7A-FE is twin cam, thats what the F means
Not a lot on the net, but Celica kept showing up
CALDINA 7A-FE, 3S-FE, 3S-GTE 1996~
SPRINTER CARIB: AE 11 SERIES 4A-GE, 4A-FE, 7A-FE, 1600, 1800 1995~1998
Premio 4WD AT211 7A-FE 1800 1995-1999-
First, let me give you some background information on the 7A-FE in case you don't already know. The 7A-FE is the last in Toyota's great line of A-series engines. It is an inline-4, DOHC, 1762cc 16v MAP-based engine. The other (very) popular A-series engine is the 4A-GE, available in beauties such as the Corolla GTS, MR2, and Levin, with 16 or 20 valves, naturally aspirated or supercharged! The 4A-GE also powers all the race cars in the KOOL/Toyota Atlantic Championship, North America's premier open-wheel development series. The 7A-FE shares basically the same block as the 4A-GE, but with 200cc's more displacement (~1800cc vs. ~1600cc), the difference being in the stroke. The 7A-FE's bottom end isn't quite as strong as the 4A-GE's though. The 7A-FE connecting rod is longer and skinnier, and the crank is not forged. Another major difference between the 7A-FE and 4A-GE is the cylinder head. Toyota designates the "F" as meaning "economy head," while the "G" means "performance head." (The following information originated from Gary M. of the Toyota Mods Mailing List) The G head uses two widely spaced cams directly pushing the valves and driven by their own sprockets. This allows for very high valve speeds and excellent valve control for better performance. The larger angle between the valves also makes a chamber with more surface area, and with a domed piston, even more surface area. This allows for more compression while dissipating the heat better, so it won't detonate as easily. Also, the ports can be straighter so that they will flow better at high velocity thus making more top end power. Why does Toyota make an F head? The F head has close spaced cams with only one drive sprocket and a pair of gears to drive the other cam. The narrow angle between the valves makes for a more compact chamber that will hold the heat in and allow for a faster burn, and the port shapes improve low rpm velocity. This all makes for a more efficient engine with more torque at low speed and cleaner emissions while burning the lower amount of fuel. Basically, that is the reason for the two designs. The latest 7A-FE actually makes as much power as the MK1 4A-GE and more torque both at lower revs, but this is all due to the 200cc's more displacement. The better G head would definitely make even more but would consume more fuel and possibly lose some low end torque. Lastly, the "E" stands for "electronic fuel injection." The 7A-FE is available in the AE102 as well as in the ST version of late model (AT200) Celicas. The engine bay of these Celicas looks almost identical to the AE102's. Click here to see a 7A-FE in a Celica. Because of this engine "sharing," just about everything mentioned here will be applicable to the Celica 7A-FE (as well as any other 7A-FE).
There is more where that last bit came from at
http://www.corollaperformance.com/Mods/ ... Index.html too
Hope that sort of helps.