Originally Posted by airjunky (Post 4255621)

Ill be a monkeys uncle if someone actually rolls into this thread and says "yea , i put a 250 on a 454 with big brodix aluminums , blower cam found the best balance at x boost with y upper anz z lower pulley " nah prob not lol .might have to spool it to make 5 pounds , but with those heads and a good exhaust , it will be a good 5 pounds and it should still start to come alive by 2500 or so

Originally Posted by MILD THUNDER (Post 4255404)

Mark, as BS aside, I am excited as heck for you, to get these engines in the boat. We know what it ran with the 420 combos, and I think you are gonna be extremely happy with these two new engines in your boat. You did an excellent job on last years interior makeover, and now you're gonna have some sweet engines to push that boat to speeds it's never been to. You did it right. You didnt cut corners, trying to reuse old pistons, rods, half azz machine work, reusing old heads, and what not. You spent some coin, but I feel you did it right. It makes life much easier for the guy doing the assembling and what not, dealing with someone who's willing to take the steps needed. I've seen way to many guys want to cut corners, and not only does it make life hard for the builder, it usually comes back to bite everyone in the azz.

I would like to come down with Mike to help dial it in on the maiden voyage if thats cool with you guys.

Originally Posted by ealesh33 (Post 4255049)

The correction factor is to simulate that the conditions are X everytime, and there are a couple different formuals that can be used, one of these formulas your dyno uses to take current conditions and make adjustments to the output to simulate the X conditions. I never mentioned changing the correction factor, nor does my guy try and hit numbers at all. My point was a good dyno operator can minipulate the machine to make damn near any number you want. You can also do a quick blast while the motor is cooled down, but the oil is still hot to make more power on that pull. Ny guys dyno is known to be on the conservative side.

Ill give you a good example, and this is an example that Bob gave me the other day. He spoke of a builder that his dyno is very conservative, on any given day you could put a motor on it, and then take to another dyno and run it and the motor would make 30-40hp less on his dyno then the other, its just the way its set up. And in reality the "number doesn't matter, the dyno is a tool to tune, make sure there aren't any issues with the motor, and also to find where peak power is.

A good question is in order to make 691hp 667ft lbs with this set up, what do you think this motor is making NA to get those numbers?

Originally Posted by ealesh33 (Post 4255128)

I don't have all the answers, not even close, but i figured you would have some more answers then you do, as I thought you were an engine builder? i may be thinking of someone else but I thought I read you have been building motors for 30 years? I don't build engines, I know a little about a little but, but like I said I'm not a builder. What kind of builds have you done with 454's and what kind of power did they make? Is this the first 454 with a blower or 177 you have done in 30 years? I'm here for the same reason you said you were, I'm looking for data.

I mean if you take some figures into play like each 1 lb of boost equals 25hp, that's kind of a blanket round statement but it's also referring more so to a bigger blower then a 177. Also have to take heat into effect, and with a 7" bottom pulley to 3.25" blower pulley you are spinning the blower 12,923rpms, From general reading the 177 is a 13,000 max rom blower, but I can't say how factual that is, and if I recall correctly i think it was Joe that posted that somewhere. On a stock 525sc that blower spins roughly 11,200 rpms makes 5-5.5psi of boost and adds roughly 120-125 hp to the 420 merc platform which kinda supports or is pretty close to that 25hp per 1psi of boost theory. Now there comes a point where the blower is starting to generate more and more heat and I'm sure that hp per boost starts to fall off, that's just a theory though. so if we use that figure 25hp per 1psi of boost and I think tthat's a little generous for this blower spinning at that rpm, at 4.2psi of boost would equate to a 105hp. Based on that thinking then without the blower the motor is capable of roughly 586hp NA. I am very curious how close that estimate is honestly, as I don't have real data to back that up. I'm sure there may be some variables that I may not be considering

Originally Posted by MILD THUNDER (Post 4255720)

HP per lb of boost has several variables. Temperature in the manifold, parasitic loss from the blower, and so on.

On a build like this, you can have a procharger making 4psi, a Whipple making 4psi, a roots making 4psi, and have very different numbers at the flywheel.