Going to the DYNO
 

Today were putting one of my 525EFI's on the DYNO to get a baseline before a rebuild. Motor is going to get dynoed just as it came out of the boat. Headers, full serpentine belt, stock fuel system,everything OEM. Motor has about 220 hours on run time.

Will give results later today if everything goes OK.

If there is nothing wrong with them other than standard wear.....my guess is 548hp with accys.

1st set of numbers 569 hp at 5200rpms, 596 tq at 4600. Going to get numbers verified, but I think your right on.

SURPRISED ME!!!

Numbers verified. I think those are amazing numbers for a engine with over 200 hours and in full dress. So much for the 525 rating. With numbers like these I'm sure the people who bought the 575's over the 525's are HAPPY!!! Just in case anyone is interested, motors were in a 42 Fountain Poker Run boat before they were installed in my 42 Fountain Ex I'm pointing that out to show that the Motors have been run PRETTY HARD.

That's good number I was always told that the 525 number was at the prop correct me if I'm wrong but that sounds about right if that's the case.

Those numbers still seem about 20-30hp high. Dyno numbers depend a lot on the dyno, operator and correction factors.

DTS Dyno, Checked Dyno before pulls and after pulls. Don't know how much more you can do.

The numbers sound just a tad high to me also, but what the Hell do I know. The motors might have been run fairly hard, but they havent laid down on you. FYI...if you want those motors to show at least 125 horsepower more...take them to a certain place in Pottsboro, Texas...they will show to make right at 700 HP each...corrected of course.

Dyno pulls were done a very REPUTBLE SHOP. I was there for the pulls and this is not my 1st go around with Dyno's. It really does not matter what the numbers are now,because of the rebuild that is going to take place. I will be more concerned after the rebuild.

Dont misunderstand me...I think your dyno guy had his marbles all lined up and did you a good job and if it was me, I would use him again for the rebuild pulls. I was just saying that if you wanted higher numbers from the start...go to this place in Pottsboro and after your rebuild...I would bet that their dyno would show closs to 1000 HP. Believing this guy there is like believing in the tooth fairy. The numbers that you gave here says that your guy there is HONEST...something that this other guy knows nothing about. Be sure to post the new numbers after the rebuild for us.

Who did them for you?

When I get a chance I will check with him to see if he wants is name posted on OSO. He is a member of OSO and sometimes talking about someone without their permission on OSO gets out of hand. I will say that he owns a Skater and it is a very NICE PACKAGE!!!

I dyno'd a brand new 525 EFI last summer. It made 509 (standard correction) at the prop. If you factor in 11% drive loss (which i've confirmed many times) that works out to 570 at the flywheel. So, I'd say those numbers are right on. I believe Mercury uses the more conservative SAE correction factor whereas most independent dyno shops use the standard correction factor, hence the higher hp numbers you see.

Bob
Full Throttle Marine

I believe you are right on. There are two dyno correction factor calculation factors. Merc and the car builders reportedly use one method while most smaller engine builders use another calculation which gives about 5% more hp on the dyno. Both are SAE methods and neither is "wrong" just different.

Unless the correction factor with the atmospheric data used to calculate the correction factor is posted. These discussions are not very productive.

Post the uncorrected and corrected numbers with the atmospheric data: Barometric Pressure, Temp, Humidity etc on the day of the dyno and we can have a good discussion.

BTW the data is corrected to sea level at a temp like 65 or 70 F.

If this was dynoed in Michigan this week odds are that the correction factor should not be very large if any at all due to the weather. I had a .98 CF on one of my dyno sessions which means that the corrected hp was less than the uncorrected hp due to the cool weather and the barometric pressure.

There was a dyno sheet on another web site that used 27" Hg for the barometric pressure. Standard pressure is 29.96" Hg. So these guys tricked the correction calculation to give a 1.14 CF when the actual CF should have been 1.04 or so. Made about 60 hp difference.

27" hg is very rare at normal altitudes. Maybe in the eye of a hurricane. :eek:

I like what your doing, a baseline hp vs what your going to achieve with modifications. A word about "dyno testing standards" to clear the air on your hp numbers, OEM's-ie, auto makers. merc marine etc use j 1349 which corrects to 77 degrees , 99% of all other shops use the old "std" correctected to temp of 60 degrees which is the old "detroit" standard of 60 degrees which results in numbers 4% HIGHER than sae j1349. In you case your motor made 569hp, if you take away the extra 4% the "std" correction uses your 569 hp turns into 546.34 , not a big deal since EVERYONE else (other than oem's uses this) but it clears the air on your numbers for the people in question. All my dyno testing has always been done using the " 60 degree std" too so don't feel bad , no one is lying here it is just the way the world works, just make sure your dyno runs are all made the way the original one was for accurate comparison, Smitty