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I just got back from a trip to the Silicon Valley which started on Jan. 6. I can't say anymore that I haven't made a design mistake which required me to be in the lab since August 2015. Ugh... It is time to restart the clock.

Anyway, while there I had a Nissan <whatever> rental car. I just Googled Nissan's website, and <whatever> must have been either an Altima, Maxima, or Sentra. I don't know, and don't really care which it was.

The point is that while driving it I thought of this thread. You see, that silly little Nissan was blazing fast on initial start from a stop (like when pulling out from a red light). It was so quick and nimble; I am just not used to that coming from the agonizingly slow starts with Caroline.

What a shame.
Wow, really hard to believe that with all the power in your Z06, your perception is that the Nissan was 'blazing fast' from a stop. I have never driven a rental Nissan that was faster from a stop than RedHot. Having not stomped on a Z06 accelerator pedal I don't have a first hand comparison. I certainly would be disappointed and want my Z06 checked out. Please note: I am not doubting you, just amazed at this.
 

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Wow, really hard to believe that with all the power in your Z06, your perception is that the Nissan was 'blazing fast' from a stop. I have never driven a rental Nissan that was faster from a stop than RedHot. Having not stomped on a Z06 accelerator pedal I don't have a first hand comparison. I certainly would be disappointed and want my Z06 checked out. Please note: I am not doubting you, just amazed at this.
I am pretty sure, based on other Z06+A8 owners' responses in this and other similar threads, that it is functioning as designed. Also, for me, the lag goes away in Sport and Track modes. It is just that I want the smoother ride provided by Tour, so, most of the time, I just deal with the horrible lag that goes with Tour mode. Also, after my Z06 gets going, it is SCREAMING FAST if above about 15 MPH and 3000 RPMs (I am approximating). It is just getting it going from a dead stop at idle RPMs that is the problem. I suspect it is the nannies in Tour trying to eliminate wheel spin, and the engineers who programmed it went much too far with reigning it in. They could have numbed it down tremendously, and still not gone nearly as far as they did.

I wonder if GM fixed this in the 2018s and/or the 2019s. I don't think I have heard of anyone with those model years complaining...
 

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Before the C7 I had a Subaru BRZ, then a VW GTI and I felt the difference in throttle response since day one. Both the BRZ and the GTI felt smaller, nimbler. But; how come? The C7 has more than double the HP and it is lighter, not to mention the Z06. For years, I thought it was in my head, until I calculated ( from measured data) the weight to power ratio at part throttle of the C7, then went into a 375 HP/ 5700 lb SUV and did the same. The weight to power ratios were the comparable and felt comparable (200-300 lb/HP) at part throttle. Then, I knew it was real.

All C7’s use the same TB (not sure about the ZR1), you would be amazed of how many GM models use this TB p/n. Yes, it is on purpose, and probably works as designed. I’m sure GM or Delco could have made a fun one specifically for the C7, but then the economy of scales and fuel economy ~30 mpg for a 6.2L V8 would not be there.

Switch the nannies off and see if you feel any difference. At least I don’t.

I’ve also added below a plot of the minimum measured performance of the modified throttle bodies. The fun factor seems to be on the rate of change (slope/gain of curve) from idle (5 deg) to 25 deg. The plots look very similar (a matter of scaling) but the mass air flow gains tell a different story:

OEM: 1.2 grams/sec-Deg (Baseline)

Best Aftermarket: 1.5 grams/sec-Deg (25% Increase)

Modified/Optimized: 2.3 grams/sec-Deg (92% increase)

BTW, after about 35 deg they all perform the same, I find the WOT HP gain claims from some aftermarket PTB’s hard to believe.

8-Perf Plot.JPG
 

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I am pretty sure, based on other Z06+A8 owners' responses in this and other similar threads, that it is functioning as designed. Also, for me, the lag goes away in Sport and Track modes. It is just that I want the smoother ride provided by Tour, so, most of the time, I just deal with the horrible lag that goes with Tour mode. Also, after my Z06 gets going, it is SCREAMING FAST if above about 15 MPH and 3000 RPMs (I am approximating). It is just getting it going from a dead stop at idle RPMs that is the problem. I suspect it is the nannies in Tour trying to eliminate wheel spin, and the engineers who programmed it went much too far with reigning it in. They could have numbed it down tremendously, and still not gone nearly as far as they did.

