This Stage 1 54 HP Briggs has been set up today with the X Pipe Exhaust. We hope to find out tomorrow how it works. It sounds good.
http://www.miniairboatassoc.com/cpg1416/albums/userpics/10004/normal_X_pipe_exhaust_002.jpg
I hope i have time tomorrow to do a video.
Chuck

Check out the Video of the X Pipe Exhaust.

http://www.youtube.com/watch?v=GAa3W3bs6Pc
If the video don't play, click on the arrow on the left side of the annotations box at the top of the plyer. It will ply it in a new window.
Chuck

Chuck,

Other than it looking pretty cool, what is the benefit of the X-pipes?

I've read some that claim performance increases, and others that said it didn't really make any difference.

So, what's your opinion? Inquiring minds want to know.

Thanks,

Duane

I don't know, i just work here. Ha Ha. What is suppose to happen when one exhaust ball travelling at the speed of sound passes the other pipe, the vacumn it created should assist the next exhaust ball coming from the next cylinder to help it's exit. On the other hand, when the first exhaust ball enters the junction, it could expand to where part of it would go up the other pipe toward the other cylinder and cause some form of back-pressure. I think the most performance gains would be to determine what the length of each pipe should be before and after the x junction to get the best exhaust timing. I know a well designed X Pipe exhaust system will help balance the motor and eliminate some of the viberations. This motor does seem to idle better and not shake as much. This week, i want to do an RPM test with the X pipe and without the X Pipe.
We did run this 16 ft boat this afternoon with 4 adults ( about 620 lbs ) and got it up to 24 miles per hr. I thought that was real good considering the weight of the boat. I also plan to check the bottom of the hull to see if it needs some work to free it up.
Thanks, Chuck

Chuck,

Please keep us posted. I'm not planning to do the same with the 4A084, but it would be nice to know what difference it makes.

Thanks,

Duane

It would be harder to do on the 084. It is an odd fire motor so cylinders 1 & 2 have to be on the same collector and cyl 3 & 4 on the other collector. This would help tune the exhaust and then run them thru the X Pipe. I beleave it would be a big benefit so i plan on doing one on my jig motor. I hope to do it soon.
Thanks, Chuck

When I was researching the airboat sound topic, I seem to remember reading something about the x pipe also having a tendency to make the motor a little quieter.

Chuck, have you noticed any sound decrease as a result of the x pipe?

Bruce

It does sound different, so this week when we do the RPM test with straight dual exhaust vs X pipe, we will get out the db meter and do a sound level test. Thanks Flathead.
Chuck

I'm the owner of the boat Chuck has been working on. I can tell you (without the benefit of the db meter) that the X-pipe exhaust designed and built by Chuck appears to be doing for the B&S motor, what is does on car motors; smooth out the exhaust and quiet the sound. The motor has a pleasing, low throaty sound without harsh pop pop pop it had before. It will be interesting to find out if the db meter validates what my ears are hearing or it results in any performance gain. This was an experiment from the start (neither of us had seen or heard of an X-Pipe on a B&S) and Chuck did it just to see what would happen.

By the way, if you all didin't know it already, Chuck and his entire organization do great work!

George


16 FT Dixson Twister, 54HP Stage One B&S, SS Riggin by Ned and Engineering by Chuck

George,

Welcome to the forum !

Thanks for the report. Your boat is certainly different. :D No, you don't see X-pipes on B & S engines everyday. You and Chuck may have started something here, and "may" get credit for being the first.

It'll be interesting to find out how much difference it makes in sound level, and any performance differences as well.

Chuck may look like an old geezer, but he does know his stuff. ;) He's not lead me wrong yet.... but there's been a couple of times I didn't follow his advice, and regretted it. :(

Thanks,

Duane

Great idea, I know the NASCAR guys use this theory on their cars. Now just hope it don't only go in circles and only turn left. :lol:

Question Chuck?? If the pipes are all the same length (084) why would it matter what side the pulse came from? The pulse would get to the "X" at the same time either way. I'm asking because I have no idea, only the little voices in my head. I don't have my mufflers on yet so maybe I'll try it if you think it's worth a try.

Hey Papee, in exhaust timing, as each cylinder fires, that exhaust ball gets to the junction before the ball from the next cylinder that fires. If the headers are tuned properly, all the exhaust balls will be evenly spaced as they flow and will create a balanced vacumn or what is called scavenging. Tuned headers should be designed by the firing order just like the intake is.
Thanks, Chuck

Papee,

I had this wild idea, in a dream, of building my exhaust system below the engine, with all 4 pipes meeting together in a common expansion "can", with one large outlet.

After I woke up, I decided that I'd had too many beers the night before...

Seriously, in my browsing on the internet, what I've learned is that a "properly tuned" exhaust with X-pipes works well with high performance engines that have a lot of valve overlap. That's part of why the NASCAR engines idle so roughly. They have way too much valve overlap at an idle.

According to what little I've been able to find, our 4A084 engines have "zero" overlap. So there'd be no scavenger effect to help suck a charge of air/fuel mixture into the cylinder for the next cycle.

The 4A084 is basicly a lowly tuned engine designed to run 24/7 on low grade fuel. An X-pipe exhaust may look very cool, but it'd be like putting lipstick on a Pig. It'd look nice, but it'd still be a Pig at heart. :o We love 'em, but they're still just Pigs from a performance perspective.

