Question for Dhadley

[OBJ]

Dale I know this has been asked before but I can't find the thread. I got an 86" 90hp Johnny which runs to the hilt when I press it. I've come by a bubble back exhaust and fillers and am wondering if will help the engine breath a little easier if I installed the bubble back. Not looking for an increase in HP but would like to get the fuel consumption down a little. I've already got Boyesen Reeds in the engine.

Thanks.........Jim

 

[Dhadley]

Re: Question for Dhadley

Good combo. What kind of rpms are you at now?

 

[OBJ]

Re: Question for Dhadley

Depending on the load....5800 to 6000 rpm.

 

[Dhadley]

Re: Question for Dhadley

Ok, perfect. Yes, the bubble can be put on and I'd think you'd gain some. Probably 100, maybe not more than 200.

Here's what we found -- you don't need the filler blocks that are bolted inside the exhaust cavity. The motor actually breathes easier without them. I know, it seems like they are like a header and it should work better with them. Actually on a V6 they do work but the exhaust is different on a V4.

The center divider is cut at the bottom on the late model V4 crossflows too. If it's easy to make that cut when you do this, then do it. It's not something that has to be done on a 6000 rpm motor. However, if your looking for much more rpm then we need that cut.

 

[OBJ]

Re: Question for Dhadley

OK thanks Dale. I probably won't get to this till the end of the season.....too much in the shop and she herself won't give it up....... but I just wanted to be sure before I got into it. I'll let you how it acts after the change. The engine itself runs really well and I get compliments on it all the time. But the gas will eat ya' up when you get out pulling tubes and such. That's what it's like when ya' get 4 grandkids out on the river and they all love the water.....d

 

[Rudy Brown]

Re: Question for Dhadley

OBJ, if ya dont mind, what kind of boat do ya have the 90 on and what's the prop/pitch. I'm curious. Thanks, Rudy.

 

[91cajun]

Moderator - Please help

Moderator - Please help

I can't post anything or send you a PM. I'm trying this just to try and get in. What's up?

 

[xtraham]

Re: Question for Dhadley

what is a bubble back?

 

[wilde1j]

Re: Question for Dhadley

Exhaust cover on the rear of the engine.

 

[xtraham]

Re: Question for Dhadley

:/

 

[Dhadley]

Re: Question for Dhadley

Sounds good. Just let me know if you need anything. We gotta do all we can to keep the kids on the water!

 

[OBJ]

Re: Question for Dhadley

Rudy....I have the 90 mounted on a 16' StarCraft SuperSport.....aluminum. Prob is a 13 7/8 X 21 SS.

 

[Rudy Brown]

Re: Question for Dhadley

OBJ, your boat probabaly is a lot lighter than my fiberglass 16' bass boat. I'm still tryin to get 5600 out of my 13.25 x 19 SS.:'( I think I'm gonna break down and get a looper 150.

 

[Rancherlee]

Re: Question for Dhadley

I'm having trouble getting to 5800rpm with my 88spl also. I'm only turing 5200rpm with a factory OMC 17 pitch aluminum prop for 38mph on gps on a 16 foot aluminum side steer. Dang thing litterally jumps out of the hole and right to 38mph but the engine just doesn't seem to breath well enough to get anywhere near 5800rpm.

 

[Rudy Brown]

Re: Question for Dhadley

Rancherlee, I'm having the same problem as you. With my boat loaded with me, wife and 2 kids, 5200 max @ gps verified 42mph. Now with me by myself, 5400 @ 48mph. I'm up to the last hole now and just waiting for my next off day so I can test at the river. I want 50mph @ 5800 but we'll see.