Kmot

My Feedback: (24)

The airplane looks great! The multi-mufflers have to go, for aesthetic purposes.

My FS400 ran great on, get this, Tower Hobbies glow plugs. Which I believe are just standard OS two stroke plugs without the OS punched into the case. Well, it ran great as long as the plugs were heated by battery power. This is when I blew all the original OS "F" plugs at once and needed something to start and run the engine with.

Carosel43

Cheers tom, the red is more of a blood red than the camera shows. I think it got confused by the shiny finish and the light was poor. In any case im quite happy.

As for the tower plugs i wonder if they are os no8's. i ask because laser 4 strokes will apparently run on 2 stroke plugs very well. i know many come back for service with two stroke plugs. I have never tried personally so cant really comment

Reverend

My Feedback: (3)

Right, swapped six plugs, finished the collector ring (tried something new with it ) and put the engine back on the stand. The collector has not been cleaned yet and will be sprayed in high temp zinc.
when everything was finished it was quarter to late but I could not resist giving the engine a quick flick in the workshop.

1. with the OS plugs it started on the first flick and idled perfectly on the "factory setting" (needle flush with throttle arm and then 1/2 turn in) All three jugs fired even after disconnecting the glow @ 1100 idle.

2. I did not go over 1/4 throttle seeing wife and kids are asleep and I do not want the third world war to start in my home.[&:]

3. The Saito sounds absolutely ÃœBER-EVIL with that ring [>:] !!! I changed the exhaust to a kind of trumpet shape that gets wider toward the exit... What an evil deep grumble the engine has now. I HAVE to record that cause that is the kind of sound I could actually make .... to .
Hope to find the time to run it outside soon

Carosel43

rev you tease, telling us about sounds we cant hear! as for your rpm i think the best got was 900 idle with no glow support, but to be fair its always been the top end i have had issues with. i look fwd to hearing more!

Reverend

My Feedback: (3)

by special request

again, quarter to late, family asleep so only a short idle passage. Sound is not quite as good as in real. Video done by iphone and the mic sucks. []

[youtube]http://www.youtube.com/watch?v=pGR3uJnxm2k[/youtube]

SrTelemaster150

That's why I would convert a 450R3 to Electronic ignition even though I would retain the glow fuel for more HP than gasoline.

Carosel43

ooo rev, sounds nice! i look fwd to a full throttle report now! also yourexhaust is pretty cool. do you silver solder them?

SrTelemaster150

Yes $300 is a lot of money, but subtract $55 for 6 OS type "F" plugs & another $35 for a good quality glow harness & the cost difference is cut to about $210. That's about 11 gallons of fuel for the harness scenerio, about 1/2 that for onboard glow. Given the 25% better fuel economy of EI over glow ignition & figuring a conservative 3oz per minute fuel consumption rate on glow ignition, it would take about 40/20 hours of flight time to break even on fuel savings alone depending on if one employs a simple harness set-up or onboard glow.

It would take an entire season of extensive frequent flying to realize the cost savings over the harness set-up, less for the onboard glow.

Over the life of the engine, the savings would be substatial in either case

IMO, onboard glow is not relevant whan EI is not that much more, requires a lot less battery weight & improves HP, user friendlyness & fuel economy. A harness is somewhat less difference in lifetime savings & would take longer to realize a cost savings overall, but it is still substantial over the life of the engine.

Reverend

My Feedback: (3)

...and then you crash the darn thing after 3 hours flighttime [&:]
I have learned to think more in short terms.

But thank you for your input.


@Carosel: Does your 450 have the old or the new saito plugs? The new ones have "Saito SS" Stamped on them, the old ones do not. The old ones are absolute rubbish. I had them in my 450 and tried them in a normal FS-91 and a Laser 100 and the engine wouldn't even start [] The newer "Saito SS" fom my FA90R3 work in the OS and the Laser.

