How can one get a real world comparisons of how a given engine compares to other engines of the same size? We know that manufacturer numbers are almost useless.
I bought my first 4S engine a few months ago. Its an ASP 65. I did a search on this engine and as usual some say its a strong engine and others say its not. Ive run almost a gallon of fuel through it and its able to turn an APC 12-6 at 10300 rpm steadily with a lot of smoke coming out. I can get it to about 10600 with less smoke but it will not maintain this RPM. But I don't know if this is good for this sized engine or not. Where can I find practical numbers for given engine sizes and props to compare?

Thanks,
~Jay

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I would change the prop to a 13x5 or 6. Try to keep the ground rpm below 10k rpm to provide some latitude for gaining rpm once flying.

I'm not saying that you will damage the engine by running it that fast, but I don't think that you are getting the best power and throttling characteristics out of the engine with a .50 sized prop.

I have heard good things about ASP engines, generally. In fact, I just bought one of their 1.80 engines. Haven't ran it yet, but I'm moving in that direction.

I had a ASP 65 at one time. They have been replaced by the 70 which shares several components

My ASP 65 had considerable more power than my Saito 65 mainly because the valves and carb are bigger.

I liked the engine very well for a 65 four stroke.

I'm not sure how the smoke thing works I have a asp 52 4 stroke turning a apc sport 13x4 at 9800 it's on a funfly that never sees full throttle except going vertical and no matter how rich I run it it doesn't put out much smoke so little in fact you really have to look hard to see it in the air even if it's so rich it is way down on power
So I run it maxed out on rpm then richen it till it drops 500 rpm with about 1/4 in it the tank and the plane held up vertical not much smoke
I was putting it on a new plane last week so I pulled the head to look it over and everything looked great a nice golden brown with no deposits
I think with todays super pressed castor and better oils there's just less smoke I run omega 15
now my son in laws satio 82 smokes pretty good on the same fuel not sure what the difference is other then I use a tach and he doesn't which I've told him would be a good idea.

Ski, I have at any one time about 17 Saitos, there does not seem to be a rhyme or reason as to why some some smoke and some don't. Here is my old High compression .80 running inverted and no smoke, then my 1.00 making plenty.

My enya 46 4S turns a 12/x6 at 9400, but I think these engines are among the most powerfull ever made.

Both a friend and I have OS 91 Surpasses. They are just alike and with the same prop and fuel

His will not smoke unless set too rich to fly.

Mine still smokes when set correctly.

Jaysbird, that 10,300 sustainable figure is pretty impressive. My OS .52 Surpass does somewhere in the high nines on that same prop.

What are your performance expectations?

I try to get my 4 strokes in this range to be around 9800rpm or so (maybe 9799 or 9801 but you get the idea). 10k rpm is spot on to revving that engine up. No damage or anthying like that, they are likely safe up until 12k (per the instructions I imagin) but there's no need to go that high with a 4 stroke. If you're getting between 9 and 10k rpm you're probably pretty good to go. I would suggest as others have to try a 13x6. My magnume 61 4 stroke pulls that pretty well at 9300 rpm. My OS FS-61 pulls a Zinger (wood) 13x5 prop at 9800 rpm and it's over 20 years old (on 15% fuel).

4 Stroke performance and 2 stroke are very different so it takes a little adjustment in attitude between the two. Since I've been using mostly 4 strokes the last few years I've completely shied away from 2 strokes mainly because of how high they rev. Its just frightening some times...makes me not want to get near them (which is good I guess) but a 4 stroke I'm more comfortable with.

Hobbsy. Why is the picture of the 100 so sharp and crisp??? Isn`t that engine supposed to shake like c..p

Must not be shaking? If he used a fast enough shutter speed to stop the shake, it would stop the prop also.

My conclusion is that the engine is not shaking.

I was just joking and was thinking about the thread "DO ALL SAITOS SHAKE LIKE C@#P"

Asmund, my PSP is rubber mounted so it could shake if it wanted to but it is as smooth as silk. Anybody that tells you that a Saito shakes doesn't have it set correctly, or they have it on one of those planes with a non existent fuselage. My 2.20 shakes a little between 3,500 and about 4,500 but it is probably at the upper limit for the rubber bushings.

