Silvanskii

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Hello all, I haven't much experience with US 41 engines, but I know they have a low power to weight ratio.

A friend of mine wants to upgrade an airplane he has with a US 41, to a 50cc size engine (trust me, the plane can take it that's not an issue), but he doesn't want to have to mess around with drilling new holes in the firewall for the mounting bolts. I recommended looking into Quadra (52) since they and US are essentially the same company.

So do Quadra 52's and US 41's have the same size mounting plate that he can swap his 41 out and put a 52 right in it's place? Are Fuji's, Brisons, or Sachs the same to? Also, if anyone knows how much longer from mount to prop hub these engines are he'd be much obligued !

Thanks!

Mike Bogh

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Desert Aircraft DA-50...

Antique

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The bolt pattern on the Quadra/US engines is the same...Nobody else uses the cast cup mount as standard equipment, so unless someone bolted one of those onto the engine it will be different...B&B Specialties sells the mount, and there are many Zenoahs with it also..The Bennet Built engines use the cup mount....
FWIW...US Engines and Quadra are not the same company..The US Engines company never had anything to do with the Q50 and 52... The Q52s now come from Wisconsin, Tom Sabatini has the rights to the 50 and 52.....

Silvanskii

My Feedback: (17)

Thank you RCIGN!

So just to make absolutely sure, a Q52 will bolt right into the same bolt holes as the US41 will, without any modifications, and any engine with the universal cup mount would fit.

Cool!

Well a DA-50 would be awesome to, but it's only...say..... 400 dollars more! Plus you'd have to gut the firewall to accomodate the rear intake.

Silvanskii

My Feedback: (17)

I saw a Fuji 50 and a Taurus 50 in the classifieds, so they would both need to have the cup mount to be directly compatible with the US41, no?

Antique

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Yes

famousdave

My Feedback: (61)

What kind of plane is it ? Scale, 3D, etc. Chances are if it has a US41 on it now and it flies, a DA, ZDZ, Brisson will tear the wings off.

I used to hate all magneto engines, but after tinkering with them all, there is only that is very nice. Zenoah. Two words.. they always run. I have had nothing but problems with Fuji, quadras, and weedies like poulans, etc (why bother)? If you cannot afford to do it right.. then why do it? I cannot tell you how many planes I have seen pounded or sidelined when people try to use these cheapo engines that never seem to run.

If you want t 41 sized replacement that has more power and runs great - try the G38. If you want to spend a few extra cash and lose one pound of excess baggage on the G38 .. get an electronic / CDI ignition conversion like what RCIgn is offering. One of the best running engines I have seen is one of his G26's. In fact it starts and idles better than my DA.

I paid $220 for my NIB G26, I have seen G38s on ebay for $265 add the conversion and you are still less than 400. The others start at $450 and you have to buy a muffler.....

DP

shenion

A Q-52 would be a good choice as far as mounting, but the carb is on opposite sides IIRC. (I think it can be reversed.)

A G-45 with a B&B cup mount would also be close as far as mounting.

But these will likely be differnet lengths and have side-mount mufflers. So it will not fit in the cowl the same.

Personally I'ld bute the bulled an get a ZDZ, Brison, DA or other "modern" engine. The Q-52/41 are basically 20-year old designs. Good engines, but there is much better.

I agree that the Zenoahs are reliable. A bit older design in power/weight but damn reliable.

Silvanskii

My Feedback: (17)

Thanks all for the help.

Actually my friend has a 1/5th scale warbird that needs more power, weighs ~22 lbs now.

I've had good luck with Quadra that's why I mentioned it. Obviously he doesn't want to hack up the old cowling any more than he can.

Does the G-38 have a similar side carb mount?

And what about the Walbro 144 carb replacement and straight pipe for more RPM's? Oh and replacing the magneto with a CH ignition would help to I think, by about a half pound?

rmh

If the warbird is too heavy - how does more power really help?
too bad we can't buy more runway instead .

shenion

It is side mount, and I think on the same side. For a Zenoah, I'ld go with a G-45, the G-38 is about the same power as the Q-41. It looks like the G-45 has the carb on the opposite side.
I put a #144 on my Q-42, no real change, but low end did seem smoother. I did replace the stock muffler (and originally removed the baffle). That did help as the stock can muffler is a bit restrictive. But there is not much you can do with a '42 that will make a big change in performance.

An ignition may pick up a little RPM and drop about 8 oz.

I think whatever engine you use, you will need a new cowl as the carbs and muffler positions will be different.

