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Thread: Texas Speed Stage 3 VVT Camshaft C7 GS does not make power before 4600 rpm

  1. #41
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    Quote Originally Posted by Sachs View Post
    This morning I did a test. I took the OEM LT1 Intake manifold from my 17 SS 1LE and put it on the vette.

    Noticeable torque increase in the problem area. My cylinder airmass at 3800 rpm is at 0.74g, instead of 0.68g with the MSD (MAF at 195g/s instead of 170g/s). Definitely a flow issue between heads/IM/TB...

    I'm assuming +8% airmass = +8% torque...
    Maybe the msd needs a bigger throttle body? OEM zr1 95mm TBs aren't that expensive...
    2019 C7 ZO6 M7.

  2. #42
    I know there are some common rules of thumb for RPM shift points and peak power, but is there one for decreasing airmass? I would think the optimization would not just be at the inflection point/peak of airflow, now airmass should theoretically drop after peak torque, but I know you should keep revving it after but I think its dependent on your next gear ratio as well.

  3. #43
    Quote Originally Posted by HeavyChevy305 View Post
    Maybe the msd needs a bigger throttle body? OEM zr1 95mm TBs aren't that expensive...
    Yep, I've had some people telling me that I should put a 95mm TB...

  4. #44
    Typically my airmass increase up to max torque then plateau or decreases slightly...

  5. #45
    I really hope we can end up using the C8 LT2 intake manifold, from what I am seeing it should help a lot. Apparently the LT1 intake manifold is extremely limited just due to how crowded the runners are and its the C7's fault since there is so little clearance, I am hoping there is enough room in the Camaro to put a LT2.

    Also I wonder how it would do if you tried a truck intake?

  6. #46
    Guys,

    Airmass comparison between stock IM/Stock TB vs MSD (slightly ported)/87mm ported TB. 2800FT elevation



    Stock TB/IM is better all the way to 5800 rpm.

    You can see that even stock IM/TB struggles a little from 3400-4000
    Last edited by Sachs; 03-29-2020 at 11:00 AM.

  7. #47
    More data with the FBO data.

    This matches the dyno almost exactly. All data at 2800-3000Ft elevation



    With my heads and MSD the cam makes more power starting 5200 rpm, which the airmass shows. The biggest torque difference is 4000 rpm, airmass shows the same.

    The stock IM diminish by half the torque loss, but clearly makes less power than the MSD up top, by 4-5%

    Clearly Airmass is a good indicator of the power

    What is weird is from 3000-3400 the TSP makes more or less the same torque than OEM then falls off from 3400-4200 rpm. I clearly want to try the ported heads.

    Last edited by Sachs; 03-29-2020 at 11:53 AM.

  8. #48
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    Do you have a graph of your afr through the pull?
    2019 C7 ZO6 M7.

  9. #49
    I can do one, but 0.86-0.88 Lambda through all the pulls

  10. #50
    Ordered ported heads yesterday. Will see how it does when I'll receive them.

  11. #51
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    The ported MSD with a stock sized throttle body would actually reduce air velocity into the cylinders. I think you need to go with a 95mm throttle body with those ported heads and the MSD to improve your velocity and low end torque. Since the cam is stuck at 0 movement now you also need to consider how it was installed/ground. When you do away with being able to move the cam around you go back to the old days of only having the power band in certain areas unless you dramatically increase the airflow in and out of the engine. And even then you will never get a power band as wide as you would if you were able to move the cam around.
    Last edited by TriPinTaZ; 03-31-2020 at 08:14 AM.
    I've tuned a few things...

  12. #52
    I agree for the 95mm.

    As far as powerband, my engine feels much stronger from 2500-3300 than from 3300-4100, so I really think this is a airflow issue between heads/IM/TB in those rpm, like stalling airflow. Probably gonna buy a Soler Perf 95mm TB...

  13. #53
    Here is the airmass values I just grabbed from my logs in excel for comparison:

    Capture.JPG

    228/236 Intake/Exhaust Duration
    111-ICL
    114-LSA
    0.635/0.635 Intake/Exhaust Lift

    Ported Stock LT1 Heads, Milled 0.015

    Ported Stock LT1 Intake

    Ported Stock LT1 TB

    Everything else stock, exhaust, headers, etc.
    Attached Files Attached Files

  14. #54
    Very close to mine with stock IM...

