383 Lt1 CAM god's look here.
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Nice times and with a killer short time..Ive got about the same MPH, but the last time since I went, my ET was off by about .5....and my 60ft was only a 1.8,lol..Installed a Racetronix PnP kit, and that car came alive
..Can't wait to get back and try it again ![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
I used to have that cam, I THINK it likes the 66-6800rpm range, if that helps any.
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I used to have that cam, I THINK it likes the 66-6800rpm range, if that helps any.
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I wasn't kidding about the whole cam god thing . I need a custom grind. The car runs good, I get it. But I have some other issues going on. like the fact that the cam is **** for Nitrous or the fact that I keep lifting the heads of of the motor on a 150 shot.
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This thread just confuses me. What of all the people on these boards that claim between 380-420 rwhp etc on stock cubes with an le2..All these 383's only putting out in the 360's.
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You have somthing else going on besides the cam affecting your nitous rwhp #s.That cam is actually been known to make good #s on the bottle.You are not using enough nitrous to warrant a dedicated cam.I would suspect third gear is silpping which is why you went slower mph with 4.10 since the car is in 3rd alot longer .Which also would explain the low dyno #s on the bottle.The 3.23 will cause your converter to stall higher which is possible why your 60' was better.I agree that you do need rim screws though.
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I have already assumed that (Mr.Obvious)J/K.Maybe he could elaborate a little more for us like type of kit,brand,and actual jet sizes.I am not a nitrous GURU but, some guys in here are and might be able to help him out.Sometimes you got to drag all the info out of people in here so you can give a diffenative answer.
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A cam optimized for nitrous (N) is quite different than a cam optimized for NA use. It has the potnetial to make more power while on N, in the most extreme case on the order of 10-15% of the nitrous boost, but lose quite a bit compared to an optimzed NA cam off the juice. I want to take a minute to explain a little about this and offer suggestions about compromises that will work pretty well with either.
Using N poses a problem. An optimum head for nitrous use would have a larger exhaust valve at the expense of a smaller intake valve. When you add N, you are drastically increasing the volume of exhaust gasses needing to be pumped out. If you add a 150hp shot on to a 300hp motor, 50% more exhaust gas is created, for example. Not only due the pumping losses go up dramatically, there is more residual gas and contamination of the intake charge to deal with. The exhaust valve area would need to be 50% larger to fully compensate.
Not only is 50% more exhaust valve area completely impractical, it would severly compromise NA power. So, the cam must be used to compensate. The method of compensation is to open the exhaust valve earlier. As a rule of thumb, the range to look for is 10-20 degrees earlier with 150-300hp of nitrous. There are a couple of ways to open the exhaust earlier. We can increase the LSA, increase the exhaust duration, or advance the cam. As with all aspects of cam design, there are always tradeoffs. Increasing the exhaust duration will also increase overlap when typical cam profiles are used. If we had exhaust lobes specifically designed for nitrous available, which most of us do not, just the opening side could be lengthened. Increasing the LSA opens the exhaust earlier, but decreases overlap. As with a wider exhaust lobe there will be a downside if the overlap was correct in the first place.
This leaves us with advancing the cam. Let's look at some valve events by starting with a typical aggressive SBC HR cam: 294/300 on a 110LSA installed 4 degrees advanced. The valve events are IO/IC-EO/EC 41/73-84/36. This gives us 77 degrees of overlap. We want to use a 100hp shot and compensate by opening the exhaust 10 degrees earlier. The valve events we want are 41/73-94/36. To get this, we can open up the LSA to 112.5, increase the exhaust duration to 310 degrees, and install it on a 106ICL (6.5 degrees advanced). We now have valve events of 41/73-94/36 with 77 degrees of overlap - just what we wanted. This might lose 20hp or so compared to the first cam off the juice, but gain an additonal 20-30hp on it.
The compromise position is somewhere in between. Open up the LSA a couple of degrees, advance the cam a couple, and bump up the exhaust duration a bit. The choice is yours - but keep in mind that most cams are so far from optimized in the first place that a properly chosen nitrous cam is likely to be better both on and off the juice.
the 306's specs are 230/244 .510/.540 112lsa, so it has 14* more exhaust duration and .030 lift....using the above data....it would be an OK nitrous cam not optimal, but OK
Last edited by Ray@Nitrous Outlet; 01-06-2008 at 12:42 AM.