Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster General Discussions

Reply
 
LinkBack Thread Tools Display Modes
Old 08-05-2013, 12:43 PM   #1
Registered User
 
Join Date: Mar 2013
Location: Indiana
Posts: 177
Garage
Question for Mechanics: 2200-2500rpm or 2700-3000rpm, what is best???

OK, I want the opinion from the people that actually work on Porsches or have a very good understanding of the design and internals of the 986 engine. What is the best operating rpm for our cars??? Is it best to keep our engines closer to 3000rpm when at cruising speed or at near 2200rpm?

I enjoy spirited driving as well as the next guy but I want to know when I'm just cruising around, what is the healthiest rpm range for my 986?
Meat Head is offline   Reply With Quote
Old 08-05-2013, 12:47 PM   #2
Registered User
 
Perfectlap's Avatar
 
Join Date: Nov 2004
Location: New Jersey
Posts: 8,696
why did you choose 2,700 to 3,000?

I've yet to read an article by an engine expert that speaks of anything below 3,000 as being beneficial to this car on this particular issue.
__________________
GT3 Recaro Seats - Boxster Red
GT3 Aero / Carrera 18" 5 spoke / Potenza RE-11
Fabspeed Headers & Noise Maker
BORN: March 2000 - FINLAND
IMS#1 REPLACED: April 2010 - NEW JERSEY -- LNE DUAL ROW
Perfectlap is offline   Reply With Quote
Old 08-05-2013, 01:01 PM   #3
Registered User
 
Join Date: Mar 2013
Location: Indiana
Posts: 177
Garage
Quote:
Originally Posted by Perfectlap View Post
why did you choose 2,700 to 3,000?

I've yet to read an article by an engine expert that speaks of anything below 3,000 as being beneficial to this car on this particular issue.


No particular reason. I'm actually just thinking around 3000rpm. I find it very hard to believe that running the car at a constant 3000rpm+ is good for the car. It may be better for the IMSB but I question if you are not stressing other key components of the engine.

I will admit that my car background is mainly American muscle cars (only owning 2 previous Porches before the Box) but running most engines at + 3000rpm constantly would not be healthy in the long run.
Meat Head is offline   Reply With Quote
Old 08-05-2013, 01:27 PM   #4
Registered User
 
Perfectlap's Avatar
 
Join Date: Nov 2004
Location: New Jersey
Posts: 8,696
lower rpm, less lubrication.

Engine is not going to fail because of high rpms. It's going to fail for a slew of other reasons that you can't address while driving.
Those have to be addressed before you get in the car.
__________________
GT3 Recaro Seats - Boxster Red
GT3 Aero / Carrera 18" 5 spoke / Potenza RE-11
Fabspeed Headers & Noise Maker
BORN: March 2000 - FINLAND
IMS#1 REPLACED: April 2010 - NEW JERSEY -- LNE DUAL ROW
Perfectlap is offline   Reply With Quote
Old 08-05-2013, 01:56 PM   #5
Track rat
 
Topless's Avatar
 
Join Date: Nov 2006
Location: Cucamonga CA
Posts: 3,654
Garage
Disclaimer: Not a factory certified Porsche mechanic.

I have been wrenching them for many years and have yet to toss a Porsche boxer motor.
I see very little in common with a pushrod V8 so that is probably not the best comparison benchmark. Every motor has a RPM sweet spot depending on engine load where the combination of balance, lubrication, cooling and wear are at their best. My personal choices:

No engine load- 800 RPM idle
Flat, straight highway miles with very low engine load 2-3K RPM
Moderate engine load for passing, hill climbing or canyon carving- 3-5K RPM
Heavy engine load for max performance or motorsport- 4K-redline

I see no reason to ever drive this car below 2k rpm. The motor design is such that it could cause excessive lateral loads especially on the timing chains and IMS bearing. It even feels ugly in that range when leaving from a dead stop. As long as you don't load the engine by passing or climbing I see no problem cruising straight and level at 2.2K rpm. Just downshift to climb hills. A pushrod V8 was designed to cruise at much lower rpm and has no ugly spot in the 1500 range. Apples and oranges.

