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Saito Gas conversion experience

Old 11-04-2017, 02:21 PM
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raron455
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Default Saito Gas conversion experience

Fellas, Iam currently putting together an ESM B25, I struggled with a engine choice and decided I wanted the 4 stroke sound , I decided to go with Saito FA180s, My plan is to send them off to CH ignitions to have them converted over to CDI ignition and gas carb setup. I have seen multiple videos of all kinds of saitos with this conversion done, they appear to be very stable and run great. I know to expect a power loss with gas conversion, I also know gas will make the engine temps higher, so I will assure proper cooling of the engine. My main concern is Engine Life, I have read and had others tell me converting a saito to gas will kill it, stating that the rods, and crank will fail. But then have read from others that they have had the conversion on their saito for years??
I would appreciate any ACTUAL experience with SAITO conversions, yours or a friends, I don't want to dump all this money into converting some engines I am already pretty deep into, just to have them fail from oil starvation, or hammering of the rotating assembly that may destroy it.
Thanks Fellas
Old 11-04-2017, 02:24 PM
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Hobbsy
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Use the recommended 20 to 1 gas to oil mix and you'll be safe.
Old 11-04-2017, 08:16 PM
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the Wasp
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Saitos uses quality metal so I agree with Hobbsy,, just do a good brake-in on them, at least 1 gallon each, and as for running hot it wouldn't hurt to make up some good Air-dams in your cowls

Jim
Old 09-27-2021, 03:27 PM
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jorgeelizondom
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Default How hot is too hot?

Hello,
I just converted a Saito 300 twin and it runs very hot. Like 165C.
Is this normal?
How hot is it too hot for these Saitos?

Thanks
Old 10-23-2021, 01:25 PM
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1967brutus
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Originally Posted by jorgeelizondom View Post
Hello,
I just converted a Saito 300 twin and it runs very hot. Like 165C.
Is this normal?
How hot is it too hot for these Saitos?

Thanks
Temperature values in and of themselves are pretty much useless without knowing HOW they are measured.
Assuming you use a temperature probe near the combustion chamber: For a bench run, that is probably pretty "normal". Normal in the sense that on the bench an engine gets quite a bit hotter than in the air.
Don't run them WOT continuous on the ground. Short run-ups of up to 30 secs with some idling cooldown in between is acceptable, but don't set it WOT for a full tank or so.
In the air, full throttle is possible, but I would advise against running WOT continuously. Flying normal (using full throttle when you need it but reducing throttle on the downlines etc etc) should be enough to keep temperatures in check.
If cowled, pay thorough attention to proper baffling, and you should be OK.

Saitos, on account of their cylinder and head in one casting, can handle gasoline pretty good, better than any other glow fourstroke out there.

FWIW: I have converted a few Saito's to gasoline for clubmates and friends, they all run just fine and so far, I have not yet heard of faillures.
Use 20:1 or fatter (I myself prefer 15:1 in the over 1 cu.in. Saito's and 10:1 in the smaller ones) and you really would have to push one to break one.

I myself do not own Saitos, but I have converted 4 or 5 for others. My own engines are ASP and the occasional OS, all converted to gasoline, and I have not yet damaged one, or even been able to determine any wear or deterioration. If ASP can handle it, Saito sure can as well.
Old 10-23-2021, 11:56 PM
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Watch out, I have the FG-30, the con rod has no bronze bearings,, look what happened to mine on 5% Motul 710 oil and a 16 x 8 APC prop,,,in straight and level flight in my ESM Stuka.

Old on the right, my home made bronze replacement on the left,,,


Old 10-24-2021, 12:21 AM
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1967brutus
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Originally Posted by paulinfrance View Post
Watch out, I have the FG-30, the con rod has no bronze bearings,, look what happened to mine on 5% Motul 710 oil and a 16 x 8 APC prop,,,in straight and level flight in my ESM Stuka.

Old on the right, my home made bronze replacement on the left,,,

I have no clue as to why Saito recommends such ridiculously small props for their engines. From what I see on my testbench, 16 x 8 is way too small. There are huge variations in propload between the different brands, and for example a Master Airscrew 16 x8 will probably exceed 9K on the bench while a grey Graupner 16 x 8 will remain just shy of that, meaning that there is a good possibility you simply overrevved it, because with a relatively sleek airfraime like that, it probably has hit close to 10K in level flight. A heavy prop like APC wideblade or a Grey Graupner, 16 x 8 might have been acceptable, marginally. But in a WOT dive, you're still in the danger zone.
There is no point in revving gassers that high. The nice thing about gassers is that they like to labour, not rev.

FWIW: People who know me from RCG know that i invariably advise to use more oil than Saito prescribes. I do not say that for fun or to discredit Saito... 15:1 is a way better ratio for the 180/FG30, the one I converted produced a nice 2,5 [email protected] RPM with, for example, a 16 x 8 x 3, and is currently doing its job in an ESM Bonanza
Old 10-24-2021, 03:50 AM
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Thanks, I do have a wooded 16 x 6 three bladed wood, maybe next flight,,
Old 10-24-2021, 04:02 AM
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1967brutus
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Originally Posted by paulinfrance View Post
Thanks, I do have a wooded 16 x 6 three bladed wood, maybe next flight,,
A 16 x 6 x 3 spins about 30% lighter than a 16 x 8 x 3 of same brand/design, and only marginally heavier than a 16 x 8 two-bladed prop, so still might be a touch too light.
Strictly my opinion, but these engines should be propped for 8K on the ground max if you want to keep them...
Old 10-25-2021, 07:31 PM
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in my link below scroll down a bit. it says to use 16:1 to 20:1 in the FG30. I think that is a mistake, and it should be 16 to 20 ounces.
https://www.horizonhobby.com/product.../SAIEG30B.html

note that Saito's Cams are not as peaky as other brand engines are, meaning the Saito will produce more performance with a lager prop than other brands will with that same prop..

