steve I know you have similar views – my experience driving different configurations of cars does not tally with the simplistic reductions offered up as a response to discussions about the merits or faults of differing platforms that often find there way onto threads here. Its surprising to hear so many feel its nice and clear. In fact I would go as far as to say that its one of the debates that shines a light on who doesn't know what they are talking about quite quickly; but this is the internet and the rules are different here. With the recent round of thought provoking “imagine if…” firing my synapses and sending me off on a tangent, I thought it might be of interest to dig out some data, roll it out here for others to look at and see what shakes out. To that point, I will post up data from a lap round the same track in my 997 Cup and my F430 Challenge and we can –hopefully- all discuss what it means in terms of the cars/platforms from a purely objective standpoint. I think its interesting to look at so hopefully others do to. For those of you that like your info to be unsubstantiated or subjective laden – fear not for you will be catered for too. I will finish up with some thoughts gleaned from the sweat of my palms and the twitching of my bum. Old School measuring devices to which we can all relate. Lastly, I am not a pro level driver by any stretch. These data traces are up – with reservations at doing so – to simply look at the way the two cars get round the track.

The use of an F430 Challenge and a 997 Cup here offers something that I think is useful to look at in the context of this thread. Being spec cars they make ideal candidates for giving some interesting insights. Both cars are closely related to the original/fundamental model platform design used by that particular model and neither is subject to any balance of power regulations. Trying to compare using say a 997RSR and an F430GT would be pretty much meaningless for both these reasons. What the Challenge and the Cup cars represent then is in essence the base platforms turned up to 11. Adding to the interest is that – in my hands at least – I found both cars to be pretty much bang on each other with respect to lap times wherever I went. Both cars made their way round the track in noticeably different ways but ultimately did it in the same time. This means that when looking at the different data traces from a lap in each we can really see the different approaches unfold. The parts where one car is faster aren’t just because the car is ultimately faster in general. That's an important point to grasp and cant be stressed enough. In the case of the laps shown here the Cup was 8/100ths faster. So to the data traces themselves. To keep things simple I have just put the basics out on display here. I know many will not be used to looking at data squiggles so it may not be that intuitive to begin with. In terms of what you are looking at, the top window is engine speed (red), the second window is vehicle speed (blue), the third window is throttle (green), brakes (purple) and steering (red), while the fourth window is lat G (blue) and long G (orange). I will post up circuit maps with braking etc later but I will start with these for now as they are the most interesting thought not the easiest first time round. If I post the maps people will ignore these and miss a lot of what is going on. By looking at these traces and following your way round the lap from left to right you can see what the car is doing and what the inputs are as it laps. You can see when throttle was applied and how much, when brakes were applied, when steering was applied, the vehicle speed at any point including entry, mid corner and at the end of the straights. You can also see how much G the car is pulling for each event. It can take a while to visualise it all together but once you get it its really quite interesting to see the differences between the two cars and where the strengths are in each.

get a job !

HaHa. Where do you think I find the time to post

Fun topic as saw Rob Wilson the other day on his way to a Gig and told him just got a Scud GT3 .......... but after years of Porsche GTr and RSR race cars he asked why , well just a change for fun ....n So how was it well only done about 15 laps of Silverstone GP , but very different to drive more like a heavy single seater but great over the curbs better mid corners , not as good on the brakes but easier to drive faster more balanced .... Is it faster , as Fiorano says no , just different but well worth having a change , very enjoyable

919 is mid engine, 918 is mid engine the new 913/960 super car will be mid engine. Porsche want to win races all these new cars are mid engine, to allow them to win races !

^^^^ Cali Track ?

keep it lit said: ^^^^ Cali Track ? You know it. Nice pick

PorscheGT4 said: 919 is mid engine, 918 is mid engine the new 913/960 super car will be mid engine. Porsche want to win races all these new cars are mid engine, to allow them to win races ! well David good luck on beating the old layout trophy hunt

This was an informative read and thanks for posting along with the data traces. One aspect I noticed was the braking traces - the 911's looked quite spikey, whereas the Ferrari's was much smoother. So the Ferrari is easier to brake into the apex?

