Switchcars tutorial on Porsche Overrevs - how to read DME reports

[@richardh1773]

One other thing worth pointing out for all those who are hyper focused on DME reports...People spend hundreds of thousands and sometimes millions of dollars on pre-DME readout Porsches every day without a clue about how many over-revs these sometimes less robust engines have experienced. DME reports are just one tool in evaluating a car and it's nice to see someone has taken the time to educate buyers on this largely misunderstood topic. I recently sold a 996 GT2 on BAT and had to educate numerous knuckleheads who had no idea what they were talking about. Good job Switchcars!

[@iamu]

Doing the maths on the back of my head...- takes the phone to make the math 😂😂😂 Your sarcasm and sense of humor is the greatest i've seen. Must have seen all your videos from Vinwiki 10 times by now. I let them play when i'm alone in my car, commuting.

[@stefanwinter1377]

Shrewd explanation!

[@squicker]

Thank you, this is the best explanation I have seen of rev range reports. My 997 Turbo had a few hundred in RR1 and RR2 but nothing higher. I took it on a track day and I racked up 5402 in RR1 (as I chase the red line and usually shift dead on time), and then 700 in RR2. Then one day, when road driving, I hit the rev limiter hard when shifting up from 2nd to 3rd, and when plugging in Durametric, I could see 8 entries in RR3, which up until your video I thought was impossible and was terrified I'd damaged my engine somehow. Then one day I plugged in Durametric and saw 1 entry in RR4 and 1 entry in RR5, I was at this point beset with grief! So I have, over 1739.8 operating hours, with the last entry being 17 hours ago: RR1 = 5402 RR2 = 700 RR3 = 8 RR4 = 1 RR5 = 1 RR6 = 0 And that seems quite tame on a 997 Turbo with 58,000 miles on it, would you agree?

[@switchcars]

totally normal

[@BuckMcAntlerson]

This was fantastic on every level. That whisky 🥃 cut had me rolling btw.

[@henrycollins2478]

Absolutely enthralling

[@stefansch2]

This is a fantastic explanation. Well done, Sir. P.S. - I’m impressed that I’m the second Stefan to comment on this video...

[@stefanwinter1377]

😁

[@nonenone77777]

Doug, definitely enjoy the content that you create in all the channels especially VINWIKI. That said, us Cayman owners feel neglected: you mentioned nothing about the 918 or 718s, especially the GT4s. Any thoughts on at least both GT4 gens? What are their healthy/redline ranges and such? Thanks!

[@toddvanrossum9476]

Awesome video...very entertaining and informative, well done!

[@seattimetv]

Anyone salivating over the sound of the OG Metzger 996 sound?🇩🇪

[@jfinks]

19:28 - Truth. I’ve witnessed it first hand from the technician side of things. Find yourself a technician that can explain over-revs by calculating piston speed in meters/second and hire him/her to evaluate your potential procurement of a sports car.

[@sSW-nu1lb]

very useful thank you. now i'm well informed for the next big decision!

[@MIXMASTERRONEDEE]

That was brilliantly done my good fellow, bravo..

[@smason4622]

first post in 7 months. definitely worth the wait.

[@Inazuma68]

Well done. I drive a 996.2 GT3 and had some range 1 and couldn‘t figure out, what that exactly means. 4 years later, the car still pulls strongly 😎. But I must say, I usually shift between 7800 and 8000 because the power curve is going down and I see no benefit in scratching the rev limiter. But I would say far more important is driving carefully as long as the oil temp is low.

[@jayi836]

Thanks for the detailed explanation.happy with my 997.1 TT

[@nullstring1]

NUNDERSTANING. Thats gold Doug.

[@SteveReed33]

Would love an update on how overrevs are counted in newer cars (Specifically a 718 GT4)

[@robocop3059]

Great explanation! Thank you sir!!

[@kasstty]

This is some great quality content. Good shit!!!

[@Torquenbeans]

How do you only have a little over 1k subscribers? You're possibly my favorite story teller on vinwiki, besides rabbit but c'mon it's rabbit.

[@switchcars]

Thank you for the compliment. I am not actively promoting our channel nor intending to be a KZbin personality, as much as I enjoy telling stories. Storytelling doesn't pay the bills, the day job does.

[@samshamansky]

Great video. No pansies.

[@aquatone61]

The only thing I would change is the number you divide by, it would be 6 or the # of cylinders. That is what the Porsche USA warranty department told me to use when looking at overrevs for CPO.

[@switchcars]

No because only three cylinders fire per rotation/each cylinder fires every other rotation - it’s a four stroke engine not a two-stroke.

