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

  1. #21
    Quote Originally Posted by HeavyChevy305 View Post
    O.P. you locked out a VVT spec cam? If so, I also suggest you take the lock out and use their phase limiter and use their vvt table specs.
    TSP sells by default the 0 deg lockout kit with the stage 3 cam. They say cam phaser stability is not assured at high rpm and they had issues with customers keeping the VVT running into big issues like valve piston clearance.

    They call it VVT but it is not. I had the tech support at the phone about that...
    Last edited by Sachs; 4 Days Ago at 03:54 PM.

  2. #22
    Quote Originally Posted by mbray01 View Post
    The first thing i notice in log, is the fuel you are commanding vs what you are achieving. I didnt look at the tune, but i am going to assume you have a ton of fuel in the pe table, to compensate for a lack of fueling in the airflow tables. It looks like your maf is way off, as well as vve. Honestly until that is corrected, its not going to be happy, and it will limit torque output, as it clearly is. The log clearly shows 3, 4, even 5 degrees being pulled
    Nope, my MAF is table is less than 1% off. I tested it again this week end in MAF only mode with DFCO and O2 sensors disabled (as well as VE) . My Wideband/ commanded is very good. The VE tables are between 1-3% good.

    My PE table is around 1.10 to 1.15 now. On the run shown as example I was a little bit richer as a test. Right now my lamdba at WOT is 0.88

  3. #23
    Much more work to change the timing than doing the heads. And playing with fire. Don't know if you realize how much work doing a cam is on the LT1 and on a C7 in particular. I've done it twice now so I know...

    I'm in contact with several forum and common agreement is that I need heads with this cam... With my lift the stock heads flow less... And there are some examples of smaller ports making harmonics in air flow at some rpms with big cams, with back pressure waves disrupting the flow. Consensus is that I need heads and a bigger TB, possibly porting my MSD.

  4. #24
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    Quote Originally Posted by Sachs View Post
    Nope, my MAF is table is less than 1% off. I tested it again this week end in MAF only mode with DFCO and O2 sensors disabled (as well as VE) . My Wideband/ commanded is very good. The VE tables are between 1-3% good.

    My PE table is around 1.10 to 1.15 now. On the run shown as example I was a little bit richer as a test. Right now my lamdba at WOT is 0.88
    When calibrating the VVE and MAF, You should leave DFCO on.
    2019 C7 ZO6 M7.

  5. #25
    Quote Originally Posted by HeavyChevy305 View Post
    When calibrating the VVE and MAF, You should leave DFCO on.
    No, otherwise It messes up the table. All learning stuff I read or watch tell to disable DFCO... Everytime you lift throttle, If you leave DFCO on will give false values. If you disable DFCO ECU always commends a lambda target.

  6. #26
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    Quote Originally Posted by Sachs View Post
    No, otherwise It messes up the table. All learning stuff I read or watch tell to disable DFCO... Everytime you lift throttle, If you leave DFCO on will give false values. If you disable DFCO ECU always commends a lambda target.
    Leaving it off makes the trims richer than they really are and throws off the air model at least in my personal experience. I calibrated my car to -1+0 LTFT. I decided to turn DFCO off to get the "flames" out the exhaust and after a day or two it threw the trims off and started shutting my throttle and pulling timing. Turned it back on and the problem went away.
    2019 C7 ZO6 M7.

  7. #27
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    Quote Originally Posted by HeavyChevy305 View Post
    Leaving it off makes the trims richer than they really are and throws off the air model at least in my personal experience. I calibrated my car to -1+0 LTFT. I decided to turn DFCO off to get the "flames" out the exhaust and after a day or two it threw the trims off and started shutting my throttle and pulling timing. Turned it back on and the problem went away.
    Isn't there a disable fuel trims below a certain airmass table? I think you would have to adjust this to avoid that issue if someone wanted to leave DFCO disabled.
    I've tuned a few things...

  8. #28
    Quote Originally Posted by HeavyChevy305 View Post
    Leaving it off makes the trims richer than they really are and throws off the air model at least in my personal experience. I calibrated my car to -1+0 LTFT. I decided to turn DFCO off to get the "flames" out the exhaust and after a day or two it threw the trims off and started shutting my throttle and pulling timing. Turned it back on and the problem went away.
    When you do MAF or VE calibration you don't care about LTFT or Short trims. You disable your stock O2 sensors and run with your wideband to create an error table between commanded and measured. Using LTFT/STFT to do that is no good, means you have no wideband
    Last edited by Sachs; 3 Days Ago at 03:55 PM.

  9. #29
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    Quote Originally Posted by Sachs View Post
    When you do MAF or VE calibration you don't care about LTFT or Short trims. You disable your stock O2 sensors and run with your wideband to create an error table between commanded and measured. Using LTFT/STFT to do that is no good, means you have no wideband
    Of course I have a wideband and my actual matches my commanded.
    2019 C7 ZO6 M7.

  10. #30
    If you guys don't do it already, I'd suggest learning to filter data within the scanner histograms.

  11. #31
    Im putting a c7 z06 on the dyno tonight with the same cam, just from the street driving it doesn't feel super great power wise and it has ported heads, blower and a 18% lower. My bolt on zl1 definitely feels more robust down low. I have SOI dialed in fairly well but I will play with it more. Curious to see how it does, maybe its just my perception.