Sorry for taking so long to get back on this. I will look at re-upping the images tomorrow and put side by side track outlines up too. The short answer is that the Ferrari is easier to drive in all aspects relative to the Porsche. Totally different in terms of inputs needed, what the car itself does and what it asks of you. Both are intense of course but its a very physical effort to get the Cup round the lap in a way that the Challenge is not. The longer answer is that there is quite a bit going on in those brake traces. It's a mixture of the limits of my skills, the difference in the way the cars drive and the difference in the controls. It's probably worth mentioning that the Ferrari has ABS, ASR, Paddle shift (with only 2 pedals) and an ECU controlled autoblip function. The Porsche has no ABS, 3 pedals (clutch needed for downshifts), sequential shift lever and my right foot working as brake, steering, throttle blip for rear lock up prevention and traction control. It's a busy place in there from the start of braking until you get to full throttle. The brake traces are actually showing line pressure (but expressed as a %) so the feel in the car isn't quite as bad as it looks from the traces (assuming it was the pedal movement) but it definitely could be improved. Some of the spikiness you can see is simply my inability to hold pressure perfectly stable whilst throttle blipping on downshifts - the green spikes will show where the blips were, as will the red rpm spikes in the top window. Some of it is also my response to small lock ups during braking and some is the result of the way in which I apply the brakes in the Cup. I personally tend to spike the brakes for the initial application then pull them back as speed drops and the rear wing stops pushing so much. This is especially true for the braking events where initial speed is at the higher end of things. All of this combines to make the pressure trace look like it does. In the Challenge its much more like braking a road car in many ways. Way less going on as you really just need to push a brake pedal and tap a paddle. There is also not the same fight to get it to turn that there is in the Cup.

An example of the differences in different platforms could be seen with less exotic machinery in the car's competing in the Porsche Club Championship where cars in each class ran to factory standard bhp as a maximum and a minimum weight such that all models ran to a very similar power to weight ratio, yet there were front, mid and rear engined models competing against each other. Certain circuits would prove to favour a particular platform but generally the matching of performance was achieved. Having raced in it in cars of all 3 platforms (and won repeatedly in front and rear engined, 2nd place being my best result in mid), I fully agree that the driving experience was different in each and they all had their specific characteristics and particular strengths and weaknesses (not all necessarily just down to the platform though). From my "bum dyno" the 911s were always the best, although my performance in the 944 S2 was more dominant (until I wrote it off ), despite being the easiest car to drive (or maybe because of it?). The lack of serious competition in the class helped how it looked but comparison to the highly competitive class above is valid and I beat a lot of them too (including qualifying on the front row at Oulton Park). Ultimately I think what matters most is (the results when racing followed by) how big the grin on your face is when you come off the track.

The hardest 911 possibly to drive fast is the 993 GT2 R , intercooler over the back as well to complicate the pendulum effect as well as turbo lag where suddenly mid corner you have 50% more Power and even more Torque , no power steering .......agricultural chassis ........balance Phahh , muscle it around ..trail braking , correction of understeer using the throttle ... all fun and then in the Wet ........Goose you remember Spa in wet with the big wing.. So Modern Porshce 996 onwards not really the same ... But both P and Myself have really enjoyed the Ferrari experience after a life of Porsche. Peter

If one takes away the passion from the debate and just looks at the traces and lap reports objectively its pretty clear that there are aspects of different layouts that are advantageous in comparison to others. It's not exactly an out there idea of course but when the more usual form of discussion pops up it just gets buried under the avalanche that ensues. In the examples here its pretty clear where the Challenge platform is better but also where the Cup platform is better. Neither is better in absolute terms - the salient point of this whole thread - as they ultimately combine - in my hands at least - to give the same lap time albeit in two rather different ways. This reasoning extends to many platforms however I only had data for my Challenge and my Cup to post. Including the data was something I felt was important since without it one ends up debating from the subjective and things will go nowhere. As mentioned earlier, a drivers sense of what is happening sometimes doesn't match the reality of what is actually happening. I will re-up pics shortly and add lap graphics too

Do you think the Cup would be any quicker if it also had ABS, ASR, 2-pedal-paddle etc, or just easier to drive?

It would certainly be an easier drive in terms of everything going on with the controls but I dont think it would be ultimately faster under good conditions. I've not seen Cup cars retro fitted with ABS or with Paddleshifts put up times that are markedly faster than the same car without when the fast guys get in them. The learning curve to get to the times would be less with the gadgets fitted though I suspect.

Since its the Porsche forum. Cup lap first. Pics back up hopefully Edited by fioran0 on Friday 27th March 12:40

And the Challenge lap Pics back up... Edited by fioran0 on Friday 27th March 12:41

Cup Track Report

Challenge Track Report

Side by side. Porsche is red.

I WILL drive that circuit one day hopefully !

And just missing the point, as per the norm... Looking at the data it should be quite clear that each platform has different strengths over a lap. That is why its so interesting to look at in this context. The dance steps are different as each car makes its way around - at least in my hands - but each gets round in ultimately the same time in this case. It's hardly a stretch to take a view that there are merits to each approach, but given that these merits can be viewed clearly in the data itself without much of a hunt one would think the discussion could move on a little at least. Two examples that should be pretty clear to folks looking are i) how the Cup gets on throttle much earlier than the Challenge car in many of the corners - look at the green trace and how much time is spent flat at 100% and how quickly it gets there on exit; and ii) how the Challenge car takes much more speed to the apex of many of the corners than the Cup can. Edited by fioran0 on Friday 27th March 23:46