YMMV
__________________
2009 Cayman 2.9L PDK (with a few tweaks)
PCA-GPX Chief Driving Instructor

Last edited by Topless; 08-05-2013 at 02:02 PM.
Topless is offline   Reply With Quote
Old 08-05-2013, 02:40 PM   #6
Registered User
 
Steve Tinker's Avatar
 
Join Date: Dec 2008
Location: Queensland, Australia
Posts: 1,522
Didn't I read somewhere about a natually occuring harmonic vibration in the flat 6 engine design that happens at around 3,000 rpm?

I've always had it in the back of my head to drive either just below or just above the 3,000 rpm threshold - there again at my advanced years, I could be talking out of the back of my head too......
But the everyday sweet spot must be in the 3,500 to 4,500 rpm pulling through the gears - very addictive!
__________________
2001 Boxster S (triple black). Sleeping easier with LN Engineering/Flat 6 IMS upgrade, low temp thermostat & underspeed pulley.
2001 MV Agusta F4.
Steve Tinker is offline   Reply With Quote
Old 08-06-2013, 06:20 AM   #7
Registered User
 
Join Date: Apr 2008
Location: Southern New jersey
Posts: 1,054
IIRC Jake mentioned avoiding cruising @ 3000 RPM a few years ago, but haven't heard anything since. I'm at 3K all the time, since it equals my 75 MPH highway cruise speed.
stephen wilson is offline   Reply With Quote
Old 08-06-2013, 06:45 AM   #8
Registered User
 
Coffinhunter's Avatar
 
Join Date: Jun 2012
Location: Spring Hill, Florida
Posts: 442
Garage
Quote:
Originally Posted by stephen wilson View Post
IIRC Jake mentioned avoiding cruising @ 3000 RPM a few years ago, but haven't heard anything since. I'm at 3K all the time, since it equals my 75 MPH highway cruise speed.
I am usually just a hair over 3,000 since I cruise between 75-80 to work everyday. With the speed limits on US freeways being what they are, there would be no need for 6th gear if we couldn't drive at 3,000 RPM.

I do shift down to 5th if I am going to pass though.

The only thing that I have ever heard as being bad is driving at less than 2,000.
__________________
2003 Boxster S, 6-spd, Seal Grey/Grey top


Ka is a wheel, and everything is 19
Coffinhunter is offline   Reply With Quote
Old 08-06-2013, 07:35 AM   #9
Registered User
 
tonycarreon's Avatar
 
Join Date: May 2009
Location: Frederick, MD
Posts: 1,396
if the car couldn't handle higher RPMs, it wouldn't go that high. the limiter would kick in earlier.
__________________
"Speed has never killed anyone, suddenly becoming stationary... that's what gets you."
tonycarreon is offline   Reply With Quote
Old 08-06-2013, 11:27 AM   #10
Registered User
 
Join Date: Mar 2013
Location: Indiana
Posts: 177
Garage
Quote:
Originally Posted by tonycarreon View Post
if the car couldn't handle higher RPMs, it wouldn't go that high. the limiter would kick in earlier.

You can't be serious??? Trust me, NO car is going to stand up to constantly bouncing it off the rev limiter LOL. Just because something can handle it doesn't mean it is good for it.
Meat Head is offline   Reply With Quote
Old 08-06-2013, 11:33 AM   #11
Registered User
 
Perfectlap's Avatar
 
Join Date: Nov 2004
Location: New Jersey
Posts: 8,696
Quote:
Originally Posted by stephen wilson View Post
IIRC Jake mentioned avoiding cruising @ 3000 RPM a few years ago, but haven't heard anything since.
Other way around. He instructs 3K RPM driving for his engine customers.
__________________
GT3 Recaro Seats - Boxster Red
GT3 Aero / Carrera 18" 5 spoke / Potenza RE-11
Fabspeed Headers & Noise Maker
BORN: March 2000 - FINLAND
IMS#1 REPLACED: April 2010 - NEW JERSEY -- LNE DUAL ROW
Perfectlap is offline   Reply With Quote
Old 08-06-2013, 11:59 AM   #12
Registered User
 
Join Date: Apr 2008
Location: Southern New jersey
Posts: 1,054
He may now (and I think it's Above 3k, not At ), but at some point in the past it was recommended to not stay at that RPM. I'm not 100% sure it was Jake.

