What are yall's opinions on..........

[302w]

.....putting some mods on a 115 crossflow? I just rebuilt it and now I want to get a little more power out of it. What are some mild mods that I can do to wake it up a little. When I rebuilt it, I bored it out to .044 over with oversized pistons. What would be some of the most cost effective mods that I could make? Thanks in advance!!

[Rickracer]

http://forums.screamandfly.com/forums/search.php?searchid=350390 There is lots of good info in these threads. :cool:

[302w]

Sorry but the link didn't work

[Paul Vaillancourt]

302W,
You may be able to benefit from some boat setup work to get more speed, Like maybe a transom jack or just moving your motor up on the transom.

I gained 10mph when I added my transom jack, low water pick up and 26 pitch over the hub chopper prop.

Does your motor have the flat back or bubble back, also does your boat have a pad?

[302w]

The 115 is a bubble back. Is that a good thing or a bad thing. The boat does have a pad. The only thing that is keeping me from putting a jackplate on is the age of the boat. I mean, it's in great condition but I would hate to put more stress on it.

[Paul Vaillancourt]

YES, the bubble back is a good thing. If you do go higher with the motor ADD a water pressure gauge to make sure that you are getting cooling water. Maybe just try moving it to the highest position on the transom.

Also I sent a check for your change and a couple stickers out on monday they should be there soon.

[302w]

Thanks Paul!! I measured the propshaft height and it sits exactly at 3.5 inches below the pad. With my 19 inch prop I could hit 6k rpms every now and then. I think the raker you sent me will work well. BTW, what's the difference in the bubble back and flat back V-4's?

[Paul Vaillancourt]

That is a "tuned" exhaust by the factory. The flat back motors were less hp. When everything was crank shaft rated the bubble back was a 140hp and the flat back was 115hp, when they went to prop shaft rating the 140hp turned into a 115hp which is what you have.

I run mine 1" below the pad, I like the Hydraulic transom jack because I can adjust the motor down to get on plane then jack it up for top speed. Some props I have tried cavetate real bad when the motor is up high and your trying to plain.

If you do a search you may be able to find more acurate info on mods.
You also want to keep the motor reving at around 5500rpm your motor makes peak hp at 5250rpm according to the manual.

I am no expert just a do it yourselfer so far I have learned enough about porting to know I destroyed at least one of my v-4 blocks trying to port it myself.

Good luck,
Paul

[302w]

I really appreciate your help Paul. I was wondering about the exhaust the other and my question is, is it possible to just drill out the exhaust in the mid section and add a bobs exhaust snout and still maintain structural integrity of the mid section? With the stock turner still on will drilling out the exhaust even make a difference in the noise level?

[Paul Vaillancourt]

You might get more replys if you post your question in the tech talk section with the heading omc v-4 mod or something like that and some of the experts may help you out.





I really appreciate your help Paul. I was wondering about the exhaust the other and my question is, is it possible to just drill out the exhaust in the mid section and add a bobs exhaust snout and still maintain structural integrity of the mid section? With the stock turner still on will drilling out the exhaust even make a difference in the noise level?