I wonder if GM fixed this in the 2018s and/or the 2019s. I don't think I have heard of anyone with those model years complaining...
Rodney, I'm curious if you took your Z06 to the dealer for the suspension software upgrade. Those that did report a smoother ride in Sport mode. Of course it doesn't fix the lag problem but it might make it more comfortable to leave the suspension in Sport.
 

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Rodney, I'm curious if you took your Z06 to the dealer for the suspension software upgrade. Those that did report a smoother ride in Sport mode. Of course it doesn't fix the lag problem but it might make it more comfortable to leave the suspension in Sport.
No, I haven't done that yet, Paul.
 

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I wonder if GM fixed this in the 2018s and/or the 2019s. I don't think I have heard of anyone with those model years complaining...
Those use the same TB p/n as in previous MY's. If you have that p/n, airflow vs. throttle plate angle is fixed by the geometry and there is no way around that.
 

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Those use the same TB p/n as in previous MY's. If you have that p/n, airflow vs. throttle plate angle is fixed by the geometry and there is no way around that.
Yeah, I understand.

There are really two issues at play here.

1) There is a lag which occurs when pushing the pedal from a dead stop at idle, and watching/feeling/hearing the RPMs fall before rising. That is, I believe, pure Z06+A8 nannies and could be fixed in software, since I can eliminate it with a different drive mode other than Tour.

2) The other issue is the one you mention about the sluggishness which occurs for low throttle input even after the car is moving. This is what you describe as addressable with a new throttle body.

I can live with the second issue (although it would be nice for the Z06 to be as snappy as my now-defunct, old 1999 Oldsmobile Intrigue was around town, or as zippy as that recent Nissan rental was). However, the first issue is the one which, by far, annoys me most.
 

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If you still have an extra throttle body left, I would love the opportunity to try it out and give you some good feedback on it. My '16 Stingray, Z51, has TSP Long tube headers, high flow cats, and performance tuned by PCM of NC. I am running right at 500hp at the crank, but I am sure the throttle body needs some mod to it. Let me know, your throttle body may be the answer I have been looking for. I am wondering how it might affect my current tune.
 

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I just got back from a trip to the Silicon Valley which started on Jan. 6. I can't say anymore that I haven't made a design mistake which required me to be in the lab since August 2015. Ugh... It is time to restart the clock.

Anyway, while there I had a Nissan <whatever> rental car. I just Googled Nissan's website, and <whatever> must have been either an Altima, Maxima, or Sentra. I don't know, and don't really care which it was.

The point is that while driving it I thought of this thread. You see, that silly little Nissan was blazing fast on initial start from a stop (like when pulling out from a red light). It was so quick and nimble; I am just not used to that coming from the agonizingly slow starts with Caroline.

What a shame.
Man, can I so relate to your comment. Over the last couple years, my wife and I had a Mini Cooper for a rain car. We had the same results with it. As a matter of fact, I once told a good friend of mine, who owns a '16 Z06, that I could probably beat him off the line, at least for the first 50 yards. That car felt like it had the fastest throttle response of any car I have ever owned. We never actually tried, but it sounded good at the time. LOL!
 

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OK guys, I did get one of Manta's customized TBs and installed it yesterday. I have only driven it about 20 miles around town, but the huge noticeable difference is from idle to about 40 mph. It is unbelievable how it reacts at takeoff, and that is in Touring mode. I am going to drive it to church this morning in Sport mode and see how it feels. As my signature block indicates, I have a lot of performance mods added to my Stingray, but I always had a hesitation from idle, but it is now gone, and a huge improvement with Manta's TB. Even with a normal take off from idle, the tires attempt to break loose if I"m not careful. It was never that touchy before. I am totally impressed, and actually find it hard to believe that a custom TB can make that much difference, hell, it's only a little increase in air flow! LOL! Just thought I would share this here. Of course, mine isn't a Z06, but I would bet it would make a difference there also.
 

