Latest project done, home built "Genturi"

[FIRE UP]

Gents,
After camping in a couple of situations where it was sort of "close quarters" over the last couple of years, it has been determined that I should have had "Genturi" long before now. It's not only common courtesy but, it's a lot healthier in terms of anyone that close to your rig, to not have to breath that exhaust if you happen to be camped that close to each other.

Well, I saw them at Quartzsite for $119.00 total. I pondered it for a day and, when a friend came back to camp with one, I thought I'd go pick one up the next day. Well, the old fraise, "You snooze, you loose", yep, it applied to me and they were all sold out.

So, back at home and check Camping World and a couple of other sights and, they hovered around $130.00 and up, and some added shipping. So, I snooped around on the net and found out there's been quite a few of you that have made them yourselves.

So, I looked any pictures that were displayed and thought, heck, if I can pull the radiator out of this big beast, if I can disassemble 3/4 of a 7.5QD generator for a sensor/rotor/head gasket replacement, if I can install a Hydralift motorcycle carrier/lift on the back, I CAN BUILD A GENTURI!!!

So, off to Home Depot for an 1 1/2" EMT elbow, and some sort of light weight 3" tubing. The rest of the paraphernalia for constructing this little project I figured I had laying around someplace. Well, regular PVC 3" tubing and, ABS 3" black tubing was just too darn heavy. I went out to the garden department and found some light weight, plastic 3" drain pipe but, it was white and none of them were real straight.

So, while wandering around in the store, I happened upon the rain gutter section. And low and behold, there was some "down spout" tubing that was white and, some was brown. I picked up a 10' section of the brown and it was incredibly light. So, my brain started straining to come up with a plan for utilization of this rectangular stuff as opposed to using the larger, 3" round stuff, if I could find any I liked.

Well, I came up with Plan A and, headed out the door with one stick of brown down spout, a couple of support clamps and, a couple of extension connectors and the EMT elbow. I got home and went to work. The first thing I had to do was cut a "V-notch" in the center of the EMT elbow and put just a tiny "kink" in the bend to get it to bend straight up. Then I had to cut a couple of slits into the one end so a regular 1 1/2" inch muffler clamp would clamp that EMT bend to the stock exhaust pipe of the gen.

Then came the formation of the double bend brackets that transitioned the EMT elbow to one of the coupler/extensions. As you can see in the pic, I didn't just pop rivet to the coupler. I "sandwiched" the coupler with small pieces of aluminum and then, attached each double-bend bracket to that aluminum. I did that for one main reason. I figured pop riveting just to the thin plastic of one of those couplers would not last all that long and vibration etc. would get to it and I'd have crack appearing soon after it went into service.

So, it was just a tad bit more work to fab up all those little pieces of aluminum but, it made a serious difference in the stoutness of the setup. Once that was done, then I installed it on the coach/gen exhaust pipe. Now, to lower the long stick of down spout into that coupler. The connection is great. Now, I need some stabilization, about half way up that pipe. Hmmmm, what to use? I was thinking of running down to Harbor Freight to pick up some suction cups that I'd seen in another home built genturi. But, DING! A light bulb just popped on in the old brain.

I've got a "Go Pro" camera that I use for motor cycle rides and other actions sports. It came with a suction cup and a mounting arm. So, I retrieved that suction cup and stuck it to the side of the rig, at the highest point I could. Now, all that's needed was something to adapt it to the upright pipe.

Well, about 10 minutes of "MacGyvering" and, DONE! Well, it was all done and mounted. Now, for the true test, will it work? Zoom, the generator started. The home made genturi is as stable as a rock. There's no movement what so ever.

I got out my trusty infra-red heat gun and checked the temp of that plastic tubing etc. at various time and distances up the pipe. The highest the temp ever got, after about 20 minutes to a half hour with no load, was about 120 degrees. I could put my hand on that down spout anywhere and not burn my hand. It had no signs of getting soft from being too hot.

