Where is the best acceleration in each engine? As it relates to MPH?

I took a 2.9 for a test drive. It seemed to really shine in 2nd gear from 40mph to 60mph, and in 3rd gear from 70mph to 90mph. Can you guys chime in and give me some idea of the conversion to mph, for each engine's sweet spot in the RPM's range? I was just curious where the real pep is in each engine, as it relates to daily driving... in 1st, 2nd, 3rd, 4th gear (4th gear is already way too fast). How do you guys rate the Cayman and Cayman S in gearing, and being in the right RPM to pull off a quick pass on the highway (55-75mph speed limit) vs driving in town (35-45mph range) ... did Porsche get the gearing and rpm's right, for fun on the public road? 2.7- 2.9- 3.4- 3.4 gen. II -

I'm no expert but I like being above 3800rpm when passing. It's a good rpm in any gear for quick throttle response. Mine is a gen 1, 06CS with Softronics remap and other mods though; not stock.

So above 3800rpm's in 2nd or 3rd gear equates to how many mph on a 3.4 2006? Everyone talks about HP, torque, and rpm's.... I'm trying to convert this into mph. (for example... and this is just a guess?) 2nd gear in a... 2.7 hits its best acceleration between 40mph and 55mph 2.9 hits its best acceleration range between 45mph and 60mph 3.4 hits its best acceleration range between 55mph and 65mph 3.4 gen II best acceleration range between 65mph and 75mph 3rd gear... 2.7 2.9 3.4 3.4 gen II

There is a simple rule for maximizing acceleration at a given mph speed. Choose the gear that operates the engine as close as possible to its horsepower peak. Everything else follows from that.

I guess the reason for the question... needs better explanation. Why don't car companies sell cars, with information that makes it easier to pick which engine is best for your personal driving needs? I've looked at a new 2.9, used 2007 S, and still wondering if I need to spend the extra money to go for the 2010 S. If I had a 2nd and 3rd gear chart. It would be kind of fun to look at where the car offers the most thrill, and how far above the speed limits I'd be on my favorite roads. Like most folks.. I want to maximize my fun with this car... and not buy something that is over-kill or under powered. I just thought this might be fun, helpful and interesting? :gossip: I'd love to have a good chart... and hear what experienced owners thought about how well their car fits in with the roads they actually drive on. (would anyone ever admit, a car with less HP might be more fun because its not over-kill for the speed limits in their local area?) 3rd gear (I'm looking for something like this? I'm just guessing?) 2.7 Cayman has the most "wow factor" from 60-80mph 2.9 Cayman has the most "fun factor" from 70mph-90mph 3.4 Cayman give you the biggest kick in the pants from 80-100mph 3.4 (320hp) has a sweet spot in 3rd gear at 90-110mph Maybe as a non-track guy... I'm asking a question which is so simple, that I'm embarrassing myself? I've done a few test drives. And you always get the instant rush of having a new car for a short time, and everything is exciting! I was hoping to get longer-term opinions of what the car is like after the owner has had time to settle in and live with it. Maybe I should have started a poll to construct my data chart? By simply asking, what engine do you have and what range of speed (in mph) is most fun in 3rd gear, 2nd gear?

Sorry but I'm no help. i'd normally be more than happy to go out and write up some numbers for you but I'm out of the drivers seat with a foot injury right now. All I can say is that 3rd & 4th get a pretty good work out in my CS. 5th & 6th are really unnecessary except for those intent on on getting maximum mpg. You can break any posted speed limit in your area in third.

The attached charts of accelerating force (lb.) versus speed (mph) in gear should answer your questions. Enjoy! I calculated the curves based on Porsche's published stock specifications for torque vs. rpm, gear ratios, final drive ratio, and tire size for the: 2007 987 (2.7L), 2007 987S (3.4L), 2009 987 II (2.9L), 2009 987S II (3.4L), and 2009 987S II (3.4L) PDK . These idealized, straightforward calculations assume that the torque specified at the flywheel is conveyed to the rear wheels without loss (friction) in the drive train and also ignore aerodynamic drag. As I could not find a published value for the gear ratio of 6th gear for the Gen II manual gearbox, I took a rough guess. Based on the ratio for 5th gear (0.84), 6th gear for the Gen II is an extreme overdrive.

Good job on doing the math on this. Your charts very nicely demonstrate the point I was making, namely that lower gears produce stronger acceleration. For maximum acceleration you want to hold it in the lowest gear possible, up to redline in that gear. When you upshift you lose significant torque multiplication from the gear box. BTW I think the vertical axis on the charts should be lb-ft, not lb.

Good work. So..peak acceleration occurs at peak Torque then, not peak horsepower as stated above - correct?

Thanks for offering to help. Hope your injury gets better fast, so you can get back in the drivers seat

Both statements are correct; the latter is almost aways true, but there can be exceptions. First, the two statements refer to slightly different things. Yes, it's always true that "peak acceleration occurs at peak Torque" in a given gear . However, when comparing two gears for a given car , say second and third, the acceleration possible in second gear at any rpm may be higher than the acceleration that's possible in third gear. In particular, as can be seen in the charts for the various 987's, the acceleration possible in second gear within the allowed rpm range is always greater than the acceleration that's possible in 3rd gear. In fact, examination of all the curves for all the 987's and all gears indicates this is almost always the case. This is why jake said, and I'm paraphrasing, that for maximum acceleration (meaning time to speed or distance) it's best to run the engine out to red-line before upshifting. However, while running out to red-line almost always results in the fastest time to distance, it's not universally true. In general it depends upon the shape of the torque curve and the particular gearing. For example, see the acceleration curves for 4th and 5th gear for the 2007 987S. These curves intersect at about 120 mph, which is a couple of hundred rpm below red-line in this particular case. So, in theory optimal time to distance would be achieved by shifting just below red-line. (That assumes the driver has infinitesimal reaction time.) To get back to your original question, I think you can see from the charts that Porsche has chosen gearings, including tire sizes, that result in placing the broadest, higher parts of the torque curves for a given gear in similar speed (mph) ranges. For example consider and compare the curves for all cars and a given gear. Look at 2nd gear and also 3rd, which is a very versatile gear on the street and at the track, as was pointed out in the above thread. The broad part of the torque curves all occur in nearly the same speed (mph) range. Note too though that the accelerating force is almost always higher for a given gear and speed (mph) range for the larger engine. (The exception is for the automatic.) That means for whatever speed range (mph) you are comfortable with, eg. obeying the speed limits, Porsche has designed the gearing such that you are able to accelerate faster the larger the engine is. So, how much fun do you want to have at 50 mph? 0.5g? 0.33g? Note, drivers have been known to receive tickets for having too much fun, i.e. accelerating too quickly - aka careless driving, even while obeying the speed limit. My daily driver is a 2007 Cayman S. It's way fun - both on the street for my daily commute, and also on the track. See 2009 Motor Trend Best Driver's Car - Best driver's car competition - Motor Trend Buy what you're comfortable with. A certified pre-owned 2007 987S is a great value and great car. However, things almost always get better, so I imagine the 2009's and 2010's also provide wonderful driving experiences. Enjoy the process of being able to select one.

Thanks Jake and Topdown. We're all on the same page now.