Sorry about that, as I said I was only making a little joke. I don`t believe that Saito`s shake more that anything else myself. Not many Saito`s around here, but a friend have an old(15 years) 80 that is just as smoot as my mag 91

No apology necessary, keep right on jokin, a little levity is needed here from time to time. I see many posts on here that bring a smile and a shaking of the head.

Actually they don't shake much with one exception - the ------- 1.00. I too have heard conflicting stories on this but my personal experience is that they do shake a lot - I have 2 of them both around 3 gallons old (15% Nitro / 20% oil mix) have tried a heap of different settings on the fuel needles but they both shake more than the other Saitos in my hanger (.56's, .65's, .72's, .82's, .91, 1.20's 1.25's & 1.80's). they all run exceptionally well - except for the shake on the 1.00's. and yes I do balance my props, spinners etc.

I have two 100's and they are as smooth as any of the other 14 Saito's I have.

I have a friend and his 100 shakes

Don't know what the difference is.

Yes - I also know people with non shaking 1.00's I wish I knew what the difference was too. I have even had them try tuning for me but they still shake. It seems that it is a pot luck thing - I bought both of mine at the same time for a project a year or so ago and I guess they both came out of the same pot. They seem to run smoother once the revs get above about 3500.

I have now put the two 1.00s in a semi scale B25 where the low speed shaking kinda complements the scale nature.

I'm still addicted to my Saito's though - in fact all of my personal sport planes (as opposed to the ones that the two teenagers fly or the competition planes) are powered either by Saitos or Gassers (50cc and above). I let the teenagers use the other engines, but they have Saitos too.

Stange, my fl 70 doesn't smoke at all unless it is to rich to fly, but when i drop it down below half throttle i nice streak of smoke comes out. It is kind of wierd because the midrange doesn't feel or act rich.

Thanks for all the responses. All very good info (got a little off subject with the shaky Saito stuff but its OK........ Its all in fun)
Anyway, the reason I mentioned the amount of smoke it made was incase those of you who are familiar with 4S engines might realize the engine is set rich,and not quite broken in. So if 10300rpm was weak that could be the reason why.
The engine is going to be used in a .50 sized Zero warbird. I wanted a 4S for the sound and I'm willing to sacrafice vertical performance for speed.
Artisan, I will try the 13-6 prop, but would I get the same effect by going up in pitch instead of diameter? (as a side note,I originally had a MA K-series 12-6 prop on it because it looks better but I could only get 9600 rpm out of it.The APC out performed the MA by 700+rpm!)
Another issue is because of the short nose of a Zero (and probably because its a cheap ARF) I had to add a whole pound of lead to the nose to get it to balance. AUW is 7lbs 8oz. At this point buying a bigger engine is not an option but I wanted to get an idea from some experienced 4strokers how this engine compares to others of similiar size and if it has enough omph to pull this weight.
And finally maybe those of you who have several engines (2s &4s) might create a reference post with practical rpm figures of what your engines are capable of with different sized props. That way when a modeler like me with no experience with 4Ss will have a real world reference to compare the various engines that are available.

Thanks again!,
~Jay

I've used up to a 10x9 APC prop with my 61 4 stroke but that was on a 6 or so pound spitfire. I would suggest that if you're looking for speed you head down in diameter and up in pitch (which you already know).

So instead of a 13x6 maybe an 11x9 or 10x9. Props aren't expensive in those sizes so experiment and let us know how it goes.

CORRECTION....(to my previous side note comment on post#20).....and with apologies to MasterAirscrew. the MA prop I had on my engine was a 12-9 and not 12-6. So it was an unfair comparison with APC. Now I think I will try the MA 12-9 since 9600 rpm may be in the optimum power range for this engine and has plenty of pitch.
I will let you know, Submikester and others, how it goes.

Wayne,


It is hardly so. This prop (I suppose APC) at this RPM is just 0.64 HP actual output.

The Enya .53 4C was notable for being exceptionally powerful; not the .46.

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Too much caffeine in the fuel?

Unfortunately I wasnt able to get any flight testing with this engine. I took the Zero out for its maiden today but there was not enough toe-in on the mains and I couldnt get a good take off roll because of ground looping. I tried to bend a little toe-in but must have compromised the gear blocks because the right side gave way on the next attempt. The damage is minor but I could feel some cracked and/or loose wing ribs that will have to be repaired. It may be a while before I can get to it as I'm so busy these days. However, the ASP really ran and idled good. Hopefully I will be able to repair the plane soon and see what this engine will do.