[@aquatone61]

I know it’s a 4 stroke but I’m telling you what PCNA had us do….. They count the number of cylinder ignitions, that’s all there is to it. To make the numbers correct for crankshaft rotations it would be double but we divided the number ignitions by six.

[@switchcars]

@@aquatone61​​⁠if I understand you correctly, if there are 300 ignitions, by my math that would equal 100 crankshaft revolutions. By their guidelines they are saying it’s only 50 revolutions? Either I’m missing something, or it makes less sense than the presidential debate, or both.

[@shahrukhbakar3248]

The 991.2 GT3 (redline 9000 rpm) VAL also mentions value Z201_Maximum engine speed reached (e.g. 9367 rpm) but also value Z202_Total operating duration at engine overspeed (e.g. 0.40 seconds). On this VAL, let's say values Z211, Z212, Z213 (Overspeed ranges 1-3) show # ignition events as 259, 89, 28 respectively, occurring at times 2454.0 min, 12006.0 min, and 11838.0 min respectively. No events in range 4-6. What are the rpm ranges for overrev ranges 1-3? How would you interpret this VAL? How is it possible to accumulate range 2-3 overrevs without triggering a range 1 overrev? I have heard something about the way the counters operate in that they count in 'bins' of time and one can accumulate higher range overrevs without triggering lower range overrevs if the event is very very brief and does not trigger that 'bin' of time in the lower overrev.

[@shahrukhbakar3248]

Doing the math, if we add up the total number of overspeed ignition events, 259 + 89 + 28 = 376 events. Since one crankshaft rotation gives 3 ignition events, there are 125.3 crankshaft revolutions in overspeed. Of course, not all these events happened at exactly 9000 rpm, but will be at a weighted average of the overspeed range events. For convenience, if we use 9000 rpm, then 125.3/9000 = 0.013925 minutes or 0.83556 seconds were spent in overspeed. Why would the manual calculation above be different from the VAL readout of 0.40 seconds?

[@plexinico]

Besides the money shift, will bumping into the rev limiter in 1st and 2nd for split seconds do harm to the engine on a regular 997 Carrera S?

[@switchcars]

No harm at all in pinging the rev limiter.

[@slow5043]

Great video!

[@carmelothegoat1892]

That lip smack at the beginning 👌🏼

[@stevewodell6183]

Very informative

[@Angry-Lynx]

Cool what bout 981s thanks

[@optinum]

So the 996 produced a overrev when you bounced off rev limiter but not the 997 GT3?

[@switchcars]

That is correct, and according to design

[@optinum]

@@switchcarsjust curious do you know if it would produce an overrev on 991 GT3 generation if you bounced off rev limiter?

[@chipper442]

“ unless you’re a pansy” LOL

[@jameswillard1]

Hey Doug - would you pass on a 997.1 Turbo with a DME report that shows 11 previous ignitions in range 6? Thanks in advance

[@switchcars]

Need more info! Email us the full report

[@BillMacD93]

"Unless you're a pansy" lol

[@DJ_Driven]

What's the real deal why doesn't Porsche ECU automatically cut ignition / fuel to prevent over revs?

[@switchcars]

They do cut it at redline, but no computer can prevent mechanical overrevs which are the only concerning ones

[@unakuruwa]

This👍🏻Is for the whiskey

[@justasquirrel644]

…no foolproof system, but you will encounter many tools. Truth! 😂😂😂

[@JoeyGLI]

The amount of times I picked up tires from treadmaxx and didn't see you ripping around is a tragedy 😂

[@ZondaF355]

Genius...

[@jamesmeneses4821]

Nice, but you lost me after you mention the over revs on a 987 and 997 in range 3 and 4. So easy to red line a 987 and/or a 997 at the track without even driving it hard.

[@joey7253]

So .09 of a second at 9000 rpm and then the engine is jerked back to 7000 rpm immediately. Sounds pretty brutal to me.

[@switchcars]

7000 RPM? No. Redline (on a GT3) is 8400 RPM, and the engine does not record ignitions between 8400 and 9000 RPM. So it's just .09 seconds at/above 9000 rpm, and then the engine speed slows mechanically at a normal rate. You're mixing the facts of a 997 GT3 overrev/redline vs what I estimated to be the average redline for purposes of explanation.

[@TheDonshaz]

Next time put your notes under the camera youre looking at 😂

[@cameronp5728]

jesus i cant take this guy seriously

[@switchcars]

That's ok, that makes two of us!

[@cameronp5728]

@@switchcars it's okay Mr. 4.4k subs. It will stay that way

[@miralemnermina142]

​@@cameronp5728smartest gt3 owner that doesn't go on a track :)

[@Dogdogdoga]

Thank you

[@scottyb4606]

Awesome - excellent video. Thank you