GaryV

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Hi,

I bought a used Sig SU-31 ARF this past spring (at Joe Nall) it had a US-41 on it.
I had a hard time getting it started, (the bearing on the spring start wasn't working properly) but after it finally started it ran good. I should also mention that this was my first experience with gas engine planes.
The plane weighed 17 pounds, it flew ok but would run out of power when trying to fly pattern manuevers.
I happened to have a new G-38 on hand that I had to put on a Bud Nosen Trainer that I was rebuilding for a R/C skydiver drop plane.
I then put the G-38 on the SU-31 thinking I might get better performance, guess what, I couldn't tell a bit of difference in performance between the two engines. ( alse note that the G-38 has not been broken in it has maybe a 1/2 gallon of gas thru it)
I then bought a DA 50 for the SU-31 (the engine hasn't made it on the plane yet, read on)

Now the Nosen Trainer has been finished and the G-38 put on it, the Nosen trainer weighs 21 pounds set up with one drop box.
Guess what, barely enough power to get the plane off the ground with one skydiver aboard and I want to eventually carry three at a time, 2 1/2 to 3 pounds each.
So, now the DA-50 goes on the Nosen Trainer, there is no comparison between these three engines, the DA is in a completely different class, it starts easy, runs great and has plenty of power.
I think it was well worth the extra money. (engine $549, Slimline Pitts muffler $129, Dave brown spinner $30, Carbon prop 22x10 $46)
Now, if I could only afford another one.
I will attempt to add a pic of the plane.

Gary VanFossen
Virginia

[img][/img]

GaryV

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trying pic's again

Tired Old Man

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If the plane currently weighs in at 22 lbs, you don't want the Quadra. Look into a modern 50 to 52cc engine. They are lighter, with a much higher power to weight ratio. They are also VERY reliable. Changing the mounts is not a big price to pay for reliability, adaquate or excess power, and reliability.

Silvanskii

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Well thanks for the replies, the only issue is the money though.

What engine has the most bang for the buck?

Waco

My Feedback: (265)

I got a poulan 46cc that has been converted by RC Ingition and is ready to use complete with RC ingitions electronic igition system. The engine has never been run except by RC ingition when set up. This produces about the same as a bme 44 in power. If you are interested I would let you have it for 300.00 shipped. at about 3 1/2 lbs it is about as good as you can get without spending 500.00 on a engine.

shenion

Personally I think the ZDZ'z. But any suggestion could provoke a holy war

I have a ZDZ-40 on my GP PW Extra. It looks like a tiny glow engine sitting in the cowl. It matches the Q-52's in RPM/power.

A ZDZ-40 would be a considerable increase in power over the US41. But it will weight about 1.5 lbs less with muffler. Also, it is a rear carb engine so mounting is different. The ZDZ-40B is a great deal as it contains everything you need including a prop, battery, prop drill jig. Just mount and fly.

Really, you should consider the weight. and size of the engine and how it fits in the cowl. The new low-weight engines usually require added nose weight an a scale warbird. That is why the Quadras and Zenoahs are popular, the added weight is needed for balance.

Waco's 46 should do well. The Poulan 46's have replaced several Q-42/US-41 engines at our field with good results. They are almost 1 lb lighter and have more power. His price is good, most spend about $350 for the engine and the conversion. We have one of Ralph's conversions here and it runs great.

I have seen Poulans converted for almost nothing if they use the stock magneto. Need an electric starter as they don't flip-start well on magneto. The Poulan is a great engine for the price.

Check the 4-sale forums, you might find a Q-52 at a good price that would bolt in with a B&B cup mount. You can find decent used ones for under $300.

Silvanskii

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I know all about the holy wars that happen on a daily basis here heh...

What size prop does a Poulan swing? Are the dimensions similar to the 41's??

Waco

My Feedback: (265)

The poulan will swing a 20 in prop. you might be able to go with a 18 in. prop if you keep the pitch high. as far as compared to the US 41 it is smaller in size with less weight I never had a US engine so I can not say for sure.

shenion

My Poulan 50 will turn a Pro Zinger 20x10 in the 7200+ RPM range.
A US 41 will do a 18x10 about 7300.
A Poulan 46 will do a 18x10 about 7600, 20x10 in the 6600 range IIRC.

Static RPM wise on an 18x10 or 20x10, the Poulan 46 does no seem a lot more than a US41. But in the air, it is considerably different. If you combine that with the drop in weight it is significantly better.

Dimensions are similar, actually mine is shorter as it does not have a cup mount (nor will one fit.) Most people use a Hangar 9 mount. The Poulans are unique in that they have mounting rails like a glow engine.

BTW, a spring starter off a '41 will work on the rear shaft. You just need to find a way to hold the spring. But a spring starter/magneto would weigh as mucg as a US41. ELectronic ignition adds power and reduces weight.