Jim

Last edited by the Wasp; 10-25-2021 at 07:44 PM.
Old 10-25-2021, 08:24 PM
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Originally Posted by the Wasp View Post
I think that is a mistake,
Nope... personally I would not even run it leaner than 15:1, but that is me. There is no gains to be had from skimping on oil.
Whatever you do, do not run it leaner than 20:1 and the fatter the better.
Old 10-26-2021, 11:36 AM
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OK, 15:1 /10oz, cause as they say straight gasoline has more lubrication than alcohol does.
if you search RCU's Saito Club page you will see some people use less oil in their Glow Home Brews than Saito recommends.

I agree the 16x8 is too small, cause if you put that 16x8 on the Saito 180 Glow engine it would turn up around 10,000, maybe even more (that's a no-no). if you search RCU's Tachometer page you will find people are turning an APC 17x8 right around 8,800/8,900 RPM with their Saito 180 Glow engines, so in this case on this page I do not believe the Rod was the problem.
(yes, for a time I had a 180 4-stroke glow engine of a different brand than Saito. but that's a mistake in my life we wont talk about LOL)

here is a prop note that most do not think of; with 2 closely, equally weighted props with the same type blades More Pitch vs More Length is not equal. (example; APC 11x8 / APC 12x6) more pitch only loads an engine more.. while a longer prop produces more flywheel effect/ more prop momentum.
and yes of course a heaver prop will produces more flywheel effect/ more momentum.

a funny side note here. if you go back to Chey's Corvair engine, it had no "Case to Metal" bearings inside the engine. no Cam bearings, no Crank bearings. only Rod bearings

Jim

Last edited by the Wasp; 10-26-2021 at 11:47 AM.
Old 10-26-2021, 11:56 AM
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Originally Posted by the Wasp View Post

a funny side note here. if you go back to Chey's Corvair engine, it had no "Case to Metal" bearings inside the engine. no Cam bearings, no Crank bearings. only Rod bearings

Jim
Jim,

Not sure where you got that(?)
"No main bearings"

Every one that I had the pleasure of building surely had metal shell, steel backed split insert bearing sets



Old 10-26-2021, 01:34 PM
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Originally Posted by the Wasp View Post
OK, 15:1 /10oz, cause as they say straight gasoline has more lubrication than alcohol does.
if you search RCU's Saito Club page you will see some people use less oil in their Glow Home Brews than Saito recommends.

I agree the 16x8 is too small, cause if you put that 16x8 on the Saito 180 Glow engine it would turn up around 10,000, maybe even more (that's a no-no). if you search RCU's Tachometer page you will find people are turning an APC 17x8 right around 8,800/8,900 RPM with their Saito 180 Glow engines, so in this case on this page I do not believe the Rod was the problem.
(yes, for a time I had a 180 4-stroke glow engine of a different brand than Saito. but that's a mistake in my life we wont talk about LOL)

here is a prop note that most do not think of; with 2 closely, equally weighted props with the same type blades More Pitch vs More Length is not equal. (example; APC 11x8 / APC 12x6) more pitch only loads an engine more.. while a longer prop produces more flywheel effect/ more prop momentum.
and yes of course a heaver prop will produces more flywheel effect/ more momentum.

a funny side note here. if you go back to Chey's Corvair engine, it had no "Case to Metal" bearings inside the engine. no Cam bearings, no Crank bearings. only Rod bearings

Jim
Not sure what you mean by "15;1/10oz"... is that 10oz per gallon? If so, that is too fat, because that would be 12,8:1 EDIT: if you are talking Imperial Gallons and ounces, then you would be correct, that would be 16:1 and perfectly acceptable...

In any case, here's the Saito 180 that I did for an aquaintance:
It is spinning a Grey Graupner 3-bladed 16 x 8, which is a fairly heavy prop not only in weight but also in prop-load. It does a respectable 2,5 horseys here, and from the owner I got word back that after flying it some, it gained somewhere between 5 and 10% since.
In order to get it to run like that, I placed a 2 mm thick thermal insulator between header and carb, and modified the angled groove in the throttle barrel "a tiny bit".
Fuel here is 15:1 regular pump gas with Castrol PowerRS 2stroke

Very user friendly engine... Cold start:

Last edited by 1967brutus; 10-27-2021 at 02:03 AM.
Old 10-27-2021, 05:55 AM
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Originally Posted by 1967brutus View Post
Very user friendly engine... Cold start:
https://www.youtube.com/watch?v=5cb2Jc1vIHc
No surprise,
Most Saito users are well aware big block Saitos are super.
User friendly indeed. The primed FA-180 on methanol is a super steady one flip start engine.

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