turbogrill

Hi,

It seems like they should have bumped up the rev limiter to 7500 on our beloved 996 3.4L. Do you agree?

I can't drive it without hitting the rev limiter at least once or twice, it makes plenty of power at 7000.

dporto

Unless you're driving it only on a racetrack or only drive in first or second gear, your statement makes little sense...

turbogrill

haha, good point.You would have to be a maniac if that happens in 5th.
But even on the street in 2nd I find it hard to not hit the rev limiter. I have so many "Range 1" ignition and they are always very recent. Luckily no "Range 2".

I am curious if 2nd is a bit short or something? I find it a little hard to rev match from 3rd to 2nd

DBJoe996

They are indeed sporty engines....but hitting the rev limiter one or two times everytime you drive it sounds excessive, and perhaps a little bit abusive. Hope you have it fully warmed up before you do that. How many tire sets do you go through a year?

NuttyProfessor

Range 2 is considered over-rev. If you don't have any numbers in range 2, then you're fine. In fact, it's not uncommon for even the more skilled track junky to hit in range 2. That's why is smart to scan cars with a Durametric or other scanning tool. I wouldn't buy a 996 if it showed high numbers in range 2. The newer 911 cars have 6 ranges.

DBJoe996

Maximum horsepower is achieved at 6,000 RPM, so bumping up to 7,300 RPM at rev limiter doesn't get you much that much more.

DBJoe996

Here are the transmission drive ratios

Splitting Atoms

I bought a durametic pro recently, primarily because I was curious about the number of over revs on my 99 C2. My car spent the first 42k miles of its life as a Michelin Research and Development tire testing track car. Has 92k miles now with the original untouched engine. The number of level 1 over revs are maxed out (a little over 3 minutes at the red line). The ECU doesn't record any more than that. There is no ECU data as to when the over revs hit the ECU limit. It could have a lot more than 3 minutes at the red line. I have hit the red line on second gear pulls myself, so the last level 1 is fairly recent. Fortunately, the number of level 2 over revs is low. About 3 seconds worth and they occurred years ago when it was a tire tester. Note that some people have had engine failures with less than 3 seconds of level 2. The ECU doesn't record the maximum RPM. Three seconds at 7800 rpm is not as significant as 0.25 seconds at 9000 rpm.

My car came from Brumos Porsche with multiple mods when it was purchased by Michelin. One was an X51 type baffle which probably contributed greatly to the engine lasting this long. (I guess I can't say that the engine is untouched since it did have the X51 baffle installed very early in it's life).

I use it primarily as a track car now. I drive it like I stole it and it's a ton of fun.

turbogrill

Thanks!

I thought that max power was about 6500 rpm? Can't find a stock dyno anywhere. But I remember seeing that power is pretty much the same from 6000 to 7000 rpm?
You want to shift after max power so you get right back into the meat after your shift.

With the gear ratios above this is the RPM you end up at if you shift at 7000 RPM:

(1st->2nd): 4031
(2nd->3rd): 4836
(3rd->4th): 5618
(4th->5th): 5812

With the gear ratios above this is the RPM you end up at if you shift at 7300 RPM:

(1st->2nd): 4204
(2nd->3rd):5044
(3rd->4th): 5859
(4th->5th): 6103

So if you over rev a little you end up where there is more power.

Also looking at these ratio they really makes sense, I guess Porsche knows what they are doing. Going ***** to the walls in 4th->5th gives you a very nice 'area under the curve' power. With 2nd to 3rd you end up very close to torque max, that is also good.

btw, I am far form an expert but happy to discuss.<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--><!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--><!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--><!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}-->

DBJoe996

I think more relevant is the speed achieved in each gear at maximum RPM. If you are bumping the rev limiter in any thing other than 1st or 2nd, I do not know where you can do that except on a race track because you will be exceeding any normal type of driving situations.

turbogrill

Looking at these numbers they don't make sense. 300hp @ 6000 RPM is 262.6 ftlb, more than the 259 ftlb at 4750.

I think the owners manual came with a dyno?

DBJoe996

It did. Torque drops considerably after 4750 RPM

turbogrill

Thanks!

Where did you find the engine specs you posted above? Seems to be a typo, max power is at 7000 rpm.

NuttyProfessor

I completely agree with Joe here. He makes a very important point. Hitting the rev limit once and blue moon is not a big deal, but pushing to the rev limit every time you drive is excessive and damaging to the motor. Plus, as you can see you're not adding anymore HP to the mix either.

Prelude Guy

This thread made me laugh.