The car is a 5 door Civic VTI-S (MB6 which was manufactured for the UK market. They come with a B18c4 engine, which is the European version of the B18C1 engine. So when I am looking for tuning info I have to look at Integra GSR's. I have recently been doing some reading up on may be up grading the header and exhaust system and I had to change the gasket from header to cat. So I decided to measure the sizes. What surprised me was the header outlet size, It is double walled with the inner diameter measuring 43mm (1.7") ID, but it only reduces to this diameter in the last inch or so. Before then it is much larger 47.5mm (1.85") ID. Why do Honda reduce it like this, surely it is a restriction? Is the USDM GSR header the same or is this a strange euro only header. The other strange thing with the header is that the 4 to 2 part of the header is tubular with no heat shield either and not cast iron like all standard Honda headers I have seen other than the ITR. Can any one help on this?? I was thinking of getting the end cut off the header and removing the restricting diameter so it exits with a 47.5mm tube ID what do you think. My old D16Z6 header was similar with this restriction.

 

Hi, I also have a mb6, I can't really help you because exahust is coming next in my tuning step..i know that b18c6 and b18c4 headers are the same, centerpipe and exahust are different..one of my friends put on his mb6 itr's centerpipe and exahust and he says it goes a lot better..I'm planning to buy all the exahust system from SS because it's quite cheap..
The only tip I can give you is to shorten the gear ratio..i put the 2nd the 3rd and the 4th gear of a 1.6 vti and now it has improved a lot..
I also have one question: are b16a2 and b18c4 cams the same?
I put the b16a2 in my b18c4 cause i was told they went better..but i can't sense the difference

 

From what I have read the B18C4 cam is not supposed to be as high a lift as the B16A2 cam, but then again with out tuning you may not be able to feel the difference, Plus the vtec rpm point is higher on a B16 if a remember.

I am very interested in your coment about your friend who fitted a ITR center pipe and muffler. Did it really fit straight on? or was it a lot of work. That was an idea I have been considering doing.

The B18C6 that the euro ITR engine right??

By SS do you mean supersprint?? I have there cat replacement pipe. but there pipe work it the same diameter as standard an not the larger ITR pipe work size which we need to maximize performance (57mm OD). I you look at there dyno graph for the ITR it does not have a supersprint centre section it uses the standard honda one. THere stuff is expensive over here in the UK, what prices do you pay for it in Italy????????

 

Thanks for the info on the header. Do you think it would be worth removing the restriction. so the diameter leaving the header would be 47mm ID.

I have attached some pics of the manifold to show you what i meant by tubular design. Have you seen a standard Honda header that looks the same. As I doubt Honda made a special header just for my model car.

The OD of the 4 -2 section is 38mm.

 

b18c6 is itr eudm code.
SS is supersprint
this is the link at the topic with his impression (it is in italian) http://www.hciforum.it/viewtop...arico
Itr centerpipe and muffler have the same attachment (in italy we call them flange..don't know the exact word in english) and do the same curves,but the centerpipe it's a little bit shorter than the mb6's one.
He spent 50 euro to adapt it and to mount it, which is quite cheap considering the ridicoulus price you pay for a used itr exahust

 

Thanks for that. I will try find out how much I can get a ITR exhaust for. I had a scan of the italian forum. I could make out they were taking about diameters of the exhaust system. What did they say was the outside or inside diameter of the ITR exhaust? . and yes flanges means the same in English. So i know some italian now. Its nice to here from some one with the same car. I cant find many good forums with info on the MB6.

 

outside diameter 57mm inside diameter 54mm
http://www.jpcar.net/forum/vie...t=mb6 this is a link of a french forum in which you can find other info about mb6
and also here http://forum.hondarevolutions.com/index.php you can find some info's
Damn this car is RARE

 

I know there Rare, but they an awesome car. Practical and quick. I had found that hondarevolutions.com but you have to pay to be a member to look at Forum. I like the pic of the Racing MB6, I remember watching one in the International Saloon Car championship some years ago. Wish we could find out the guy that helped tune the car. the will have to try and translate the forum and understand more.