Here's one mention of it:
http://www.renntech.org/forums/topic/38120-3000-rpm-ims/

Another:
http://www.pedrosgarage.com/Site_5/The_Bad,_the_Ugly_and_the_Good,_part_2.html

Last edited by stephen wilson; 08-06-2013 at 12:07 PM.
stephen wilson is offline   Reply With Quote
Old 08-06-2013, 02:35 PM   #13
Registered User
 
tonycarreon's Avatar
 
Join Date: May 2009
Location: Frederick, MD
Posts: 1,396
Quote:
Originally Posted by Meat Head View Post
You can't be serious??? Trust me, NO car is going to stand up to constantly bouncing it off the rev limiter LOL. Just because something can handle it doesn't mean it is good for it.
that's not what i said at all. i said if the car couldn't handle 5k rpm (for instance), the limiter would kick in before it hit that. i never said to go down the road bouncing off the limiter.
__________________
"Speed has never killed anyone, suddenly becoming stationary... that's what gets you."
tonycarreon is offline   Reply With Quote
Old 08-06-2013, 05:20 PM   #14
Registered User
 
Perfectlap's Avatar
 
Join Date: Nov 2004
Location: New Jersey
Posts: 8,696
Quote:
Originally Posted by stephen wilson View Post
He may now (and I think it's Above 3k, not At ), but at some point in the past it was recommended to not stay at that RPM. I'm not 100% sure it was Jake.
Flat6 say 3K. At least once, in response to a forum member asking about Pedro raising the issue of harmonic vibration in the m96.
__________________
GT3 Recaro Seats - Boxster Red
GT3 Aero / Carrera 18" 5 spoke / Potenza RE-11
Fabspeed Headers & Noise Maker
BORN: March 2000 - FINLAND
IMS#1 REPLACED: April 2010 - NEW JERSEY -- LNE DUAL ROW
Perfectlap is offline   Reply With Quote
Old 08-06-2013, 06:57 PM   #15
Registered User
 
Join Date: Jun 2013
Location: Socal
Posts: 560
I thought it was all about the variocam kicking in around 4k ....

In all honesty , with learning on the fly ecu maps the best thing to do is unplug the battery for 30 minutes then drive it like you stole it .

Don't believe the snake oil , don't believe the Internet , don't worry , just drive
Ian c is offline   Reply With Quote
Old 08-07-2013, 03:22 AM   #16
Registered User
 
Join Date: Apr 2008
Location: Southern New jersey
Posts: 1,054
I agree. Don't drive by fear of what may happen, it's about having fun!
stephen wilson is offline   Reply With Quote
Old 08-07-2013, 11:16 AM   #17
Registered User
 
Join Date: Mar 2013
Location: Indiana
Posts: 177
Garage
Quote:
Originally Posted by stephen wilson View Post
I agree. Don't drive by fear of what may happen, it's about having fun!
This has nothing to do with fear ??? It has to do with wanting to do what is best for my engine when day to day driving. I don't understand why people have such a problem with Box questions when it has to do with driving them in a subdued way??? Does everyone that owns a Boxster drive it like a bat-out-of-hell 100% of the time LOL ??? My Boxster gets plenty of play time action but every time I take it out for a drive I don't feel the need to attack the Road .

I'm just trying to find out (from those with real mechanical experience on the 986) what is the most healthy rpm range for our Boxsters when cruising .

Meat Head is offline   Reply With Quote
Old 08-07-2013, 11:37 AM   #18
Registered User
 
Join Date: Apr 2008
Location: Southern New jersey
Posts: 1,054
Sorry, these type of questions always seem to get side-tracked into an IMS discussion!

