MaxLTV

It's not that difficult to make a 9K rpm engine in general. It's difficult to make one with such a huge cylinder sizes - increased cylinder displacement increases reciprocating mass of pistons, speed of pistons, size of valves and required valve opening etc. It's possible to make a tiny engine rev to over 10K even without use of exotic materials, but for such a big-piston engine, Porsche had to get very creative with making thing lighter and stronger. Some things with the engine layout helped though - short-stroke big bore pistons reduce piston speed at a given RPM (potentially at expense of optimal thermal efficiency, though), and opposite layout with its natural balance and short crank reduce the negative impact of vibrations. Still, it's a masterpiece and one of the reasons I'm more excited to drive this car than an equally fast or even faster car with a more primitive engine.

GrantG

Exactly my point. This is why I think if Porsche wants to continue to increase the power, stay NA, and keep the 911 chassis huge there is no alternative but to switch to Flat-8 soon.

Shrinking the chassis back to 993 size, using more exotic lightweight materials, or going turbocharged or hybrid are other alternatives for keeping the Flat-6 with increasing performance.

sccchiii

As good as a flat 8 sounds on paper you will not see a flat 8 in a production 911 any time soon, especially for a limited application like a GT3/RS. The board would almost certainly shoot down such a plan. The development costs would put the "to market" price of car in stratosphere unless they decided to lose money on each one which wouldn't make financial sense based on current market performance on the GT lineup.

GrantG

The 9A1 motor is modular and its contraction to a Flat-4 (to be used in the Boxster/Cayman/718 later this year) as well as expansion to a Flat-8 were planned from its beginning.

Also, I think the 960 might use a turbo Flat-8 while the GT3 could use an NA version, further sharing some of the development costs.

drdonger

My buddy recently bought a 458 with 130k miles and the engine still runs fine. I'm pretty sure if a 458 can last 130k miles a GT3 should be able to. Who knows though. I haven't seen a 991 GT3 with a lot of miles yet.

GrantG

Wow - that's the most miles I have ever heard of for an F458!

Although impressive, there really is no comparison between road and race track driving and the question was specifically about track miles. Any idea if your friend drives often on the track?

drdonger

I think the car was an exotic track rental car.

GrantG

Interesting- rentals are not known for their gentle treatment. Good data point!

Shahano

130K miles on a 458 and still running fine?? that 200K km.. Wow that is impressive.

Zeus

Maybe Porsche will go with a Flat-8 in the 960, keep the Flat-6 for the 911 range, and Flat-4 it for the Box/Cay line; all 9A1 based.

Things are looking up for Ferrari engines. Good reliability.

Speciale's engine is a beast: 9K redline. Copper-topped 14:1 pistons.
LaF 6.3 V12 redlines at 9,250 I think.

Wonder if the F12 GTO's engine will be another leap forward...

Shahano

I want to go for a drive... Looking forward to a nice Saturday monring drive tomorrow

Manifold

Keep in mind that, even at the track, the car upshifts a little below 9K in auto mode (~8800?), and spends most of its time per lap considerably below 9K.

This question of engine durability is a non-issue for me until the warranty is close to running out, and I may reach 50K miles before 4 years at the rate I'm going.

Since it's primarily a track car for me, I take it fairly easy with the car on the road, and I drive it hard on the track, though I let it warm up properly before pushing it, and I try to always do a cool down lap.

Preventing accumulation of over-revs by having the PDK will probably help a lot with engine durability, especially for the cars that are tracked a lot.

Regarding oil changes, the way this thing burns oil at the track, I guess it's in a process of continuous oil change?

alexb76

On similar subject, why RS redline was dropped? Wasn't it proving reliable at 9K, so they dropped in the RS model? Doesn't that mean that GT3 9,000 redline may actually been too much?

Gravs

[QUOTE=Manifold;12404218]Keep in mind that, even at the track, the car upshifts a little below 9K in auto mode (~8800?), and spends most of its time per lap considerably below 9K. QUOTE]

Mine shifts at 9,000 rpm in auto.

Gravs

Longer stroke to get the RS from 3.8 to 4.0 litres means for the same piston speed you need slightly lower rpm. So they probably did it to keep various stresses from increasing. But Porsche is also saying it doesn't need to go to 9k because for max performance it's not necessary i.e. if you shift up at 8,800 you're into the high power band. So we don't know which is the primary reason - there's probably a bit of both in there. I think PeterVB has done some numbers that appear refute the later reason so perhaps it's more about the former