Since I found no real specs on just how far away from the tubing the exhaust tip should be to create the venture effect, I just "Winged" it. I got about a 5/8" gap. When I first fired the gen up, since I don't smoke, I needed something to tell me if a "venture" was actually being created. So, off to the paper towel rack and, a butane lighter was obtained.

I lit the paper towel on the corner and let it get going a bit. Then I blew it out and of course, it was smoldering. I held that smoldering section close to the venture area and wow, it sucked that smoke right up. I was happy.

So, for about $20-$25, I got a perfectly working "Genturi". That of course does not include the spare aluminum I had laying around and, the 1 1/2" muffler clamp I already had and, the Go Pro camera suction cup mount. Take a look at the pics and see what you think.
Scott

[autofish]

Fire up have you ran the gen with a full load as the ex temp is much higher as is the ex vol. would like to see if the plastic still holds up. Good job looks good. Let us know.

[FIRE UP]

Originally Posted by autofish

Fire up have you ran the gen with a full load as the ex temp is much higher as is the ex vol. would like to see if the plastic still holds up. Good job looks good. Let us know.

autofish,
No Sir, no real load on the initial test run. But, I've got a seriously large project ahead of me that is part of that generator. I've got to install a new stator because mine was damaged due to an exploding magnet. So, that project will started today. Once it's complete, of course I'll be running a max load on it to make sure all is functioning correctly.

Then it will be a true test of that plastic "Genturi" system. We'll see then.
Scott

[D Lindy]

FIRE UP; what is the distance between the top of the EMT and the bottom of the Down Spout?

[FIRE UP]

Originally Posted by D Lindy

FIRE UP; what is the distance between the top of the EMT and the bottom of the Down Spout?

D Lindy,
I was waiting for someone to ask me that. Although I didn't actually put a tape on it, from my years and years with a measuring tape, I'm estimating real close to 5/8" of an inch. In one of the write-ups I found while doing my research, I found one fella who put the EMT right up inside the plastic tubing. He reported that plastic tubing doesn't work, got too hot. Well, to me, if you don't have some sort of distance from the inlet of that down spout, and your exhaust exit of the EMT does go too far into the pipe, you won't have two things.

1. No ability to attract cooler air from around the inlet of the down pipe.
2. Immediate heat exhausting from the tip of the EMT thus causing melt down of the plastic pipe.

At least that's my thoughts on this venturi thing.
Scott

[Libero]

Looks cool, Any reason you chose a plastic down spout vs an aluminium one?

I often wondered why a coach could not come with roof generator exhaust or at least a customized extension with snap on features to put the exhaust up and away. Perhaps they exist albeit I have never seen any.

[D Lindy]

FIRE UP; 5/8" doesn't sound like much. From watching the video on installing the CAMCO unit it almost looks like there's about 2-3" between the exh. pipe and the stack. I might try to check 1 out @ CW and see if I can check the gap. Too little gap and like the 1 guy found out the stack will get too hot, to big a gap and then not enough draft develops.

[FIRE UP]

Originally Posted by D Lindy

FIRE UP; 5/8" doesn't sound like much. From watching the video on installing the CAMCO unit it almost looks like there's about 2-3" between the exh. pipe and the stack. I might try to check 1 out @ CW and see if I can check the gap. Too little gap and like the 1 guy found out the stack will get too hot, to big a gap and then not enough draft develops.

D Lindy,
You could be right there on the gap. I just winged it in determining the gap. In a way, it's adjustable. If I find out that for some odd reason, the gap needs to be increased some, all that's needed to be done is, drill out the rivets and slide the whole thing up some and re-drill it and rivet it.
But, time will tell on the big test when I get this upcoming project done.
Scott

[Lt46]

My 1st DIY attempt with building the Genturi resulted in failure. I used the 3" pvc sewer pipe, which had been generally accepted by most DIYers as the product of choice. For the most part, that worked OK until that one 90*+ hot summer day, when the sun baked down on the genturi side of the rig and had the genset running for hours in an attempt to keep the old girl cool. We were winning this battle but I also noticed that a "wave" or "ripple" effect was taking shape in the pvc tube. What was once a straight pipeline running up the side of my coach had become a wobble, ripple, wave looking pipeline. This customized look took a permanent hold once the evening cool arrived. In conclusion, I believe the confluence of the direct sun and non stop running of the genset produced enough heat to permanently disfigure my DIY genturi.
I opted to purchase the real deal and be done with it.

