Courtholl

I am running a 502 HO that is putting out about 450hp. I think I have a 25 pitch mirrage on there now. I have a 27 pitch in the garage. running on a 1989 24. What should I be seeing for speeds. I am hitting 60mph at about 4700-4800 rpms. I think the rev limiter is set for 5300 or 5500 (have to look at it again). I can bring thetrim up more, but I am starting to walk at 60 mph. What typeof speeds should Ibe seeing? Engine is running great, but wondering if I need to adjust the throttle, or if I just need totrim it more.

I also want to get it to stop walking. I have the larger k-planes. Working on trying to adjust them more, but I need to tighten up the throttle so I can adjust them.

Any feedback regarding what I can do to see better speeds. I would think the boat should see 70 relatively easily.

littledcsrodshop

What are you using to get your speed reading ? gps or regular speedo ? 60 mph @ 4700-4800 rpm with a 25 mirage is more prop slip than you should have. How shure are you that it is a 25 pitch ( I know you said I think it is a 25.) That is the 1st thing I would check.
I would assume that you are running a bravo 1 with it being an 89 model is that correct ? Also what type of steering do you have ?

Courtholl

I am using the GPS (handheld that is mounted). I will have to look, but I am pretty sure it is a 25 pitch. Steering is mayfair twin hydraulic. I looked at the GPS and it did not note MPH, but said Kt or possibly NT. I think. Wondering if it is reading in knots, but the speedo was reading about the same number. If it is knots, then I would be at about 70 mph.

It is a rebilt Bravo one with upgrades (not sure of exact upgrades). Outdrive has about 10 hours on it now.

IRONMAN

Is that a Mirage or the mirage Plus? I get 60 gps at 4650 with a 23 mirage Plus. Either way Scott is right about the slip being high. As for the walk I think that you probably have a little air in the steering system (rams) that you need to bleed out. When the boat is out of the water there should be zero play in the drive with a good dual ram system. You also may want to check the tach reading with a calibrated shop tach. Good luck, Chris

Stormrider

1. You need to know your prop pitch.
2. You need to know if its kts or mph.

I ran a 23mir+
4000rpm = 52mph
4500rpm = 60mph
5000rpm = 68mph
5500rpm = 75mph
all mounted gps speeds.

onesickpantera

I ran a 25 Mirage(non-plus) on my 24 with bone stock 502 mag 415hp. Best I ever saw was 73.3 once and it would consistantly run 70-71 at 4900rpm with two people. With 4 people and full tank of gas it would run 68-69 at 4800 rpm.

ziemer

Most GPS's will read in either, depending on the settings. My Garmin 72 has the option to read knots or mph and I think they come defaulted to read in knots. Also, 1 knot is about 1 1/8 mph.

Courtholl

I am trying to work on the GPS. I think it is reading in knots. My wife and I think we are flying, as our faces are being pushed back, etc., but the GPS is reading 60. When I looked closer, it said KT. 60 knots would make sense, as that would be 70 MPH. That is when we start bouncing/walking a little. Just downloaded the manual, and am going to try to switch it to MPH. Now I don't have to burn as much gas, and can actually try to run at about 55-60 instead of running at 60 knots/70 mph all the time.

Jumped the gun on this one a little, but you guys are a wealth of info.