13 replies to this topic

[meldert]

I have shown a few pics earlier with the work in progress, here is the finished item.

exhaust manifold 4-1 (still missing lamda sensor fitting)


Another angle


Fitted to the car together with the rest of the system. 2.5 inch all the way, including a metallic hi-flow cat.





Lambda sensor fitted


With fake bottom exhaust tube for standard looks


Rear clam fitted


Clearance inside clam


No problem with engine warning light so far, the engine is running fantastic with a wonderful character. The sound is great and wery racy but not to loud, will fix a soundclip later this week.

Have to do a few adjustments after the first run since the heat has chancged the shape of the tubings slightly, but then everything will fit perfectly. Will also add some heatshields.

Next thing to do is a new intake manifold and then ofcourse a remap.

[speedster]

Oh! That is sweet! Lonnng headers too! Where it is placed, will the Lamba collect emission data from all four cylinders? Probably not an issue - You will end up with two different coloured end pipes, with the fake pipe not exiting any exhaust fumes. Painting the insides of both tail ends black will hide that fact.. Top job, well do!

Edited by speedster, 26 June 2006 - 12:49 AM.

[rabidh]

that looks awesome! So... think you could be persuaded to make some up, or do you have any dimensions info on where you got the bits from?

[Arno]

I have shown a few pics earlier with the work in progress, here is the finished item.

Very nice work! Congratulations!

Minor remark.. Perhaps a good idea to move the lambda sensor a little further downstream, right in front or behind the flexi pipe. Should not be a big issue though, but at the moment it could be having some difficulty getting a good reading of part of the exhaust gasses from 2 cylinders.

If you do decide to sell these, then for people who want more silencing I guess it would propbably be possible to fit a similar sized silencer on the left side as well, so there are 2 silencers in-line?

Bye, Arno.

[RWinstanley]

I agree with Arno, in it's current position it's not ging to see flow from all the cylinders, i'd reposition it to either outside of the first bend, although that's a bit close to the silencer. I wouldn't put it on the inside just round the bend as i'd expect to get a region of low gas flow and recirculation. The better position would be after the flexi as the flow would have had time to become more fully developed. Is the cat a ready made unit or one custom made? I've only ever analysed systems with pre cats (it's alot harder when you've got to meet euroIV), but we always found that the flow through the pre cat was far more uniform if the flow was angled to go across the substrate eg looking along the flow direction enter top left leave bottom right and the cat angled at about 30 degrees. I always assumed VX systems where stright on due to space constraints or does it not matter in the main cat or has nobody looked into it.

[meldert]

Thanks for the encuraging comments! Sorry guys, I have no plans to make more of these and sell them. This is my first try on making an exhaust so I can't really claim it is that good either but initial tests certanly seems good... And as I said the sound is great in character but not loud... Since this is the first prototype i might do a revised version next winter but don't count on it. If you are interested in doing a copy I can take some more detailed pictures and post some measurments. It wasn't that hard to put together (I had help welding it all, though) I basicly used 90 degrees bends and straight pipes carefully measured and cut for the manifold then I point welded all of i together in the right shape. Then I left all of it to Dude for the final welding. The rest of the system was as easy, just standard parts carfully put together... Was planning on another type of silencer in the beginning with inlet and outlet in the same end which would shorten the whole system considerably but i couldn't get hold of that (it was on backorder). The one I use now is three ways inside so it is definitly silent enough. But not ideal for optimum flow. Another option would be to put just two straight thru silencers as suggested by Arno but that might be too loud. My initial idea was one straigth thru together with the U-shaped one mentioned above. If it is something i might change in the future it is to try out some of these ideas with different silencers, but at the moment I'm quite satisfied. Need to put it on a dyno to check eventual performance gains though... It feels great, especially the torque, it doesn't feel like it has the same dip before 3700 rpm as before, but it mig as well be placebo... A 4-1 manifold should be good for top end torque so I'm not too sure about what gains I might have before I do a dyno test. As for the first lambda sensor placement I have been told to put it as early as possible, thats why it's in the collector, the only possible alternative was in the bend right after the collector or in the cat itself similar to the one in the other end of the cat. The straight pipe between the bent and the flexpipe is a sliding joint so I can't put it there. I dont think i will have a problem with where I put it, since the exhaust comes in pulses from two pipes at a time and probaly fills the whole collector with every pulse. Sure, the bend right after might have been a better alternative but on the other hand the flow thru that rather tight bend might not be smart to disturb even further with the lamda sensor.

