PDA

View Full Version : New Exhaust



Ron
07-29-2005, 04:04 PM
I am thinking of putting through the hull exhaust on my Regazza. Has anyone done this and if so, were there any issues? Was there any interference with the built in swim platform? What can I expect to see in HP gains? I am running a 460 King Cobra that is a little bit better than stock. Any input would be appreciated.

onesubdrvr
07-29-2005, 04:16 PM
I am thinking of putting through the hull exhaust on my Regazza. Has anyone done this and if so, were there any issues? Was there any interference with the built in swim platform? What can I expect to see in HP gains? I am running a 460 King Cobra that is a little bit better than stock. Any input would be appreciated.

:biggrin:

Ron,... I have recently done this to my Regazza, eazy enough, but not the cheapest thing in the world as you can not go through the transom, you have to go through the sides. That being said, check this out,

See pictures in post #6 of this thread
http://www.donzi.net/forums/showthread.php?t=39911

Wayne

ps feel free to ask any questions!!

Ron
07-29-2005, 04:31 PM
Any significant HP gains? In other words, was it money well spent? That's my only concern is spending wisely. I currently get about 50 mph out of the boat at 5100 RPM's ( at 1/3 tank gas and two adults) but would like a little more if I can get it, or the same at a little lower RPM.
:biggrin:

Ron,... I have recently done this to my Regazza, eazy enough, but not the cheapest thing in the world as you can not go through the transom, you have to go through the sides. That being said, check this out,

See pictures in post #6 of this thread
http://www.donzi.net/forums/showthread.php?t=39911

Wayne

ps feel free to ask any questions!!

onesubdrvr
07-29-2005, 04:38 PM
Any significant HP gains? In other words, was it money well spent? That's my only concern is spending wisely. I currently get about 50 mph out of the boat at 5100 RPM's ( at 1/3 tank gas and two adults) but would like a little more if I can get it, or the same at a little lower RPM.
Significant? Hard for me to say, I did it all when I replaced my V-6 with a V-8, I think it's probably worth about 10-15hp, 1-1.5mph. Money well spent depends. For me, yes, I love it, and don't care about noise level. I installed new manifolds and risers (old ones off of the V-8 I rebuilt were rusted), If yours are usable, then it will be less,.... The hose I went over to the sides with was $14.00/ft. The 90's at the risers to turn to the sides were $25.00/ea, and the side exit tips were about $350.00. I love it, it sounds nice,...but, keep in mind, mine is NOT switchable, so it's allways loud, keep that in mind if you ever want to be quiet. You CAN put in a captains call system to go either / or, but that's going to add about $500.00 (if memory serves me correctly). Why do you say you're King Cobra drive is weaker than stock??

Wayne

Ron
07-29-2005, 05:03 PM
By better than stock I mean it has a few more ponies than it did when stock. Probably about 350 - 375 Vs the original 330. It's bored a little over but has pretty much everything else stock. Just put all new exhaust risers and 90's as the old ones were shot. Was trying to get a little more and still retain all the dependability of a stock motor and fuel economy.

Your exhaust looks good. Don't think I have ever seen a side exhaust before. Nice job.

onesubdrvr
07-29-2005, 05:14 PM
By better than stock I mean it has a few more ponies than it did when stock. Probably about 350 - 375 Vs the original 330. It's bored a little over but has pretty much everything else stock. Just put all new exhaust risers and 90's as the old ones were shot. Was trying to get a little more and still retain all the dependability of a stock motor and fuel economy.

Your exhaust looks good. Don't think I have ever seen a side exhaust before. Nice job.
Thanks for the compliment,...
Got'cha, I thought you were talking about you're drive itself.

Regardless, It's only a little bit more umph, but the sound is nice. What is your goal, just a couple of more, or is there a bigger goal in mind? I mean, if your goal is a big jump, I'd look at supercharging. I don't think they make a kit for the 460, but a supercharger is (I think), a good $ / $ investment, kinda pricey, but good gains, and reliable WHEN SET UP RIGHT! Doesn't require tearing engine apart. Though no kit available, could be made to work with some bracket work / etc. Also requires some carb rejetting, timing adjustments / etc. Of course, some of the Guru's around can give better information here.

If you are just looking for a little bit, try some prop testing

Wayne

Ron
07-29-2005, 05:23 PM
Thanks for the compliment,...
Got'cha, I thought you were talking about you're drive itself.