    But I'm at 3000 FT. Are you in elevation or at sea level ?

    Mine would be in the 0.92-0.95g at sea level...

    If those airmass are at sea level it is pretty low...

  15. #55
    So barometric pressure is 14.1-14.2 psi here (for some reason barometer readings on the logs fluctuate and they fluctuate badly when you go WOT they tend to increase although not that much, no idea why unless it building up a vacuum behind the barometer?, which I'm not sure if the baro reading is taken from the MAP?), I think its around 1000 ft here.

    The average "Air Density Torque Multiplier" for the data samples from the log is 0.986 and for the Rotofab test samples its 1.03. This is weird since the stock and Rotofab runs were taken back to back within 20 min of each other in the same weather conditions. I am assuming this may be helpful to know, but I am wondering if there is maybe another PID we should be looking at instead of Airmass? Does this PID have all the external calculations factored in?

    I do agree that the airmass is kind of low, I swear I remember seeing airmasses in the .90 grams before. Just another thing that makes no sense and makes you second guess yourself. I need to go back and find a good log of before I had the cam and heads and do some more comparisons since the preliminary comparisons I have done against when it was stock aren't looking to good and have me worried I have done a lot of work for nothing. I know subjectively the car does feel more powerful at 6000 rpms and up, the stock cam just completely dies at that high of RPMs. It just sure does feel like the supposed 100+rwhp gains from cam and worked heads are advertising hype. I though I would feel more not just at really high rpms from the increased lift and therefore flow, as well as the increased port flow and bump in compression

  16. #56
    Taking a quick look at a log I took before the cam and heads were put on and I am seeing 0.89 g at 4000 rpms, this is just with the same stock ported intake and TB and Rotofab minus the cam and heads. Air density torque multiplier is 1.0156, baro is at 14.1-14.2, and IAT is at 63 F so maybe a little cooler. What I meant in my above post is that should we be multiplying the cylinder airmass number by the air density torque multiplier? or maybe the air density torque multiplier is already factored in to the final airmass value reported? Either way this is really disappointing to see haha

  17. #57
    I reach 0.86-0.87g at 13.3 psi (92kpa)... So at 14.2-14.3psi you should reach 0.92-0.93g or more

    Think main difference is not having headers on your case and pretty much stock intake...

  18. #58
    Just ordered a Soler Performance 95mm TB with 95->103mm adapter plate for the MSD Manifold

    That and the ported heads should help my case a lot hopefully

  19. #59
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    If you want to know the real difference in Airmass look at your MAF Hertz/airflow g/s as this is the base value used in Airmass calculations. Rotofab with stock IM and TB vs Rotofab with MSD and ported 87mm TB. I think you're running into some turbulence and/or loss of velocity in the lower RPM range.

    Another thing is the VVT3 cam is designed to allow to keep the cam movement. You could potentially solve some of the low end torque issue by not locking the cam phaser and then advancing the cam a few degrees on the way up to peak torque, then zero it out there, then maybe 1 or 2 degrees retarded to redline. Adding ported heads and a 95mm TB will help but you might still not have the torque you're looking for.
    Last edited by TriPinTaZ; 04-01-2020 at 11:05 AM.
    I've tuned a few things...

  20. #60
    Quote Originally Posted by TriPinTaZ View Post
    If you want to know the real difference in Airmass look at your MAF Hertz/airflow g/s as this is the base value used in Airmass calculations. Rotofab with stock IM and TB vs Rotofab with MSD and ported 87mm TB. I think you're running into some turbulence and/or loss of velocity in the lower RPM range.

    Another thing is the VVT3 cam is designed to allow to keep the cam movement. You could potentially solve some of the low end torque issue by not locking the cam phaser and then advancing the cam a few degrees on the way up to peak torque, then zero it out there, then maybe 1 or 2 degrees retarded to redline. Adding ported heads and a 95mm TB will help but you might still not have the torque you're looking for.
    Texas speed says cam phaser stability is not assured with this cam, thus does highly recommend locking it at 0.

    Did not take my chances with that, but I asked them.

    And yes I see less MAF with MSD/Ported TB than stock IM\TB in those ranges.
    Last edited by Sachs; 04-01-2020 at 01:49 PM.