My blower cam I ran in my 8.4-1 540 when it dynoed N/A (with blower belt OFF) at 657 hp was like 253/259 with .640/.660 lift if I remember right (been a while) , torque peak was 665 ft lbs at 4800, made 660 ft lbs of tq at 3800 with a funky 15 ft lb dip between there BUT remember this was a low compression motor built to be ran with a supercharger with cam waaaay to big for the compression ratio being dynoed normally aspirated, so this came was far from optimum for running N/A. IF I was dynoing it again today I would use 87 octane because compression is so low it might actually work slightly better. I would believe your motor should be making 680 ft lbs of tq all day long if everythings right. I hope you find some resolution Tim, Smitty

I am dynoing this same 540 on dyno in my own shop in next few weeks in normally aspirated configuration, the 315 afr heads are slightly different (been ported even more) and cam is even bigger, even less than ideal for a normally aspirated motor but I want to see what current hp is, I will post numbers. Will be testing a even bigger throttle body too, Smitty

interesting stuff smitty,looking forward to seing the results.

Soon as the 540 is dynoed N/A the heads and modified MPI intake are coming off, intake is going on my econo/mild build 502 (I just finished building long block on) that I'm dynoing next then putting in my 272 Baja to sell in spring. The heads and a second pair being built identical to them are going on my hp 500 efis out of my 33 scarabt along with cams, intake work etc. Got alot of projects going on with my own motors this winter!

what did the boat have for stock motors and how fast was it w/ them?

sounds interesting,,,what brand dyno you have?
my friend is actually giving me his old set up,i'm getting excited to get it.Of course the latest software is gonna be fun to buy.

Ray said head chambers were right on, was all calculated by bob to be 9.6, when compression test was done averaged 165, all were within a few PSI.

Seem similar boat I am mistress 25 mirage plus spinning 5500 was best at 73.7 with old engines this year best was. 73.2 with new engines that I expected to be more, I know it takes power to push my boat. I was told identical builds to mine made 716 hp and 693tq at 6000 with 4500 doninators. I can't fit them under hatch so I went 1050 (4150) carbs but they are not robbing 100+ ho per emgine that's for sure

Norm schenk of competition fuel systems relocated from Tuscon arizona to my town, he owns a gopower 750 dyno thats been upgraded to hold about 950 hp, he installed his dyno in my shop and i get his carburetor expertise and use of the dyno in exchange for shop space im giving him. He has done developmental work for stromberg and various people thru the years such as david Vizard on this dyno, only drwaback is it wont hold enough tq to dyno 1000 ft lb tq blower motors. Uses depac software, since setting it up he has dynoed his mule motor SBC on it within 3 hp of what it made 2 years ago in arizona and on several pulls over several days its repeated same results so looks like will be a good deal all around.