Petevb

Careful- it's awarded based on "technical merit", which means you don't necessarily want one. A turbo has won outright each of the last 10 years, but primarily due to efficiency: 7 of those have displaced 1.5 liters or less.

A technically superior engine is often very different than something you'd actually like to drive. While I applaud rewarding good solutions to ever more stringent regulations realize that you'd get an entirely different list if you prioritized based on things enthusiasts value highly: response, involvement, acoustics, weight, etc.

randr

Petevb - I think you'll find the mill in the 488GTB is a very responsive engine - last Xmas I had a good hard look at the Spyder, the engine is spectacular in both delivery and response. Also the 3l bi turbo in my daily S is very responsive (I looked at theses debates ages ago - the telemetry is pretty conclusive).

I think we all recognise we're well beyond the era of single large turbos and low compression port injection engines. If you stop and think for a moment and ask a simple question - why would a 3.9 l V8 bi turbo have worse throttle response than a 3.8l NA engine. The simple answer is it won't and in terms of responsiveness it literally blows the doors off the NA . Actually its not really that close .

I suspect, whilst there is a lot of commentary from various sources in relation to the latest turbos - the reality is that there isn't that much commentary from people who live with them - its worth trying something like the new 991.2 GTS, 488GTB or AMG GT S/R to see how far these engine have come - they have been developed specifically to deliver a linear response as well as superior all round performance. Don't misunderstand me, I like my NA GTS a lot but for performance going forward, in lieu of displacement, you have to have turbos.

Ultimately Porsche understands its market, if that market is NA flat sixes they will continue to deliver them - however if you look at the over all product line: 718, 718S, 991.2, 991.2S, 991.2GTS, 991.2T and 991.2TT (thats an awful lot of turbo technology and thats where the sports car sales are).

If you look at GT standings the turbo engined Ford and Ferrari teams are in first and second place - the NA cars are last and second last.

The future will look like a mid-engined GT2

Bardman

I recently had an extensive test drive of a 991.2 GTS and I was shocked at how little emotional response it triggered. I was fully expecting it to surpass my GT4 in terms of desirability, but I left the dealership feeling a little non plussed. If this is the future of sports cars, then I will be buying 2nd hand cars in future.

Apart from the non linear response, the biggest issue I had was that it didnt make any sound at all. It was fitted with a sports exhaust, but the sound coming out of it was like a vacuum cleaner. I had both windows down, and went across my favourite bridge which has walls either side, but it seemed almost silent.

Given the 2nd hand market for 991.1 GTSs with a manual gearbox is tight, I had semi seriously considered a 991.2, but I could never trade my GT4 for one of those - I cant comprehend anyone spending $300k+ (in Aus) for one.

Mark Dreyer

I just picked up a 2014 Cayenne GTS to replace the Touareg TDI I'm selling back to VW. I am hugely impressed with how this truck holds the road through turns. And I own a Boxster Spyder, so I know a well handling vehicle when I drive one!

Petevb

It's a topic we've already beaten to death, but let's discuss Turbo for a moment and why future cars "need to have it".

We'll start with your 488 example. EVO's review sums it up nicely:
"The simple facts are that the new engine gives you more of what you can't use (outright power) and less of everything that can make any journey feel special (immediacy of throttle response, noise and that feral rush to 9000 rpm)."

Even modern turbos are less responsive than the best of their normally aspirated counterparts. The difference might be academic to most people in most situations, but there is an impact beyond feel. A couple years ago Walter Rohrl was giving rides down an impromptu snow covered single track in a 991 Turbo S at the Cayenne launch in Sweden. While on the roller coaster ride I asked: he much prefers normally aspirated for that type of driving due to the increased precision. When I pressed him to quantify how much less precisely he was able to place the car due to the turbo lag he pondered before replying: "two feet".

So it's not just old single turbos that lose something. Racing anti-lag systems have proved that lag likely will eventually be eliminated, but so far it has not, especially at the lower end of the powerband. And the very things that make them more responsive (lower boost pressure, etc) hurt their power bands and power to weight ratios.