The cams used in the hot-rodded Briggs engines are different. They are made with a lot of cam over-lap. An X-pipe exhaust may help them a lot, if designed properly.

Just my opinion...

Thanks,

Duane

Yea, it only helps pull on the intake if you have valve overlap at bottom dead center which we don't have at this time. However, with the tuned header tubes the right length, you would eliminate the echo effect from traveling back up the tube and putting pressure back into the cylinder before the exhaust valve closes. If an echo caused from expansion of the exhaust ball when it enters the collector gets back into the cylinder and fills the cylinder to 10 %, the intake stroke can only fill the cylinder to 90 %. Remember, the exhaust ball ( pulse ) travels at the speed of sound. This is caused alot by short tube headers which are cheaper to build.
The more we work on and run these 084's, the more mods will show up and the more power they will produce.
Thanks, Chuck

Duane,

Thanks for the welcome. Both Paul Dixson, original builder of my Dixson Twister, and Chuck have been very helpful in getting this boat where it is today. I wanted a boat for fishing in REAL shallow water for redfish and trout in the mangrove backcountry where the big engine airboats can go, but not float. The 16 foot hull does this nicely. This boat has opened up a whole new fishery for me and my fishing partners and as of right now, I don't have much company in the places I fish.

The stainless steel rigging is an absolute necessity for the constant diet of salt water this boat has received. I decided to take the conduit rigging off before it experienced any type of failure. It's in fair shape and for sale (cheap!). I had the original plywood floor replaced with diamond plate aluminum which saved some weight. 12 gallon diamond plate gas tank looks good and matches the rig nicely. The Stage One engine mods on the B&S have kicked the speed and load bearing capability of this boat to where it's more capable in deep water and faster in the shallow stuff. I'm hoping the longevity of the motor has not been affected. I should be able to take three "regular size" people and still get a good turn of speed. Once we dial in the three blade IVO, she'll be done (that is until one of you smart guys come up with another "got to have it" goody). We'll post some pictures when she's finished.

This forum has been invaluable in the search for infomation on this relatively new aspect of airboating. Without this forum, and guys like Paul and Chuck, I would have made many more mistakes.

Very respectfully,

George
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16 Dixson Twister, 54 HP Stage One B&S, Rigging by Ned and Engineering by Chuck. "This is easy, just add money"

George,

It sounds like you're well on your way. Please keep us informed on how it works out.

I'm also using SS for my rigging, because much of my running will be in salt water, in the inner marshes of the Outer Banks.

I haven't done my floorboard yet, because I'm still working on more pressing things. It's probably going to be aluminum diamond plate. I'd considered using SS expanded metal, but with the re-inforcement needed for that, the aluminum plate would probably weigh less. I've also considered other options, but I'm leaning toward the aluminum for now.


Thanks,

Duane

Here's an update:

I picked up the boat on Sat from Chuck's place. We dialed in the 67" Three Blade IVO propellor so the engine would turn 3900 RPMs. I took her out and ran her in the saltwater that afternoon. The wind was blowing about 15-20 and had the water a bit on the rough side. Still, she ran 27.3 MPH at 3940 RPM's with two people (400 lbs) onboard and across the wind. The water was about 2 foot deep at that point.

On Sunday, I took her out of Chassoswiskta River. The wind was down and the water was shallow. Got her up to 28 mph in less than a foot of water. The real improvement has been with the cruising speed. Before I almost always had my foot down the throat of the carb to get her to run 18-19 MPH. Now she cruises at 20 MPH at about 3200 RPMs! A real good improvement. Now I can cruise at a reasonable speed and RPM. She's up on plane in about 15 feet and has noticeably more push when you hammer down. All in all, I couldn't be more pleased.

I'll take some pictures and see if I can post them here. My thanks go out to Chuck and his crew for getting this boat up to it's potential.

George

16 FT Dixson Twister, 54HP Stage One B&S, 67" Three Blade IVO, SS Riggin by Ned and Engineering by Chuck

Hey George, that is great. I was guessing 26 MPH. Maybe cutting the transom helped to free it up some.
On the X Pipe test, the engine RPM stayed the same but the sound was 2 db quieter. So we did get some benefit. Thanks Guys
Chuck

Chuck,
Chuck,
I really haven't mashed the pedal down all the way and hold it there in some skinny water without the wind either at my back or in my face. I'm guessing with just me and in calm and shallow conditions I might be looking at 28-29 MPH! Anyway, I'm really pleased with the whole boat. The stainless rigging is great and Ned built it just the way I wanted. Now I have to mount my headlight receptacles and get after some frogs.

The water hasn't turned cold enough for the reds to get back in the creeks yet. Need a couple of cold fronts and we'll be ready to get after them.

P.S. I have your dealer tag.....sorry about that.....I'll get it back to you soon!

George

16 Ft Dixon Twister, 54 HP Stage One B&S, Custom Stainless X-Pipe exhaust, Three Blade IVO, Aeroprop 1.68 reduction, stainless rigging by Ned, Engineering by Chuck Rackley

Hey George, Thanks for letting me know about the dealer tag. We will put it on and forget whose trailer we used it on. I have already been warned about looseing my dealer tags.
Thanks, Chuck