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metraman
09-06-2005, 04:55 PM
Does anyone have a feel for what the newer hull designs might be worth over a 1988. My 25P Mirage turns (true 5300 RPM) but 71 MPH

Thanks
ChromeGorilla
09-06-2005, 05:07 PM
That sounds just about right. The hulls are the same, are they not?
metraman
09-06-2005, 05:13 PM
That sounds just about right. The hulls are the same, are they not?
Seems someone posted a while back they were different. Sure looks like others run 74-75 with the same prop and less RPM. I don't plan to spend any addition money on a slow hull.
Thanks
ChromeGorilla
09-06-2005, 05:42 PM
Materials and weights may be a contributing factor. But as far as dimensions of the hull and design, the same isn't it?
metraman
09-06-2005, 06:58 PM
Have you got a picture of the bottom of your boat? I could tell if they are the same.
Pismo
09-06-2005, 07:07 PM
Is the prop a Mirage or a Mirage Plus which acts like 1/2-1" higher in pitch due to the added cupping, what drive ratio? A 25" Mirage plus at 5300 with a 1.5 drive should be going about 77-78mph. What engine/drive/prop/setup. TRS? GPS speed or speedo? Tach on?
metraman
09-06-2005, 08:11 PM
Yes as I said 5300 is a good tach reading GPS is 71 It is 1.5 gear Bravo as new Mirage 25P boat weight is 3660 full of gas.

Just want to know if the Hull is different and I know it should be 77-78 but it's not.
gcarter
09-06-2005, 08:20 PM
Most of the 454's and 502's stock boats I've been in have gone about your speed.
Not until pretty serious modifications have been undertaken has there been any great improvement.
ChromeGorilla
09-06-2005, 09:50 PM
You keep posting a Mirage 25P. I am running a Mirage Plus 25P.
metraman
09-07-2005, 04:48 AM
If the plus is worth 3-4 MPH i will get one.
Pismo
09-07-2005, 07:23 AM
The Mplus won't give you 3-4mph. What engine? is it stock? What year? How are you getting so many rpms? I guess before rev limiters. I find I need to trim almost to the limit to get full speed, but to get 5300rpm you must be trimmed up well. Your slip is high. If you had extra drag from excess weight, damaged/hooked bottom, etc you would not get to these high rpms. The slip is from the prop somehow. Either ventilating, maybe blowout from the early Bravo lower unit problem (it was too short until about 1989/90) or the prop itself. If you can borrow a MPLus 25" try it. If it solves the problem then it is the prop itself, if not then it's blowout or ??? Tough problem.
metraman
09-07-2005, 08:14 AM
Anyone got a plus they would like to sell? Is there a sight to get the dimensions for the newer bravo drives heights? That makes sense the motor pulls hard but the boat hits it's max at 71 no matter what prop I have on it a drive swap would be a easy fix. I have looked can't find any numbers on the drive it has lots of paint.

Thanks
mattyboy
09-07-2005, 10:03 AM
I think the only change to the hull over the years was the reversed chines for a drier ride not sure what effect that would have on performance
oh and the rocker hull for the BH setups
boatnut
09-07-2005, 10:04 AM
Yes as I said 5300 is a good tach reading .

I am curious to know how you are determining that the tach reading is accurate? I have a similar problem where I am turning more RPMs than I should be considering the prop and HP I have so I am now under the assumption my tach is not accurate. A 10% error is 530 RPM.
metraman
09-07-2005, 10:46 AM
Checked it with 2 different hand held units both hand helds were the same dash tach was 100 RPM high at 5000
Spoke to the people at BAM they say the 1988 and newer Bravo drives are the same size so that's not the issue
gcarter
09-07-2005, 11:11 AM
Anyone got a plus they would like to sell? Is there a sight to get the dimensions for the newer bravo drives heights? That makes sense the motor pulls hard but the boat hits it's max at 71 no matter what prop I have on it a drive swap would be a easy fix. I have looked can't find any numbers on the drive it has lots of paint.

Thanks
I know on the Alpha I, the #'s are under the decal on the port side.