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YOUR RESEARCHIncrease revlimiter?
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Use r51 port combination
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The same goes with the cylinder heads, I use my R51 port combination for these heads in most cases.
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The 996.2 is slightly faster due to better power-to-weight, and I suspect (not having driven one) that it's quite a bit easier to get the maximum performance out of it.
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EDIT: that said, I would suspect the first thing that breaks could be the rod bolts, or maybe some component of the valvetrain, such as a valve seat or retainer clip.
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Interesting, I find the 996.1 (3.4) not peaky at all, but rather, pretty smooth power delivery that requires prodigious use of the entire rev range to keep up with a 996.2 (3.6), which I find, more peaky, particularly via torque between 3,000-4,000 RPMs.
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The 996.2 is slightly faster due to better power-to-weight, and I suspect (not having driven one) that it's quite a bit easier to get the maximum performance out of it.
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EDIT: that said, I would suspect the first thing that breaks could be the rod bolts, or maybe some component of the valvetrain, such as a valve seat or retainer clip.
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Yes, it�s a bad idea.
Plus, the is no reason to increase it because the engine doesn�t make any more power (area under the curve) above the current limiter. Increasing it will not make the car any faster.
EDIT: that said, I would suspect the first thing that breaks could be the rod bolts, or maybe some component of the valvetrain, such as a valve seat or retainer clip.
We love tunes that raise the rev limiter.. Economic stimulus is the best word to describe it.
The stock hydraulic lifters in these engines are barely good for the stock rev limit.
Also, there's no more power to be made up there, just RPM that = friction that = wear and oil temperature.
It feels like if I would shift a little later it would end up more in the power band on the next gear.
On track it also nice to overrev a little to avoid shifting some times.
So rod bolts and lifters are two candidates to meltdown at 7500 rpm.
I found a tune that would raise the limiter a lot!
I will pass on it, just curious. Sounds great on paper.
Thanks!
There's lots of tunes that will raise the rev limiter a lot. Of course, these are generally the remote tunes that should be avoided at all costs, anyway.
This is why these engines need more torque, and a focus on this, rather than some magical HP number.
I focus on building power across the entire power range, with a focus on the area below 6,250 RPM. I just finished an R43 that made 460HP peak, and never needed to rev over 6,500 RPM to do so.
I re-checked my math, and you are right, the engine would make more power, even if there�s a pretty sharp decline in torque after the current 7,300 RPM redline. At 7,500, the engine looks to make the same power as it does at 5500, and the shift points indicate that there would be a benefit.
Like everything else, there�s always some trade off. The 996 GT3 has a redline closer to 8,000, and peak horsepower 500 RPMs higher than an mk1 996, and it took a completely different engine and a lot more money to make that work.
I guess if you are tracking or racing the car, one could argue HP is better than torque. For street use, perhaps torque is better.
The R43 is the culmination of 15+ years of M9X development. We never "just add displacement". Doing that is an instant way to create a misconfiguration. The R43 engine has its own camshafts, and I have 4 different sets of cam timing for these that will move the power range wherever I want it to be. The same goes with the cylinder heads, I use my R51 port combination for these heads in most cases. No part of this engine's combination is stock, it uses no stock internal components with the exception of timing chain guide rails, and tensioners. This is how I can tweak power to match what the purchaser needs for the application.
I see some people just increase displacement, and the net result is the engine makes LESS power than factory. It is, and plays will be "all in the combination" when it comes to building a true performance engine.
Let's never forget that horsepower is, and always will be a direct derivative of TORQUE. Horsepower is simply Torque X RPM.
In every case that I have optimized torque at all RPM range, the engine performs better. This is how my wife sets (and still holds) 5 Land Speed Records. I never paid attention to HP, it was always my goal to stretch the torque out as far as possible over the RPM range. She set those records with an engine built from used parts, and a few off the wall, very unconventional ideas.
As soon as you stop trying to make some big peak HP figure that's impressive, you have finally learned what is required to build a powerful engine. If I hand someone a dyno graph, and watch their eyes go straight to the peak output, I immediately know that they are completely, and totally lost. It will take a decade to teach them how unimportant that freaking number actually is~
This may be eye opening for some. Watch until the end to see what valve springs look like at 14k.
You Tube
I can't seem to get the video to display right, so you'll have to click the link
You should see what spring rates look like when we pull engines apart that have had raised rev limiters. At times the springs will fall off so much that it leads to misfires that can't be diagnosed.
