ABC's of ABC vs. RINGED
|Basically, there are two types of R/C model engines available, the "TAPERED
FIT" compression and the "RINGED" compression engine. There is a
signifigant difference between these two types of engines in how they make the compression
seal. Within the TAPERED FIT engines, there's ABC, AAC,and ABN metalurgy to make the
compression seal. The RINGED engine technology is an aluminum piston fitted with an iron
ring sealing against a steel cylinder.
It would be best to define what exactly each type is, and how it differs from the others.Then compare their performance and durability.
ABC = Aluminum (PISTON), Brass (CYLINDER) Chrome (CHROME PLATED cylinder internally) The compression seal is made by a slightly tapered fit between the piston and cylinder. The brass cylinder has the same expansion rate as the aluminum piston therefore, it maintains a good seal as the engines heats up. Since chrome is substancially harder than the aluminum piston, this is a (semi) bearing surface between the piston & cylinder therefore there's no scuffing or galling, if there's adequate lubrication.
ABN= Aluminum (PISTON) Brass (CYLINDER) Nickle (NICKLE PLATED cylinder internally) The compression seal is identical to the ABC. IE:tapered fit
AAC= Aluminum (PISTON) Aluminum (CYLINDER) Chrome (CHROME PLATED cylinder internally) The compression seal is identical to the ABC. IE:tapered fit
RING= Aluminum (PISTON) Steel (CYLINDER) Iron (RING) This is the oldest and original technology whereby the compression seal is derrived from the ring to cylinder fit.
You may wonder why there's 3 types of Tapered Fit engines IE: ABC, ABN, and AAC. You can thank our EPA (Environmental Protection Agency) for that! Chrome plating is a very environmentally polluting process and the high restrictions placed on the chrome plating process back in the 60's forced many platers to find alternate methods of plating or quit plating all together. In the "old days", it took 2 substrates to bond chrome. One layer of BRASS, and one layer of NICKEL prior to the chrome plating. Some engine makers opted to eliminate the chrome thus leaving the nickle as the top surface, hence ABN. Nickle is hard, but not as hard as chrome. New technology was developed in Japan whereby chrome could be directly deposited on aluminum thus eliminating the brass and nickle hence AAC. Between ABN and AAC, the AAC technology appears to be better, however neither is as tough or as ABC. Most engines made in Tiawan use ABC simply because they don't have to adhere to EPA requirements (YET). Until the EPA bans their importing ABC engines.
Super Tigre in Italy, was the first engine maker to distribute ABC engines. However, several engine makers claimed they developed the technoloty! HB of Germany, Enya of Japan and Super Tigre of Italy, all claim the development. But the fact is, everyone jumped on the ABC technology and produced their version. Along with ABC cylinder technology came schnurle porting. Schnurle Porting greatly enhanced engine performance regardless of the type of compression seal used. Early engines used a deflector on the top of the piston to direct the intake flow upwards since the intake was straight across from the exhaust (known as loop scavenging). Schnurle intake ports (called transfer ports) were on each side of the exhaust thus eliminating the deflector as well as increasing the intake flow, plus having no deflector allowed higher compression ratios.
The piston ring is the first compression seal method developed, and has a long history going all the back to the fisrt internal combustion engine. The piston ring is still used and is as popular as ever by many engine makers, especially in the larger glow engines. All gasoline engines without exception use piston rings.