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  #191  
Old 01-12-2019, 11:20 PM
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charosenz charosenz is offline
 
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Location: Longview, Wash
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Quote:
Originally Posted by BillL View Post
I would agree with that, but vibration will be another matter. You can use thinner wall or smaller diameter tube for a tension only link. Just for the esthetics. I see Ken Krueger post here sometimes as "Sky Designs". A static stick modeling of this should not take much computer work and will answer all the questions of loading.

When my SAE mini BAJA team did our design ('77), it was before ready availability of FEA models. My team member with the structural/frame assignment came in with a model made out of coat hangers and soldered together. It was wonderful because we could see the stiffness and load it by hand. We immediately found the weak area and added a cross brace. It was Auburn's only National 1st place.
Bill

Sounds like a great project, I bet it was super fun! Thanks for sharing .
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  #192  
Old 01-12-2019, 11:24 PM
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charosenz charosenz is offline
 
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Default New mount lower support members

Well I actually got time in the shop to day to add those A-G, B-H members.

Here is a pic. I know this will be obvious to many, but if you are new to the thread, I was encouraged to add the members that are the unpainted tubes. They are only roughed in. Not welded. I hope to get the welder next weekend.




Here is a shot of the roughed in new members on top. They are also only taped in place. The blue triangles are were there will be gussets.


Last edited by charosenz : 01-12-2019 at 11:36 PM.
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  #193  
Old 01-13-2019, 07:25 AM
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DanH DanH is offline
 
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Quote:
Originally Posted by charosenz View Post
Here is a shot of the roughed in new members on top. They are also only taped in place. The blue triangles are were there will be gussets.
Charlie, let's have some fun.

Imagine you're driving your Jeep along a jungle trail, when you come to a piranha-infested river. The helpful natives have erected a bridge. You must decide. Is it safe to drive across, or have the natives set a trap for the invaders?



Your co-driver, being a master of gearbox design, insists the bridge is fine, so you attempt to drive across. Sadly, it collapses, and you are both eaten by the piranhas. The natives are greatly amused.



The natives were clever. They built a Warren truss, but left out one member. Without it, the result is a concentrated bending load.

Let's return to airplanes. First, thank you for reconsidering your lower mount triangulation. We all want you to succeed.

Now about those upper mount points. Previously we talked about how rubber mount points make the aluminum plate (bolted across the back of the engine) ineffective as a tension or compression member in a truss. Slobovian Charlie quite correctly noted that many mounts do depend on the engine to complete a truss, which is true. In fact, many don't even bother to create a truss. Although such structures may be strong enough to avoid the piranhas, they will exhibit low stiffness. Flexible structures are a wild card you don't want.

Like the jungle bridge, completion of the Warren truss requires one more member:



The gussets? Ditch 'em. Without the above truss member, they add little stiffness while creating a stress concentration. With the added truss member in place, they are entirely unnecessary.
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Last edited by DanH : 01-13-2019 at 08:20 AM.
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  #194  
Old 01-13-2019, 09:19 AM
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rv6ejguy rv6ejguy is offline
 
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The new bottom tubes look good.

I'd be concerned the top angled tubes meeting the middle of the unsupported lateral tube near the firewall won't be as stiff as if could be. Ideally, you'd have another pickup point there tied into substantial firewall structure, that being tied into the upper longerons. Since this is a lot of work, Dan's suggestion is an easier fix for less weight.

Dan, thank you for adding an interesting storyline to a rather dry subject.
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 431.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


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  #195  
Old 01-13-2019, 10:15 AM
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charosenz charosenz is offline
 
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Talking

Dan, Ross,

Thanks for the comments.

For the sake of the natives I'll do it. It will be easy to add.

For all the fun we are having with this topic, IMHO it is not completely accurate to say there is no support between the top two posts now. We are all comfortable with the rubber mounts handling the 300+ lbs of the engine in all 3 axis of pressure, albeit most is tension/compression. So while I agree that adding another member between the posts is a good addition, it is not accurate to say there is no support there without it.

Just think, if the engine set up doesn't work I can always put this mount in the bed of a truck to use as a hitch for a 38ft 5th wheel trailer, wa da ya think?

Charlie
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  #196  
Old 01-13-2019, 10:47 AM
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charosenz charosenz is offline
 
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Default How much does it weight ?

One of the questions, I get asked the most is "How much does it weigh"?

While having so much fun with the mount I took the time to weigh the engine "as is". Some of you who have been following this thread will know that I showed a pic of the engine without any components, just the long block and I am pretty sure it came in at 201 bls.

Right now it is at 276 lbs. This includes:

1) T3/T4 Turbo and adapter mount plate. (Probably 16lbs +/- 2)
2) Alternator
3) New idler pulley.
4) Starter
5) Throttle Body
6) Intake
7) starter ring gear the PSRU mount plate
8) Top, Bottom, and both side mount plates
9) Misc stuff

For me, this is not bad at all. Here's the pic.



Here is the Turbo side as weighed.



Charlie

Last edited by charosenz : 01-13-2019 at 11:21 AM.
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  #197  
Old 01-13-2019, 05:34 PM
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rv6ejguy rv6ejguy is offline
 
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Not bad, that's within about 25 pounds of my Subaru with the same stuff attached.
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 431.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


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  #198  
Old 01-13-2019, 06:47 PM
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charosenz charosenz is offline
 
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Ross,

Yeah, it's not the most powerful engine, nor the lightest, but "bang for the buck" it has a lot going for it. Especially knowing it is entering its 12 year in production, that in itself is remarkable. And...it has a 2.0L stroked version still in production as well. (added - and you can buy complete engines with less than 5k miles on them for $800 all day long...)

The Achilles Heel in these "Alternative" engines is often the PSRU - gearbox), and sometimes the ECU. Fortunately SDS EFI makes the ECU a breeze. I hope the PSRU from Viking shows it can stand the test of time. I am happy with it so far. I will post the pics of the new unit soon.

Charlie

Last edited by charosenz : 01-13-2019 at 07:12 PM.
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  #199  
Old 01-14-2019, 10:41 AM
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Major-Tom Major-Tom is offline
 
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May I ask what happend to your "old" PSRU?
And what did it cost you? The Viking Homepage list just one PSRU for 3000USD and for me it is not clear what is included in that price... What about Damper, Mountingplate ...
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  #200  
Old 01-14-2019, 09:55 PM
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charosenz charosenz is offline
 
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Quote:
Originally Posted by Major-Tom View Post
May I ask what happend to your "old" PSRU?
And what did it cost you? The Viking Homepage list just one PSRU for 3000USD and for me it is not clear what is included in that price... What about Damper, Mountingplate ...
Tom

Viking offered me the HD PSRU for $1000 plus a return on my old unit. I thought this was fair so I jumped on it.

I know I paid extra for the 3 prong flange that bolts on the crank but I honestly cannot remember how much, I want to say $200. But it is important to remember that my project is far from what Viking typically does. I think the Guibo unit was extra too but I cannot remember how much, may be $100?

I also want to point out that the bolt pattern for the PSRU gearbox was not an exact match for my engine. Four of the 5 standoffs were a direct fit, but I had to machine a piece to pick up that 5th bolt.....

Let me know if you have any other questions. Happy to share what I am doing.

.......now if that welder would just show up!!!

Charlie
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