I'm not simply anti-turbo, nor am I someone who's never tried them- I've owned about 50/50 Turbo and normally aspirated over the years including modern twin turbos. I respect their flexibility and actually enjoy the spice they can add to power delivery, but as power climbs I've come to the conclusion that for a max performance sports car if you can make your target power with normal aspiration that's still superior (response, complexity, reliability, noise, etc). There's only one real roadblock to making that power, and that's fuel consumption and the resulting emissions. That's the only reason Turbo engines "are the future" as you put it. Because by other metrics that matter to sports cars normally aspirated remains superior.

Weight is an example- despite fancy weight savings the new 9A2 Turbo engines such as the one in your 991.2S have 6% lower power to weight ratios than their older 9A1 counterparts. In fact Porsche's highest power to weight engines have all been normally aspirated. The high point is the 918's 4.6l V8 which makes 608 hp from just 300 lbs. This is not too far off double the power to weight ratios of any of Porsche's Turbo engines. It also crushes the power to weight ratios of the 488 or any of the newer McLarens. Thus in a perfect world you need to ask yourself- if 608 hp isn't enough why not make an engine like that bigger?

Both noise and throttle response can be engineered, and clearly the new Turbo engines are closing the gap rapidly, but this idea that everyone's doing it so it must be "better" is fundamentally flawed. If regulations and costs were not forcing their hand neither Ferrari nor McLaren would have turbos, and in many ways it's the holdouts like Porsche that have found ways to overcome the emissions and fuel economy pernalties and keep their top engines normally aspirated that are more impressive to me technically. As for your point about the winners circle at Le Mans it's been said but apparently needs repeating: BOP.

At the end of the day I'm not sure what you're really asking for. I think it might be more power, and you believe you can't achieve that power with a normally aspirated engine? If so I would argue, but that's really another topic again.

enduro911

Geez, take my eye off this thread for a moment and it's 5+ pages. Love the conversation and please forgive the catch-up effort coming here:

There were regs restricting various components at that time as well, there simply weren’t enough. MB came into the series with a huge naturally aspirated engine that made great HP and torque. Porsche was running a turbo 6 that which was also restricted (like the MB and Mclaren), but didn’t have the powerband or the top end to stay competitive. Back then things were more unrestricted, but not completely. The real issues with those cars were 1) cost of the street car and 2) the fact that the street cars were so compromised. Again, per my earlier post if you force the hypothetical GT race car to essentially be the cost of the street car plus the costs of the add-ons that you could buy as an owner from a parts catalogue and keep the scope of the upgrades minimal, you wouldn’t need the oversight as the rules would likely govern the process to a much greater degree.

I wouldn’t mind an approach like this but I think it’s a bit too simplistic. If you make a bigger car, then the car may have a better wheelbase and width, but would weigh more. However, that would be offset by having to run a “minimum weight”. IOW, I think it favors one type of car over the other. Same with the max. HP. We’re all becoming more conscious of economy and emissions. Thus, force the cars to have a certain efficiency level AND meet some emissions requires. You can still run without mufflers though. You know, for sound purposes!


There’s an excellent article in Racecar Engineering about why Porsche went the NA route. The pointed to 1) packaging 2) weight and 3) the smaller powerband being offset by the BOPs ability to “get it right” so to speak. Why were they hopeful of this you may ask (see next quote)?

Ford “overlooked” the charge air temps in all the races leading up to Le Mans but, suddenly, with better tuning and denser, more humid air, they found a bunch of power at Le Mans last year. BOP wasn’t monitoring charge air temp before that. Pretty large oversight IMO. However, per Porsche (per the article), the governing body is taking steps to control all variables which gives Porsche confidence that they could run whatever engine they like and have a somewhat decent shot at being successful. To me, this is dangerous insofar as the governing body can make such a huge oversight in setting the rules and also because it allows so manufacturers to be "lazy" (not produce something that is as good as it could be with the knowledge that they'll receive help).

I don’t disagree with you here. The TransAm stuff is fun to watch and obviously the bodies of the cars connote a certain brand loyalty but there’s no real manufacturer participation there. Nothing in those cars is, IMO, making your Corvette street car better.
This is an excellent analysis of how everything would devolve under a “pure race car on the street” scenario (i.e. CLK GTR). However, I would again say that if manufacturers were limited to selling a street car at or below a certain price, then having relatively minor room to upgrade the street car to make it race worthy, and the cost of the upgrades plus the cost of the car couldn’t exceed a certain number, AND you had fuel flow/emissions controls, I think you eliminate the likely path you’ve outlined below.