I think Topless already answered your question best.
stephen wilson is offline   Reply With Quote
Old 08-07-2013, 12:25 PM   #19
Registered User
 
Join Date: Apr 2012
Location: Ontario, Canada
Posts: 598
Pedro has suggested a harmonic inbalance to the engine at 3000 rpm's that can lead to vibration in the car. Frankly, I have never noticed it and 3000 rpms, at least in 5th gear in a 2.7, is right around my usual highway cruising rpm. I believe he also suggests that his re-engineered front engine mounts can reduce the effect.... In any event, I have read nothing to suggest that the engines should not be cruised at that rpm, nor that it will contribute to IMS shaft bearing failure, etc.

And for what it is worth, I am with Meathead on this. I have fun driving my car every day, even though I seldom take it to redline. I do not lug my engine, but I also don't drive it excessively hard. I will occasionally take her to 7000 rpm rather than the 7200 rpm redline in first and second gear (positively love the sound), but more often than not, even when driving quickly I will shift at about 6000 rpm's. Frankly, the torque curve has flattened-out by then and there is very little to gain by pushing the envelope if you are not tracking the car.

The same is true of shifting. I never hurry my upshifts as the rpms need a chance to drop a bit before engaging the next higher gear. This puts less strain on the synchronizers and adds to smoothness, all while acknowledging that it may reduce the acceleration times marginally. I also ALWAYS double-clutch my downshifts, not only because it is fun and because I love the sound of the blip of the throttle, but also because it is smoother and again, puts less strain on the drivetrain. Braking? I never intentionally leave my braking to the last possible fraction of a second on the street. Apart from wear and tear on the brakes, the risk of encountering an unexpected patch of gravel, dirt, uneven pavement, etc. that increases your required stopping distance can be ignored only at your own peril (and frankly, the peril of others using the roadway). Lets face it, even with a relatively conservative approach to braking and cornering, I have nevertheless on occasion found myself going too hot into some corners.

Simply put, I do not baby my car, but nor do I abuse it or operate it in a way that makes errors potentially more serious - i.e., over-revs, 'beating' the synchros, rushing shifts and hitting the wrong gear with potential over-revs that could destroy the engine, etc. To me 'performance driving' on the street is much more akin to driving an endurance car than qualifying a formula 1 car; 10/10's is not only harder on any car, it also leaves very little margin for error. Do I care that someone else could drive my car slightly faster over the same roads? Not one iota. Indeed, in my experience I am often able to keep pace with even potentially faster cars that are being 'over-driven'. Big slides requiring big corrections will inevitably slow your exit speed out of corners and, in a car without huge power and torque, that is a sure-fire way to go slower rather than faster over a given section of roadway.

Brad
southernstar is offline   Reply With Quote
Old 08-07-2013, 12:47 PM   #20
Registered User
 
Perfectlap's Avatar
 
Join Date: Nov 2004
Location: New Jersey
Posts: 8,696
I think the problem is that people get very used to driving passenger sedans which are usually very quiet and docile. They start to think that this is 'normal' type driving. \
When they get into a car with the engine directly behind them, and one that makes quiet a racket when it is operating in its version of 'normal', it leads them to think that they're 'over-doing it' or that they are inviting an engine problem by getting the revs up. For starters, while these aren't derived directly from race engine like on a GT3, they are still engineered to 'live' in the area of the rev counter that is nothing like that of a street car whose slush box is constantly short shifting.

It's somewhat counter-intuitive, a Boxster that is getting poor gas mileage (relative to an econo box) and making its passengers annoyed that driver can't ever hear them, is probably an engine that is running EXACTLY the way the engineers intended. And one reason why GT3 drivers always have a second car.
__________________
GT3 Recaro Seats - Boxster Red
GT3 Aero / Carrera 18" 5 spoke / Potenza RE-11
Fabspeed Headers & Noise Maker
BORN: March 2000 - FINLAND
IMS#1 REPLACED: April 2010 - NEW JERSEY -- LNE DUAL ROW

Last edited by Perfectlap; 08-07-2013 at 12:55 PM.
Perfectlap is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 03:17 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page