According to magician, the S4P engine was NOT directly moulded from Lotus Esprit(I guessed it wrong,previously I thought it was). however it contain some DNA from that engine, such as tall body, twin cam, strong wall, huge crankshaft & long conrod. Genetically, these kinda engine setup is meant for high power output, very suitable for high compression. Room for expanding horse power is tremendous on S4P.

However, it oso posses its own disadvantage. Long conrod & huge crankshaft is bad for low end torque. It takes more energy to get it move. On the bright side, once its momentum created, less effort is needed to continue its cycle. This also explained earlier Campro tend to have torque dip below 4krpm, which later overcome by the assistance of IAFM.

We've briefly discussed about possibility of improving the Campro characteristic, but we do came to a conclusion, that the IAFM was bad for people who doesn't know how to control their throttle. The assistance of IAFM allowed more A/F induction to overcome the torque dip, which also directly projected on vacuum reading. It is very hard to maintain vacuum from standstill to momentum motion, partly bcoz of the SYSTEM is trying to overcome the torque dip. Whereas after 3krpm, its relatively easier to maintain higher vacuum(less throttle action). By disabling IAFM, extra A/F being taking can be avoided, but torque dip like any other old WAJA/Gen2 is ineminent.

I've understand from this lesson, the Campro S4P engine is made to work with momentum. The higher RPM it goes, more momentum to help ease the pain of sucking too much fuel. I conclude that the S4P family share the similar experience, some has extremely good FC, and minority suffering from it, was generally affected by driving habits/road condition/travel distance. In short, the engine is very suitable for long distance cruising, but the traffic jam itself can really kill its fuel economy. If I make a comparison between my then 4G13 & my S4PE, I believe my Iswaga's engine is much compact with shorter stroke that can easily attain low end torque, which hardly affect my FC despite I was doing a lot of short distance travel.

P/s: the side note, that Gen2 owner claims he's paying around 25cent/km in Sepang region on average basis. I'm glad my GaGa stay slightly below 20cents region despite my travel distance is uber short. I believe GaGa's light weight body contribute to that, and believe it will do well on long distance travel just like any other cars.