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Thread: New Cam

  1. #1
    Senior Member Naaman's Avatar
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    Cayanne
    98 Z28 Vert M6

    New Cam

    So... there is a frustrating story behind all of this, but here is the dyno from the new cam (to add to the frustration).

    The outgoing cam was a Comp cams off the shelf that came out of another car when mine happened to need one to go with the new heads I ordered a couple of years ago. It ran good until a lifter got stuck. The lifter started acting up shortly after the valve springs were replaced, which gives me heartache about the work that was done in the heads... but anyway...

    The stuck lifter wound up grinding down the cam lobe on cylinder 8, so I needed to get new lifters and a new cam.

    We ordered a custom grind from Cam Motion.

    Here is the dyno graph:

    img002.jpg

    Here's the sad bit: the custom grind makes less horsepower/torque than the outgoing off the shelf cam (yes, the baseline is the upper graph).

    I know that dynos are not the most reliable indicator, but I figured it would only make sense that a cam that was spec'd for the rest of my set up should outperform one that was off the shelf. I seem to get less fuel economy as well, but I'll give the computer time to relearn my driving (I'm assuming that the tune needs time to see the patterns...?).

    On the bright side, the engine idles and revs just a bit smoother, and there seems to be less chatter and clatter internally compared to when the Comp was in there. It feels more like a "factory" quality build (the ramps on the lobes are less aggressive, I guess) and there is less lugging when idling through a parking lot (though at really low rpms, it still lurches as normal)

    The seat-of-the-pants dyno seems to notice the loss of torque below 3K, but after that, it feels just as fast... though I was hoping for something that would feel (and actually be) fastER.

  2. #2
    Veteran pajeff02's Avatar
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    It does take some time for things to settle in as the PCM relearns. I presume that your tune was adjusted for the new cam? Same dyno and tuner as before?

  3. #3
    Senior Member Naaman's Avatar
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    98 Z28 Vert M6

    Same, same. But... totally different conditions. The baseline was done in 66 degrees with 7% humidity, while the new one was done at 96 degrees with 40%. The correction factors were applied, so it's as close to apples-to-apples as I'm gonna get.

    Interestingly enough, the original tune was performed in conditions that are "better" than the SAE standard (so the correction factor was 0.99). As I understand it, the amount of power actually produced when that run was performed was about 1% higher than what is shown on the graph.

    The second tune has a correction factor of 1.08, which I guess means that the power produced was about 8% lower than what is on the graph, but the math approximates what the power would be in "standard" conditions (77 degrees and 0% humidity and some specific amount of inches of mercury, as well).
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    Senior Member Naaman's Avatar
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    Cayanne
    98 Z28 Vert M6

    Same, same. But... totally different conditions. The baseline was done in 66 degrees with 7% humidity, while the new one was done at 96 degrees with 40%. The correction factors were applied, so it's as close to apples-to-apples as I'm gonna get.

    Interestingly enough, the original tune was performed in conditions that are "better" than the SAE standard (so the correction factor was 0.99). As I understand it, the amount of power actually produced when that run was performed was about 1% higher than what is shown on the graph.

    The second tune has a correction factor of 1.08, which I guess means that the power produced was about 8% lower than what is on the graph, but the math approximates what the power would be in "standard" conditions (77 degrees and 0% humidity and some specific amount of inches of mercury, as well).

  5. #5
    Senior Member Redphoenix1998's Avatar
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    What are the specs of the old cam vs the new cam? Comparing your old results to your new, based on a .99 correction factor your numbers as compared to your old baseline would be 323.80hp/316.38tq. Also based on the way your curve has shifted, I would say the cam itself is smaller than your original cam.
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  6. #6
    Senior Member Naaman's Avatar
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    Cayanne
    98 Z28 Vert M6

    I don't have the specs for the old cam. I did get the specs for the new one, but I don't have a basis for comparison, so I haven't even looked at them, honestly.

    The way I read it, the "raw" results for the old cam were 362hp, and the new cam would have been 328hp.

    Anyway, I'm trying not to be to bothered by it, since the dyno is not a perfect means for comparison. Although the curve shift probably does tell a reliable story.
    Last edited by Naaman; 08-06-2018 at 10:31 PM.

  7. #7
    Senior Member Redphoenix1998's Avatar
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    Quote Originally Posted by Naaman View Post
    I don't have the specs for the old cam. I did get the specs for the new one, but I don't have a basis for comparison, so I haven't even looked at them, honestly.

    The way I read it, the "raw" results for the old cam were 362hp, and the new cam would have been 328hp.

    Anyway, I'm trying not to be to bothered by it, since the dyno is not a perfect means for comparison. Although the curve shift probably does tell a reliable story.
    Yeah my focus was on the curve shift which told me that this cam is smaller but similar in profile to your old cam. Cam Motion is good for custom grinds depending on your mods. We had them grind us a new cam to try to correct a weird dip in power mid RPM for a car we were doing. The headers on the car were custom fabricated which caused a weird back pressure mid RPM that caused the power curve to dip and you could feel it slightly in the middle of a WOT run. The cam fixed it after we explained what the issue was. We lost in the low end but gained HP at the top.

