800hp from what?!

[Matts94Z28]

Stolen from another forum.

Originally Posted by Matt M

The next day, we replaced the plugs and regapped to .024ÔÇØ At this point, we had also surpassed the limits of the boost sensors in the car and on the dyno. We replaced the dyno boost sensor with one that had adequate range. We could not add any more boost with the controller, so we installed stronger springs in the wastegate. By pull 38, we were out of fuel pump and needed to address this.

With a voltage booster on the dual pumps set to 21volts, we were ready to continue.
After a couple more pulls, we were spinning the slicks pretty bad.

I lowered the pressure in the slicks to 6psi, tightened the dyno straps even more, and raised the tire pressure back to 22psi, which made the straps extremely tight. We also regapped the plugs to .022ÔÇØ. The next pull(#42) was 792whp at 42psi
By pull 46, we reached 820whp at 45psi
Here is a vid:
http://www.youtube.com/watch?v=naOFb0nB9kY

Dyno chart:


Ryan left for the night, but I had time for a couple more pulls. Pull 48 was 829whp at 46psi. We were now out of fuel system again as well as ignition system.

Originally Posted by Matt M

On Friday morning, we discussed where the car was at and where we thought it could end up. Our thoughts were that we needed more boost, more fuel pump flow, and a better flowing downpipe. Of course all along, we were considering the chance of a catastrophic engine failure that might spew parts and oil all over the dyno and bay. My estimation was that we would get to the 725-750whp range at which point something major would break. This is why we set the fuel system up to support about 750whp. The voltage booster was a nice temp fix, but we still could not get the pressure to flow enough fuel with 45+psi boost pressures. To solve the fuel delivery issue once and for all, I had my wife drop off the pump that is supposed to be going in my Corvette this summer. It is a 1500+ HP Magnafuel pump which is the same as the one I run on my 8 second drag car. With the 2 LSJ pumps in parallel feeding the Magnafuel pump, all of the pumps would be pushing less pressure(relative), yet we could achieve 90-100 psi at the fuel rail with more than enough flow to max the 190lb injectors.

While I worked on putting together a system to integrate this pump into the existing fuel system, Ryan built a 3.5" downpipe. When he finished installing the downpipe, he helped wire up the fuel pump. Here is a pic of the 3rd fuel pump with its temporary mounting location:


Somehow we managed to find every fitting and hose that we needed to install this pump in place of the filter. I didn't have to purchase any new parts or even wander more than 10 feet from my toolbox! It sure feels good when things work out that well. We installed the pump and turned the key and were pleasantly surprised to see that the base pressure was stable at 41psi with all 3 pumps running.

Next, we replaced the TiAL 44mm wastegate with a Precision 46mm gate that allowed us to switch to a 26psi spring setup. Combined with our boost controller, this would give us boost control up to ~55psi.

We put the car back on the dyno, turned it down a bit and made a pull. The first pull was 834whp at 44psi with an over-rich afr! This meant that the downpipe and fuel pump solution were both working well. Leaned out, we managed 859whp at 45psi. We turned it up a bit, tuned some more, and put down 870whp at 46 psi. We then hit 880whp at 47psi. Here is an in-car vid at that power level(windows closed):
YouTube - Ryan's ZZP LSJ Cobalt In Car Dyno

Over the next few pulls, the peak horsepower gains were diminishing pretty quick. However, torque was still climbing. The result was a flatter, wider power band which is nice, but we were still looking for peak power numbers at this point. Ryan replaced the plugs again and dropped the gap to .020"

By the time we reached 51psi, we hit 890whp. The next pull was 891whp. This pull was 54psi on the hit!
YouTube - Ryan's ZZP LSJ Cobalt Dynos 891 WHP

The next pull was 894 (891 with smoothing)

The next pull hit 898whp, but we got a code for accelerator pedal position sensor and it closed the throttle mid pull. We didn't figure out why it threw the code. However, looking into this, we discovered a possible leak at the throttle body silicone coupler, so we replaced it. The next pull was nearly 55psi and it held boost longer, which means we probably did have a leak. Unfortunately, power fell off on this pull with the peak only hitting 892. Only, lol. We let it cool down a bit and turned the boost back down a couple lbs, but the next pull(pull #60) only hit 866whp. Our initial diagnosis says that there is a an issue with the head gasket. The car still starts and drives around completely normal, but I'm guessing if we did another pull, the power would fall off a little more yet- Which brings us to the conclusion of our test. Yes, we failed to find the limit of either the ZZP rods or the new ZZP block girdle. I promise we will try harder next time.