softmuffin said:
Hello dude,
I just feel a bit weird for you brother case. Since ur brother is using 4G93P why want to change the head to 91. pick up or for fun ...
anywhere no hardfeeling
No heart feelings.. n no offence. Well this is the problem. Many ppl cannot tell the different between 4G91 n 4G93 head. Maybe for you guys quite technical a bit then only know. Just like my bro. he know nothing. Actually it's a conned job. The mechanics charge him for RM800 for everything and told him is 4G93 head. Sound very cheap right but there's a story hidding behind. Ok let me cerita a bit, this is an experience. Hope you guiys nvr fall into a trap again.
There's once I almost also kena conned. There's one guy in autoworld forum selling the head and I was in doubt and finally at that time one of a guy i knew from the forum he is interested into sohc to dohc and finally i have allowed him to do the conversion. First I don't know it's a conned job and I hv tried my best to explain to the guy. Finally he also understand cos the person who sell the head I also not meet b4. At the end found out the head is from carb head. I felt so sorry to him.
The cost for everything is RM800. Head included plus siap pasang dan jalan.
This mechanics sucks, he took my bro. intake manifold and put in imported 4G91 DOHC manifold. The problem is EGR missing and a lot of carbon being collected inside the piston. The cable for auto cruise took away (but my bro. found it early and ask it back). The old head being giving to him. The timing belt is not 100% new. When the bullet start to making tick tick tick noise my brother asking my help to repair it and since mine one done is good in Ipoh, therefore I took my bro. car back to Ipoh and do a top overhaul. I can recommend this mechanics is very good. He's very good into stock car, turbo or modification car, he cannot do. He has a lot of manufacrturer manual that's why he can do kinda job like blue printing.
Ok back to the cerita. When he took out the head, he found the EGR is missing, not the original intake manifold. The timing belt is wear n tear about 40%. When he did the top overhaul, I could easily spotted the head of the piston were covered by a thick carbon. He said the reason bcos no EGR.
I have done a lot of research into differences between 91 and 93 dohc head.
Obviously the piston cylinder size on the head is different. 78.4mm vs 81mm
2) Cam profile different
3) Valve spring is different. 93 is 5mm higher
4) The inlet air/gas hole for 91 is smaller. The exhaust if I am not mistaken is the same.
There's 2 ways to verify whether is 91 or 93 head.
Measure the cylinder size. Or get a venturi/gasket for the 93 manifold inlet, you could check it and compare.
Since the problem found out. 91 head matching 93 block, my mechanics suggest my bro. to port the inlet hole as big as 93. The polish it. Well the head can be ported at the end. The only cannot be changed is the cam profile and valve spring. The cylinder remaind it and didn't overbored it cos it's not so important. Overall is just a few cc different and not worth to spend rm100 to overbored it.
Anything you wanna know, I can share.
I just converted to a GTi engine and sold my head in a package for RM600. The head just done top overhaul and only few months usage.
