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-   -   LS Exhaust manifold build questions/suggestions (https://www.offshoreonly.com/forums/do-yourself-boating-budget/323948-ls-exhaust-manifold-build-questions-suggestions.html)

dereknkathy 03-17-2015 08:29 AM

Steal harness off whatever engine came out. Would have pretty much the same sensors...

Bondo 03-17-2015 09:10 AM


Originally Posted by dereknkathy (Post 4277981)
your design IS the old log style revisited. just because you can do it doesn't mean it is a good idea. you have enough fabbing work to do without tying yourself up on an exhaust project.

Ayuh,.... Agreed,.... 'n the single tubes comin' off the heads would be a Red Hot fire hazard to boot,.....

If they didn't burn the boat to the water level on the 1st hard run,....
The spark plug wires would be burnt up junk in a weekend,....

turbom700 03-17-2015 09:17 AM


Originally Posted by Bondo (Post 4279829)
Ayuh,.... Agreed,.... 'n the single tubes comin' off the heads would be a Red Hot fire hazard to boot,.....

If they didn't burn the boat to the water level on the 1st hard run,....
The spark plug wires would be burnt up junk in a weekend,....

Sch. 10 SS tubing doesnt exactly get red hot. I have run this stuff(where the left over are coming from) on my turbo motors on the dyno for 10+hr at full load with out it turn red hot. Yes that is 10+hrs.

I guess I will learn this one the hard way put I have been told that wont work a number of times and I usally find away to prove them wrong.

Just keep in mind that this isnt a offshore go fast boat, its a pontoon. It will spend more time idling then WOT.

dereknkathy 03-17-2015 11:03 AM

I am not saying it wont work. I am saying it is too involved and time consuming to be worth the trouble to save 800 bucks. And you are guaranteed to have to R&R at least once to fix leaks...

phragle 03-17-2015 01:14 PM

Your doing 10 dollars worth of work thats not going to help performance to save 1 dollar in parts......

turbom700 03-17-2015 02:07 PM

For one I enjoy Fab work, and I will have less money in these headers then the cheapest set of manifold out there. I look at it this way, I would rather try and fail then not try at all. The job I have today is because of this philosophy.

I'm working on tipping the two outside (2 and 8) in towards the middle and instead of 4" pipe making it S.S bent sheat metal for the water jacket. This way I can get withing 1" of the header flange.

If I wanted easy and had money to burn there would be a 350 mercury outboard hanging on the back of the boat, then again I would fit in with everybody else on the lake and what fun is that.

phragle 03-17-2015 02:22 PM

Im not saying dont try stuff yourself,,,Im saying if your going to try stuff, try stuff thatmakes a difference.

getrdunn 03-19-2015 08:16 AM


Originally Posted by f_inscreenname (Post 4277730)
I would be looking for a set of 496 manifolds. Most sets can be had for less then your parts list costs.

Yes to this comment. Do a google search etc and or call some marine speed shops. I've spent a lot of time at more power racing in Sparta mi and the owner still recommends the 496 manifolds to this day if your on a budget. They are heavy however they make more power than stock.

I also may have missed it somewhere but I assume you primary tubes are water jacketed. I really like the idea of your enthusiasm if it's really what you want to do however if your gonna do that then design and build something that's equivalent or better than that of the performance aftermarket exhaust currently. Headers are ridiculously priced however play a very important role. I have acquired a lot of equipment over the years and enjoy fabricating etc but honestly even I would stay away from this unless it was for a jacked up 72 Chevy truck. Think safety yourself, loved ones and others. This could go really bad.

It's probably more so that you just want to do this and once again I understand however put an ad in the wanted section for Manifolds. I would be there would be a lot of people willing to give you manifolds for the cost of shipping. Just a thought.

getrdunn 03-19-2015 08:20 AM


Originally Posted by turbom700 (Post 4280003)
For one I enjoy Fab work, and I will have less money in these headers then the cheapest set of manifold out there. I look at it this way, I would rather try and fail then not try at all. The job I have today is because of this philosophy.

I'm working on tipping the two outside (2 and 8) in towards the middle and instead of 4" pipe making it S.S bent sheat metal for the water jacket. This way I can get withing 1" of the header flange.

If I wanted easy and had money to burn there would be a 350 mercury outboard hanging on the back of the boat, then again I would fit in with everybody else on the lake and what fun is that.

I wish there were more people like you around this world and I don't even know you personally.
Water jackets need to be right up to the flange. Your looking at 1300 deg exhaust temps.

turbom700 03-19-2015 08:24 AM


Originally Posted by getrdunn (Post 4280956)
Yes to this comment. Do a google search etc and or call some marine speed shops. I've spent a lot of time at more power racing in Sparta mi and the owner still recommends the 496 manifolds to this day if your on a budget. They are heavy however they make more power than stock.

I also may have missed it somewhere but I assume you primary tubes are water jacketed. I really like the idea of your enthusiasm if it's really what you want to do however if your gonna do that then design and build something that's equivalent or better than that of the performance aftermarket exhaust currently. Headers are ridiculously priced however play a very important role. I have acquired a lot of equipment over the years and enjoy fabricating etc but honestly even I would stay away from this unless it was for a jacked up 72 Chevy truck. Think safety yourself, loved ones and others. This could go really bad.

It's probably more so that you just want to do this and once again I understand however put an ad in the wanted section for Manifolds. I would be there would be a lot of people willing to give you manifolds for the cost of shipping. Just a thought.

I might just build them to build them if they work great if they dont then I'll buy some, Like I have said before this isnt a offshore boat. When the manifolds are done you can beat your ass that I wont be closing the hatch and never looking at them.

As far as the 496 manifolds go I assume your talking about the 6.0l ls motors they put in wakeboard boats. Correct?? as 496 BBC manifolds wont fit.

It seems finding a used set of those isnt easy to come by as I dont think they made alot of those boats. I could be wrong and I'm all ears if you want to point me in the right direction

Mike


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