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OK guys, I did get one of Manta's customized TBs and installed it yesterday. I have only driven it about 20 miles around town, but the huge noticeable difference is from idle to about 40 mph. It is unbelievable how it reacts at takeoff, and that is in Touring mode. I am going to drive it to church this morning in Sport mode and see how it feels. As my signature block indicates, I have a lot of performance mods added to my Stingray, but I always had a hesitation from idle, but it is now gone, and a huge improvement with Manta's TB. Even with a normal take off from idle, the tires attempt to break loose if I"m not careful. It was never that touchy before. I am totally impressed, and actually find it hard to believe that a custom TB can make that much difference, hell, it's only a little increase in air flow! LOL! Just thought I would share this here. Of course, mine isn't a Z06, but I would bet it would make a difference there also.
Reminded of a graph I published to show why I thought a Vitesse would NOT have an effect on 60-foot times in drag racing. Basically air flow cannot occur instantly when the throttle is open, no matter how fast. The transient airflow takes a finite time. Flow cannot exceed the speed of sound, for example. That's why you see lightening before you hear the resulting thunder! The graph on the left was from a tech paper displaying the measured transient flow through a throttle body and calculated flow.

Just found the graphs on the right from Katech who, as expected, had the tests to show the transient air flow improvement with one of their ported OEM throttle bodies. They show a 27% improvement in transient response. They quote that as a 27% reduction in time to fill the intake manifold with air. The shape and smoothness of the inlet and in their case reducing the throttle shaft thickness all prove an improvement.
transient_flow_& Katech.jpg
 

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Jerry,

That is correct. Notice, that the point of my modification is not to make better 0-60's mph times at WOT, but to increase power/weight ratio at part throttle by making manifold pressure recovery (a transient process as you well said) and air flow greater in that range. This will make the car more nimble, just fun to drive.

I terms of sonic flow, I found the OEM TB chocked at part throttle, and will not respond to back pressure (manifold vacuum) but it will respond to throat area increase and it's geometry (discharge coefficient improvement). For instance, I found that the OEM TB was chocked and under-expanded at part throttle, configuring the interface w/ the "proper" nozzle can further accelerate the flow to slightly supersonic.
 

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OK guys, I did get one of Manta's customized TBs and installed it yesterday. I have only driven it about 20 miles around town, but the huge noticeable difference is from idle to about 40 mph. It is unbelievable how it reacts at takeoff, and that is in Touring mode. I am going to drive it to church this morning in Sport mode and see how it feels. As my signature block indicates, I have a lot of performance mods added to my Stingray, but I always had a hesitation from idle, but it is now gone, and a huge improvement with Manta's TB. Even with a normal take off from idle, the tires attempt to break loose if I"m not careful. It was never that touchy before. I am totally impressed, and actually find it hard to believe that a custom TB can make that much difference, hell, it's only a little increase in air flow! LOL! Just thought I would share this here. Of course, mine isn't a Z06, but I would bet it would make a difference there also.
OJ, thanks for your feedback. I have had mine in the car for a few months now, and experienced the same, but there is nothing like confirmation from somebody else, specially yours that has some other mods. Glad to see it works there too. Please, keep us updated as you go.
 

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Manta-C7, I can see what you are talking about in driving around town. My complaints have always been the lag off the line, but I do also feel the sluggishness for part throttle application when, for example, driving along at 20 MPH and wanting to accelerate smoothly with the rest of traffic up to 35 MPH. Often, I get left behind while others pull away unless I press the pedal more than I would have to press it in other cars. I had thought before that it was strange that I couldn't keep up with the flow of traffic in town in the Corvette unless I consciously tried; previously I had attributed it to, "I guess I just drive the Corvette slower" but now I am thinking that I drive it slower because it does not respond as rapidly as other vehicles do for a very mild throttle push.

If I were out of my powertrain warranty, I would want one of your modified throttle bodies.
 

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I don't think the Vitesse will make a bit of difference for the lag on the Z06 with the A8. The Vitesse changes the percent throttle for a given pedal depression. That isn't the problem with the Z06+A8. The problem is a time delay in throttle response, not an issue with throttle percentage.

