SpinnerRow

Is this a decent RPM for this motor with about 32 ounces of fuel through it?

Engine: Super Tigre G-51 Ringed
Muffler: Stock
Fuel: Ritch's Brew 10%, 11% Synthetic / 11% Castor
Propeller: MAS Beechwood 11x6
Conditions: 70 degrees, Elevation: 620ft
RPM: 10,700 slightly rich

What could I expect with a quiet tuned pipe and header with this engine? I'd like to be able to turn a 12x4 well above 12,000 with a pipe. Is that too optimistic?

rainedave

My Feedback: (1)

SR, I have a used G.51 I will test with some 11x6's and see what I get.

In the meantime, take a look at what my G.45 did with various 11x6's:

http://www.rcuniverse.com/forum/fb.asp?m=8189268

The G.51 has different porting/timing than the .45, so it may not be a good comparison.

David

Hobbsy

My Feedback: (102)

SR, my early SuperTigre .51 has always turned a Graupner 12x6 at 10,500 on Fox 5% with 20% castor. Your numbers are good. As a Diesel my .51 turns a 12x6 three blade at the exact same rpm.

rainedave

My Feedback: (1)

SR, I ran and tached my Italian G.51 today. Here's what I got:

temp: 77°
Powermaster GMA 5/22
K&B 1L plug
APC 11x6
12,679
6.35lbs. static thrust
1.13hp

For comparison's sake, here's what my ST G.45 did with the same prop and fuel:

12,853
6.52 lbs. static thrust
1.18hp

David

SpinnerRow

I'm going to try an APC 11x6 tomorrow and see what I get. You're getting close to 2000RPM more than I am. That is a HUGE difference. Will the prop make that much of a difference?

I ordered a MACs pipe for it and I have a quiet tuned pipe that I'm planning to use on it. It will go on a 4lb Little Stick.

How are you guys calculating thrust? Is there a site some where that will tell you?

rainedave

My Feedback: (1)

Yes, Pe Reivers' spreadsheet:

http://www.mvvs.nl/prop-power-calculator.xls

David

rainedave

My Feedback: (1)

I went back and read your first post again. 32ozs is not much fuel for a ringed engine, that's only four 8oz tanks... hardly enough to even begin breaking it in.

Don't peak the engine until you have more time on it. Here are Clarence Lee's ringed break-in instructions (in a letter he wrote me). If anyone alive knows how to get the most power out of a ringed glow engine, it's him. Be patient. Your engine will break 12,000 in time.

David

SpinnerRow

Man, what a difference a prop change makes!

12,520 on an APC 11x6
13,540 on an APC 12x4

Still a bit rich. it went lean real fast with the 12x4 and I think I saw 13,750 on the tac with the 12x4 but it was way too lean. Hope I caught it in time.

Conditions today: 64 degrees 98% humidity (rained the last couple of days)

That 12x4 isn't going to be the prop for me afterall. I think an APC 12x5 would probably be perfect on a pipe. Now if I can get 13,500+ on the APC 12x5 and pipe, that will be quite beastly enough for me I'm sure.

Nice, inexpensive engine for sure.

rainedave

My Feedback: (1)

Glad to see it's running well. Please keep it rich for a gallon and it will continue to get stronger with each flight.

David

MetallicaJunkie

the ST 51 is an underrated engine, i have one in a H9 Tango with a 12.25x3.75 apc and it has unlimited vertical

rainedave

My Feedback: (1)

MJ, that's interesting because APC lists the 12.25x3.75 as a C/L prop and I've always suspected that the G.51 was originally developed as a C/L engine.

I bet it would do well with any of the bottom three props listed here:

http://www.apcprop.com/SearchResults.asp?Cat=15

David

MetallicaJunkie

hey thats great, i didnt know those size props existed... the 11.5x4 looks to be another good 3d prop, and the 11.5x6 for nice sport flying thanks

rainedave

My Feedback: (1)

I bought one of the 11.5x6's for my AX.55. 11x6's seemed too small and 12x6's were too big. I haven't flown it yet, but I'm hoping it will be the "Goldilocks" prop for this engine.

David

SpinnerRow

Interesting that you guys are talking about the APC 12.25x3.75 prop. I went to the hobby shop today to get a 12x5 but they were out and I ended up buying the 12.25x3.75 APC instead. If that one ends up working out, I'll have to get taller landing gear to use it. The MACs header for this engine should be here tomorrow or the next day. I have about 48oz through this engine so far and once I hit close to a gallon, I'll put the pipe on it and see what it will do. I'm really impressed with it so far. It seems to have really good transition (low end tuning took some getting used to) and the response is really good. My Little Stick is going to love it I think. I'll get some numbers for the 12.25 APC this weekend and post those up.

SpinnerRow

Final numbers are in. 72 degrees and 98% humidity - been raining off and on all day.

