SUPERSTITIOUS

Yeah I been running a 28 bravo this summer

Superbabi

I got my best speed on the B1, 29"

jayhawk261

Keep the prop info coming! I am running a 25P Mirage Plus 3 blade. I don't think I'm getting the rpm's I should be, and I have just about zero bow lift at top end. I can leave the tabs full up and the nose stays flat and almost looks pitched down a hair to me.

With the 454 mag mpi and the headers I am seeing about 4700 rpm at WFO with the 25P. I have talked with Hydromotive about re-pitching it to a 24 and doing what they call a recreational lab. I guess they do some lab work on it, but don't thin it out so much that it has any weak points.

Thoughts? Does this sound like a good idea, or am I pi**ing in the wind here?

By the way, I don't have GPS, but at WFO around 4700 rpm, my speedo reads 74 - 75. Who knows, maybe 69-70?

SUPERSTITIOUS

Jayhawk
#1-Get a handheld GPS. You wont regret it...

jayhawk261

I have been siting on the fence on that for some time now. I've been too cheap thus far to buy one, but I may break down and do it. Even the Hydromotive people wanted the gps speed!

Pat McPherson

Jayhawk,
You have Sean Dutra's old 24' step bottom with a 454MagMPI, right?
Believe me a Bravo 1 prop is far better all around.
Dave M. has the same boat and when he had a 454MagMPI, he ran a 26p B1.
Have you checked that engine out thoroughly? It sounds like she down on power a bit. You should be able to spin a 25p Mirage 5000rpm and a 26p B1 4900.
Do a compression and leak down test. It may be time to freshen the engine. Check the fuel pressure and I would recommend sending your ECU to Mark at Presion EFI or to Tyler Crockett for re-cal. CMI Headers will hurt performance on an EFI engine if it is not calibrated properly...

jayhawk261

I suppose it's possible there is some wear on the engine. It simply seems to start and run well though. It has no hiccups, no smoking, no strange noises, no oil blowing into the bilge or anything. I know this in itself does not mean that it isn't ready for freshen-up, but I've worked on engines long enought to recognize some signs that point one problem or another. I may go ahead and run a compression check.

As far as hving the mpi re-flashed, would an exhaust change make enough of a difference in A/F ratio to require it? I know on my Mustang that going from stock to aftermarket exhaust made very little difference in the A/F ratio.

I did go pick up a Garmin ETrex Legend GPS tonight. At least I'll be able to record my speed this weekend and get a real idea of where I stand.

Pat McPherson

It is debatable...
Most say NO with an upgrade to a performance manifold like Gil or Stainless Marine. YES, if true headers like CMI or Lightning are added.
I would check the fuel pressure and adjust to the high side as a minimum.

jayhawk261

Is the regulator adjustable on this engine?

I have been considering sending a tailpipe back to CMI to have an O2 bung put in it. That way I can at least monitor the A/F, and I'll know if it is off. IS there software available to tap into the stock EFI computer to change parameters?

z.zuperboat

Jay Your Going To Play With It Already! Your Done, The Hook Is In And Your Being Realed In. Next Will Be A 30 With Big Power. What Im Saying Is Welcome To The Club.