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YOUR RESEARCHWhat engine characteristics allow the GT3 to 9k RPMs
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Fill cylinders
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Suggestion
At 9000+ RPM the cylinders do not have much time for the air to fill the cylinders, so to enable the engine to breath at higher RPMs the camshaft profile must have a longer duration of open time.
What engine characteristics allow the GT3 to 9k RPMs
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Suggestion
Cast rods or powdered rods are for production engines and not for sustained high RPM's /competition use ..and require no maintenance ( depending on actual stress/fatigue imposed)
What engine characteristics allow the GT3 to 9k RPMs
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Fill cylinders
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Suggestion
At 9000+ RPM the cylinders do not have much time for the air to fill the cylinders, so to enable the engine to breath at higher RPMs the camshaft profile must have a longer duration of open time.
What engine characteristics allow the GT3 to 9k RPMs
Use ..and require no maintenance ( depending
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Suggestion
Cast rods or powdered rods are for production engines and not for sustained high RPM's /competition use ..and require no maintenance ( depending on actual stress/fatigue imposed)
What engine characteristics allow the GT3 to 9k RPMs
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Can anyone please explain to me what characteristics or parts or design allow the Naturally Asperated GT3 Mezgers to redline at 9000 RPMs where as other Mezgers redline lower???
My guess would be a shorter stroke, since the piston has less distance to travel from Top Dead Center to Bottom Dead Center it can travel that distance more frequently.
Lightweight one piece intake lifters are a big part of the story. If I ever rebuild my Turbo engine I am getting rid of the heavy and useless two-piece intake lifters.
At 9000+ RPM the cylinders do not have much time for the air to fill the cylinders, so to enable the engine to breath at higher RPMs the camshaft profile must have a longer duration of open time. It also help if the lobe seperation ( intake vs exhaust overlap) is reduced....GT3 cams have more open time duration and less lobe seperation..
Also at those higher RPMs, the stress on the rods is multiplied by the square root, so the GT3 has Titanium rods for more strength and less weight...
Ti rods are a little lighter. If you get good quality will they last just as long as good steel rods? Is there more more maintenance requirements for Ti rods? (Al require routing removal and measurment which make them out of the question for me)
RegularGuy,
Given your posts, it looks like you are building a widebody 996 that revs to 9000 rpm; and you are in need of a scanner.
Looks like you are building something special. Love to hear about it.
You'd be much better off just buying a used cup motor or a crashed M96.76 and making it work in your chassis than trying to do anything to a M96.01. All the FSI 4.0 dynos making 320whp on DynoJet say enough.
I'm a wannaB engineer. I've always been a diesel guy. Keeping RPMs low (with high torque) is what allows many Diesel engines to go 500k miles. Right now I'm just fascinated in why these cars can go to such high RPMs without grenading.
You could spend the next couple of months on YouTube on the topic. Plenty of viodoes on rebuilding mezgers as well as F1 which used to rev to 20k. Hammond on either Top Gear or his new show went into great detail on a video regarding cannons to F1 wrapped around metal and mechanical advancements. Good luck with tour search.
I think it was mentioned earlier, the Mezger GT3's in 996/997 rev out to 8000 or 8250 RPM which is not completely crazy. The Ford Shelby Voodoo 5.8 liter V8 revs to 8200RPM redline with an 8500 RPM limiter! The 991 GT3's are the 9000 RPM 4 liter monster units.
Cup engines have no place in a street car. I know, I built a 996.1 GT3 with a 997 Cup engine.
As PorscheTech says, the one thing that gives the N/A Mezger the ability to rev, is it's cams (lift, duration and overlap) but in addition to the cams it's the Variocam programming and plenum chamber resonance flap programming.
And for what it's worth, the 996 GT3 inlet cams can be fitted to the 996 Turbo engine, and the Turbo engine will then rev 1200rpm higher. It's what Ruf did with their Nardo conversions. They quoted 600hp, but it's suggested that's understating the true number...
https://www.rs6.com/showthread.php/2...&highlight=ruf
Titanium Rods are the cats meow, they are lighter and stronger than forged steel rods and require no maintenance...( depending on actual stress/fatigue imposed)
Forged steel rods are the go to rods for any serious RPMS...and require no maintenance..( depending on actual stress/fatigue imposed)
Aluminum rods are lighter than steel rods but are also larger and require more clearance space..usually for drag race only and require frequent inspection or replacement ..(depending on actual stress/fatigue imposed) .
Cast rods or powdered rods are for production engines and not for sustained high RPM's /competition use ..and require no maintenance ( depending on actual stress/fatigue imposed)
I agree
That Ruf conversion is very cool....
