Well as some of you know, I pulled the motor a few months ago and put on a set of Striker heads as well as the JM cam. I had DC Performance do the tune on the car, and it bascially put out 580 RWHP and 581 RWTQ. This was with some highflow cats and very small 1 1/2" headers. I felt that with the small tube headers and cats, there was a restriction in the exhaust at close to 600RWHP. Because I V-banded the cats in place, it was easy enough to V-band a section of 3" stainless in place of the cats. This was much cheaper than a new set of headers.
This morning I was off to my long time friend Andy Green's shop, he owns A&A Corvettte in Oxnard CA. I've known Andy for over 20 yrs now, we both were building small block 400's for TPI IROC's back in 1986 when fuel injection was a bad word. Anyway Andy let me use his Dyno to test my theory on the cats. The first stumbling point was that we couldn't get a proper signal from the spark plug wire. After a few passes and no real solution, I just used the info we were able to get. I guess the dyno defaults to a speed value to calculate horsepower insted of rpm. I did three passes and yielded similar results. 584 RWHP was about the average, the software showed an erratic torque curve do to the signal.
I was more interested in the torque value down low as a comparison to my earlier passes at Dan's shop. The motor was on the warm side as Andy's fans are set up for the Corvette's bottom feed cooling system. It seems that the cats are really not much of a restriction after all, granted different dyno, different day, and tunning not optimized for a catless aplication. Regardless they are going back in. In my mind pulling the cats in a stock application is a complete waste of time. Hope this helps anyone on the fence. More tests to come.
This morning I was off to my long time friend Andy Green's shop, he owns A&A Corvettte in Oxnard CA. I've known Andy for over 20 yrs now, we both were building small block 400's for TPI IROC's back in 1986 when fuel injection was a bad word. Anyway Andy let me use his Dyno to test my theory on the cats. The first stumbling point was that we couldn't get a proper signal from the spark plug wire. After a few passes and no real solution, I just used the info we were able to get. I guess the dyno defaults to a speed value to calculate horsepower insted of rpm. I did three passes and yielded similar results. 584 RWHP was about the average, the software showed an erratic torque curve do to the signal.
I was more interested in the torque value down low as a comparison to my earlier passes at Dan's shop. The motor was on the warm side as Andy's fans are set up for the Corvette's bottom feed cooling system. It seems that the cats are really not much of a restriction after all, granted different dyno, different day, and tunning not optimized for a catless aplication. Regardless they are going back in. In my mind pulling the cats in a stock application is a complete waste of time. Hope this helps anyone on the fence. More tests to come.
