'17 BRZ PP vs. '11 Cayman 2.9

[PorscheUnlimited16]

Only about 5 percent of Porsche owners actually track their sports car. The other 95% have them as an accessories... like a fancy wrist watch. To take a date to the movie theater, or to pull up somewhere fancy and have it valet.. Hence why it’s an option and not standard on regular models (non Gt/Gts/turbo) trims. ) Standard models without Psm still handle incredibly well with the E version.

[ZDan]

Yeah, kinda lame of Porsche to not have lsd as standard equipment. That said, on street tires (RE71R), given 45F/55R or "better" (i.e. more rearward) weight distribution, limited slip not strictly needed. DRove a student's 981 without lsd, on RE71Rs, I did not miss it at all to be honest. Was going decently quick in it too, 2:09s at Watkins Glen, low 1:13s at NHMS South Oval config. Would have won his class in time trials

On the 987 the optional lsd is a small clutch type with *very* modest ramps (i.e. very little lockup).
https://www.planet-9.com/threads/the...ssected.44005/

[WolfpackS2k]

Originally Posted by Dirty Harry

Re-reading this, I can’t believe some Porsches don’t come with an LSD as standard, Porsche is supposed to be the pinnacle. Is PSM that good that it doesn’t need it? It’d be interesting to see a comparison with a non-LSD/PSM only Cayman.

Mid-engine cars with less than 400 hp do not need LSDs. All it does is add weight. Sure I suppose it might help for autoxing, but on a road course - no difference. An LSD wasn't even an option for most of the 987's production run. I believe it was standard on the 981S, with an option eLSD also available. LSD is more necessary for the 981 to make it feel as nimble as the 987 (it's a bigger car with a longer wheelbase).

Originally Posted by PorscheUnlimited16

Only about 5 percent of Porsche owners actually track their sports car. The other 95% have them as an accessories... like a fancy wrist watch. To take a date to the movie theater, or to pull up somewhere fancy and have it valet.. Hence why it’s an option and not standard on regular models (non Gt/Gts/turbo) trims. ) Standard models without Psm still handle incredibly well with the E version.

BTW PSM stands for Porsche Stability Management. All Porsches built since 2005 have PSM standard.

But yeah, midengine / rearengine cars really don't need LSDs until you get up to insane power levels.

[Yoshoobaroo]

Originally Posted by WolfpackS2k

BTW PSM stands for Porsche Stability Management. All Porsches built since 2005 have PSM standard.

@PorscheUnlimited16 means PASM

[WolfpackS2k]

If he is, then he needs to tell us about the E version, because I've never heard of such a thing.

[Yoshoobaroo]

Originally Posted by WolfpackS2k

If he is, then he needs to tell us about the E version, because I've never heard of such a thing.

I think by E version he means E-diff, aka braking the spinning wheel when it loses traction.

[ZDan]

PSM for sure has to be turned off for trackwork with the 987 in the dry, so *if* it includes an e-diff feature I'm sure it gets turned off with PSM. In treacherous wet conditions, however, PSM is *very* good.

A serious track build on Hoosiers or other uber-grippy tires will almost certainly require a limited slip, but an aftermarket unit is a better bet than the dinky optional Porsche LSD. Which apparently wears to the point that it's essentially open after some number of track days anyway.

For street car on streetish tires and suspension, I'd say LSD not required.
*IF* I get another Cayman for street/track, LSD won't be a requirement for me, which opens up the available cars IMMENSELY!

[WolfpackS2k]

The electronic differential Porsche offers on the 718 (and 981 before it) (and 911 I guess) is an active overdriving unit. Specifically designed to improve handling. I highly doubt it is deactived if PSM is "shut off". BTW most Porsche models won't let you 100% turn off PSM. I can turn it off on my Cayman S but it isn't really off. Still kicks back on if things get really wild - found this out when trying to do donuts in a parking lot after a snow storm.

[ZDan]

Originally Posted by WolfpackS2k

The electronic differential Porsche offers on the 718 (and 981 before it) (and 911 I guess) is an active overdriving unit. Specifically designed to improve handling. I highly doubt it is deactived if PSM is "shut off".

This post is about 987.2
But quick readup on 981 sez that PTV option is a clutch-type limited slip (probably same or similar to the dinky 987 unit with modest ramps and designed for very minimal lockup) combined with electronically controlled braking of the inside-rear on corner entry to improve turn-in. Might be fine for normal "spirited" driving but at the track you might want that feature turned off to conserve rear brakes.

BTW most Porsche models won't let you 100% turn off PSM. I can turn it off on my Cayman S but it isn't really off. Still kicks back on if things get really wild - found this out when trying to do donuts in a parking lot after a snow storm.

Some have reported having to disconnect a yaw sensor to fully turn PSM "off". In my case I drifted my Cayman around regularly with PSM "off" and got plenty sideways without feeling anything and without the any lights flashing. Might not have been "fully off" but it let me hang it all the way out wihtout interfering Fun...

[CSG Mike]

Originally Posted by Dirty Harry

Re-reading this, I can’t believe some Porsches don’t come with an LSD as standard, Porsche is supposed to be the pinnacle. Is PSM that good that it doesn’t need it? It’d be interesting to see a comparison with a non-LSD/PSM only Cayman.

What if I told you McLarens all have open diffs?

[Dirty Harry]

Originally Posted by CSG Mike

What if I told you McLarens all have open diffs?

Didn’t know that until you told me. There goes the idea of a McLaren drift car, unless I get a later model with drift mode, but that’s kind of cheating.

[ZDan]

Originally Posted by Dirty Harry

Didn’t know that until you told me. There goes the idea of a McLaren drift car, unless I get a later model with drift mode, but that’s kind of cheating.

No reason electronically actuating the rear brake shouldn't allow drifts.
Drift control just turns up or down the volume on all nannies together, apparently. It isn't a "drift mode" exactly. https://jalopnik.com/the-mclaren-720...ink-1794879518

Regarding using brake-diff:
Worth noting that getting a limited slip function by braking the inside rear when it starts to spin is different from using a limited slip diff. Braking the inside rear just throws power away, turns it into heat with zero thrust. With a limited slip the inside wheel trying to spin actually directly adds torque to the outside wheel and contributes to acceleration.

If you have gobs of power and brakes are sized to deal with the added use/heat, and have excellent computer control to accurately and predictably apply the inside rear brake to simulate limited slip, braking the inside rear might be fine. I don't know if it's as good a solution for a car with limited power though.

[Irace86.2.0]

Originally Posted by CSG Mike

What if I told you McLarens all have open diffs?

What if I told you all 86's have LSDs?

[Yoshoobaroo]

Originally Posted by Irace86.2.0

What if I told you all 86's have LSDs?

Eeeeehhhhh, teeeeechnically the base version in japan came with an open diff....