My personal strategy for GT racing would center around 1) concept engineering/speed/reliability per dollar and 2) keeping them close to their road-going brethren. Let's take a real life example. What does it take to make a standard Grand Sport Corvette into a reliable track car? Whatever that number is, if GM chooses to continue to sell the initial car at a lower price point with cheaper parts (bad oiling, cooling, brake cooling) compared to Porsche, they have a greater budget as they take the street car and turn it into a GT race car. However, in this scenario, the costs of their upgrades couldn't exceed a certain number either. Thus, you're essentially solving to the same race car price (street car plus salable costs of upgrades). So, Mr. Corvette Owner can 1) pride himself at owning the basis for a successful GT race car 2) root for his chosen team and 3) follow suit in the upgrades process with the SAME PARTS as the factory team if he’s got the money to do so. Porsche could do the same with the GT3/2/960/Cayman. If Ferrari chooses to sell a 488 at a very high price, but then have little "upgrade" room in their budget, that's tough. This is offset by the fact that the amount of R&D that you put into making the street car that expensive should mean fewer necessary upgrades to make it into a competitive GT car.

One additional thought here. Understandably, Corvette couldn't sell many cars branded as "Corvette" for 200k (people being brand snobs). Because of their street car pricing, they should be forced to sell more of those cars than a brand like Ferrari that operates much more like a boutique operation.

randr

. LOL This the usual journo BS......

Stop and think - a V8 3.9l engine is a V8 3.9l engine add two turbos and it delivers more work in less time that is a fact This means it is more responsive.

The throttle response is the same as found in the equivalent 3.9l NA engine.......stop and breath, think......

I suggest you go and drive one - I have. Its an event, as is the pull to the 8000rpm redline.

By the way I have collected loads of telemetry from my .2 S, and GTS - check it out - it may inform your opinion. I'm not going to get into a debate about this. You are right its been done to death - and the most noise comes from those that don't have significant current experience with the new engines.

Also I suggest, before making comments about weight you look at the power to weight ratios as integrals of the torque curve

Bardman - the new engines are more linear than the NA engines - a flat torque curve delivers a linear response. What you have written is incorrect. I can't square away your comments on sound. All I can say is my car sounds good - perhaps I need to post an accoustic map.

The GT4 is well, a good car but it doesn't handle as well as a .2 S/GTS with RAS - this is also a measurable fact, it also doesn't accelerate anywhere near as hard, and because its manual you'll probably chuck 3rd at some point. So all it has is a somewhat louder exhaust. If you're happy with that - great.

I'm not interested in the "purist" line at all - this is clearly where the thread is headed. I simply request the GT division completes the journey it set out on. If they want to make "rich mans ricers" aka purist cars - great - if thats the case I'm not interested.

LMP1 and GTpro are test beds, testing and identifying what works, what doesn't work, whats reliable and whats not reliable etc. All I'm asking is the GT division build the best base car they can make - they already know what it is.

Petevb

Still unworkable. Fuel limits mean the win goes to the car with the best aero and newest engine (small frontal area, high BSFC, etc). Any car not built to those rules (that price point, etc) can't compete, and lets be honest- most manufactures playing in that price range are in no position to make entirely new models. Of course someone like Toyota might be, and might be willing to sell it at a loss, so again there goes your series. If you could regulate costs (as opposed to price) you might be able to block that, but that in itself is entirely impossible because costs are both gameable and unknowable.

Variations on these rules (build 500 street cars, etc) have existed since the 60s. They were abandoned because they didn't work...

enduro911

Thanks for the input but I dont know if I agree with your first point. If the fuel consumption regs were particularly stringent, I think you have a point. However, if they were opened to allow for a reasonable consumption, but closed ended enough to prevent manufacturers from producing too much power, which would be another important variable, wouldn't other factors such as the size of the frontal area, downforce produced by said area, and gearing playing a huge role? Furthermore, with the fuel economy regs tightening, wouldn't manufacturers already be making progress towards these ends anyway? Rules governing emissions and fuel consumption have already forced street going engines in certain directions that manufacturers are currently racing.