  8. #8
    Senior Member Naaman's Avatar
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    Cayanne
    98 Z28 Vert M6

    Yeah, the peak power seems to be more or less the same (I can't say whether 4hp is really a "drop" in power). Also, the airflow through the engine is not fully worked out yet.

    One of the things that I am still trying to work out is the exhaust issue. I don't want headers, but have been considering extrude honing. The biggest problem I see is the flattened section of the mid pipe being a restriction point. If I opened it up, it would (presumably) land me where I don't want to be with respect to ground clearance (it's one of the reasons I don't want headers).

    Although I'm wondering if a flat design that is wider would allow for airflow sufficient to see a gain from a freer flowing exhaust manifold.

    In any case, this cam does have better street manners, but the outgoing was wasn't bad, honestly.

  9. #9
    Veteran pajeff02's Avatar
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    I wouldn't waste the money on extrude honing. Minimal gains for the $$. LT's or nothing on our cars.

    Will be heading out your way again in early November...

  10. #10
    Senior Member Naaman's Avatar
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    98 Z28 Vert M6

    November is a great time to come. It's hot as ********************************* out here right now. It's miserable, but I every time I find myself grumbling about it, I remind myself to bask in the glorious freedom of one of the Nations true free states. :P

    What part of town will you be staying in?

  11. #11
    Veteran pajeff02's Avatar
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    We'll be north of the city up in Saddlebrooke again.

  12. #12
    Senior Member Naaman's Avatar
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    Cayanne
    98 Z28 Vert M6

    Oh, okay. Out by Tucson. Is it high altitude out there? We tend to take day trips up the mountains around Phoenix (Sedona, Flagstaff, etc) to escape the heat once or twice a summer. In fact, we are considering doing that this month. Won't be able to take the Chevy, though, since It'll be a family affair.

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    Veteran pajeff02's Avatar
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    We're down in the valley. I always enjoy running up Mt. Lemmon for an $8 cookie and the cooler temps.

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    AZ is one of my favorite states. Spent some time exploring out there last Oct.
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    Veteran pajeff02's Avatar
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    We really do enjoy our time out there. Every year we find new things to do.

  16. #16
    Senior Member Naaman's Avatar
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    98 Z28 Vert M6

    Yup.


    Mt. Lemmon is one that I have yet to visit.

    Not sure what you all's radius is, but if you can handle a little bit of amateur spelunking, check out Lava River Cave in Flagstaff.

    Just this past spring, I took the family up to Page and we did a tour of Antelope Canyon, checked out Lake Powell on the boat and took the kids on a whole lot of off-trail hiking (though, there are a lot of trails available, too).

    I've been to Springerville once for a quick stop, but am planning to go back soon for some actual hiking and tourism.

    Some awesome scenery on the way to and from doesn't hurt, either.

  17. #17
    Veteran 35th-ANV-SS's Avatar
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    Quote Originally Posted by Naaman View Post
    Yup.


    Mt. Lemmon is one that I have yet to visit.

    Not sure what you all's radius is, but if you can handle a little bit of amateur spelunking, check out Lava River Cave in Flagstaff.

    Just this past spring, I took the family up to Page and we did a tour of Antelope Canyon, checked out Lake Powell on the boat and took the kids on a whole lot of off-trail hiking (though, there are a lot of trails available, too).

    I've been to Springerville once for a quick stop, but am planning to go back soon for some actual hiking and tourism.

    Some awesome scenery on the way to and from doesn't hurt, either.
    I spent a week going from Phoenix to Sedona to Flagstaff and many places in-between. Page was one of those stops. Antelope Canyon was fantastic. As was Horseshoe Bend. Couple of shots from that trip.

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  18. #18
    Senior Member Naaman's Avatar
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    So awesome!

    We did Horseshoe Bend. Was a nightmare with my little ones in tow. Like, a hundred tourists all crowding around the edge of a cliff absorbed in their selfies and phones, not even paying attention to little kids who might be underfoot. I had to keep the kids about 100 feet from the edge, and my wife and I took turns taking them one at a time to go see it. Was worth it... just wish that the reality had been more like what all the pics show: just one person getting the view all to himself (of course, this is only due to clever image cropping).

  19. #19
    Spaz is My Mentor SMWS6TA's Avatar
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  20. #20
    Veteran 35th-ANV-SS's Avatar
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    Quote Originally Posted by Naaman View Post
    So awesome!

    We did Horseshoe Bend. Was a nightmare with my little ones in tow. Like, a hundred tourists all crowding around the edge of a cliff absorbed in their selfies and phones, not even paying attention to little kids who might be underfoot. I had to keep the kids about 100 feet from the edge, and my wife and I took turns taking them one at a time to go see it. Was worth it... just wish that the reality had been more like what all the pics show: just one person getting the view all to himself (of course, this is only due to clever image cropping).
    You were smart about it. Lots of accidents happen there annually. Even as an adult, you need to be careful. I sat down further away and kind of "scooted" towards the edge unless I was not near anyone else. If you go at sunrise, a lot less people. That first photo is Devil's Bridge in Sedona. It's around a 2 mile hike to get to. We hiked it at sunset and were rewarded with those awesome rock colors. Bad part was it was pitch dark about 3/4 of the hike back. There was 6 of us with flashlights which made it not terrible, but predators like lurking in the night. Anyway, didn't mean to gunk up the thread. Got a little sidetracked.

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