Rev

Carosel43

One thing thats been forgotten about the CDI tweak on the 450 is that its twin plug, so will you have to use 6 cdi units?! if so then clearly its far to costly. Even if you go for one plug the cost of those little spark plugs is very high. Also my glow driver thing cost about £50, so if they did a 3 pot cdi for say 80 or 90 then i would do it no questions asked. but right now i just dont think its economical.

As for my saito plugs they are ss types. if these are better then i dread to think how the others were!! in any case, are the F's better than the ss's?

SrTelemaster150

No need for 6 spark plugs, you just use 1 plug per cylinder. I save old burned out glow plugs to use in the other hole. My 300TTDP is a "Dual Plug" engine hence the "DP" suffix. (I clip the post off to identify burned out plugs) You can't use "live" glow plugs or one would loose the timed spark advantage as the engine would then have glow ignition on top of the spark. After the initial start up on spark, the engine would revert to glow ignition once the live plugs became lit.

The $12 Chinese plugs have actually performed a bit better in my Saitos than the Rimfires W/better idle & perhaps just a little better top RPM.

Cost of a 3 cylinder CDI. $315 total

Trigger ring= $30
Hall sensor $8X3=$24
Module $75X3= $225
Plugs $12X3=$36

C&H has been looking at developing a unit similar to the one on the new Saito FG84 gas version of the 450R3. It uses 1 hall sensor W/4 magnets. 3 for triggers, 1 in reverse polarity to "sequence" the spark from 1 module.

[youtube]http://www.youtube.com/watch?v=lwCd76ZBtOE&feature=player_embedded[/youtube]

This system would be more cost effective than 3 seperate single modules as well as somewhat lighter & simpler, but the drawback is that if the module goes, it would be a bit more expensive to replace than a single $75 module.

SrTelemaster150

When are we going to hear some WOT runs?

BTW: I love the FW 109-A fan. At 1st I was wondering if you had some sort of flywheel on the prop.

jaav

Well I had a bit of a teary eye tonight as I put my old friend into a box ready for recycling..Thought of the good time I had listening to the roar fo the multi cyls...
Never did get to test my new multi OB glow system I designed and made.... Still thinking about the 55cc twin to replace the 400..

What is the power diference between GI and SI engines with the same swept cyl capacity? I seem to remember that the Glow (GI) engines make more power than sparkies..

SrTelemaster150

That power difference is most likely due to the lower octane of gasoline over glow fuels. That factor require less aggressive spark timing and/or lower compression. When glow fuel is retained W/CDI ignition there is usually a power gain IME.

My preliminary tests W/an FA150 showed a 150 RPM advantage W/spark ignition running the same 15% glow fuel. I did not experiment W/more spark advance beyond the 28* initial setting. Further testing W/E-85 on spark ignition showed an additional 200 RPM gain when the ignition timing was advanced to 35* BTD fro the intial 28* setting.

My last test session W/an FA91S showwed that maximum HP was realized @ 36* BTC ignition timing. The little 91 gained 200 RPM on spark ignition over glow ignition on the same 15% glow fuel.

You can read about in [link=http://www.rcuniverse.com/forum/m_11163452/tm.htm]this thread on CDI ignition conversion results[/link]

I see no reason to think that a radial engine wouldn't see similar gains.

Reverend

My Feedback: (3)

Good morning gentlemen,

I managed to take both engines to the field yesterday and rev them up without the inhibitions towards my neighbours

The good:

The FS-400 is running the way I want it to. It is turning the APC 20x10 @ 6750 rpm. I can live with that given the fact that APC props tend to eat some power. Like the transition, like the top end and LOVE the idle [>:]. The Ecomrc Wedell has been pushed to late October and I need an airframe to put that engine in so I called up a flying buddy and finally made a quite good deal on an aeroworks stearman. He flew it with a saito. I think the 400 will so just fine.

