I have a couple of Enya 15-IV engines that used to be RC. I fitted them with venturis and ST G-51 C/L
needle valve assemblies. They fit just fine and the hole in the spray bar is just a little bit off center.

They run ok with the ST NVA's but I noted that the hole in the ST G-51 spraybar is larger than that in
an OS spraybar for FP/LA 15's and 20-40's. I have to be extra careful not to flood the Enya 15-IV when
starting on the test stand. I don't have an Enya spray bar to compare with.

So what effect does the size of the hole in the spraybar have on engine behavior? Should I be concerned?

Thanks,
Chris

       Chris, I've used the Enya 15's extensively. I can say first hand I have good comments and negatives. On the plus side its a powerful engine but it does have its attitude problems. I was using the 3303 model 111 at first. This is where I learned about the spraybar problems. I was using the needle and bar for the FP.30-40 size. This caused problems all over the place. It was not getting enough fuel due to the bar taking up too much venturi room. I initially thought this was the over restrictive muffler. I drilled it out to the max then initially went with the tongue muffler. This helped but didn't cure the problems. This engine really ran away towards the middle of the flight. These engines like to run fast to begin with and I was using a APC 7x6 and would really let it wind. I then came in inverted one day which damaged the needle and I purchased a new one. I went with the FP.15 size OS needle this time and things improved 100%. I don't recall the diameter of either spraybar, but it was a distinct difference just by looking at them. I currently run the IV 3304 now. This engine has differences such as no casting obstructions in the exhaust port and a slightly larger cylinder head as well. I'm using the Enya needle in this particular one. I would say that there is a chance that the size of the ST needle could ultimately have an effect on your performance due to the large spraybar. If its working for you fine but I've had to file a flat on the one side of the bar to lessen its diameter in other engines. The other and probably less risky option would be to open the the hole up in the venturi a few thousandths. Without having your exact size of spraybay and venturi diameter its all but a guess. I also learned that the engine was much happier with 10% nitro and higher with a 20% castor content. I was using 25% and greater which caused some pretty heavy carbon deposits. I believe this was quickened by the engine getting very hot at times. The Enya instructions suggests the use of 20% oil content. In the event your searching for a tongue muffler a Randy Smith type for the Fp.40 is pretty close if you carefully line it up on the stack. I opened the holes to 7/64 and didn't drill any additional ones and was able to use the stock muffler strap. I truly believe the engine would run much better with a good uniflow system. Most of my planes with the short nose wouldn't allow for a tank I wanted. On my next one I plan on mounting a plastic uniflow setup on the inboard doubler. Ken

Ken,

Thanks for sharing your experience with the Enya 15 engines, it is really helpful.

I'm using an Enya 15-III venturi, part number 15321. The ID seems to be 6mm - didn't use any precision measuring tools, tested with a couple of drill bits 15/64 was a little loose and 1/4 too big. The ST G-51 spray bar is about 4mm. From the Enya web site it looks like the 15-V venturi options are 6mm, 6.7mm, and 7mm. I've only run these engines on the test stand so far, but have been using PowerMaster 10% nitro 22% oil (half castor half synth). I've also got OS A3 plugs in them. I'm now thinking I should bore out the venturi a little bit but may wait until I can get one or both engines in the air and see how they go.

As far as the flooding goes, I think the ST NVA closes down ok. The flooding when trying to start is probably just my being not familiar yet with the Enya 15's. I just want to choke and flip them as much as I would one of my larger engines.

These two Enya 15-IV's are headed for a twin, but I haven't yet decided on which or what just yet.

Thanks,
Chris

The O.S. 15 ones (holes) are to small for .35s
and 1/8 copper plumbers tube for tanks is to small for .40s

AHA . Here in the antipodes , Colonies etc
PLUMBERS SUPPLIES  have THICK WALL copper tube.

BORE is approx. 1/16 th In.
OK for a G-15 FI . not as fragile as the

THIN WALL K & S  tube , whose bore must be 3/32 or thereabouts .
Making it twice the cross sectional area,

Theres static drag on the wakks of a tube making the effective Dia. about 90 % .

If you like chasing your tail , try the thick wall on a 40 FSRS.
She leans of above half hight. amongst other things. And adds to the grey hairs .

Sorry for the confusion as to BORE .                                                                        Matt.

( Wouldve sworn id used large bore in that tank. Too many late nights . Pays to have a check list )