[Mr Miyagi]

Nice piece of workmanship there bud! I like the "Go Pro" suction cup and mounting arm idea way better than the rubber bungie cords that come with the Camco unit.

This will come in handy at the NASCAR races where they pack us in like sardines and state beach dry campsites.

If it does succumb to the summer heat, no need to drive back out to the "Q" as wally world has them for $109 now.

[Libero]

I like the suction cup idea also. I do not have any suitable bracket or securing mechanism to attach a gen-turi to, so now that I have seen the suction cups, I will be looking at that option. I am also considering devising some way to carry sling the gen-turi hardware in a tube under my RV. I now have limited storage space since I downsized.

[Dunner]

I used about 18" of galvanized 3" tubing before mating it to the 3" PVC. I also found it to be quieter with the elbow even or slightly up inside the tubing.

[FIRE UP]

Gang,
Thanks for all the replies. If, when the "big test" is complete and, failure is emminant, I think I might be able to salvage the lower components and just replace the plastic tube with an aluminum one. If that should work, I really don't care if it get's all that warm. I won't be walking up to it and touching it every five minutes anyway. I would have to simple re-devise a way for the suction cup support to work with aluminum. That stuff is easy.

But, we'll see. I'm in the process of putting the generator back together as we speak. Should be a "full load" test, later this evening. Thanks again.
Scott

[NeilV]

I believe the Genturi is CPVC and not PVC. PVC is for temps below 140 while CPVC will stand up to temps of 180 and possibly higher without distortion.

[Mitchyb]

Hey guys, dumb question here but besides directing the exaust upwards, does this direct the exaust noise up as well?

[Dunner]

See post #12.

[FIRE UP]

Originally Posted by Mitchyb

Hey guys, dumb question here but besides directing the exaust upwards, does this direct the exaust noise up as well?

Mitchyb,
Not a dumb question, we learn from forums like this. Anyways, in the short test I ran with my new gadget, I think I found the generator exhaust note to be a percentage quieter. Now, just how much, well, not really sure. I suppose a "db" meter of some sort could tell the real actual difference. But, most generator exhaust is not that loud anyways. When you walk up to ours when it's running, we can hold a normal conversation right close to it without yelling etc.

But, to answer your question, yeah it's probably a bit quieter, based on the distance from the EMT tubing bend exit, to the inlet of the up-right tubing.
Scott

[Libero]

Re noise check, if you have a smart phone I suggest you download a noise meter app, I have a db meter and the app is reasonably accurate and usefull.

If you place your monitoring device at specified positions without the Gen-turi and record the results, then do the same test with the Gen-Turi attached, The results would be interesting to see.

I did this some time ago with various noise absorbing materials. This gave me great empirically derrived data on which to make decisions re the effectiveness of the various noise abatement methods.

Hope to see some data on this. One needs a relatively constant ambient environment to get the most accurate results.

[FIRE UP]

Originally Posted by Libero

Re noise check, if you have a smart phone I suggest you download a noise meter app, I have a db meter and the app is reasonably accurate and usefull.

If you place your monitoring device at specified positions without the Gen-turi and record the results, then do the same test with the Gen-Turi attached, The results would be interesting to see.

I did this some time ago with various noise absorbing materials. This gave me great empirically derrived data on which to make decisions re the effectiveness of the various noise abatement methods.

Hope to see some data on this. One needs a relatively constant ambient environment to get the most accurate results.

Libero,
Not a bad idea Partner. The wife has a smart phone, mine's one they used during the civil war. I showed this answer to her and she's checking for apps for either her Smart phone or, her I-pad. We'll see. Thanks for the suggestion.
Scott

[Libero]

Good luck, hope you post your results. The App I have is simply called "Noise Meter" from the Android Play Store. It is likely the same from the "App Store".