As you've learned by now, it's not a good idea. And if you talking track use, shifting at around 6k will often result in slightly better lap times than shifting at 7k (I know from experience). These engines run out of torque above 6k.
I would disagree, since we have a gearbox all that matters is HP under the curve.
If that is created by high revs and low torque or low revs and high torque doesnt matter.
Take a look at the early cars,, 60's 70's,,, Porsche offered almost unlimited gear options but only a handful of engine changes..
Likely because they were at the profitable limit of material technology, and gears were comparatively easy.. Other than tear down...
haha, no I wont
But I do think it's the HP under the curve that matters on the track, not Torque under the torque. ( 500nm at 4000 rpm is better than 1000 nm at 1000 rpm).
Curious why you think it's better to short shift?
Want to learn that is all.
Sometimes the answer is not the answer. Kind of like when you want to find something, it�s often in a place one is least likely to want to look.
Technically speaking, HP and area under the curve is what makes a car go the fastest, but remembering the tortoise and the hare story, too many folks focus on a single metric without consideration for the end game.
Perhaps short shifting is safer and easier on the engine, and maybe the focus is now on turning and braking better, which results in faster lap times.
I used to tend a bunch of rental cars,, I had a guy that was a awesome drive but couldn't make it through a race without over revving,,
One day I got a sick idea and Iunhooked the tach, put a 5800 rpm pill in the rev limiter.. and set the shift light to 5600..
He turned his fastest laptimes ever.. the bright light fixed him.
The car was quite capable of turning 7K+ but he kept revving the engine to 8 or 9 trying to hug the red-line because
he was convinced that's where the power was.. Turns out a 6.0 Liter 600HP V8 can get a lot done cruising at 5500.. LOL
Yes as a crew chief I'm occasionally kind of a dick..
I don't think it's been mentioned, but I think the relevance of this question is highly dependent upon whether you have 996.1 or 996.2. The 996.1 is just getting into the "happy zone" as it approaches redline, so I get what the OP is talking about. I too would never recommend overrevving, but I get the point. The "peakiness" is one of the things I like about the 996.1 -- it reminds me of the 70's 911e where the power comes on at high RPM. There are times I wish the 996.1 had a bit more low-end torque, but the peakiness hearkening back to the early cars balances it out for me.
I have not driven a 996.2 (so correct me if I'm wrong), but my understanding is that it is torquier at low-end, so short shifting is a lot more practical and revving to redline is less necessary and/or less beneficial than on a 996.1.
Interesting, I find the 996.1 (3.4) not peaky at all, but rather, pretty smooth power delivery that requires prodigious use of the entire rev range to keep up with a 996.2 (3.6), which I find, more peaky, particularly via torque between 3,000-4,000 RPMs.
I agree, "peaky" isn't really the right word -- I really meant that the power keeps building all the way to redline -- pretty much exactly what you are saying. It takes a bit of concentration to get the maximum performance out of a 996.1, particularly in 1st and 2nd when the revs build so quickly. If you get it right, the 996.1 is a fast car. The 996.2 is slightly faster due to better power-to-weight, and I suspect (not having driven one) that it's quite a bit easier to get the maximum performance out of it.
First off I agree that it's not a good idea to increase the rev limiter, assuming that engine longevity is important. OTOH if my only concern is getting the fastest time on a track or dragstrip, I'lll shift at the highest RPM possible. In racing I'm concerned about torque at the wheels, not at the crank. Granted that torque and HP decrease as you approach redline, but that decrease is easily offset by being in a lower gear. Torque(wheel) = engine torque X gear ratio X final drive ratio. So although engine torque decreases as redline is approached, that loss is easily offset by the advantage of the higher gear ratio in the lower gear. You have to do the calculation for each car, but typically the gear ratio loss from 1st to 2nd is around 53%, 35% loss from 2nd to 3rd, and around 25% from 3rd to 4th, etc.
So if you are at a dragstrip and want the fastest time, you have to stay in the lower gear as long as possible, notwithstanding the loss of torque at the crank.
^^^^ All this..I have increased the rev limit on a few 996's after then engine was fitted with good H-beam rods, but on a stock rod engine I would definitely not advise it.
It's simple physics, torque x gear ratio = acceleration. Even though the engine torque falls off at high RPM, the Torque x gear ratio = acceleration will be higher than that calculation after the gear change.
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