I don't think I explained what I was saying well if you're using the words "new models". My thought was that the standard road going cars would remain as the manufacturer was likely to develop them anyway, but the manufacturer would essentially be allowed a second chance to improve them for racing. Sure, a better design could come right out of the box (Vette or 911 could be turned into a mid-engined car), but the R&D would drive price up so that would need to be balanced against the ability to improve what's in place.

As far as companies taking a loss to produce these cars, I don't have an answer. That's the reality of motor racing. Mercedes F1 LOST money in 2014 when they won the constructor's championship. Sure, the costs for the new engine tech is likely to be amortized over the following years, but there's never been any stopping a manufacturer from losing money to win races. Also, I would think that there would be a market for your car if it keeps dominating the competition and can be purchased and upgraded to essentially be the same car. Brand loyalty, driving experience, etc aside, people want the best and what's in front.

Petevb

Your consistent attack of "journalist BS" is amusing. In part because I'm one of those guys you're complaining about. One of the guys that "doesn't own the cars they write about". So at least you got one thing right, though I have enjoyed owning a number of the cars we're discussing.
I'm also an engineer, and your definition of "response" does not match the industry's. Take a 4.5 liter, 14:1 compression ratio V8 as in the previous 458 and drop displacement to 3.9 liters and 9.4:1 as in the 488 and you will find the engine makes far less power and is far less responsive without boost. You're losing ~15% power due to "downsizing", but the far bigger factor is the low compression which not only knocks back power but kills throttle response.

Unless you're using a race-grade anti-lag system such as that found in WRC you won't already have boost in the intake. Building that boost takes time, that time dulls the responsiveness of the engine. This is not "area under the curve", this is the time between your foot moving and the rear wheels reacting by changing torque delivered. When you're balancing the car and controlling the line primarily with the rear wheels rather than the steering wheel you're making many throttle adjustments per second, and any delay in that response makes all the difference. It's measurable, those with experience can feel it and it's a large part of the reason Ferrari engineers admit they would not have gone Turbo if regulations hadn't forced them to (same with Porsche engineers if you catch them in a quite moment). And while I understand you might not be able to feel it I'd suggest you consider the fact that there are those that can.

Once the response issue is cured (and I suspect it will be eventually) you'll just be left with weight, complexity, reliability and noise (subjective- some will say that's already good, but for an RS I'll take 9k every time).
Let me reiterate: at 6000 rpm the 918 is only making 400 hp, yet it already has a better power to weight ratio than any street turbo engine Porsche has ever made. And it goes on to rev to 9150 and make 608 hp. If you've got some "area under the curve" math that can change these facts I'm all ears.

You've clearly have made up your mind, and no opinion, expert or otherwise, is going to change it. If you're not going to listen to someone like Walter Rohrl, voted "driver of the century" and working for a company that's deploying turbos across its range, you're certainly not going to listen to me. Luckily Porsche builds cars for both of us, and if they don't McLaren or Ferrari will be happy to take your money.

randr

The Speciale was 14:1 - one of the reasons it was special, on the other hand the Italia was 12.5:1 - and the V8 3.9l GTB is ~ 10:1. I think the AM Vantage is ~ 11. (For reference the Porsche 3l twin turbos are nominally 10:1).

The effective compression ratio of a 3l turbo motor at a nominal 10:1 with ~5psi boost is ~13.4:1 and at 15psi its about 20:1 (at sea level).....whats the new GT3 13.3:1???

I'm an engineer too (or rather was before business) and I am happy to cough up I can't tell the difference in throttle/ engine response between the Italia and 488GTB. I haven't driven a Speciale so I can't comment on that particular car. But I can comment on the 3l twin turbo - on a 2-3-4 track the telemetry is conclusive (1Hz), there is no discernible lag. This should be no surprise as you don't need very much boost to have a high effective compression ratio.

I'm sure there are those that can feel something - I think they are the same people that don't notice the lack of power in NA cars prior to going on cam

Now lets look at power to weight (engine HP)

(1) 991.1 S - 991.2 S (from torque curve - 4000rpm to redline) - .1S = 238hp/tonne .2S = 257hp/tonne
(2) 991.2 GTS - 991.1 GT3 (from torque curve - 4000rpm to redline) .2 GTS = 282hp/tonne .1GT3 = 255hp/tonne

How about we talk about WHP and the higher losses that high revving cars generate.......relative to lower revving cars

Reliability - World Endurance Championship GT - 1st Ford (turbo) and 2nd Ferrari (turbo), the two laggards are AM (NA) and Porsche (NA).

