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Discussion Starter #1 (Edited)
There is a much debated problem w/ the throttle response of the LT1/LT4 engines, manual or auto, the issue has been described in this and other forums (Corvette, Camaro, Trucks, SUV’s), just to mention a few descriptions:

- Throttle Lag
- Delayed response
- Car feeling heavy or not nimble
- Difficulty climbing hills at low/moderate throttle
- Uncertainty when passing other cars or unpredictable response at low/moderate throttle
- Stumble when shifting on manual transmissions

You name it, this has been my issue w/ my Corvette 7 since test driving at the dealership. I've tried a Throttle controller, AFM disabler, ECM Tuning, and arguably the three most talked about ported throttle bodies (PTB) out there. I have also combined some of the above w/ some success but still not enough. One just needs to hop into almost any other comparable car to feel they respond better.

After spending so much time/money, I decided to take it upon myself to find out, I also have all the equipment needed at work (measuring, testing, simulating, machining etc.)

Long story short; it is the throttle body. Between idle (~5 degree throttle) to ~30 deg throttle angle the amount of mass air flow (which is proportional to power) puts our cars at a weigh to power ratio similar to that of trucks and SUV’s, both in terms of absolute value and rate of change. Not to be confused w/ the weight to power ratio that is usually published, which is calculated at WOT, above 35 deg throttle angle our engines shine. It is on the part throttle range (idle to 30 deg) that the issue exists.

I’m not going to speculate on the reasons, but I can tell you that our throttle body p/n 12678223 or 12620263 is used in many GM vehicles and that such throttle response helps w/ fuel economy. That helps to keep parts cost low and meet EPA requirements for the fleet. However, I do not think one size fits all and that a high performance car needs to sacrifice performance for economy.

The throttle controller and the tune improve response by making the throttle plate move faster between the 5-30 deg range. Faster, but it still needs to go through a tortuous path for the air flow, and the manifold pressure doesn’t recover as fast. It is a transient process, and it is from the intake manifold where the pistons suck the air from. Notice that this is not true throttle response, it is just tricking the ECM into thinking you have pushed the accelerator pedal harder. The actual throttle response is the same, only physical changes to the throttle can make for a true throttle response.

The existing aftermarket ported throttle bodies also helped, they do change the throttle physically, but their effect only starts to take place at about 25 deg in what I thought was the best one of them. Definitely a step in the right direction, but I noticed they were not optimized and that more could be extracted from them, that is a throttle body that can increase the absolute value and rate of change of mass air flow right from idle and up to 35 degrees to achieve the same weight to power ratio (in that range) of similar high performance cars that feel nimble and fun to drive at part throttle.

Another long story short, I reversed engineered 10ea OEM throttle bodies, 3ea aftermarket ported throttle bodies, and a benchmark (competing car maker model) OEM throttle body. Optimized/modified the OEM throttle body to meet the benchmark throttle response as well as the goal stated above.

Our modified throttle bodies (MTB) are made (CNC machined) from a brand new OEM throttle body, flow and engine tested. Our design has been fully vetted by Corvette 7 Z06 owners, fully and openly tested by Corvette Forum members. Driven in different conditions/modes for a few thousands of miles now at extreme temperatures and altitudes.

See pics below for more insight into what I’m talking about…and most importantly what do you think? All comments welcome.
Please visit us at : SolerEngineering.com

Thanks,
 

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Any links to real world performance? Any back to back dyno’s? Quarter mile passes?


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Discussion Starter #3 (Edited)
We concentrated in the idle to 33% TP range where the problem exists, and there we doubled the slope of the curve to gain MAF rate of 2.4 g/s-deg from 1.2 g/s-deg on the OEM. That reduces the weight to power ratio at low throttle in about half too, and makes our cars feel lighter and responsive. We are very confident that manifold pressure will recover faster too (less transient), as well as the boost will kick in earlier.

You can also see that we added what it takes to perform at WOT, unfortunately, we are not confident we can get an accurate measurement for the small percent it would yield at best (~10-20 HP). Standard Dyno, total scale, accuracy, and repeatability are not suitable. Although this wasn't the point of the mod, we'll find a way to quantify it.

Other than the plot provided, all we have is plenty of real happy Corvette 7 and Camaro 6 owners. They have also logged performance and got the same results. BTW, another measurable characteristic of the curve is the wider "knee" shown below, that means predictability/control.
 

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Any links to the Corvette’s or Camaro’s running your modified throttle body?


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Are you a vendor here? Cant find your subforum.
 

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Papi, yes they are a vendor as I had to confirm today. Vertical Scope doesn’t seem to announce new vendors or update the vendor section very quickly.


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Discussion Starter #13
Just verifying again...ZERO tune required, and it will not void factory GM warranty.
Correct, just bolt it on. One of the easiest mods out there. Installation instructions attached (for Corvette 7) it should be very similar for a CTS-V.

Voiding factory warranty is completely under your control.

Thanks,
 

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Gotta say, probably the BEST explanation of the science behind an aftermarket modification I’ve EVER read. Very detailed & thorough, but not like reading a rocket science journal. You convinced me enough on paper to take the plunge in real life.

https://www.solerengineering.com/technical
 

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Discussion Starter #16
How does this differ from pedal commander or COW booster etc?
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Glad you asked, Larry.

If you look at any of the plots above, the green curve represents the OEM airflow vs. throttle blade angle (could also be translated to TP%). This is the actual response curve of the OEM valve (TB) itself. When you add a throttle controller (TC) or change the pedal mapping with a tune, you are just running faster along that curve by tricking the ECM into "thinking" that your accelerator pedal depression is actually greater than it really is.

Now, our Mod is the red curve, again this is the actual hardware response (TB/Valve) and it's shaped more linearly, smoother transition to power starting right off idle, it is more responsive and more predictable regardless of how fast the pedal mapping moves along the curve.

We'd like to think that we have cleared the mechanical component (hardware) of the response problem, while the TC/Pedal Map takes care of making the pedal stroke feel shorter.

These are not mutually exclusive, in fact, they help each other achieving a custom throttle feel even for the most demanding of drivers. Many people use both.

Note: This is not a recommendation to use both mods, our TB's are aggressive in response by themselves, adding a TC in combination w/ our TB may render a car uncontrollable at some settings. This is a matter of taste, skill, and risk tolerance. Please, use caution.
 

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For me every box is checked and no check engine light after 55 miles and this thing fixes everything listed and more. I have a 2019 with the Billy Boat system and K&N CAI and the Range AFM disabler and what I was noticing when lugging around at 55-60 mph in high gear how the car delayed dropping a gear on light acceleration around town but now the transition is smoother without delay. I have not made any hard acceleration yet because I want to make sure the learning is done and that's not what I bought it for anyway but the driveability is unmistakably improved right out of the gate. If you have 10 minutes and a little over $400.00 to spend you would be hard pressed to to find a better use of your money or time. Call Mike
Throttle Lag
- Delayed response
- Car feeling heavy or not nimble
- Difficulty climbing hills at low/moderate throttle
- Uncertainty when passing other cars or unpredictable response at low/moderate throttle
 

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Discussion Starter #19
Well, many Corvettes Z06 and Camaros ZL1's enjoying the benefits of this easy and very effective mod. A few CTS-V's running our parts and they love it too.

Check our reviews at corvetteforum. com. Everyone there agrees we have the best modified throttle bodies for the LT1 and LT4 engines.

Thanks,
 
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