M50B25 Inlet Manifold Install

[wildeboy]

I have finally installed my M50B25 inlet manifold!

It has been sitting in my garage for at least 6 months, firstly waiting for me to pluck up the courage to do it, then finding out my insurance wouldn't cover me with it fitted!

I finished it at about 11.00 this morning and have been driving it pretty much ever since!

What a nightmare to install though! I started it yesterday morning!!! I just bought the manifold and made the fitting kit myself as I went along, it's not the prettiest looking but it is almost all hidden underneath. I think in hindsight I would have been better off buying a ready made kit and saving myself a few hours!

I thought I had finished it last night just as darkness fell, I started it up and it just died, I could only keep it running with the revs at 4000 and it really wasn't happy! I got the torch out and it took about 30 seconds to find the ICV hose had come loose, right underneath the manifold, right at the back. So this morning it all had to come out again.

I started it up and took it for a test run, the difference wasn't huge but it was noticeable, and it sounded better too. I went back home and took it for a proper test this afternoon, wow, what a difference. As soon as I set off I could feel and hear the difference, it's like it needed turning off and on again to reset something. Over 3000 rpm it just flies, it's at 6500 before you know it, and the noise if fantastic. There is no obvious loss of torque at the lower end, it seemed to pull away at 30 in 4th ok as normal (if that's what you want to do, it sounds much better in 2nd though ).

[Southernboy]

Well done!! It is a worthwhile upgrade. Are you going to have it re-mapped to take full advantage of all that air??
My next trick is to have the boot re-configured to copy the M version, with the battery in the middle, and a second silencer / exhaust on the right. The 2.8 as you know has the spare wheel etc which takes up space on the right. I found a company here, and with some decent photographs of the interior layout of the boot, and some pics of the layout under the car, these guys reckon they can do the change plus fit the dual system for around £.400.00. Includes making the matching cut-out on the rear bupmer, and channelling the right hand exhaust all the way from the front box. So, a week for that, and then with the intake conversion already installed, it'll go for a re-map. Hopefully getting the air in and out efficiently will add a few horses..

[wildeboy]

Hi Southernboy,

It sounds like you are taking it a stage or two further than I am going to!

I quite like the idea of opening up the oem exhaust to make it more free flowing but I am not sure how much difference it would make, there would still be the restriction in the cat and I can't afford to start replacing that, I have a very small Z budget! I also need to get hold of a (pre 04/99 I think) 2.8 rear exhaust section as I want to keep mine just in case!

Same goes for the remap, I would love to have a live custom remap but the cost is again just too much at the moment, I am not sure if there is a cheaper alternative?

I am still running the stock air filter, I have a BMC induction kit but need an angled hose to fit it down towards the headlight, it won't fit otherwise. I am going to nip out a lunchtime tommorrow to get one. That will hopefully add bit more air into the mix as well.

[Southernboy]

I have the benefit of living in a country where it isn't law to have a cat on my car. But it is as important if not more so to get the exhaust gases out. They are more "voluminous" because they are under huge pressure than the intake gases. Having being heated in the combustion process they expand, and to get them out as quick as possible makes good efficiency sense, as they will hinder the free flow of the piston when it is on it's exhaust stroke.
Anyway, It's a fairly cheap option to do here I think, and the benefits will show on the torque curves. The top power won't change, but I should have greatly improved acceleration.