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os 46la vs irvine .46

Old 08-19-2005, 06:38 AM
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Default os 46la vs irvine .46

hi every 1!!


me and my friend have both got planes in my plane i have a irvine .46 and in my friends plane he has a os .46la. But his engine is disapointingly weak my irvine is 1 and a half times powerful than it i asked some at my fling club y this is and he says that the os .46la are light engines but considarably weak is this true?
Old 08-19-2005, 06:41 AM
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Default RE: os 46la vs irvine .46

Is the Irvine bushed or BB? Hold old is each engine and what fuel are they running. I hear the Irvines are good and stand by the LA as a reliable and honest engine.

Run LA's on 10% and they sing. They may not be a powerhouse but they are better than some would have you believe.
Old 08-19-2005, 07:40 AM
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Default RE: os 46la vs irvine .46

im unning mine on 5% and he is running his on 10% there both good runners but mine is better(irvine) and my 1 is more reliable and uses less fuel.
Old 08-19-2005, 07:41 AM
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Default RE: os 46la vs irvine .46

my 1 is 9months months and his 1 roughly about 2 years he bought his off ebay.
Old 08-19-2005, 07:48 AM
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Default RE: os 46la vs irvine .46

While there is some difference in fuel and age I would suspect the Irvine is marginally better (perhaps it's BB).

10% Nitro makes my 40LA sing. Sure it's no powerhouse but it actually outperforms a 46LA.

Taking RPM measurements and comparing in flight similar aircraft:

40LA with 10x6 prop on 10% = 11500RPM
46LA with 11x6 prop on 5% = 9500RPM

If I assume the increase in capacity is offset by the increase in prop size (46) then I can't understand how 5% extra nitro can account for another 2000RPM. I don't see that on other engines when changing nitro content.

In the air, my 40LA performed marginally better in top speed but the 46 definitely had more initial power.
Old 08-19-2005, 07:56 AM
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Default RE: os 46la vs irvine .46

A slight change in fuel (5 or 10%) doesn't make much if any difference in performance. Experiment with props sizes, and you can usually improve flight perfomance of any airplane/engine. Usually engine HP numbers are given at RPM's that you do not reach with the recommend props. I have found that often you do better by dropping the pitch of the prop by 1 inch.

Irvine engines are great running engines. I ran a .36 for over 160 hours and pretty much wore it out. I like it enough for that size of engine that I bought 4 more. Be aware of the "block size". For instance the .25 and .36 were the same size and weight. Now they have punched the .36 out to a .39 displacement. Their next block size is 40 up to a .53 at the same basic weight. I would recommend alway buying the largest displacement in a block size for best performance.
Old 08-19-2005, 08:16 AM
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Default RE: os 46la vs irvine .46

While I agree a 5% to 10% nitro change usually doesn't amount to much it is noticable on an LA. Not so much a power increase as the engine just runs smoother.

Reading the LA manual suggests that 16000RPM is achievable with recommended props. Personally, I find that very hard to believe that an LA would reach 16000RPM with any prop.

I kept to 10X6 partly because that's what fits the spinner AND that it gives me adequate performance for the plane. I have purchased some 11x6 props but have yet to run them (spinner...).

There is no doubt the Irvine engines are good. I've never seen one but they have a reputation for being very good. Are they ball bearing engines? If so, it's easy to see that they should outpower an LA.

My LA has had approx 15-20litres (say 4-5 US gallons) of fuel through it. It just keeps on running better every tank full, although I do wish for more power. Recently I put an AX in the same plane, take offs are better as is overall speed but I can't say the plane is significantly better in all regards. More testing required.

Oh, I agree on the "There is no replacement for displacement" argument as long as you don't get ridiculous.
Old 08-19-2005, 08:35 AM
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Default RE: os 46la vs irvine .46

I would try a 10-5 prop to replace the 10-6 to raise the RPM and make a bit more power. Often not much difference in speed due to the rpm increase.

Irvines are BB. This is a good thing IF you keep the bearing clean. If you are still taking a bunch of dirt baths with the front end of the airplane, then the plain bearings are hard to beat (much easier to clean).

I've seen plenty of good running LA engines. They like fuel with a bit more oil. Their timing is a bit on the mild side, so they are easy to start, and idle well at the loss of a bit of top end power. Traditionally OS engines were timed this way and Super Tigre were a bit more aggressive. But today, companies like OS have engines all over the tuning spectrum to give a bit of product differentation between their engine lines.
Old 08-19-2005, 09:24 AM
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Default RE: os 46la vs irvine .46

Interesting thread.

The 46 LA and the 46 Irvine aren't really in the same class. The Irvine is a respectably powerfull BB sport engine, while the LA is a simple low-cost entry-level engine (& the least powerfull 46 engine currently on the market). While the 40/46 LA engines are schneurle ported, they lack boost transfer ports -- this is the primary reason for their weak output (it has nothing to do with ball bearings, or the lack thereof). For example, the very similar TT 42 GP has a boost transfer port & is substantially stronger than the 40 LA & easily matches the 46 LA, despite having the same small carb-throat size as the two LA engines.