On the other hand, I am sure the lag is something which could be tuned out, if someone were willing to go that route.
They each do completely different things. The throttle controller opens the throttle blade quicker with less pedal movement. The ported throttle bodies provide better air flow. My neighbor put the ported throttle body on his C6 Camaro and then installed a Pedal Commander (which I just installed in my C7). He likes them both.

I installed the Pedal Commander in my C7 two days ago but it was raining so I couldn't take it for a run until this morning on the way to work.

First Impression: Holy Crap!

I set it the Pedal Commander to "Sport" (not Sport+, just Sport) and I put my car in sport mode. I went to pull away from a stop sign with a normal and reasonable pedal force (not flooring it) to about 1/4-1/3 pedal and there was an immediate response... tires squealed and car started to fishtail so I eased off. No doubt about it, same if not better resoponse than I got with my F150 5.0 Liter after installing it. I had a 35 mile ride to work and played with it. Response at 70+ MPH in taffic, passing, etc. was fantastic. I touch that pedal and the response is immediate.

So, while I still want to find a safe stretch of road to try the 0-60 comparison with it on and with it off and capture on the PDR, regardless of that outcome, I am happy with it. Worth every penny and still the most bang for the buck on any mod to date.
 

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I drove my Stingray another 100 miles yesterday, stop and go traffic, and on the Interstate. I am still blown away by the difference Manta's (Solar Engineering) TB makes in the performance of my Stingray. It is absolutely more fun to drive, and seems to even make the transmission change quicker in the lower gears, and more pronounced. Just a seat of the pants impression. I know you guys must be getting tired of hearing from me, but, even with all my other mods, this TB literally speaks for itself every time I drive the car.

On a side note, I also tried to add a Peddle Commander(PC) to it on Thursday. We could not get it to function properly. We kept getting a CEL so we removed the PC, waited 15 or 20 minutes and reinstalled it. On the second attempt we not only had the CEL again, but the RPM went to 3500 on its own. That got my attention, so I removed it and got my money back, and gave up. I might add, I purchased the PC from a shop I have dealt with for over 30 years. Their installer has installed hundreds of PCs, but none in a Stingray. He is very OCD with his installs, strictly by the book. He even took my key fob into their office area to ensure it would not interfere with the install results. He and I worked on it together. The only thing we could think of was something about my other mods and dyno tune was keeping the PC from communicating properly with the ECM.
 

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Hi all - I have a manual 2015 C7 Z06 that has a throttle lag issue. It does not happen when accelerating through the gears, whether from a standing start or otherwise. It happens when going at a steady speed in OTHER than 1st gear, and mainly at lower rpm (under 3500). It is perhaps a half second lag and then power comes on strong. If I just feather the gas before standing on it, it does not seem too bad. OF course when the power does come on it's crazy fast and hard to keep the tires from getting loose. Could this be a TSB issue? It feels like a throttle response/drive by wire issue. Did not happen on any other car I have had including Vipers, a VW GTI with a turbo, 91 ZR1, etc. Any ideas? I have been living with it and have not asked the dealer yet. Do love the car otherwise. Thx.
Did you ever come to a resolution? I drove a Z06 for the first time a couple days ago. I've been considering getting another Vette now that the C7s are so cheap, but having a hard time deciding between the GS and Z06.
What you described is exactly what I experienced in my friend's '19 Z06. I felt like I was in a turbocharged car waiting for the boost. I did not try using much throttle in first, but it was very noticeable in both 2nd and 3rd. It's exactly what you do on a test drive, cruise at a steady speed until the road opens up and then nail it. I expected the TC light to start blinking but instead I got nothing initially and the power built up for what felt like half a second before I was at full acceleration. The TC light never flashed.

My daily driver for the last 6 years is an S4 with a supercharged V6, and that thing has Tesla-like response (short gearing and AWD also help). My weekend toy is a '13 Gallardo, which also has no perceivable delay. My C6 had pretty much every bolt-on, including porting the TB, and it had very good response. It wasn't as quick as either of my other two, but the difference was minor.

I've read several threads now, and yours is the only post I've come across that sounds exactly like what I felt. Hope you found a fix.
 

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Welcome to our forum JDWK and good luck in your search!
 
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