Have a 2000 6 speed manual. Engine is standard apart from Vararam intake and Vortech's supercharger kit.

Car makes good maximum power approx 290 KW (386 HP) at rear wheels. This is in Australia on a DynoDynamics chassis dyno which has 30% loss so its making approx 550 HP at the motor.

Problem is that as can be seen from attached dyno sheet it has a massive power dip starting at approx 5200 RPM.

Fuel pressure is fine, boost continues to go up nicely, air/fuel ratio is not good but wouldn't account for a 90 HP drop. Timing is not retarding during this period. Vortech suggested spark blowout and we put in some cooler plugs with a .035 gap which didn't help.

Bit of history - mine was one of the first proper 2000 kits shipped and as none of the tuners in Australia have LS1edit for a corvette I thought it would be good to get the superchips programmer from Vortech. First program they sent me the car shut down into limp home mode as soon as it went into boost, but otherwise ran OK as long as I didn't go full throttle. Contacted Vortech and they said they'd send me the wrong program and to reflash it back to standard and send it back. As I was looking at a 3 week turnaround I didn't reflash it back to the factory program as the car really didn't run at all with the factory program and I had committed with a Corvette Club to have the car on their display at a major Car show. When the new program arrived I reflashed the car back to stock with that program and then flashed the new program in. Result was dyno sheet below.

Car was obviously running very rich so I decided to buy Ls1Edit and take it to the local tuner. They've had the car nearly two weeks and haven't been able to figure out the power drop. One of the things we're wondering is that when the Superchips programmer write back the factory program it obviously only writes back what it changed. So if the first program wrote something the second didn't then it would still be left behind. Perhaps it changed something that Ls1edit can't read. Strange though that the EFIlive monitoring isn't showing anything.

Anyone have any ideas ?

Thanks,

Dave.

 

Most likely it is Timing or Air/Fuel related.
Superchips isn't the most accurate programming.

We need to see Timing and Air/Fuel plotted from 5000-6500rpm.

 

Air/Fuel ratio is along the bottom of the graph. In the power drop range its varying between 10:1 and 11:1 . Don't have a graph of timing bit it's fairly consistent. Tuner has actually developed a program with proper air/fuel and timing engine makes a lot more power everywhere but still has this massive power drop.

 

Your computer could have been corrupted from all the different programs going in and out of it. I had a very rich spot around 3500 to 4200 RPM, which caused a similar low spot. I too had tried LS1 edit along with another programer. Mike Morgen went ahead and flashed my computer back to stock and then reprogramed it again with his updated files and every thing came out great.
Good luck,
JB

 

Very hard to read the graph.
The power curve looks much more like a HP curve than a TQ curve.
Your power loss is right at Peak TQ which is where you need to pull the most timing. You are also too rich if that is an A/F graph.

Most likely too much timing at peak TQ.
What did your OBDII logs show for timing between 5000-6500RPM?

 

For the record the power drop was caused by the fuel pump. Changed to the racetronix fuel pump and power curve is perfect and the engine picked up an extra 40 RWHP at peak RPM.

Also if you click on the graph you'll get a bigger version which is easier to read.

Thanks,

Dave.