[youtube]http://www.youtube.com/watch?v=QDSzXxOHVAY&feature=g-upl[/youtube]

The not so good:

I ran the 450 too and was a bit dissapointed at the revs I got. 5750 from a 22x10. I tried just about every trick I know but it was not possible to get a singe rpm more out of the engine.
On the way home it hit me. My ring collector lacks a preasure nipple and to make things worse I had blocked the ventilation nipple after swapping the engine for the 400 on the stand. I am sure I am loosing some RPMs there as the engine has to suck fuel against a vakuum. Also want to try a 22x10 APC because on the 400 the 20x8 Wooden Prop gives 800rpm less than the APC Prop with the thinner blades. I thought of something else in the car too. I am not qite sure if that FW-190 spinner backplate with those litte blades isnt eating power too. Can't be much though.

[youtube]http://www.youtube.com/watch?v=xYTogArP5pQ&feature=plcp[/youtube]

To be continued

Rev

Carosel43

Hi Rev, the best i have ever achieved on a 22x10 using the 450 was about 6500. even on a 22x8 i cant get over 7000. My prop of choice right now is a 21x8 menz (same as the 400) and as the weather looks decent i think i may do a few runs today or tomorrow as i only gave it a little run last time. Rpm on the 21x8 is 6650 for the 400 and 7200 for the saito. The engine pretty useless below 7000rpm

Reverend

My Feedback: (3)

we are doing something wrong. A friend of mine has his 450 doing 7.200rpm on a 19x12 THREEBLADE! Thats almost 5,7bhp. I am barely getting 3,1bhp. Apart from that mine simply SOUNDS wrong.
Listen to that F5F bearcat on YT with the 450. That is how it should sound.

I bought my engine used and am slowly taking into concideration, that the previous owner had the engine apart and timed it wrong on reassembly.

I think I will have to tear the engine down in the long months of winter.

SrTelemaster150

I find that odd as my 300TTDP swings a 22 X 10 XOAR @ 6500 & a 22 X 8 standard Zinger @ 7100.

Even factoring a few hundred RPM fbnoost on the 300TTDP or the EI doesn't really compare as 50% more displacement for the 450R3 should still be able to beat that by a significant margine.

SrTelemaster150

Is the FW 190 fan pulling your engine down?

Maybe you should try it W/O the fan just to level the playing field as far as props.

Carosel43

what nitro is everyone using though? im using 5% and am getting 4.3hp. to be honest i think thats pretty good as the quoted 5.5hp will be at about 8500 rpm i expect. also if i swtich to a 22x8 graupner gsonic i get about 7400rpm, but that prop is far too noisy inflight. so the menz 21x8 @ 7200 is good for me at the moment. i just need to fly it a little more

Also check this out, not many people are doing any better http://www.rcuniverse.com/forum/m_33.../tm.htm#333408

Kmot

My Feedback: (24)

Rev, your 400 sounds amazing!

Carosel43

agreed! also the 450 sounds like mine, hunting for rpm, it wont sit still. Tomorrow im going to give it a go, see if i can get something decent out of it!

SrTelemaster150

Ah, 15% Cool Power is what I use.

That might make some difference.

Also, what was the density altitude like when you did your tests?

Hot, humid conditions can reduce power output significantly even if the prop has less dense air to bite into.

I saw a 200 RPM drop from a cool (high barometric pressure) low humidity day (high DA) to a warm muggy afternoon.

All props of a given diameter/pitch are not equal either.

When I do comparisons for GI/EI I do the runs on the same day W/identical props & try to make the runs in close succession so DA does not change significantly.

I'm still curious to see how much that FW 190-A cooling fan on Reverends engine will contribute to RPM reduction. It might be significant.

SrTelemaster150

I also wonder if that large diameter ribbed collector ring is inhibitting gas flow.

I see many motorcycles W/wrap on the header pipes to keep heat in to improve flow velocity. Is a cooling affect from the ribbed collector doing the opposite?

SrTelemaster150

A bit of cam timing advance could account for your exceptionaly good low RPM idle performance & poor top end performance. 1 tooth on a 48T cam gear would be 15* advanced.

High performance aftermarket automotive timing sets have +or- 4* advace/retard capabilities built in to shift peak performnce RPM a bit. 15* would be a LOT of cam advance though. I'm n ot sure the valves would even clear the pistons @ that much advance. If it was 15*retarded, I don't think you would have the good idle performance you have.