Porting / polishing an M25 12 head

[525iBoy]

Hi, anyone tried this .. if so what's their experience. I have driven a friend 3.0 12v Mercedes 124(OH NO mercs on this website!!) that was ported and polished and the response was much much better. smoother& more powerful throughout the entire powerband, and it wants to rev more easily too. Idled wonderfully.grant it was a mercedes engine, but with 12v and a straight six configuration it should be somewhat representative of our m20 m30 engines. Power outputs are similar..

 

[naza2]

i know a guy in puchong who like the color yellow and likes to do this kind of stuff to his car. but i can't reveal his name. *cabut*



come laa scared aahh?

 

[E34EuroTouring]

Your car has M20 engine with SOHC but it revs quite well for an engine that age. Doing port and polish will give you better top-end but sacrifice lower end torque.
This means up to 4000 rpm there is little else happening. From 4000 rpm to 6500 rpm, there is a quick rush, so fast that you will struggle to shift fast if its a manual. For auto, it will shift at 6000 rpm or a little more depending on the load of your car.

If your head is going to be out to change the head gasket, its a good time to do it. Get the valves adjusted as well since that will improve the FC and give better smoothness. I got valve angle job done by mech but polish the intake manifold myself using Metric Mechanic charts. My M20 revs better than an M50.

To cure low-end torque problem, I had 535 AFM fitted with Apexi SAFC-II controlling it. Torque comes about 3200 rpm rather than 4000 rpm. It has K&N cone with custom headshield, intake noise louder from 4000 rpm and above, must my noisy exhaust drowns that noise.

 

[525iBoy]

hmmm interesting.

btw how much for 535 AfM and apexi control...? does it cost you much in fuel consumption?

 

[Fuhrer]

dude save all this money to try and achieve a few ponies & drop in an M50..instant 192 HP!

 

[magicfox]

Originally posted by naza2@Jun 21 2005, 10:56 AM
i know a guy in puchong who like the color yellow and likes to do this kind of stuff to his car. but i can't reveal his name. *cabut*



come laa scared aahh?

eerrhhhh.. apple ah????

:lol:

 

[teejay]

corrections.....

ZAPPLE.......!!!

 

[magicfox]

Originally posted by teejay@Jun 21 2005, 11:32 PM
corrections.....

ZAPPLE.......!!!

oopss.. my bad.. sorry..

zapple..

 

[Zoggee]

Originally posted by E34EuroTouring@Jun 20 2005, 09:58 PM
Your car has M20 engine with SOHC but it revs quite well for an engine that age. Doing port and polish will give you better top-end but sacrifice lower end torque.
This means up to 4000 rpm there is little else happening. From 4000 rpm to 6500 rpm, there is a quick rush, so fast that you will struggle to shift fast if its a manual. For auto, it will shift at 6000 rpm or a little more depending on the load of your car.

If your head is going to be out to change the head gasket, its a good time to do it. Get the valves adjusted as well since that will improve the FC and give better smoothness. I got valve angle job done by mech but polish the intake manifold myself using Metric Mechanic charts. My M20 revs better than an M50.

To cure low-end torque problem, I had 535 AFM fitted with Apexi SAFC-II controlling it. Torque comes about 3200 rpm rather than 4000 rpm. It has K&N cone with custom headshield, intake noise louder from 4000 rpm and above, must my noisy exhaust drowns that noise.

wow...!!!! you are good.!! B) thats exactly what I've experienced. B) cool man...very cool..!! :wink:

 

[Zoggee]

cipek..Kena again... :beaten:

 

[E34EuroTouring]

525iB,

The 535AFM has some history behind it. I got it from Bruno (of bmwE34.net) and Bruno got it from Justin (of Justtin RedFive MotorSports). It was $75US but I donated $25 to Justin's cause during the time. So that was $100. The Apexi was $400 (obtained new from HK).

The rigging and tuning was really exciting. I could dial up and down the power so conserve the FC if needed, tho the car will be sluggish. ECU adaptation was rather quick within about 15 mins of brisk driving. There is a saying, " I need to teach the car , new tricks..."!. Turns out to be true. Tested that on the track as well.

I got a littel crazy with my car at the time. Even bought a Rotrex supercharger for it but never installed it. Still new and in the box. Even tho my touring has M50TU, I still like the simple M20 engine as it is simple to fix and has cheap parts. M50 and Vanos has a different torque curve and coupled with a manual tranny, is very nice.