G-51 with about 96oz of fuel through it:

Stock muffler and APC 12.25x3.75: 12,200
Stock muffler and APC 11.5x6: 12,180

Macs 2961 header and an old disk type quiet tuned pipe:

APC 12.25x3.75 - 13,170

1 inch off the header:

APC 12.25x3.75 - 13,700

5/16" off the header:

APC 12.25x3.75 - 13,910

1/4" off header

APC 12.25x3.75 - 13,980 with a lean pinch just over 14,000

Geez, that is insane with close to 10lbs of thrust! I can pretty much swap the 11.5x6 with the 12.25x3.75. Numbers are close to identicle with the 11.5 being 150 to 180 behind the 12.25.

I may need to go back and do some re-enforcing on the firewall of my 4lb Das Little Stick!!!!

here is a pic of the Little stick with an OS46AX on it but I'm going to put this 51 on it.

Thoroughly impressed with this engine. Very good slow idle and a decent transition.

rainedave

My Feedback: (1)

Very impressive numbers! Yeah, I would epoxy some triangle stock behind the firewall. And, go over all glue joints; make sure you have the wing center section wrapped with glass cloth, etc.

I put a pipe on my Super Tigre .40 Bluehead. It's already turning a 10x6 at 14,111 with a stock muffler:

http://www.rcuniverse.com/forum/fb.asp?m=8181884

With the pipe I expect to break 15,000. It might be interesting to lengthen the header and see what it does with an 11x6, too.

I had to send my Canon camera in for service, so this is a poor quality cell phone photo.

David

SpinnerRow

What is significant about a Bluehead because 14K on a stock muffler is rockin'!

The plane already has a glassed center wing, glassed firewall with triangle stock and a slather of epoxy all in the fuel hatch so I'm hoping it is enough. I'm using an 8oz Kirklands water bottle for a fuel tank. They are short and fat and exactly what I needed after I cut 3/4" off the nose of the plane when I was building it. Can't wait to fly it.

rainedave

My Feedback: (1)

Sounds like you got it taken care of.[8D]

These engines were also sold with natural aluminum heads. I'm not sure what the difference is because I've never owned the natural version. My OS .40FSR does about 13, 500ish with its stock muffler, so the Bluehead is definitely a strong runner. The more ST's I own the more I like them.

They also made an X.40 rear exhaust that I'm sure is a screamer. They are hard to find and sell for quite a bit. I wish I had one.

Here. I found one on the auction site: 300307138535

David

downunder

AFAIK the G51 RC engine came out first and then the CL version which has a different liner with lower exhaust timing. The CL version has the exhaust opening at 70 BBDC while I believe (never had one to check) the RC is about 74 BBDC. Maybe sometime I'll fit an RC carb to mine and see how fast it'll turn similar props. I won't be using nitro though .

rainedave

My Feedback: (1)

Thanks DU. Here are photos of the two parts, r/c on left, c/l on the right. They have different part numbers, too.

The exhaust ports look taller on the r/c sleeve.

David

tony0707

hi the super tiger 51 has amazing power-   as big an engine as you would put into a 40 size plane-  i broke my 51 on an 11-5 apc by total mistake-it took me 5-6 tanks of  15% to get it to idle and run-but wow does it run-it comes close to power in some of my 61 engines  -i always remove the baffel and match the exhaust port to the muffler -by grinding the muffler out-and making the exhaust exit a bit larger-on all glo engines i own- she turns 13,200-13,400 rpms-TRY IT YOU WILL LIKE IT-that is on a stock muffler

stuntflyr

I have heard of several people using the R/C version of the G51 in CLPAas well as those using the CL version. The 12.25x3.75 propeller hascome to be a "magic" prop for several different engines in CLPA aswell. The stock CL G51's often need to have a couple of head shimsadded for lighter models as they are known as power houses and showit.

I wonder why the engine has a bad rep in RC? Is it that they aren'tbroken in carefully or possibly the 20 to 22% oil isn't adhered to?

I just bought a used one for 25 bucks for my son's BH Spitfire 40 andintend to use a Pitts-style muffler so reading these positive toastsare good to read. He'll want more speed so we'll use an 11x6 or 11x7maybe even a 10.75x7 or 8 if it'll turn it happily because he wantshigher airspeeds. We'll do a little prop testing to find that happyengine/airframe/propeller combination.

I can't wait to see how this bargain G51 does!

Chris...

SpinnerRow

I have flown my 4lb Little Stick with a G-51 and pipe 10-12 times now and it is a super fun combo. It has rocket like vertical. I may buy an ESComposites pipe for it to take 3-4 ounces off of it to get it sub 4lb. Not that I need the weight off of it but I just want to try a carbon fiber pipe!

It is hot down here in Texas but this morning I tached it at 13,800 and it cranks right up no problem, idles really good and low and has good transition.

Super Tigre G-51, header, pipe and an APC 12.25x3.75 = Killer Combo

I also have a GS-45 with a Jett Stream muffler on it and that engine is a little screamer as well. It isn't quite broken good yet but it is getting better each flight.

I'm loving this inexpensive little engine.

tony0707

hi getting 12,800 RPMS from my ST 45 -on an 11/5 apc- stock muffler-  no baffelthis 45 is a screemer-and not yet broken inmy 51 and 45 are both the italian engines-hard to beat for the dollarsthe needle valves are very sensative on these engines-so a little harder to dial in -but once you get it you have a TIGER on your handsi do not at all care for the power output of the 61 i had -and know nothing of the 75's performance