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VR modified AFE Cold Air Induction VR 2.38" Upper Pulley/Hub VR Lower Pulley
American Racing 2" Stainless Long Tube Headers with 3" X pipe
B&B Fusion Catback Exhaust VR CNC LT4 Cylinder heads VR Custom Camshaft (MILD) Retains VVT/Deletes DOD
Alky Control Methanol System VR Flex Fuel System
We are now making 772RWHP/729RWTQ..... This is a gain of 187RWHP/118RWTQ from our stock baseline #s!!!!
Unfortunately I believe we are near the limit of the stock 1.7L supercharger. After producing the #s above we removed our current 8 3/4" lower damper (approximately 10% over drive) and installed a slightly larger 9" version. As you can see from the graph below the smaller lower peaked at 13.65 psi and slowly dropped boost thru the rpm range. Adding the larger lower pulley did pick up approximately 1.5psi on "the hit", but then gradually dropped to almost the identical boost #s from the smaller pulley. We have confirmed there is no belt slip. Knowing this we can speculate we are at the limitations of the 1.7L supercharger. I do believe we can pick up some additional power with a larger camshaft and a 102 throttlebody, but I do not believe there is any power left spinning the blower any faster than we already are.
There are a couple of things to keep in mind here when looking at our boost #s...
Our Z06 produced 9.5psi in stock form
Adding our 2.38 upper pulley picked up just over 1psi
Adding our modified AFE picked up an additional pound of boost
Adding heads/cam/headers reduced our boost by almost 3psi
Adding our lower damper/ring combination picked up right at 5psi peak, but boost drops by almost 2psi by our 7000rpm redline
Keeping the above in mind it may be possible to produce 17-18 psi on a bolt on application IF we are able to fuel it. Remember, we have an Alky Control methanol system and our camshaft has the larger fuel pump lobe for additional fueling.
Our next step will be to spray our LT4. We are working with our friends at Nitrous Outlet and they have installed a custom spray bar setup in our LT4 supercharger. Once the nitrous is installed/tuned we plan to go to the drag strip and test our car boost only and on boost/nitrous.
Here is a link to another C7Z we recently built with similar modifications. .....
All of the parts mentioned above are currently available including our lower OD rings/IW Balancers. I will get some pics this afternoon and update this thread for anyone interested.
We are currently putting together various stages of performance packages for the C7 Z06. Feel free to email/call with any questions you might have in the mean time.
Last edited by Ron@Vengeance Racing; 03-20-2015 at 11:29 PM.
I asked this in your Viper Vs Hellcat Vs Z06 dyne thread, but it went down hill quick.
I think the problem with the Z06 reduced acceleration at high speed is mostly from a fast reduction of torque greater than 5000 RPM. Bolt on mods. raise the torque but the downward slope is still steep. Your VR800 package doesn't start to drop until well after 5000 RPM and not as steep after, and relatively less low end torque. Is it the change in cam timing or something else? Maybe the small blower.
Any chance you're also maxing out the CAI and just not getting any more air?
Zero chance, and what he was pointing out is that a larger lower pulley didn't yield more effective boost but only a bigger initial hit at lower RPM. Translated this means the blower casing is flowing all it can up top already no matter how much faster you try and spin the rotors. Spinning a PD blower faster when it is maxed out usually gives a bigger and faster initial torque spike, but then it falls back off on the top end indicating there is simply just no more headroom.
What surprises me is that the car made almost as much power without adding the lower at 5 less psi, yet another indication it was already near its limits before the lower was added. GM did a real disservice to any potential Z06 modders out there by not putting at least a 1.9L blower on this car
You guys have done an amazing job moving the horsepower level up. However after looking closely at the horsepower graphs from your other thread of the Hellcat and the Viper, I'm convinced that the mysterious brick wall that nobody has been able to explain has been solved.
The last 1500 RPM of this cars's peak horsepower are FLAT do to the significant drop in torque after 5000. IT NOSE DIVES. I'm surprised that I did not catch this. This is masked in 1st - 4th gear, however when this car is shifted into 5th it sits in this power band area there is little if no acceleration in HP. THEN BAM, it sits there and labors while every other car (most fast cars) accelerate in the HP graph. Thats is it, thats why these cars will jump ahead, and as the car goes through the gears it will spend longer and longer in the peak power portion of the graph, THEN, it happens, 5th gear comes and it dies.
The roll race curse has been solved! Ron, you exposed it. You have somewhat mitigated the problem with such an increase in power, however, the delivery is still similar in character as far as the flat wide peak in the HP graph.
I was not subscribing to the small blower argument before, but you have exposed and proved it is the blower!!
You guys have done an amazing job moving the horsepower level up. However after looking closely at the horsepower graphs from your other thread of the Hellcat and the Viper, I'm convinced that the mysterious brick wall that nobody has been able to explain has been solved.
The last 1500 RPM of this cars's peak horsepower are FLAT do to the significant drop in torque after 5000. IT NOSE DIVES. I'm surprised that I did not catch this. This is masked in 1st - 4th gear, however when this car is shifted into 5th it sits in this power band area there is little if no acceleration in HP. THEN BAM, it sits there and labors while every other car (most fast cars) accelerate in the HP graph. Thats is it, thats why these cars will jump ahead, and as the car goes through the gears it will spend longer and longer in the peak power portion of the graph, THEN, it happens, 5th gear comes and it dies.
The roll race curse has been solved! Ron, you exposed it. You have somewhat mitigated the problem with such an increase in power, however, the delivery is still similar in character as far as the flat wide peak in the HP graph.
I was not subscribing to the small blower argument before, but you have exposed and proved it is the blower!!
So now what??
Thanks for all your work!!
I don’t think it is only the blower. Below is a larger blower on the LT4 engine. Torque still drops rapidly after 5000 RPM.
Yes, I see that! It needs to be re-cammed. Though the HP is higher, the peak point is worse. The peak is spread out over 2000 RPM.
These HP graphs look like a pick-up truck. This is supposed to be a performance car. I just don't get why this has a such a horrible delivery of peak HP.
Yes, the immediate TQ makes for a thrilling and ultra responsive ride. However, after the initial response this thing dies. If this was 15 years ago and we were matching heads and a cam, we would be saying "it has the wrong cam" or "Carb". The thing is flat out laying down on the big end.
Tuners - that is your challenge! make this thing NOT FALL OFF!
03-04-2015, 11:35 AM
VR C7Z Update... 772RWHP/729RWTQ|13PSI|Finding the limitation of the 1.7L Blower...
Vengence
