Thursday, September 2, 2010

Another Sign of Ageing?

Hi guys.
Recently, i felt that my engine is too aggressive to use on the road. Since this car is a daily driven car, driving in town with lot of traffic jam sometimes make me feel really pissed off especially during hot days and without air-condition. LOL. What more can i do right since I'm using race spec camshaft ( 300 degree of duration ). So it will stall everytime i turned ON the air-condition during idle. Suddenly, this idea came up in my mind. It might shock some of you guys but i want to reveal something.... i just bought new cylinder head to be plonked on my engine block. Pictures below.

i will now miss the power, the touch, the sound, the hardship, the sweat & the victory. thx all motor 4g93 variable-less screamer. you will be missed. thx for the memories.

MIVEC cylinder head

Yes. As you can see from the picture above, i bought the famous MIVEC cylinder head by Mitsubishi. The technology from the cylinder head is quite similar to VTEC system. MIVEC technology is an answer to VTEC by Honda XD. Some of the specification of the cylinder head.

Mivec Camshaft Profile

mivec low lobe
Ex 232/8.24mm lift
IN 228/7.58mm lift

Mivec high lobe
Ex 285/9.83mm lift
In 300/10.41mm lift

Still didn't get the idea? here are another informations that i got from the internet which can help you guys to understand a bit more on what MIVEC really is :)

"Some types of variable valve control systems optimize power and torque by varying valve opening times and/or duration. Some of these valve control systems optimize performance at low and mid-range engine speeds. Others focus on enhancing only high-rpm power. MIVEC system provides both of these benefits by controlling valve timing and lift. The basic operation of the MIVEC system is altering the cam profiles and thus tailoring engine performance in response to driver input.

In essence, MIVEC serves the same function as "swapping cams", something that car racers might do when modifying older-design engines to produce more power. However, such swaps come with a compromise - generally yielding either greater low-end torque or more high-end horsepower, but not both. MIVEC achieves both goals. With MIVEC, the "cam swap" occurs automatically at a fixed engine speed. The cam switch operation is transparent to the driver, who is simply rewarded with a smooth flow of power.

Two distinct cam profiles are used to provide two engine modes: a low-speed mode, consisting of low-lift cam profiles; and a high-speed mode. The low-lift cams and rocker arms - which drive separate intake valves - are positioned on either side of a centrally located high-lift cam. Each of the intake valves is operated by a low-lift cam and rocker arm, while placing a T-lever between them allows the valves to follow the action of the high-lift cam.

At low speeds, The T-lever's wing section floats freely, enabling the low-lift cams to operate the valves. The intake rocker arms contain internal pistons, which are retained by springs in a lowered position while the engine speed is below the MIVEC switchover point, to avoid contacting the high-lift T-shaped levers. At high speeds, hydraulic pressure elevates the hydraulic pistons, causing the T-lever to push against the rocker arm, which in turn makes the high-lift cam operate the valves.

In summary, MIVEC switches to the higher cam profile as engine speed increases, and drops back to the lower cam profile as engine speed decreases. The reduced valve overlap in low-speed mode provides stable idling, while accelerated timing of the intake valve's closing reduces backflow to improve volumetric efficiency, which helps increase engine output as well as reduce lift friction. High-speed mode takes advantage of the pulsating intake effect created by the mode's high lift and retarded timing of intake valve closure. The resulting reduced pumping loss of the larger valve overlap yields higher power output and a reduction in friction. The low- and high-speed modes overlap for a brief period, boosting torque"

Quite long huh? hehe. To be true, I'm very sad actually to sell my beloved 93T head because the head that i built is very capable to trash some variable and lifting machine if you know what i meant but, since this car is daily driven, so i had to make up my mind and sell this head off. Hopefully the new owner will make a better setup with the head in his race machine. All the best.


p/s: i'll update on 4g93 MIVEC build up in the next post. Stay tuned!


  1. Bro, don't forget to transfer the Vtec intake manifold to the new head..... :)

  2. thx bro. but actually i'm using std intake this time. it is because i sold the stuff together with the head. furthermore i need to mod the intake flange back since mivec port design is different then 93. maybe u can see skunk2 intake in my next setup? hehehe

  3. looks like u have gone to the dark side...:)

    if for daily driving definately mives is the best route la!!

    at least you have solid lifters instead of hydraulics! keep us updated!

  4. bro
    in the other way.....
    if i custom a mivec cam shaft to 300degree will i suffer for city drive ??
    idling not stable and cant turn on the air cond ....

  5. @mugil : yes bro. since this is daily driven car, so i have to change to mivec. got power and drivable. thx for guiding me with your knowledge on 93.

    @coolman : i think if u use hicam even in mivec, u will have some prob when turn on the aircond when idling. maybe u can if u use standalone ecu since it has anti stall function. correct me if im wrong.

  6. oh i c.....
    then after plug in the mivec head into your 4g93 what is your next step ??
    and u using original stock mivec cam or ??
    and what pistons u using and how many mm ??
    mined 2 share ??

  7. i'm using mivec standard camshaft. currently using 81mm high compression piston taken from b16a p30 jdm version. what's my next step? hmmm. you'll see ;). stay tuned brother.

  8. How much sells you 4G93 head with your all modification??
    i'm verry interresting!

  9. i already sold it to a friend of mine =)

  10. Just a little question if you can help me,:
    What's ECU JDm 0450 fit in my colt gti?
    I want change ecu because my stock ecu is not reprogrammable!
    Thank you

  11. hi there. if im not mistaken u can search for 6123. im not really sure actually but most jdm ecu can be rechipped/remapped. if u buy the ecu make sure u can see an 'E' alphabet on the ecu code sticker. it means 'EPROM'

  12. ok merci!
    Je vois d'├ęcus 0450 dans le site Web