Edited by meldert, 26 June 2006 - 12:48 PM.

[meldert]

Just realised that your concerns about the lamda sensor not getting a reading from all four header pipes mig have to do with how you think the collector looks inside... This one is open (it's a bit hard to explain in words how it's made and I have no pictures) inside so there is no problem for the sensor to get a reading from all four pipes. The cat is an all metal hi-flow ready made unit btw.

[meldert]

Sorry to bring this old thread back... I started to sort out all my video footage from this summer and found this little clip where you can hear the sound of the exhaust note quite well it's not very loud but the caracter is different from original.

watch video


It also gives quite a good view of the new colour...

Just trying to decide what to do with the car this winter... hmm, new cams and intake springs to mind...

[wil_scotland]

Nice sound from the exhaust. I honestly thought it would be so so loud. Did your EML ever come on buy using that free flowing cat? Wil

[meldert]

Nice sound from the exhaust.

I honestly thought it would be so so loud. Did your EML ever come on buy using that free flowing cat?

Wil

I've had the EML come on once since fitting the new exhaust it was just after fitting, the fault code was the rear lambda sensor so i guess it got some strange readings... I did a reset and it hasn't come on since and I have done four trackdays (really pushing it) since then. My EML has come on once before of the same reason but with the standard exhaust system (precat and everything intact) so I guess my 2nd lambda sensor might be a bit knackerd or something...

the MOT here in Sweden didn't complain either.

[wil_scotland]

Nice sound from the exhaust.

I honestly thought it would be so so loud. Did your EML ever come on buy using that free flowing cat?

Wil

I've had the EML come on once since fitting the new exhaust it was just after fitting, the fault code was the rear lambda sensor so i guess it got some strange readings... I did a reset and it hasn't come on since and I have done four trackdays (really pushing it) since then. My EML has come on once before of the same reason but with the standard exhaust system (precat and everything intact) so I guess my 2nd lambda sensor might be a bit knackerd or something...

the MOT here in Sweden didn't complain either.

Sounds ok then.

[marky boy]

did you nat fancy makng the tips larger to fill the holes? Loving the welds are you going to wrap it?

[meldert]

did you nat fancy makng the tips larger to fill the holes?
Loving the welds
are you going to wrap it?

The tips are actually quite large (same outer diametre as original if not a bit larger) it looks a bit strange in the pic though... (The inner diametre is much bigger, since the walls are quite thin) But they are a bit closer together...

The bottom one is fake and I have actually lost it now... I did a bit of bad welding...

Well I'm planning to make new tips before spring, probably a letterbox one like Regal.

Well the, nice welds are made by Dude, I made the crappy ones...

No, I'm not going to wrap it. I thought about it and would have done it if it got to hot in the engine bay, but so far no problem with that.

The only good reason for wrapping an exhaust system on an NA-engine is if you have problem with radiating heat from the system.

If that is not a problem it is actually good if the exhaustsystem gives away much heat, that means that the exhaust gasses cool down, which means that the gas volume goes down, this means lower back pressure and easier flow thru the system because there is less gas volume to pass (no pun intended ).

Wrapping the system isolates the gasses and they keep higher temperature and volume, this is only good on a turbo system (before the turbo) because there you want high pressure to keep the turbo spinning as quick as possible.

But as I said, sometimes you need to wrap the system because the radiating heat causes problem somewere else... But I haven't had any problems with that yet anyway. I did make a heatshield between the manifold and the boot.

[marky boy]

if you make the letterbox exhaust curve the corners slightly i think it would look cool!