To do or not to do?

The Get Away · 10-29-2009, 05:22 PM

I am thinking of a few upgrades for this winter, what do you think? The boat is 88 311 420s 25p 3 blades. I will run a consistant 68-69mph and a best of 70.8mph (gps). I am looking into putting a set of headers, water pump crossover, and intake not sure which one. Im sure after that i will need a different set of props. What do you guys think? Does anyone have and experience with something similar to this.

454captiva · 10-29-2009, 05:32 PM

I am literally in the same boat as you are. I ditched my silent thunder and upgraded to imco exhaust but i'm still right at 70 gps. Which 3 blades are you running? I'm using the mirage non plusses in 25 pitch. I am curious to see what gains you see out of your upgrades.

The Get Away · 10-29-2009, 05:48 PM

Im pretty sure they are quicksilver. The 70.8 was a wild ride with just me and my wife in the boat. What type of exhaust did you put on? I took a 5 in hole saw and drilled holes in the bottom of my swim plat form to make it a little louder. I hope that there is someone that has done a few of these upgrades to there boat so i have some real world results. It is going to be hard to spend $3000-$4000 on exhaust and hope that it helps.

NOMO · 10-29-2009, 06:06 PM

What RPM's are you both turning? And I assume 1.50 drives? It all depends on what RPM's your motors can take because you need more r's to get more speed and then torque will come into play to turn a bigger prop. I cant imagine just an exhaust change doing much. I am running 502 ci 465 hp bravo's at 5100 RPMS 1.36 drives with 24p agressively labbed bravo 1's from BBLADES and I see on a good day running light 74MPH my setup also has GIL exhaust.

I would like to try 2" shorter drive depth to get let wetted friction but that is alot of $$. Also my boat runs just as good with stock 23p Mirage plus props.

The Get Away · 10-29-2009, 07:56 PM

i am not %100 sure but i would assume that they are 1.5. I have one motor that that turns 5100 rpm and the other turns a little over 4900. I have noticed that while running down the lake that my rpms are not sink with each other. Dont know if that would have anything to do with why one motor turns more rpm. I would like to get away with not having to put an exhaust on, I would rather do intake cam but I was told that the exhaust was a must.

NOMO · 10-29-2009, 08:09 PM

Quote:

Originally Posted by The Get Away

i am not %100 sure but i would assume that they are 1.5. I have one motor that that turns 5100 rpm and the other turns a little over 4900. I have noticed that while running down the lake that my rpms are not sink with each other. Dont know if that would have anything to do with why one motor turns more rpm. I would like to get away with not having to put an exhaust on, I would rather do intake cam but I was told that the exhaust was a must.

How long have they turning different rpm's? How many hours? I would say the top ends might need to be gone through and you could change cam, intake and carb then and that is correct depending on what exhaust you have you would need a drier exhaust to prevent reversion.

The Get Away · 10-29-2009, 08:28 PM

I have had the boat boat for 2 summers and put about 60 hrs on them and they have a total of 550 hrs and they have been doing that since i have owned it. I dont beat the **** out of it but i do open it up if im lucky once when i go out. I think that the exhaust is stock and if it would do then i would rather not change it, i would rather do the intake cam roller rockers but i don't want that to be a waste of money if the exhaust is going to restrict it either.

NOMO · 10-29-2009, 08:39 PM

Quote:

Originally Posted by The Get Away

I have had the boat boat for 2 summers and put about 60 hrs on them and they have a total of 550 hrs and they have been doing that since i have owned it. I dont beat the **** out of it but i do open it up if im lucky once when i go out. I think that the exhaust is stock and if it would do then i would rather not change it, i would rather do the intake cam roller rockers but i don't want that to be a waste of money if the exhaust is going to restrict it either.

The problem is the exhaust is restricted butthe real problem is it runs wetter with water inside of it and closer to the engine so what will help you get more power is a cam but if you go bigger on your cam you could get water (reversion) into your motor. Buy exhaust first CMI etops are $2000 per set then you will have the exhaust for when you rebuild the motors to go bigger on cam.

The Get Away · 10-29-2009, 08:52 PM

So leave it alone keep it a turn key boat and enjoy it.

NOMO · 10-29-2009, 09:10 PM

Quote:

Originally Posted by The Get Away

So leave it alone keep it a turn key boat and enjoy it.

The $$ will add up quick to go much faster! I am going through both my motors due to a valve failure late Sept and I am looking at $13000 to have both re-done with new heads, cam and intake.