Heres something to think about...

[randyrw]

Have yall noticed how crapy the horsepower curve is on our Titan's??? Look at everyones dyno sheets. The horsepower peaks at exactly 5000rpm and then fall super fast. By the time it gets to the shift point it has hardly any power. I've been scratching my butt trying to figure out why. I just got through doing some more dyno pulls on my Turbocharged Titan and I have the smae results with boost. It still peaks at exactly 5000rpm then fall big time. I was getting 335HP @5000rpm. But at 6000rpm it's around 200. That freakin sucks. The peak power should be higher with boost. The A/F ratio does not drop, so it's not a lack of fuel. Have any of yall recorded the timing to see if the timing falls off?? If timing is not the problem then the only thing I can come up with is that the heads on these motors must be very restrictive and make just for low end torque ONLY. What do you guys think? I beleive that if the shift point could be lowered we could run faster???????????????????????????????????????????? ?

[ORTitan]

Randy-
Nissan went VERY conservative on the camshafts. They are Split duration 230/232 degree with only .312 gross valve lift. The poor engine runs out of breath not long after 4000/4500 rpm, or sooner. If we want to make real headway in improving output I think a larger stick(s) is going to be vital. Of course engine management will have to be optimised. Just my educated opinion.

[TTfan-adik]

The intake runners are also restrictive. They are tuned lengthwise for a specific RPM band which is usually fairly small. Now don't start ragging on Dodges but they had a similar problem on their 5.2L and 5.9L Magnum. Read "THIRD" at the link below to give you an idea of whats going on.

http://www.hughesengines.com/general..._induction.asp

Their problem was not completely cured until Mopar Performance came out with a single plane intake manifold for their EFI. That aloowed the engine to breathe freely at a much wider RPM range.

[GreenT]

Its the cams. The intake runners are the reason we make so much torque. I doubt anyone would want to change that and the heads have tremendous potential. With aggressive cams the VK56 would be a different engine.