[napster]

I had a 496 built and here are the details I know:

The block is a 455 from a 1974 Catalina. A stroker kit was installed to get to 496 along with a .30 overbore. The entire rotating assembly is forged. The heads are the real #16 super duty heads. They were worked on by previous people (comment on that later). The heads were benched flowed and the result was 260 CFM. The intake manifold is a Edelbrock performer rpm. The carb is a Quick Fuel 850 CFM. The cam is a Butler performance custom grind. Part number is CCA-BP8041SP. Specs-294/300,242/248,.594/619, 112 LSA. The lift is using 1.65 ratio roller rockers. This cam was my pick not the engine builder. He wanted to use a different cam. The builder checked with Butler and happened to talk to Jim Butler and he said go for it. Compression is 9.9 to 1. Total timing is 35 degrees. Doug’s long tube headers are used.

Before the dyno run, I saw a formula posted by someone a while ago. The formula is used to calculate CFM flow from the heads starting with horsepower. I worked it backwards from the 260 cfm and came up with 535 HP. I know that is with 100% usage of the head flow. I’m guessed 505 HP. My engine builder projected mid 500’s for HP and low 600’s for torque.

I want to state that the dyno used is known to throw off numbers on the low side. Many people have come back to the owner of the dyno and showed higher numbers on other dynos after being run on this one.

The dyno run took place last night. I don’t have a lot of information on it right now, but I will by the weekend. Here is the limited information I have: HP 519 @ 5200 RPM, TQ 578 @ 4200 RPM
TQ/HP RPM
544/311 3000
552.9/368 3500
529.4/519.4 5200
508/513 5300
497/511.6 5400
490/513.1 5500

This is after 10 pulls and the rings are not totally sealed yet.

My reaction is disappointed. Same thing with my engine builder. The builder mentioned he thought the previous porting that was done hurt the numbers. I seem to remember Cliiff R made such a comment on the SD 455 he did a while back.

The engine builder said he could have spent another day to get another 20 HP. I said no, it wouldn’t be worth another dyno charge.

I would like opinions.

Thanks,

Jim