Raven, are you running at high altitude or at high ambient temps? I have consistently measured fresh OS 40 LA's @ 12,000 rpm with APC 10-6 props on 10% nitro, & OS 46 LA's @ ~13,000 with the same prop. Yours seem weak in comparison, particularly the 46. I have measured 46 LA's @ 10,900/11,000 with APC 11-6 props (to much prop) --- something seems to be amiss with your 46 LA. I have also seen little change in the output of those engines with varying nitro content. They run well on anything from 5% - 15% -- giving similar output.

If the 46 LA is reasonably correctly propped (9-7, 10-5, 10-6, 10-7, or 11-4 are good choices), it will work as well as can be expected.
Old 08-19-2005, 01:30 PM
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Default RE: os 46la vs irvine .46

so the 46la is thre least powerful .46 avalable
Old 08-19-2005, 06:57 PM
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Default RE: os 46la vs irvine .46


ORIGINAL: britbrat

Interesting thread.

The 46 LA and the 46 Irvine aren't really in the same class. The Irvine is a respectably powerfull BB sport engine, while the LA is a simple low-cost entry-level engine (& the least powerfull 46 engine currently on the market). While the 40/46 LA engines are schneurle ported, they lack boost transfer ports -- this is the primary reason for their weak output (it has nothing to do with ball bearings, or the lack thereof). For example, the very similar TT 42 GP has a boost transfer port & is substantially stronger than the 40 LA & easily matches the 46 LA, despite having the same small carb-throat size as the two LA engines.

Raven, are you running at high altitude or at high ambient temps? I have consistently measured fresh OS 40 LA's @ 12,000 rpm with APC 10-6 props on 10% nitro, & OS 46 LA's @ ~13,000 with the same prop. Yours seem weak in comparison, particularly the 46. I have measured 46 LA's @ 10,900/11,000 with APC 11-6 props (to much prop) --- something seems to be amiss with your 46 LA. I have also seen little change in the output of those engines with varying nitro content. They run well on anything from 5% - 15% -- giving similar output.

If the 46 LA is reasonably correctly propped (9-7, 10-5, 10-6, 10-7, or 11-4 are good choices), it will work as well as can be expected.
OK, I'm not familiar with the Irvine other than it has a good reputation. Given it's a sport engine then it's not really fair to compare it to LA engines.

Not sure what the local ASL is but it's not a huge amount, maybe 100-300m. Ambient temp is quite cool at the moment (Winter in Australia).

The prop I measured with was 10x6 RAM prop (made in England - never heard of them). I have just changed to a Master Airscrew of the same size and will be tuning and testing RPM shortly. Note I can't vouch for the accuracy of the tacho either, it's not mine and I'm sure there is some variability in accuracy. Ignoring the numbers, the engine runs sweet and sounds perfect at full throttle.

My 40LA may be the least powerful in it's class but it's not disappointing either. Sorry to harp on that but too many people rubbish these engines - they are great value and not as weak as implied.

By comparison to other LAs running at the field (mostly 46s) there is very little difference in top speed level flight against the same aircraft type. The 46LA I measured (not the same I flew against) probably wasn't the best one to compare against, the owner has had some trouble tuning it. He had an 11x6 on it from memory.

Would you consider 11x6 too much for a 40LA? I had considered trying it.
Old 08-19-2005, 07:16 PM
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Default RE: os 46la vs irvine .46

Ive got both the Irvine .46 MKIII and the OS .46 LA. the LA is by far the weeker of the 2. Both mine are running flawless and both are running on 15% the lA is turning a 10x5 APC its on a 4 lbs airplane . the Irvine is turning a 12x3.75 APC prop and its on a 6lbs plus airplane and like i said the Irvine is Hands down the power house of them . both engines are the same age and have about the same run time on them. I like them both .
Old 08-23-2005, 08:56 AM
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Default RE: os 46la vs irvine .46

Raven, an 11-6 is wildly too much prop for a 40LA (or a 46LA). I've tached that combo @ ~10,300/10,400 --- 2,400 rpm short of the torque peak & 3,000 short of the power peak.

What plane do you have it installed in? If it's a trainer, or a 3D type, an 11-4 is a much better choice (that set-up should get you ~12,000). If it's a light model with a clean aero-shape & needs a bit of speed, then a 9-6 should get you up to ~13,400 --- right on the power peak (& max performance).

For general knocking around, a 10-5 (~12,700 rpm), or 10-6 (~12,000 rpm) will work as well as anything with that engine.

The fact that top speeds with the 40LA & 46LA are similar doesn't surprise me -- you need a lot of power to increase speed very much (or a lot less drag), particularly if the engines are not correctly propped. Where you should see a big difference is in acceleration & climb --- the 46LA should easily out-do the 40, assuming the props are correct.

BTW, all of my stats are based on using APC propellers, 100m ASL, 20C ambient & 10% nitro.
Old 08-25-2005, 10:56 AM
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Default RE: os 46la vs irvine .46

so why is the os so weak?
Old 08-25-2005, 11:04 AM
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Default RE: os 46la vs irvine .46

ORIGINAL: luke21

so why is the os so weak?

No boost transfer port, a small bore carb, a small diameter crank (small-bore air/fuel passage), small inlet/outlet ports & mild port timing.
Old 08-25-2005, 03:04 PM
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Default RE: os 46la vs irvine .46

oh i get itcool

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