.051 Slit Exhaust Cylinder Confusion

Iceberg wrote:Just was going through a big box of parts and came across a cylinder and piston together. I saw the piston was an .051 piston with the machined ring around the bottom. It fits into its cylinder. The cylinder is a dual port but single booster slot per side cylinder (like the sure start #7).  Didn't all #4 and #5 cylinders come with dual booster slots? I am a bit baffled. Is this just a strange anomaly or did more of these #5 cylinders get produced? The cylinder is the slit exhaust type too like the Sure Start..

Thanks
Iceberg

Iceberg:  Possibly something homemade from leftover blank cylinders purchased from old Cox employees as they were , ah, how do I say this, let go, or asked to retired, or FIRED as ESTES took over. Been there had that done to me, but worked for government contracts so wasn’t able to fill my pockets on the way out.

   Sometimes companies asked the employees to take as much as they wanted as they left, sometimes.
Most likely the cylinders were made from blanks purchased on eBay. Some were for sale a few years ago, but it was a large lot of 500 or so and I couldn’t afford that much at the time, or now either.

   Someone else may have a similar comment.


P.s. to davidll1984: If I am not mistaken a .05RC is actually a .049 engine with RC, see hepperle reference


Happydad.                                

The 1 booster with 2 bypass setup was used for later 049 and 051 Tee Dees. The asymmetric boosters add a spin to the fuel charge and the cylinder is thus said to have more efficient fuel burn that brings equal or higher performace than old stock No4 &5 cylinders.

All TeeDee 949 cylinders sold by Bernie and Matt originate from slit cylinders that have the singleboost port, but the center bar in the slit exhaust is removed and the bottom of exhaust port lowered to have SPI

Not sur dont have a.5 tee dee To compare To to 049 but tink is som info on rc.5 use piston with the ring try piston in 049 cylinder if it fit ?? Or Not rc engines dont use spi with pipe exaust spi wit rc ring only

David the bore and stroke of .05 and.051 TeeDees are the same. The only difference is the .05 cylinder is non-SPI in order to allow the use of a muffler without its negative impact. 05 TeeDees have lightened crankshaft with a hole drilled in the crankpin to somehow make-up for the performance loss by the non-SPI cylinder.

Double posting deleted..

I got studying the cylinder lists. The .051 is a NFFS Special .051 Medallion cylinder. The one that only 258 were produced. Someone had removed it from the block and I ended up with it. Does anyone have any performance figures? Or would it be basically same as the standard .049 Medallion?

Thanks
Ice

My NFFS .051 runs just like the .049 . If your cylinder and piston is in good shape it might be worth a few bucks to some one who needs it to replace the one on their .051 NFFS motor . It could be a fake like some one bored out ( honed ) a .049 cylinder and stuck a Tee Dee .051 piston in it . With out the original crank case it really is just another .051 cylinder and piston . Kind of hard to tell without comparing it to an original NFFS engine .Most people that fly this event like a bigger plane and engine for this class and only a few people still use the .051 Medallion .

Mike1484

wat the groove on piston look and tink old .051 is taper cylinder piston dont past tdc tink nffs cylinder is Not taper piston can go tru cylinder exit on top rc.5 too y have 1 new nffs.051 piston it dont fit old 051cylinder the 051made in 70 y have a number 2 on crankcase

I have one of those assemblies too. I don't know anything about it except what I've learned here.
I bought it from Bernie a year or two ago, he didn't have any firm info on it.  I think it might be a NSSF replacement part, but I haven't had any luck figuring it out for sure. Not tapered, non-SPI, same porting as described.  

I don't think it's from a TD RC .05, the cylinder on the 05 I have isn't blued below the bottom fin and doesn't have the Sure Start slitted exhaust.  The porting on my 05 is the standard TD four boost ports.

It look like 1 Dave p u have a discarded cylinder and piston Not spare part no spare Part for nffs médalion just discarded part du To cosmétique ou look like a broker fin on top no slot for tool and just by its look tru cylinder port piston grove cant se Perfect but it look like 1 as Dave say piston cylinder Not tapered just like rc engines