Mi Downpie Chopping

[sorr 0]

In order to get the exhaist downpipe to fit on an Mi conversion I understand that it needs to be cut and shut.

 

Where is teh best place to do the cut on the pipe and what sort of re-angling is required to get it staight down the tunnel in the shell? Any pictures would be great.

 

Thank you in advance.

[Ryan 99]

I cut about 30-35mm from mine. I cut it close to the manifold flange, and then removed the short section that was left attatched to the flange. Then I got the shortened downpipe welded back directly to the flange, so it's very strong.

 

 

To get the alignment right I just copied how it was aligned originally (only a couple of degrees off from being parallel to the dividing wall in the downpipe). It seems to fit fine like that.

 

If the engine is in the car already then you could bolt the loose flange to the manifold and hold the downpipe in place to mark it and get the correct alignment/length.

 

I also had the edges of the divider welded together to stop them from peeling back and restriciting flow.

Edited October 19, 2006 by Ryan

[C_W 3 1 Cars]

The neatest way IMO is to carefully grind the weld off the top flange so it comes off, then cut about 3" off the down pipe. Bolt the flange up to the manifold then put the downpipe up to it in position and tack it on, remove it all and weld it up.

[j_turnell 137 3 Cars]

You can often get away with not cutting the downpipe atall, as long as you get a good re-angled manifold you should be fine. Obviously if there is still clearance issues then you will have to, but i'd try fitting it first.

[matt205xs 0]

when i bought my car th mi16 2.0 engine was already fitted, and my downpipe and manifold go together fine without any modifications??

 

how can i tell if the engine has been tilted??

[jackherer 543]

the 2.0 mi16 doesn't require any downpipe mods.

 

tilting is nothing to do with the downpipe, its done so the exhaust manifold doesn't hit the bulkhead, which also isn't an issue for the 2.0.

[Martin@PRD 0]

You can often get away with not cutting the downpipe atall, as long as you get a good re-angled manifold you should be fine. Obviously if there is still clearance issues then you will have to, but i'd try fitting it first.

 

 

So So So true, I have never cut the down pipe, as this is where the manifold had be re-angled to much, just call it 4 years of experience.

 

This is why the re-angled manifolds is considered the better option over the re-angled plate.

Edited October 27, 2006 by Martin@PRD

[maturin23 10]

Just to add my experiences here...

 

I converted my 8v 1.9 last year using an ally block Mi16. I bought a reangled manifold from a guy off here (completely forgotten his name!).

 

I couldn't get the manifold/dp joint to seal 100%, had to shorten the middle section and still had the problem that the downpipe rested on the subframe cross member - obviously the vibrations were terrible!

 

I finally got around to ordering a new system - Arvin downpipe and PTS Group N (one silencer box), fully expecting to have to pay someone to get it to fit. Tried a trial fitting and all three bits fit absolutely fine with no mods whatsoever.

 

Can't really explain the obvious variation in dimensions - but it might be a good excuse to give at least the Arvin dp a go. I paid around 45 quid for a new one.

[allanallen 528 2 Cars]

the 2.0 mi16 doesn't require any downpipe mods.

 

tilting is nothing to do with the downpipe, its done so the exhaust manifold doesn't hit the bulkhead, which also isn't an issue for the 2.0.

 

my 205 exhaust didnt mate up in my 2.0 conversion. the flange was at the wrong angle and it wasnt big enough to seal properly.

[miamistu 1]

I've just bought Matt Sav's reangling plate and it went on without reangling the dp. Luck of the draw I suppose

[C_W 3 1 Cars]

The mi16 manifold is longer than the 8v manifold so ideally you have to chop around 2.5-3" from the down pipe "height". It might fit without chopping but a standard manifold I'd expect to hang lower than ideal.

[petert 587]

This is why the re-angled manifolds is considered the better option over the re-angled plate.

 

I use a 6 deg. angled plate with the standard 205 downpipe. No need to chop, belt or hack anything.

[Martin@PRD 0]

I use a 6 deg. angled plate with the standard 205 downpipe. No need to chop, belt or hack anything.

 

I was waiting for that reply!, sorry it had to be you Peter, where a re-angled plate is used the changes of the manifold to crack is far more likely happed compared to our re-angled manifolds that has had the seams wielded, reinforced and also guaranteed not to crack, hand on heart not had one yet. Approx 36 sold within 12 months

 

Personally, I have had a few poor replacement aftermarket down pipes over the years coming though the work place that is the course to the problems then using either the re-angled manifold or plate, but as our re-angled manifold is shorter where the re-angled plated adds to the length to the system, then this is why our system dramatically reduces the problems with clearances.

[maturin23 10]

These are pics of the Arvin downpipe I fitted to my 1.9 Mi16-engined 205.

 

Manifold was re-angled - bought from a guy on the forum who was supplying them on an exchange basis, but I just can't remember his name

 

The exhaust is the one-silencer PTS Group N from Auto Five - (and I've realised that the bracket is not best positioned!)

 

 

All fits without any cutting. It definitely hangs lower than it should, but given there's no central box I have no problems with speed bumps/car parks with a 30/40mm suspension drop.

 

I'm very relieved it all went together nicely!

Edited October 27, 2006 by maturin23

[jackherer 543]

where a re-angled plate is used the changes of the manifold to crack is far more likely

 

 

is that comment actually based on experience of angling plates? how many have you fitted and how many have you had problems with?

[jackherer 543]

All fits without any cutting. It definitely hangs lower than it should, but given there's no central box I have no problems with speed bumps/car parks with a 30/40mm suspension drop.

 

whats the centre rubber hanger like? is the exhaust pulling it towards the back of the car or is it hanging vertically as it should be?

[Martin@PRD 0]

is that comment actually based on experience of angling plates? how many have you fitted and how many have you had problems with?

 

That is from experances with the standard manifold, almost everyone I received is either split or have been repaired before, whether its in a 205 or a 405 it will split in one day of its life time, re-angled plate simply solves the clearance problem where ours solves both, if there is anyone on the forum that has had one of our manifolds and it has split then speak up now!!!

[jackherer 543]

theres no argument from me that the standard manifolds often require repairing, however your post is specifically derogatory towards angling plates in an attempt to promote your own product.

 

from the forum guidelines:

 

- when it comes to technical information and guideance, think twice before you hit

the "submit" button - make sure that information and knowledge you are about to

share is either first hand or verified fact. hear-say and deliberat missinformation

will not be tolerated. "guessing" (within reasonable limits) is allowed if it helps

finding an answer

[maturin23 10]

The central hanger isn't spot on - the exhaust and hanger are about an inch out - it's definitely not a perfect fit, but key for me was having a good downpipe/manifold joint, getting through that bulkhead/cross member gap without fouling and no contact between the silencer and the body at the very back of the car.

 

It ticks all those boxes so I'm chuffed!

 

God knows what is different to the old standard exhaust set up, but it fits better and I've not had the grinder out yet...

[James_m 0]

Slightly O/T but Maturin, if your downpipe hadnt matched the manifold, who was you going to use in the local area to get it matched *Hopes mine does'nt need touching like yours*