Iflyglow

My Feedback: (79)

A saito 150 will easily gain 500 rpm with a 5% increase in nitro. I guess weare to spoiled in the us with nitro.

blw

My Feedback: (3)

The ratio of OS and Sanye engines sold in the U.S. vs Europe is probably close to the Saito figures. A lot of engines are sold here with shims and that solves compression ratio problems. The problem with nitro prices in Europe is taxation. We have our taxation problems too, just on other things the politicians think are desirable.

SrTelemaster150

But, it sounds to me like the problem is a CR that is too low to run W/O higher % nitro. Adding shims won't help that problem.

Going to EI would totally eliminate the need for nitro. I still have my 1st C&H ignition system. It has been through several crashes including a WOT straight in spectacal from a pretty good altitude. (not enough to execute a split "S" though) DOH! The point is, they are pretty damned durable & will outlast several airframes & perhaps even an engine that is run extensively.

The investment would definatly pay off for European FA450R3 users in increased power , lower fuel cost & better fuel economy. JMO

1QwkSport2.5r

Do Saitos usually come with any shims installed under the head from the factory? If so, they could be removed to lower the head and increase the CR some. I know very little about Saitos, so I do not know what interference the valves will have on the piston if any, if shims are removed from under the head.

SrTelemaster150

Not that I know of.

As far as interferance? I reduced the deck hieght .055" by putting a 180 rotating assembly into a 150 case. I had to add .020" shim (deck reduction now .035") & releave the valve pocket to the outside just a bit. The horizontal relationship between the valve/pocket shifted when the quench hieght was reduced.

The smaller 150 valves may not interfere.

airraptor

My Feedback: (66)

No saitos dont have a head that comes off. the head and cyclinder are one piece. you can take some of the case to gain some CR back if wanted but the gain in CR doesnt = the gain higher nitro will yield. Saitos love 20% or higher. Running Heli fuel doesnt gain as much power as regular high nitro fuel does because of the extra oil in Heli fuel. higher oil percentage displaces the the amount of burnable fuel in the chamber. this = less power. I run 16% oil in most of my engines. Some even less.

Sport_Pilot

Actually because of the high volume of fuel burned you can get away with less oil with high nitro fuel.  With 25% nitro I have used 15% all castor.  But you do want to watch for lean runs cause nitro will burn hotter if its run lean, but cooler at max power.

Carosel43

Rev, why are you worried about the 52mph pitch speed? my La7 has a pitch speed of only 56 and it goes like the clappers!

SrTelemaster150

Isn't that airspeed usually computed @ the static RPM?

If so, I would think that as the prop unloads in the air & the RPM increases, the potential airspeed would increase also.

Reverend

My Feedback: (3)

What, me worry? Nah, I just have about 60mph as a rule of thumb for Warbirds. The lighter the wing loading and the thicker the airfoil, the lower the speed can be.

Reverend

My Feedback: (3)

Gentlemen, first of all thanks for all this information. Everything has been taken into account.

Although it was 10.30pm I just had to go and check the timing.

Took off the backplate with the diffusor and checked all cylinders from 1 to 3.
TDC cylinder one > Both rockers quite the same
TDC cylinder two > delta between rockers about 4mm
TDC cylinder three > delta between rockers about -2mm

Now I bought this engine used from a US bloke who claimed he had only run it on the teststand once. Now say I believe him then that would mean Saito really messed up when assembling this engine. If I dont believe him then somebody took the engine apart and didn't time the cams properly.

Picture one shows that there will be some cleaning to be done in winter. Maybe new bearings too...
Picture two shows TDC Cyl 2
Picture three are the rockers on Cyl 2 @ TDC 2 [:@]
Picture four are the rockers on Cyl 3 @ TDC 3 [&:]

Reverend

My Feedback: (3)

...so I marked tdc 2 on the crank with a pencil, pulled cylinder2, opened the cam cover and put the cam in properly with the punchmark at the bottom. Held it with a scalpel blade so it wouldnt turn when putting it back in and voila, tdc now shows two even rocker arms.

Same for cyl three and we are good for a testrun. unfortuneatly it was 1145 by then so NOT a good Idea in the house

I am quite positive though that I have found my missing RPMs.

All done in one hour and didn't hurt at all

don olsen

My Feedback: (2)

Hmm maybe have to get mine out and start checking deeper Great info guys. Everybody happy with the 22/10 22/8 prop size ??

Carosel43

rev looking at the photo of the conrod the link rods seem to be spaced at 120 degrees? its nothing to do with your lost rpm just a point of note on the design.

SrTelemaster150

Did you check cyl 1 then 3 on the 1st revolutionm & 2 then 1 on the 2nd?

Firing order is 1-3-2-1 etc.

airraptor

My Feedback: (66)

Sport i dont know if you were refering to me or not.

kinda off subject but on these 450's they have those three cooling fins attached. Does Saito plan to add three more cylinders to have a 900????

SrTelemaster150

A 4-stroke radial can't have an even number of cylinders & maintain a consistant (evenly spaced) firing order.

Firing orders are every other cylinder.

1-3-2-1 for a 3 cylinder.

1-3-5-2-4-1 for a 5 cylinder.

earlwb

There were a few even number cylinder radial engines in the early days, but they quickly went away. The odd cylinder count and the firing order are important with a radial engine. There is a boost of power as one cylinder is firing and assisting the next cylinder on its compression stroke to fire next. So all the engine companies quickly took advantage of it.

Iflyglow

My Feedback: (79)

That is one of the rustiest engines I have seen in a while. Take the time to polish off the rust when you put your new bearings in.

airraptor

My Feedback: (66)

Thanks earl and Srtele. I wasnt aware of that.

Kmot

My Feedback: (24)

Nice detective work Rev!

Reverend

My Feedback: (3)

Hi,

I think so but just to be certain:

Picture 1 is the Saito as viewed from BEHIND.

What I did was:

1. Check timing on cylinder 1 @TDC cyl 1 > timing was OK
2. Rotate crankshaft in prop direction (clockwise when viewed from behind) by 240° to TDC cyl 3 > set timing.
3. Rotate crankshaft in prop direction (clockwise when viewed from behind) by 240° to TDC cyl 2 > set timing.
4. go to bed.

Is that correct?

Thanks ,
rev

Reverend

My Feedback: (3)

Nope, not when you look at KMOT's FS400AR thread. Check out the 400 Radials we had to deal with there. THAT is rust This is mere flashrust

But truth be told I have already ordered the bearings and plan a complete teardown of the engine in the cold months ahead. I really want to see whats inside and after the very successfull teardown and rebuild of the fs400ar I am really confident I can do this one too. There is no report on that subject yet so maybe if I document it it will help fellow modelers to overhaul their engines as well just like KMOts thread helped me.

heres some pictures of my fs400 crankshaft before and after the rust treatment.

Rev

Reverend

My Feedback: (3)

Yep, 120°. As for the Nitro, after what I have seen timingwise I will give it another try with 0%[>:]

Carosel43

If saito are using 120' thats pretty poor as the crank pin, link pin and gudgeon pin wont all line up at tdc which is hardly ideal. oh well. as for your timing there are timing marks on the cams and that silver thing on the crank