I know the dreammeter MPH pitot displays 66, handheld gps on mine displays 61 at most. Tides movement in my waters make a huge difference too, even though you can run "faster" in salt. Bottom line, the boat compared to others 60 mph boats in rough waters make it a nice ride. Grateful to own a Formula.

mine loves trim...ya, more rpms and bite still...though the bow with a wind feels loose at times, need hydraulics.

Yeah I agree that it doesn't seem that I am making the power that everyone else is. What rpms are you turning with the 25p mirages? Are you on saltwater?

I am not unhappy with 60mph but if the boat is down on power I want to know why. it has aftermarket cams, so it should be making alittle bit more. I am wondering if maybe the cams didn't add enough low end to push a higher pitch prop but instead just added power above 5k rpms? So maybe I need to try a 21p mirage, I dunno just throwing ideas out...

Your not trimming up at all at 60?
31sr1 comparison 400 more pounds than yours to start...
http://www.offshoreonly.com/forums/a...-1990-311a.jpg

I think you're starting to get on the right track...what do you know about this cam? This is really important as this changes everything! Changing a cam without adjusting for intake, exhaust, and carb settings can actually make less power.

With regard to your prop issue. The 23p 3blade mirage is the right prop (if you were running stock 454 mags). All things being equal, you may see some improvement running the mirage plus. If you've got your heart set on running 4 blade props, I've heard the SR1 hulled boats tend to prefer the Hydromotive Quad IV over the Bravo1.

Yes I bought the boat with the cams already installed. one of the motors ate a cam lobe so I tore it apart and figured out what was in there. anyways the cams are definitely designed to pull higher rpms. I am looking for the specs but can't find the right cam right now.

However I do know that the cams were spec to make power to 6k. And since it has stock mag everything else, they probably didn't add any lowend and just 20-30 on the top end. Which being that they are spec'd to 6k the extra power is probably above 5k. So this makes me wonder... do I try a 21p mirage and spin it into the 5.5k range?

the 24p bravo 1 was at 4.3-4.4k , the 22p bravo1 was at 4.8-4.9k , so I am guessing a 20p bravo 1 one would be 5.3-5.4k... however bravo stops at 22p. So I am guessing a 3 blade mirage is definiitely going to be my prop. And since a 23p mirage is going to pull same rpms as a 22p bravo 1 ... I am also guessing I need something lower than a 23p mirage to get me over 5k.

So ending my long winded rant ... should I try to spin this to 5.3-5.5k? it has racing oil and high volume oil pump and dual valve springs.

My 23 Mirage's rpms at 4900 WOT, my 22p bravo 1's at 4500...
Should let Brett from BBlades chine in here. He Knows this boat even if the build is producing strange results. my Heads dont even match motors but rpms do at WOT...:thankyouthankyou:

I can spin the old 25 Mirage 4900 rpm, shows 68 on gps. The cams in the motor might not be the best for your application.

Nope, I wouldn't bother trying to spin your engine any faster than 5000 rpm unless you're prepared to add components designed to operate in a higher rpm range. Keep in mind the blue HP425 engines operate no higher than 5200 rpm and were basically 454 mags with Gil exhaust, Wieland X-cellerator single plane intakes, and Holley 9022 800 CFM carburetors. I really can't comment on how long the bottom-end of your stock 454 mag will hold up at 5500 rpm.

I really think you NEED to find out exactly what cam you have in your engines. If your cam is too big, there's a good chance you have a more narrow and higher rpm power band that actually has you loosing power on both the bottom and top end of the rpm range for different reasons. If you have a more reasonable cam (closer to stock) than you might have a problem elsewhere.

Here is the cam that is in the motors

View Specs 11-240-4 XM278H Hydraulic Lifter Hydraulic-Jet w/ A impeller, needs improved intake, likes headers. Chevrolet 396-454 c.i. 8 CYL. 1965-1996 Xtreme Marine™ Hydraulic Flat Tappet Camshafts