# B&S 49-series (810cm3/49ci) for aircraft use - TiPi's Q&A thread

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#### Vigilant1

##### Well-Known Member
Because the pistons are smaller and presumably lighter on the "44" vs. the "49" do the crankshafts and/or flywheels differ for balance reasons?
Just to be clear:
1) The crankshafts are different on all three models (44 Commercial, 49 Commercial, and 49 Vanguard). As far as I know, of these only the Vanguard is forged.
2) The pistons have different stock numbers on all three models.
3) The flywheel is the same on the commercial 44 and the commercial 49. The Vanguard flywheel is different.

I don't know about the balancing of the crank and other rotating bits (pistons, rods, etc) using the flywheel. If they did that, then replacing the flywheel would require a new dynamic rebalancing of everything.

I'm not sure why the Vanguard 49 requires a different flywheel from the others.

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#### TiPi

##### Well-Known Member
Log Member
The conrods on the Vanguard are heavier and this will require a different counter weight on the crankshaft.
Not sure why there are different flywheels, there are actually 5 different flywheel P/Ns across the 49 range (none of these P/Ns supercede to another number on Jacks website):

The non-Vanguard heads fit some 40-series and most 44-series. The head & combustion chamber design goes back to the old Generac GN724 (724cm3) engine (current 44-series, the 40-series has the same bore).

#### Vigilant1

##### Well-Known Member
Thanks, Tipi, your compiled data is more inclusive than what I've built. I found it interesting that even the flywheel puller tool isn't the same between the models with the 594169 flywheel and the 593610 flywheel.

It does sound like buying a cheap used 44 engine might be okay for learning more about these engines. It is strange that B&S rates some of the 724cc engines at 27 hp (e.g. model 44U877-004), while some 49 series engines are rated as low as 24hp.
I suppose it is possible that the 44 series might have slightly better VE than the 49s (in part due to the shadowing of the valves by the "shelf" in the too-small head that you pointed out earlier). Still, it seems unlikely that this more than makes up for the 86cc difference in displacement.

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#### pictsidhe

##### Well-Known Member
Briggs had to heavily prune their hp ratings after being fined heavily for their 'alternative facts'.
I once compared the parts list of two single cylinder Briggs. The only part number that was different was the fan shroud. Physically comparing them revealed that red paint was worth 20% more power, compared to black paint...

#### Vigilant1

##### Well-Known Member
Briggs had to heavily prune their hp ratings after being fined heavily for their 'alternative facts'.
I once compared the parts list of two single cylinder Briggs. The only part number that was different was the fan shroud. Physically comparing them revealed that red paint was worth 20% more power, compared to black paint...
I agree, they've certainly been caught cheating in the past. The hp claims I noted are present (i.e. post lawsuit) ones, but of course they are gross HP.
I think marketing and the need to meet the wide range of lawn equipment OEM specifications with a limited engine product line explains why they have all these trim levels and identical engines (same displacement, carb, induction system, CR, etc) with different HP ratings. It doesn't cost them any more or less to label the same 810cc engine as 24, 26, and 28 HP, and the manufacturer of the ZTR wants those different engines/labels so he can have products that span the  range. As long as it really can make 28HP (gross), it is okay with me.
But I'd really like to see that test where their stock 724cc engine made 27 HP (gross) at 3600 rpm. OTOH, Tipi's 810cc engine, before extensive mods, did come pretty close to meeting the present B&S claim for his model. He saw 23-24 HP with the air cleaner on, etc. The present advertised gross HP is 27. Given the uncalibrated club, etc I think B&S comes out looking okay (provided you didn't own their stock).

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#### Vigilant1

##### Well-Known Member
I hope Tipi will choose to remove the stock "OHV" valve covers for his engine and have some made that say "UHV' instead.

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#### pictsidhe

##### Well-Known Member
I hope Tipi will choose to remove the stock "OHV" valve covers for his engine and have some made that say "UHV' instead.
Some careful panel beating could achieve that.

#### simflyer

##### Well-Known Member
Just to be clear:
1) The crankshafts are different on all three models ... As far as I know, of these only the Vanguard is forged.
2) The pistons have different stock numbers on all three models.
3) The flywheel is the same on the commercial 44 and the commercial 49. The Vanguard flywheel is different.

