I have to preface this thread with a big Thank you to Bill over at Ateco Engines he did everything he promised and was always available to answer all questions and never went any further than asked without checking in with me first.
This is my first experience not only in the "Go Fast world" but with Bill and Ateco.

My final numbers are
489.4 HP @4000 RPM
643 Foot Lbs of torque


574.3 HP @ 5300 RPM
569 Foot lbs of torque

I am assuming these are good. Can anybody confirm these are what should be expected?
Any input would be appreciated

Seem's Low.

Most 540's Are Making 650 Hp +

I agree...
seems low.

Here is my 540 build from a couple of years ago.
This was dynoed with all accessories, and thru wet exhaust, which is typically about 30-40 hp less than thru dyno headers and no accessories.

Chris

Depends on what your setup is. If you have stock iron heads mild cam and didn't spend much on exotic heads etc. then it is what it is. You made 1.06 hp/cubic inch at peak HP. With good aluminum heads, custom cams etc. you could make 1.2-1.25 hp/ci quite easily. Let us know more about your setup. Also, please include the correction factor for the atmospheric conditions on the day of the dyno.

Lot's of variables. If your buider tested with full marinization including the sea pump, alternator, PS and the same exhaust you will run in the boat this could have reduced the measured output compared to others maybe 30-60 HP at 5300 RPM. Also, if the engine was designed to run wet exhaust (smaller cam) with stock GM heads you may be in the expected range.
There are lots of boaters running 540's that could comment on the results if you post a some more info on setup on the dyno and your in the boat exhaust system.
Some marine engine builders dyno work overstates the real world in the boat HP/TQ because they test with full length dry tubular automotive designed exhaust and at RPM levels that won't make same power with short runner or wet exhaust. For many, it is a hassle and time consuming to marinize the engine and setup the shop to dyno test with water jacketed exhaust. Compare apples to apples....

Those power numbers seem quite low for a 540cid engine.....but if that is what your builder told you to expect and you are happy because you got what you paid for, then I guess it would be good.

Did you have that 540 rebuilt or did you buy it from Acto ?

My 509 Ci with steel heads at 9.8:1 compression made 676 HP N/A.

I think a 540 should atleast (very mild) do 650 + easy.

put it in the boat and see what she does. These could be "real" numbers instead of that 650 number every builder out there claims he has made. (I agree 650 is not that hard, just think these could be conservative but realistic and speeds will tell us everything anyway.

Bill built me two 509 inch motors 565 hp each have beenbullet proof for 3 years your numbers seem a little low