No money shifts but momentum will sometime push the needle into the red. Was wondering why older 911's had a 7300 redline and the 3.2 a 6300 redline. Sounds like rod bolts are the weak link but not to be worried about if under 6500 which I don't think i hit.

My motorcycle (4 cylinder) has a 15,500 RPM redline :-)

Chris

Take for example the '72-73 models
911T has a 6400rpm max and hp max @5700
911E has a 7000rpm max and hp max @6200
911S has a 7300rpm max and hp max @6500
911RS has a 7300rpm max and hp max @6300

The difference is cr and cams

the S & RS use the same cams but the larger displacement lowers max hp rpm

Smaller engines have smaller reciprocating parts that tend to be lighter and result in smaller inertial forces. Although for the specific case of older vs newer 911 there could be other reasons.

Edit: just realised you meant 911 Carrera RS.

(I believe the 991 GT3 RS has max power at 8250 rpm and revs up to about 8800 rpm.)

oops:(

I've bounced off the rev limiter a few times during autox, it's pretty soft, and I don't know at what rpm because I was pretty busy at the time. Mine has an older non SW chip, I'll say automotive ?
Funny the guys with the wrx and evos do it all the time when they run out of rpms in 2nd, but I wouldn't do it on purpose.

The 3.2 Club Sport got a higher redline - can't remember the exact number. The factory may have beefed up the bottom end, but I've never read anything to substantiate that...

http://forums.pelicanparts.com/uploa...1509403338.jpg

The '87 3.2 Carrera CS(M637) engine was the same as all the other 3.2 Carreras except
hollow intake valves
modified DME w/ 6840 rpm cutoff
omission of the active carbon tank

I wonder if the rod bolts just showed themselves to be less reliable later in the life of the 3.2, allowing for Porsche's confidence in that elevated red line back then, or if that speed would still be deemed as acceptable on a stock bottom end engine...

my 73 E had higher compression JE pistons, a DC 30 cam and ARP rod bolts. It would be full on powerband at 7,300 RPMs. It surely would have made more power at higher RPMs. At 6,000 RPM's the tack would drop at double time to 7000 and beyond if I or the rev limiter would let it (7300 rpm, S, revlimiter in the rotor). Great engine combination.

Stock E ran out of breath at 6000 rpm's

Chris

yes... that should pretty much discount the rod bolt/conrod weakness theory.

I always thought the clearances of the valves to the taller euro dome 3.2 piston lowered the rev limit. the CS may have ran with hollow valves for this reason.

3.3 930 larger displacement with milder cams and low cr piston have 6800 redline because you dont have to worry about valve interference perhaps?

can you still order these factory hollow valves? it would be nice during the rebuild.

i take mine occasionally to 7000 where there is a old school abrupt ignition cutout. not the best way to rev limit a car if you are hot out of a corner. throws it out of the balance wants to send you into the weeds.

the DME probably doesn't have a ability to have a "soft cutout" like the moderns. i dont believe the DME cuts the fuel only otherwise the motor might detonate under high load.

Run your engine to whatever RPM you want, it is your engine. I don't have to pay for your repairs.

When I rebuilt my engine I did a fly-cut on the case and ATE rod and case bolts. I have a Wong chip and he raised the red line a couple hundred RPM for stock. I still shift at 6,400. Past that is pointless. A dyno pull will show the torque is falling off at the higher RPMs. It is nothing but more noise.

True but sometimes a shift up then an immediate shift back down again is not really feasible.

i shift late out of 1st often since the gap in gearing to 2nd is country mile and falls out of the power band significantly. reminds me of a shifter kart falling off the pipe.
I havent got around for a custom gearset yet. one has to keep up with that mom in the minivan...ha!

perhaps is should just polish the lug nuts and take it to cars and coffee. seem like thats where most of the aircools are going these dayz... last pca track event i went to only had one aircooled eleven on the track. wteff happened?

It is the power falling that is an indication that one should move to the next gear!

If one upshifted when torque is beginning to fall in a 991 GT2 RS it would miss more than 200 hp:

https://i.imgur.com/TiH2OrD.png

Yea, besides the fact they call a GT2RS a 911 there is little in common with a 3.2 air cooled engine designed in the 1970s. Well they are both a flat 6 and run on gasoline in the rear of a car.

Modern turbo motors are nutso. The GT2RS is mega nutso.

All the 2.0 engines will live happily with 7300 rpm. I had a “S” rotor in my 914-6 for years with no ill effects and autocrossed it a lot. That of course was the ignition cut-out variety

I know there’s a reason for them but I hate the fuel cut-out variety. Particularly the one on our 2011 GTI. When it cuts out you are in the “penalty box” for what feels like forever - and it is in autocrossing. The problem is that the GTI is so “hushed” you really have no aural cue for when you’re approaching the cut-off and you’re too busy to watch the tach.

And there’s another variety as well. My 250 Kawasaki has an ignition cut-out too, but only one cylinder!

The point is: for optimal acceleration one should often upshift well past the peak torque rpm. In other words, the fact that torque is falling is not in itself an indicator that upshifting is advisable.

+1

if you shift at peak hp ie around 5900-6k on a 3.2 your stock 2nd gear will drop you to about 3000 rpm and thats if u want to slam shift it. 3.2 are gutless at 3k rpm... van driving soccer mom would destroy you :-)

i dont even want to think about what the rpms would be if i shifted where the torque is falling off 1k rpm earlier.

if i had a 3.6 i wouldnt need to go over the redline as often