Regardless, It's only a little bit more umph, but the sound is nice. What is your goal, just a couple of more, or is there a bigger goal in mind? I mean, if your goal is a big jump, I'd look at supercharging. I don't think they make a kit for the 460, but a supercharger is (I think), a good $ / $ investment, kinda pricey, but good gains, and reliable WHEN SET UP RIGHT! Doesn't require tearing engine apart. Though no kit available, could be made to work with some bracket work / etc. Also requires some carb rejetting, timing adjustments / etc. Of course, some of the Guru's around can give better information here.

If you are just looking for a little bit, try some prop testing

Wayne

Not looking at outrunning everything on the river just a little more than what I got now. A little fuel economy without hurting top end would be nice as well. It takes a lot of gas to push a 25 foot boat 50 miles per hour. I have always had cruisers before and this was a good trade off to have a cabin and still have some speed.

I just put $6,800 into a new motor, I blew tha last one up this spring, and thought about crate motors, superchargers, etc but decided that I would keep it close to stock for dependability and economy. I run the Columbia River, the Puget Sound and some offshore of the Columbia and don't want to have problems.

Your exhaust looks very do-able but I would want to have the option of being loud when I want to be but quiet around the marina or when the wife is aboard.

onesubdrvr
07-29-2005, 05:28 PM
Not looking at outrunning everything on the river just a little more than what I got now. A little fuel economy without hurting top end would be nice as well. It takes a lot of gas to push a 25 foot boat 50 miles per hour. I have always had cruisers before and this was a good trade off to have a cabin and still have some speed.

I just put $6,800 into a new motor, I blew tha last one up this spring, and thought about crate motors, superchargers, etc but decided that I would keep it close to stock for dependability and economy. I run the Columbia River, the Puget Sound and some offshore of the Columbia and don't want to have problems.

Your exhaust looks very do-able but I would want to have the option of being loud when I want to be but quiet around the marina or when the wife is aboard.
Got 'cha,...

Keep your eyes peeled, more people will post,...

Anyway, it's very do-able, toughest part was making sure my tips were at the same place on both sides. Corsa (www.corsaperf.com (http://www.corsaperf.com)), makes the "selector" gate to switch between the two. They offer it to doing side exit exhaust as well, if you call them, they can set you up with all the right pieces / parts. That's who I got my tips from, the rest of my stuff I got elsewhere.

Good luck

Wayne
ps. I spent some time up in Coos Bay years ago, very pretty area, would have been nice to have the boat there with me.

Ron
07-29-2005, 06:09 PM
Thanks, I already sent them an email to see what thjey got for my application.


Got 'cha,...

Keep your eyes peeled, more people will post,...

Anyway, it's very do-able, toughest part was making sure my tips were at the same place on both sides. Corsa (www.corsaperf.com (http://www.corsaperf.com/)), makes the "selector" gate to switch between the two. They offer it to doing side exit exhaust as well, if you call them, they can set you up with all the right pieces / parts. That's who I got my tips from, the rest of my stuff I got elsewhere.

Good luck

Wayne
ps. I spent some time up in Coos Bay years ago, very pretty area, would have been nice to have the boat there with me.

tmdog
07-29-2005, 06:29 PM
I believe the original question was if any speed gain thru the hull would be gained by the change. In reality , maybe 1mph or at best 2. Remember the engine will only take in a certain amount of air to release thru the exhaust. The only way to capitalize on thru the hull exh. is modifying the power plant. That means money for cam , heads, valve train, intake and carb. and other lil trinkets I failed to mention. If you like the sound of thru the hull, go for it. People will sure notice. Personally I like loud. Of course my wife stays at home. One arguement avoided.

onesubdrvr
07-29-2005, 07:50 PM
I believe the original question was if any speed gain thru the hull would be gained by the change. In reality , maybe 1mph or at best 2. Remember the engine will only take in a certain amount of air to release thru the exhaust. The only way to capitalize on thru the hull exh. is modifying the power plant. That means money for cam , heads, valve train, intake and carb. and other lil trinkets I failed to mention. If you like the sound of thru the hull, go for it. People will sure notice. Personally I like loud. Of course my wife stays at home. One arguement avoided.
Got 'cha,... that's what I kinda figures (see above)

"Significant? Hard for me to say, I did it all when I replaced my V-6 with a V-8, I think it's probably worth about 10-15hp, 1-1.5mph."

I agree, most things that are stock are engineered pretty close to each other. For example, why throw on a bigger carb, if you don't have the valves or cam to bring in more air,....carries over to the exhaust, etc.

Wayne
The Louder the Better!!