I don't know about the balancing of the crank and other rotating bits (pistons, rods, etc) using the flywheel. If they did that, then replacing the flywheel would require a new dynamic rebalancing of everything.

I'm not sure why the Vanguard 49 requires a different flywheel from the others.
So Vanguard is highest quality model of type 49? What is difference between 877 and 977?
Exist info about how to mod 49 oil pump to can use engine upright, like on SD1?

#### Vigilant1

##### Well-Known Member
So Vanguard is highest quality model of type 49?
Yes. Vanguards have a forged crankshaft, forged connecting rods, a higher quality exhaust valve and a few other goodies. See here: B&S 49-series (810cm3/49ci) - TiPi's conversion for aircraft use

Exist info about how to mod 49 oil pump to can use engine upright, like on SD1?
The most concise info is in Tipi's conversion thread here: B&S 49-series (810cm3/49ci) - TiPi's conversion for aircraft use
Obviously, this info is for Tipi's "heads down" configuration, but much still applies.

There's more discussion in this present Q and A thread on the subject of lubrication. Also, take a look at web sites showing the SE33 engine installed (heads up) in the SD-1, you can see how the oil lines are routed. More here:Briggs vanguard conversions. The stock SE33 installation requires the pilot to pre-prime the oil pump before starting the engine.
That same thread has more discussion on lubrication.

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#### mcrae0104

##### Well-Known Member
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I hope Tipi will choose to remove the stock "OHV" valve covers for his engine and have some made that say "UHV' instead.
No; you forgot. He's down under, so he's correcting the situation.

#### TiPi

##### Well-Known Member
Log Member
as per plan, yes. In reality, not yet
We moved into our new place 3 weeks ago, then off to work again for 2 weeks. I'm still in the process of unpacking my stuff and trying to fit everything into a smaller shed. Hopefully by the end of my next break I will have a shed/workshop where I can re-start my engune work.

#### TiPi

##### Well-Known Member
Log Member
No; you forgot. He's down under, so he's correcting the situation.
for the trials, I wil be using the stock pressed metal covers. I have modified one with a clear window to watch the oil flow. It is also easier to modify the drain location on the sheet metal covers (soft-solder or silver solder).
Once the oil drain is all sorted, I might get a set of Vanguard aluminium covers. There are also billet covers available but they look bulky and heavy.

#### blane.c

##### Well-Known Member
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as per plan, yes. In reality, not yet
We moved into our new place 3 weeks ago, then off to work again for 2 weeks. I'm still in the process of unpacking my stuff and trying to fit everything into a smaller shed. Hopefully by the end of my next break I will have a shed/workshop where I can re-start my engune work.
Looking forward to the end of your next break, not sure what break relates to exactly it might be an Aussie term.

#### Vigilant1

##### Well-Known Member
as per plan, yes. In reality, not yet
We moved into our new place 3 weeks ago, then off to work again for 2 weeks. I'm still in the process of unpacking my stuff and trying to fit everything into a smaller shed. Hopefully by the end of my next break I will have a shed/workshop where I can re-start my engune work.
Take all the time you need. Moving is highly disruptive, and priorities must be established (my bride thinks it is important to have an operational kitchen...go figure). Thanks very much for the work and the reports.

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#### Hot Wings

##### Grumpy Cynic
HBA Supporter
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as per plan, yes. In reality, not yet
'Life" does have a way of slowing us down.

I expected to have the roof to my work space finished a few weeks ago. This was all based on being able to do the masonry work before it got cold. Didn't happen and I had to build structure to keep the heat in. Masonry is now cured enough to let it freeze so I may have the rafters up by this weekend.

The cold weather did come in handy when the basement freezer died.....another day gone.

#### TiPi

##### Well-Known Member
Log Member
Looking forward to the end of your next break, not sure what break relates to exactly it might be an Aussie term.
we Aussies work hard, so we get a break once in a while I don't have a Mon-Fri job, I'm a FIFO worker (Fly In, Fly out). Current roster is 12/9 (days).
And yes, kitchen and house had priority over shed but I can't complain, my wife lets me have 2 aeroplanes

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