To put it another way a moderately boosted 10:1 compression engine (12psi) will be the equivalent of a 5.5l 13.3:1 compression ratio NA engine. Food for thought or not as the case may be.

Petevb

488 is 9.4 to 1 as I mentioned.

And why not recalculate those power to weights to use the top 30% of the rev range (3rd gear covers the top 28% in the GT3). You're penalizing the normally aspirated cars for their higher redline by starting at a fixed 4k rpm, a fact I'm sure wasn't lost. If you're unsure if that's fair why not also run your 4K to redline numbers against an old 450 hp 1998 viper. But of course now we're back to discussing "not enough power", which as I said previously is a whole different topic...

Sorry, did you just try to prove the lack of lag by citing measurements taken once per second? Houston, we've found the problem.

randr

LOL I did it that way as thats (approximately) the point where variocam plus kicks in. I've given you the effective compression ratios for low amounts of boost and even modest amounts of boost.

1Hz is indeed 1 reading per second - but you failed to ask how many readings have been collected - on the S its approximately 18,000 to 19,000. Thats Houstons problem solved and indeed crushed by the weight of numbers.

Try saying it, you'll find it cathartic - a 6 cylinder FI 4l 10:1 compression ratio engine with a modest amount of boost (12 psi) will deliver the performance of a 6 cylinder NA 5.5l 13.3:1 compression ratio engine.



The GTS Vs GT3 WHP (data from Sport Auto, collect on MAHA dyno). A picture is worth a thousand words - I wonder what a GT division 4l twin turbo would look like on that ...........oh wait I prepared one earlier



The above is the Maha dyno chart for a 4l AMG GT R - basically a boosted 4l six cylinder could put out ~ 500WHP with a redline at about 7500rpm to 8000rpm.

Bardman

I dont really understand that mentality. Any change in a cars architecture which trades off how a car 'feels' for performance numbers is a poor trade off IMO.

Ultimately who are you racing against? If you have the fastest car on the track or on the road, but the other drivers are having more fun, what have you gained? Bragging rights at the cafe? The best competitors amongst us are competing against themselves.

I want a car which stimulates me, gives me some sort of emotional response, and in that respect the 991.2 GTS just leaves me flat. The sound is terrible, the lag is present (yes - it really is), the gearbox is more floppy and it generally doesn't feel as connected. It doesn't feel like a AUD300k+ car.

I think the GT division now get this also. The GT4 was the first step, the 991R was the second step, and with the latest GT3 AP is now starting to position it also as a drivers car as much as it is a circuit warrior. I think this is smart business move as they will own this market.

randr

Handling is part of "feel" so is acceleration and deceleration. So for me, on track, the GT4 feels slow and doesn't handle as well as a grocery getting S or GTS with RAS That doesn't mean its not fun or good - it just doesn't hit the marks for me.

The 911R sold exactly 911 units and currently there are more 2nd hand GT4s on car sales than 981 GTS (carsales is an Australian site).

I think there is a lot of pent up demand for the .2 GT3 (it seems that quite a few people want to off load 991.1 GT3s - can't blame them).

The marketing may well win out and that may well be a great model in the short term but make no mistake "rich mans ricer" is a term thats out there. The solution is to be on the ball and lead from the front.

This means the GT division has to deliver winning M'sport cars (can't keep bleating about BOP as it is what it is - a lottery) and and ultimately marketable base cars that carry the design philosophy and are better than the offerings from other manufacturers. You need to look at the product out there four square in Porsche space, AMG GTR - AMG GTS, various McLarens etc Note the strides forward being made by General Motors and Ford.

I guess the "mentality" is, there are people that want their expensive performance cars to deliver exactly that, performance (particularly those compete in sprint series or other forms of m'sport). They expect development not stasis. The 991.1 GT3 deserved a much better engine - at least it seems the 991.2 has got the engine the .1 deserved in the first place (probably) plus better tires .

Put the engine ahead of the rear axle and we're three quarters there, add turbos and boom - thats the best base GT car they could build. If they build it I will buy it.