Hitting 5.5k often..... - 986 Forum - The Community for Porsche Boxster & Cayman Owners

blinkwatt · 03-23-2007, 02:34 PM

My newer more aggresive driving habits have the car seeing 5.5kRPM at least once everytime I take it out,is there a problem w/ that? I don't drive like around town,only on onramps. How often are you guys seeing 5.5kRPM+? I know it's a sports car,I maintain it better then Porsche recommends so I should be safe shouldn't I? I just don't want something wearing down extremely fast on me. *

*After my 13 year old brother and I got on the onramp after almost hitting 6kRPM he says, "Whoa! That sounded awesome! You know your car sounds like a video game?"

TriGem2k · 03-23-2007, 03:02 PM

I hit it ALL DAY

mikefocke · 03-23-2007, 03:05 PM

not if it is safe to drive that way where you are both for you and for others.

The engine loves to be rev'ed.

kelly1005 · 03-23-2007, 03:05 PM

After the car is warmed up to normal temps, I tend to rail on it a bunch when I can. That's part of the fun!

On a related note, it looks like there is a little light at the end of the tach. Does that come on when you've hit the rev limiter or something? I back off before I hit any red markings. I'm not that bad.

CJ_Boxster · 03-23-2007, 03:12 PM

Usually only in 2nd gear while on on-ramps.

velvet_jones · 03-23-2007, 03:43 PM

5.5k is when my intake and exhaust start to work together. You can realy feel it kick in!

MNBoxster · 03-23-2007, 04:17 PM

Quote:

Originally Posted by kelly1005

After the car is warmed up to normal temps, I tend to rail on it a bunch when I can. That's part of the fun!

On a related note, it looks like there is a little light at the end of the tach. Does that come on when you've hit the rev limiter or something? I back off before I hit any red markings. I'm not that bad.

Hi,

That's not a light. It's an Ambient Light Sensor to adjust the intensity of the LED display so you can better see it in bright Daylight...

Happy Motoring!... Jim'99

dmcutter · 03-23-2007, 04:49 PM

Even with stock everything it sounds so sweet up at the north end of the rev range. I see in excess of 5k pretty frequently. The engine is so smooth I forget to shift a lot of the time...

Adam · 03-23-2007, 07:31 PM

Quote:

Originally Posted by kelly1005

After the car is warmed up to normal temps, I tend to rail on it a bunch when I can. That's part of the fun!

On a related note, it looks like there is a little light at the end of the tach. Does that come on when you've hit the rev limiter or something? I back off before I hit any red markings. I'm not that bad.

You are doing just fine Blinkwatt. Just make sure the car is up to temp. I take it to 7,200 rpm (near redline in mine) at least once every drive usually. If you aren't excersizing the engine you aren't driving the car like it was meant to be.

Kelly, I'ved banged the rev limiter a few times and no light comes on just a slight jerk forward because of the fuel shutoff. These engines weren't designed with Sunday drives to church in mind just in case anybody was wondering.

djomlas · 03-23-2007, 07:47 PM

i love taking mine over 5k, as soooon as it goes over 5k it sounds like a diff car, especially w the intake

love it

j.fro · 03-23-2007, 07:59 PM

Take it to the limiter. That's why it's there. The car is not a pansy-a$$ high dolllar cruiser. In all honesty, it is a tuned down racecar. 11+compression?? 7k+ redline?? The computer controls have let us have this along with drivability. Take advantage!!
You won't destory our Boxster on the street. You'd be hard pressed to kill it on the track. Enjoy your car.

blinkwatt · 03-23-2007, 08:10 PM

Maybe the newer 2.7L & 'S' redline at 7k+ but the old 2.5L redline are at 6.5kRPM.

MNBoxster · 03-23-2007, 08:13 PM

Quote:

Originally Posted by j.fro

Take it to the limiter. That's why it's there. The car is not a pansy-a$$ high dolllar cruiser. In all honesty, it is a tuned down racecar. 11+compression?? 7k+ redline?? The computer controls have let us have this along with drivability. Take advantage!!
You won't destory our Boxster on the street. You'd be hard pressed to kill it on the track. Enjoy your car.

Hi,

Sorry to disagree, but the Boxster is no detuned Race Car. True, it has it's share of Race Technology packaged inside, but that's a far cry from certifying it a Race Car. The Saleen S7, McLaren F1, Ferrari 360, Koenigsegg CCX, 997 GT2, Noble M400, even a C6 (to some extent), are detuned Race Cars, but not the Boxster.

Also, consistently bouncing off the Rev Limiter is not a good Rx for continued Health or Affordability. Constantly triggering the Fuel Cut-off at high RPMs isn't good for ANY motor.

That said, running to 5500 isn't the same thing and consistent runs in this range won't do any harm so long as you keep it in good tune, buy quality fuel and keep the fluids topped up...

Happy Motoring!... Jim'99

RandallNeighbour · 03-24-2007, 07:23 PM

Quote:

Originally Posted by Adam

These engines weren't designed with Sunday drives to church in mind just in case anybody was wondering.

Uh oh. I drive the piss out of my car every Sunday morning on the way to church. I near-redline it every time I drive it, Sundays included!

Basically, I feel the need to have something to confess when I get to church, but I'm not really repentant so I don't think it really counts.

