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dual exhaust

Old 01-28-2012, 07:48 PM
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Nightow1
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Default dual exhaust

Ok I have a OPS 90 in my Cat. I was wondering how I would go about making it dual exhaust. I wanted to make it come out of both sides of the aft with a sort of oval shape. My problem, Is there some sort of special way to do this in order to maintain engine compression/performance?
Old 01-28-2012, 10:00 PM
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Ron Olson
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Default RE: dual exhaust

It can be done. Example; the gas Thunderboat classes require the exhaust to come out the rear of the boat which means that they have to have an extension off the pipe to get the exhaust out of the transom. You would have to fabricate your own dual outlets as I don't know of any made for your engine. Soldered copper tubing with T's and elbow fittings could do the job. You'd want to use a silicone tube between the header and your dual exhaust to isolate the vibrations. It's no piece of cake to do but you probably already figured out that part. BTW, extra points if you routed your water exit lines through the system.



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Old 01-29-2012, 01:21 AM
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Default RE: dual exhaust

I've done this before,as long as the internal dia. of your "tee" fitting, tubing and exhaust outlets are bigger than the tuned pipe outlet, you will not notice any appreciable loss of power... plumb your water outlet(s)? into the exhaust outlets MPB
Old 01-29-2012, 04:50 PM
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Default RE: dual exhaust

I wont have any problem with the sweating or brazing copper I Work part time as a plumber so I do a lot of it. My problem is the pipe comes straight out of the OPS 90. can I just take a couple of 90's and run it down to the side of the boat then run the pipe. And how much can you cut off the pipe before you effect the performance?
Old 01-29-2012, 05:48 PM
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Default RE: dual exhaust

As long as the pipe your using for exhaust( after the tuned pipe ) is of bigger internal dia. (of the tuned pipe) performance loss is negligible...I would keep it all as short as possible,. you dont want to create any more back pressure into the pipe,thus using a bgger tubing MPB
Old 01-29-2012, 06:26 PM
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Default RE: dual exhaust

If I'm reading Nightow's post correctly, what he's asking is can he run an offsetting spacer between the tuned pipe and the engine. If that is the question, the answer is no. The pipe requires precise adjusting of distance between the engine and widest part of the pipe. Going too far will make the tuned pipe totally ineffective while too close will make the engine's "jumping on the pipe" so sensitive that getting a good carb needle setting will be difficult at best.
Old 01-29-2012, 06:35 PM
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Default RE: dual exhaust

I believe he's talking dual exhaust after the pipe,...MPB
Old 01-29-2012, 06:41 PM
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Default RE: dual exhaust

I dont beleive the tuned pipe have even been adjusted. If I'm reading other post correctly I will need to cut the pipe down to tune it to my engine. both the pipe and engine are brand new never even ran. My problem is that there inst enough room after the end of the pipe to make it duel. the tuned pipe runs out of the back of the boat 1 3/4 " ?
Old 01-29-2012, 07:27 PM
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Default RE: dual exhaust

you dont cut the tuned pipe,just the sleeve that attaches it to the motor,someone here should be able to give you a starting point,and from the lengths you mention, you cant have more than the space needed to install the tubing, you might be able to hach off all but 1/2" of the stinger end of the tuned pipe to help give you some room,but you should not cut into any part of the divergence cones, if all else fails you might have to push engine forward,or try a different pipe, ... I hope were on the same track here.....MPB
Old 01-29-2012, 08:06 PM
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Default RE: dual exhaust

ok that helps. I might just look for a better pipe
Old 01-30-2012, 04:55 PM
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Default RE: dual exhaust

For the OPS .. there is NO better pipe.

12.8" from glowplug to bellyseam is a good starting point.

You can cut the manifold or the header on the first-cone.

Depends on the exhaust-type.

Additional water-injection will make it quieter , and you can 'tune' shorter.
Old 01-30-2012, 05:22 PM
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Default RE: dual exhaust

Great that's what I needed to know. Thank you.

So the water injection will go at the end of the copper pipe I install for the duel?
Old 01-30-2012, 05:43 PM
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Default RE: dual exhaust

The closer to the manifold ... the greater the effect on the tuned length.

For silencing only ... the stinger-pipe is the spot to use.
Old 01-31-2012, 03:19 PM
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Default RE: dual exhaust

Here are some pix of my engine and pipe just to give you an idea of what I have.
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Old 01-31-2012, 06:42 PM
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Default RE: dual exhaust

As wrote before .. on this set-up you can cut the header-pipe on the first cone.

Buy a water-OUT nipple , and put it upside-down into the pipe ,
about 1/2" after your silicone-coupler..

Attach the water-out tube from the OPS WC-head to this nipple .. and you're done.
Old 01-31-2012, 06:50 PM
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Default RE: dual exhaust

ORIGINAL: Nightow1

Here are some pix of my engine and pipe just to give you an idea of what I have.
Wow,,,! I just read the specs on that ops .90.. impressive 6hp. @ 21000 rpms.. I dont know/recommend cutting the pipe UP to 1" of the primary divergence cone and cutting off the stinger end of the rear cone to plumb your dual ex. lines....might screw everything up..... Too bad they dont make an airplane type (shorter) tuned pipe for this engine,but just to give you the thru the rear dual exaust... HHmmmmmm... start thinking out of the box here buddy....sorry to say you might trash a pipe in the process,but you gotta bust a few eggs to make an omelet... this is what I would try first...First, tune the engine and pipe for best performance, this gives you a baseline assesment of what optimum tuning is,,, from there figger out how much space up the stinger end of the pipe you would need to plumb a "T" fitting into the bottom of the rear cone ,as furhter est as you can keep this to a minimum, just enuff to spread your exhaust and exit with your 90-* elbows.... By the way...I've never heard of this bein done...........lol....... but as long as you get your baseline optimum tuning,you will always have a starting point whilst you make your corrections.....otherwise ...I"d just run the snot out of it as it is...Good luck...MPB
Old 02-04-2012, 06:30 PM
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Default RE: dual exhaust

Ok scrap the duel out the back. it wont work with the engine / boat design. So what I was thinking was 4 stacks out of the cowl coming out of the top of the boat instead of the back. something like a diesel truck. Now I assume this has been done; or can it work? I'm not thinking of anything over like 1" to an 1 1/2".  I was sitting there trying to figure out how to make it work and I might have a way to do it.  So hit me with the criticism lol and tell me what I either need to do  or look out for.
Old 02-07-2012, 02:46 PM
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Default RE: dual exhaust

Have you run this boat yet???? [:-]
Old 02-07-2012, 02:49 PM
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Default RE: dual exhaust

no

Old 02-07-2012, 03:51 PM
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Default RE: dual exhaust

you'll have a better idea/working knowledge of nitro engines/tuning these little beasties, if you got yurz runnin first,tuned the pipe etc...... ,and after all is said and done,and you remove the pipe ....you'll find all your power is lost..........is this what your aiming to accomplish??? IDK??? I dont like to criticize anyone for out of the box thinking.. but anything tapped into/between the pipe and engine for exaust purposes..... WONT WORK... [&:]

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