  12. #32
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    Quote Originally Posted by ZincGT View Post
    Im putting a c7 z06 on the dyno tonight with the same cam, just from the street driving it doesn't feel super great power wise and it has ported heads, blower and a 18% lower. My bolt on zl1 definitely feels more robust down low. I have SOI dialed in fairly well but I will play with it more. Curious to see how it does, maybe its just my perception.
    Auto or manual?
    2019 C7 ZO6 M7.

  13. #33
    Z06 has longer gearing than the ZL1, this could also play for the butt dyno...(manual)

  14. #34
    It seems like I wasn't really getting anywhere using my wideband to try to get VVE right, it would be rich one run the lean the next, I was only correcting multiply by half each time so I wasn't overshooting. Like Rob says it takes good filtering. I have tried all kinds of filters I can think of but none of them seemed to do anything. After all that trying it seems like the best way is just longer logs and maybe trying to combine logs, hit as many cells as possible with as many counts as possible to average out error. Problem is then once you hit some cells then it will swing back to rich or lean for no reason and you just get frustrated and give up.

    After trying for so long, I put my narrowbands back in and got it ok. Its no so much that you can't get it decent enough to run, but I just couldn't get under the +/-5% that people say you need to get it to to get the airflow and torque models to make everything work correctly. There's also the question of are you supposed to average both banks? This would require a custom math parameter as I don't see a built in one that will give you bank 1 and 2 average. Or are you supposed to do it a certain way? Also after all that being said I believe with a cam and overlap it screws with the O2 feedback switching and screws with the trims anyway. I see way smoother fueling that says closer to stoich in open loop than closed loop.

    TSP said the same thing that they gave up on the "VVT" and apparently are going to redesign their cam line for the GEN V without VVT. I believe mostly VVT was implemented by the OEMs for the EGR effect and lowering vaccum at lower loads. I just can't see how just phasing without altering duration and especially independently for exhaust/intake is going to help any. Maybe there are some situations where the differences in gas flow between the exhaust and intake let you take advantage of it. That being said I wish I could have still kept VVT some and used maybe a 10 degree limiter, that way I could still have the stock advance at WOT. I just didn't want to risk it given that I have already had .015 milled off my stock heads with .635 lift and apparently we have very little PTV clearance. Even with the small increase in compression, I was thinking this was more important than any potential advantage I could get from VVT.

    And the part about the stock heads being a limiter with smaller ports and harmonics? Where did you hear that? I think the Edlebrock casting requires different exhaust manifolds, and aftermarket castings seem way to expensive than they are worth. I wish I could build a ultra high compression E85 motor but its almost like there are no options to get there.

  15. #35
    Quote Originally Posted by Ben Charles View Post
    Log tq management spark!! Does it show anything in the problem areas?
    From my experiences with "Torque Management Advance", which it seems like its always a positive number that always pulls timing and not adds timing, is the most reliable indicator we have for monitoring when the PCM tries to reduce torque through immediate methods. So with that, there are a lot of times where immediate torque control source still says "Axle", TC duty cycle still looks normal (which the TC desired torque percentage and duty cycle or whatever it is also makes absolutely no sense as well) and no other torque PIDs are indicating a reduction, but "Torque Management Advance" is at some non-zero value. So is there any way you know of to tell what is actually making the torque management advance (retard) happen?

  16. #36
    My experience with large intake duration, wide lsa cams like that are exactly this. A complete loss of low end. There is really no need for anything bigger than 229-231@.050" intake duration unless you're running a high ram intake and turning 7800+ rpm. N/a these engines also need 111-113 lsa to help maintain low end. Gpi is a good example of cams that work well in lt engines.

  17. #37
    Quote Originally Posted by HeavyChevy305 View Post
    Auto or manual?
    Manual, the car definitely under preformed. It has a 18% lower headers "ported blower" "ported heads" on 91 and it made 630hp/650tq on our mustang dyno. Just for reference my ZL1 did 650/720 with upper, headers, 5" intake and e85. The graph was smooth the numbers were just low. The customer bought the car like this and took it out a few nights later and took out some bearings, after putting a new lt4 shortblock in the car (transferred the heads, cam and blower over) they brought it to me to retune it. The previous tune was a mess, 100% the reason the engine failed, the same shop also "ported the blower and heads" and I truly believe they screwed up something. Boost spikes on the hit then consistently falls and looses roughly 25kpa (no verifiable belt slip). After talking to the customer he wants to start fresh and has new heads, blower and a different cam on the way.

  18. #38
    Not to defer from the topic, but are we leaving good usable power out if I am shifting at 6800-7000 (7200 extreme rev limit cut off) with sub 236 duration cams? I have Johnson lifters and the PAC dual springs that come with the TSP kit, but I can't really find any good info on the limits for RPMs. I have heard rod bolts can be an issue past 6800-6900 since they just can't take the stress.

  19. #39
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    Quote Originally Posted by cmitchell17 View Post
    Not to defer from the topic, but are we leaving good usable power out if I am shifting at 6800-7000 (7200 extreme rev limit cut off) with sub 236 duration cams? I have Johnson lifters and the PAC dual springs that come with the TSP kit, but I can't really find any good info on the limits for RPMs. I have heard rod bolts can be an issue past 6800-6900 since they just can't take the stress.
    Watching your cylinder air mass and MAP (kPa) would be a good indication if power is starting to fall off.
    2019 C7 ZO6 M7.

  20. #40
    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...