Richard, I did read just today in Panorama's tech section where someone said it is good to near-redline a Porsche engine once in a while to blow out all the carbon buildup that might have accumulated from putzing around in the city and not running the engine hard.

So my question is, where is the carbon building up anyway? The heads?

MNBoxster · 03-24-2007, 09:47 PM

Quote:

Originally Posted by RandallNeighbour

Uh oh. I drive the piss out of my car every Sunday morning on the way to church. I near-redline it every time I drive it, Sundays included!

Basically, I feel the need to have something to confess when I get to church, but I'm not really repentant so I don't think it really counts.

Richard, I did read just today in Panorama's tech section where someone said it is good to near-redline a Porsche engine once in a while to blow out all the carbon buildup that might have accumulated from putzing around in the city and not running the engine hard.

So my question is, where is the carbon building up anyway? The heads?

Hi,

Randall, Carbon will build up on the Piston Domes, the Combustion Chamber (underside of Head and Uppermost part of Cylinder - above Piston Height at TDC) and on the Valve Seats and Valve Face. It can also migrate into the Valve Guides in extreme cases.

Although some Carbon is inevitable, most of it occurs from unburnt Fuel on deceleration. No Fuel Metering System (EFI or Carburettor) is instantaneous. If you're cruising at mid-to-upper RPMs, the Fuel Metering System is supplying more Fuel to the Cylinder. But, when you lift off the throttle such as when decelerating and shifting, more fuel is still being introduced for a short time before the system can adjust, usually only for a couple cycles, but still more than can combust completely, so some of the by-product of this incomplete combustion is molecular Carbon (as opposed to CO or CO²) which condenses on the surfaces mentioned above.

There are several problems with excessive Carbon build-up. It effectively reduces the volume of the Combustion Chamber which can lead to detonation from the resulting higher Compression Ratio. It acts as an insulator on the Valve Face and underside of the Head. This reduces the Heat Transfer from the Combustion Chamber and Valve, In the case of the Valve, it can get hot enough to warp and no longer seal properly or literally burn.

Remember, the only cooling the Valve gets is when it's in contact with the Head and can transfer it's Heat to the Head to be carried away by the Coolant (Valve in Closed position).

Also, Carbon buildup on the Valve Seat can interfere with the Valve Seal leading to lower compression as the Valve is now partially open on the Compression Stroke. This can have a cascading effect because it causes more incomplete combustion and greater condensation of Carbon (remember Carbon comprises 80% of Gasoline). Additionally, for the Exhaust Valve, if it remains partially open, it allows combusted gasses to escape rather than pushing down the Piston robbing Power.

It also insulates the Head preventing efficient Heat transfer from the Cylinder, leading to Head warpage.

Carbon on the Piston Domes can lead to improper Flamefronts, detonation, warping of the Piston, and premature wear of the Wrist Pin and Small End Bearings.

Some degree of Carbon is useful and is actually expected to provide some additional lubrication and sealing. A properly tuned engine will maintain this correct amount.

But, having said all this, there is some fallacy to the practice of running the engine at high revs to burn this Carbon. Carbon is an element and thus cannot be burned or further broken down.

Running for long durations at high RPMs can break the mechanical bond some of this Carbon has with the engine internals, and then literally blow it out of the engine and into the exhaust system as particulate matter.

But, the key here is sustained periods of high RPMs, not running up to Redline between shifts. You can actually create more condensed Carbon with this practice as you lift to swap gears and the engine decelerates resulting in a negative sum gain. And, if you think about it, you're actually running a compromised engine at high RPMs and actually contributing to any damaging side effects such as increased Carbonizing and detonation.

But, in modern ECU controlled EFI engines, with today's much more highly refined gasoline, Carbon buildup is much reduced compared to earlier designs and engines simply do not Carbon-Up as much from low or intermittent RPMs such as idling and Stop & Go driving. The main issue with these conditions is not condensation of Carbon, but the low operating efficiency of the Oil and Coolant Pumps, which are RPM dependent.

The best way to remove builtup Carbon in an engine is with the use of some solvent (engine additive) which will chemically loosen the Carbon so it can be removed from the system either as a particulate, or by being dissolved and combusted into a Carbon-bearing Gas (CO, CO²)...

Happy Motoring!... Jim'99

7th gear · 03-25-2007, 12:52 AM

Quote:

Originally Posted by MNBoxster

The best way to remove builtup Carbon in an engine is with the use of some solvent (engine additive) which will chemically loosen the Carbon so it can be removed from the system either as a particulate, or by being dissolved and combusted into a Carbon-bearing Gas (CO, CO²)...

i most appreciate your input. keep it coming.

somebody do an advanced search here on this post:
Keep her above 4000rpm and she'll thank you for it every day.
posted by deliriousga

the 1st post changed my driving as i 1st drove @ 3.5k on average. now i drive mine @ about 4 - 5k down the hwy.

further.... let me ask how much truth does the type of gas i put into my car help to break down or clean my engine parts have? i put 91 in my 986 and i read chevron has techroline

. shell has vpower

. union 76

... etc. they show pictures of a dirty part w/o their gas. then they show a clean or cleaner part after 2 tanks of their gas. how much truth to all their advertising about cleaning my engine parts will clean out the carbon build up?? i believe that most of that is ad hype but how much is kinda my question.