VintageCollector

I agree. You CAN overrev good engines slightly with relatively little consequence. From what I'm reading the Metzger motors are almost bulletproof so they don't blow up (I have a 2001 996 turbo)

It's more of a selling tool or like someone else responded, a reason to not warranty cars.

If going over the rev limit was a problem, why wouldn't Porsche just set the rev limiter a hair lower?

Just marketing is all it is.

GoGoDoDo

It is unfortunate that something Porsche implemented to ultimately decline warranty work ended up in the hands and minds of the public so haphazardly. Regardless, its out of the box and people want to see them and believe/valuate the reports/findings as they see fit. However, one cannot contest that at the extreme ends it does indicate how the car was operated. I personally have a love/hate with the DME report.

VintageCollector

Old cams, before their timing as adjustable with electronics always favored only one section of the RPM range. That was known as the 'power band' - the section of RPM where you made the most power. Old American muscle did it down low and European and Japanese cars usually did it at higher RPMs.

Variable timing allowed you to stretch the power band across a much more broad RPM range. You could 'tune' the engine to breathe well at all RPMs offering much more versatility.

It makes sense that if you focused making power at one RPM range (like high RPM the way powerhound did) then you would lose it elsewhere.

bdronsick

I've read from multiple internal Porsche sources that regardless of marketing, Variocam was implemented primarily to increase MPG for tightening US and Euro enviro regs

Makes sense cause the Cup & factory race cars (not subject to EPA) don't use Variocam at all

IE if Variocam net increased performance Porsche Motorsports would be using it

Just what I read, this is not an opinion ugh

VintageCollector

Right. If it was just raw power and speed for city driving, you'd want your vario timing to work all across the RPM range because you'd have max efficiency across the RPM range.

But if you're building a race car, you don't need power down low because you rarely spend time in the low RPM range. You just need to get the car going from a pitstop.

Also, ALL engineers are constrained with fuel efficiency and emission standards. These 'vario this' and 'adjustable that' tech features may be sold as creating horsepower but they are also very important to fuel efficiency and emission standards.

If you didn't have to worry about emission standards you could create a LOT more horsepower out of engines with little effort.

The ceiling is not only how much your engine can take, it's manufacturers trying to conform to emission laws.

The 1979-1986 930s were a great example. California models (and later US models) made 282 HP.

Canadian and ROW models made 300 HP.

Just a little work got them much higher but those cars didn't have the electronics or emission capabilities that we have today to churn out the power efficiently. You'd literally be spewing gas and fire out the exhausts. lol

I remember those days. My favorite car.

bdronsick

Yup

VintageCollector

Yes. Just posted about that. It's both. It's for driveability and emissions. All As porschetech said, all depends on what your goals are when building the engine.

VintageCollector

Just to my limited knowledge, it sounds like it.

Kind of like the fear mongering on the news. People see a little bit of bad news and run with it for miles when it may never affect them.

GoGoDoDo

Just asking...is the non mezger over rev report/impact the same as the mezger? Yes, I know they are not the same motor. My point being, the over rev can, and will, indicate a "money shift"; it illustrates "over mechanical limits". I am also aware it can indicate that a car was "tuned" and therefore was allowed to exceed the rev limiter; is this a "bad thing"?
.

bdronsick

Well, my Mercedes station wagon is very drive-able, and my VW Golf TDI gets fantastic MPG

But I'll gladly take a non-Variocam Cup replacement motor for my 996 Turbo any day of the week Porsche Motorsports wants to give me one!

VintageCollector

I'm relatively new back into Porsches so I can't answer that, and I'm a fan now. I stopped working on Porsches in 1997 and I worked my last stint at Benz from 1997 - 2009 when I left the industry all together.

All I know is what I've read here:

1) the Metzger engines are apparently super reliable and
2) over rev reports are to be taken with a grain of salt and not the doom and gloom that people read into them.

In any industry where lots of money is involved (like my other collectibles industry) people tend take a small bit of into and always think the worst and it shapes the market.

It's not like an IMS bearing which everyone knows about. The real proof would be how many engines actually develop trouble in the real world.

From what I hear, you don't hear of many Metzger engines blowing up even though we all know many of them probably spend a lot of time at redline. I probably over rev mine from time to time (especially in 1st when it's easy to do so) and while I was initially worried after learning about it but I'm not too worried about it now.

Like I said, if Porsche thought it was that serious of a problem, they'd have set the rev limiter a hair lower.

One thing I've always loved about most German engineering is how thorough it is (IMS bearing not withstanding )

Maybe someone more experienced has a better understanding?

Porschetech3

Unplugging the Vario-cam would cause fault codes for non-function. Yes would save wear on the solenoids, same as just not driving the car/starting the engine.

Unplugging the Vario -cam on 996TT would loose 150hp in mid-range while gaining 120 on top end, and a net lose of 30hp ,and end up feeling like the old 930 where the turbo hit was like a sledgehammer, nothing down low. a little in the middle, and then a big hit..I would never consider going back to that...

The solenoids and be easily replaced on the 996TT ...

Billup

I believe they are different.

https://911virgin.com/wp-content/upl...6212261995.jpg

Porschetech3

Yes it was, the tightening emissions and fuel economy was the driving force to finally get the Variable Valve Timing Technology into the production cars, where it is used for emissions and economy and a bit of performance increase, but that is NOT the extent of its capabilities.

Factory Race cars are not unlimited, in-fact they are very strictly limited..The cubic inches, the boost pressures, the number of cylinders, the type of fuel, Type of engine ,the fueling system,and yes even the Variable Valve Timing Technology is all very carefully and strictly limited..

Why would the Top Racing Format in the world (F1) go the the trouble of BANNING Variable Valve Timing Technology if it were in fact of no use for making power? The simple answer is they wouldn't ....It has been shown by FreeValve that the Infinatly Variable Valve Timing Technology that they use has a 45% increase in power over the Factory VVT..( not to mention over a non-VVT)....

GoGoDoDo

Thank you. Already understood that and was not specific enough in my comment. I specifically meant...the importance of range 1 vs range 2 vs range x....and its "impact", or perceived impact, on the motor.