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What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
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What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
As the title says, what are the differences between the Cox .09 TD and Medallion pistons/cylinders? Note, I am asking about the .09, not the .049. Thank you in advance to all you Cox enthusiasts.
mnarigon- Beginner Poster
- Posts : 5
Join date : 2020-10-09
Re: What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
TeeDee cylinders have tapered bore and 2x2 extra booster flutes in their bypass ports. Medallion cylinders are straight and have no boosters. This and the larger aperture on TeeDee cranks for fuel/air transfer add a massive surplus power to TeeDee-s. I mean 09-s too not just 049-s
balogh- Top Poster
Posts : 3924
Join date : 2011-11-06
Age : 63
Location : Budapest Hungary
Re: What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
I no longer own a Medallion .09. I have 3 TD .09's and they have sub piston induction as well. I'm pretty certain the Medallion doesn't offer sub piston induction on that cylinder. There's also a good chance that early TD cylinders had a tapered ground bore as well.
Ken Cook- Top Poster
- Posts : 4832
Join date : 2012-03-27
Location : pennsylvania
Re: What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
Thanks for the info.
mnarigon- Beginner Poster
- Posts : 5
Join date : 2020-10-09
Re: What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
And one more salient point-the Medallion 09 cylinder-in standard (ie FF or CL) form only has one transfer flute.....the R/C one has two.....likewise the Medallion 15
ChrisM
'ffkiwi'
ChrisM
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ffkiwi- Gold Member
- Posts : 228
Join date : 2018-07-10
Location : Wellington, NZ
Re: What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
I have a couple of used Medallion .09's. There is no provenence with them, but I can look to see what they were most likely built with.
944_Jim- Diamond Member
Posts : 1493
Join date : 2017-02-08
Age : 57
Location : NE MS
Re: What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
Thank you. I have a Cox .09 TD that has a damaged connecting rod. Since these appear to be very rare, from my question I was trying to determine whether an .09 Medallion might be a suitable donor. From the above comments, it appears not. However, searching on the web I didn't find any information on .09 pistons/cylinders so having a summary in this thread might help someone in the future.
mnarigon- Beginner Poster
- Posts : 5
Join date : 2020-10-09
Re: What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
I bet the piston and rod are about the same. It was the cylinder that got the taper bore and extra transfer flutes. I'll tell you what...you show us yours, and I'll show mine. I can have the Medallions popped apart first thing in the am. My build room is unheated, and it is uncomfortably cold in there right now.
Oh,.and I have calipers if you want OAL from piston crown to conrod end. Or crown to skirt.
Oh,.and I have calipers if you want OAL from piston crown to conrod end. Or crown to skirt.
944_Jim- Diamond Member
Posts : 1493
Join date : 2017-02-08
Age : 57
Location : NE MS
Re: What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
pistons and rod lengths are the same
Ken Cook- Top Poster
- Posts : 4832
Join date : 2012-03-27
Location : pennsylvania
Re: What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
I took some photos and measurements of the Cox .09 TD that I have.
The piston length is 0.4980 inches crown to skirt and the total length from crown to connecting rod end is 1.1690 inches. The piston diameter is 0.4965 inches with no detectable taper from crown to skirt.
The cylinder has twin bypass ports with no boost ports. The top fin is not milled. At the crown, the cylinder diameter is 0.4950 inches and at the skirt the diameter is 0.4980 inches, showing a measurable taper in the cylinder. The piston/cylinder combination has SPI as shown in the last photo.
The cylinder looks OK, but the connecting rod was damaged (together with the backplate and crankshaft, notice the galling on the crank pin and the abrasions on the connecting rod end, but I have found replacements for the backplate and crankshaft.)




The piston length is 0.4980 inches crown to skirt and the total length from crown to connecting rod end is 1.1690 inches. The piston diameter is 0.4965 inches with no detectable taper from crown to skirt.
The cylinder has twin bypass ports with no boost ports. The top fin is not milled. At the crown, the cylinder diameter is 0.4950 inches and at the skirt the diameter is 0.4980 inches, showing a measurable taper in the cylinder. The piston/cylinder combination has SPI as shown in the last photo.
The cylinder looks OK, but the connecting rod was damaged (together with the backplate and crankshaft, notice the galling on the crank pin and the abrasions on the connecting rod end, but I have found replacements for the backplate and crankshaft.)




mnarigon- Beginner Poster
- Posts : 5
Join date : 2020-10-09
Re: What are the differences (if any) between Cox .09 TD and Medallion pistons/cylinders?
The piston looks scored pretty bad . Can't tell about the cly.
getback- Top Poster
Posts : 8897
Join date : 2013-01-18
Age : 65
Location : julian , NC

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