downpipe question

[dark_sounds]

hi, need ammo against pricks at my RSR.

got a powerflow... i told them downpipe back,,, (not inc downpipe obviously)

i noticed when looking under the car that on the 318is, theres 3 boxes,

how far back does the down pipe go? (by the rear of the drivers seat?) and does the downpipe have a silencer/box attached to it??

cheers all,

[Gwynleym10]

The 318is doesn't have a downpipe as such as it has a tubular header.
I think it does have 3 boxes.

[dark_sounds]

right, looks interesting, so if i was to have an exhaust "after the down pipe" then it would be after the box? in the middle pic?? or will it be just after the two pipes become one? ( where the hole learing to number 18 is?) is that a join that comes apart? hence you can eliminatte the box and replace with stainless tubing??

[jonbuoy]

The middle pic is your catalytic convertor. You will have to get a Cat back exhaust or get a de-cat pipe to replace it and then add the rest of the exhaust.

[Gwynleym10]

the join at 18 is a weld... it would come apart with a hacksaw..but then what?

I think you should get it from gasket number 2,(2nd pic) so you replace all the pipe's.

Or you could just get it from 2 (3rd pic)

[E30Mark]

The middle pic is your catalytic convertor. You will have to get a Cat back exhaust or get a de-cat pipe to replace it and then add the rest of the exhaust.

It's not a CAT!!!!!!!!!!!!! unless you have the lambda probe fitted. This CAT thing comes up quite often with the 318iS, I've never known anyone to have a CAT fitted, it's just a resonator.

The definition of 'front pipes' is a bit dubious here i suppose.... technically the pipe that comes off the manifold should be called 'the front pipe', but it's not just a pipe in this case as it has the front resonator attached to it...

So I'd say the down pipe includes the front box, therefore the if your changing the exhaust after the down pipe this will be the last two boxes only.

[jonbuoy]

The middle pic is your catalytic convertor. You will have to get a Cat back exhaust or get a de-cat pipe to replace it and then add the rest of the exhaust.

It's not a CAT!!!!!!!!!!!!! unless you have the lambda probe fitted. This CAT thing comes up quite often with the 318iS, I've never known anyone to have a CAT fitted, it's just a resonator.

The definition of 'front pipes' is a bit dubious here i suppose.... technically the pipe that comes off the manifold should be called 'the front pipe', but it's not just a pipe in this case as it has the front resonator attached to it...

So I'd say the down pipe includes the front box, therefore the if your changing the exhaust after the down pipe this will be the last two boxes only.

Considering i have never seen a 318is exhaust and am going by the diagram i am saying this IS a CAT!!!!!!!!!!!!!!!!!
As it does have a Lambda Sensor!!!

[dark_sounds]

easy gentlement,,, basically mine doesnt have a cat,,, but i asked for a system downpipe back,, and they just done the rear two boxes, so im assuming thats right,,, though i though it was going to be from the first point where the weld is. otherwise its equivalent to a cat back exhaust really as its not full....

also powerflow dont deal with downpipes. or so says the manager guy, they will cut off though they wont deal with the down pipe section that connects to the manifold.

[jonbuoy]

easy gentlement,,, basically mine doesnt have a cat,,, but i asked for a system downpipe back,, and they just done the rear two boxes, so im assuming thats right,,, though i though it was going to be from the first point where the weld is. otherwise its equivalent to a cat back exhaust really as its not full....

also powerflow dont deal with downpipes. or so says the manager guy, they will cut off though they wont deal with the down pipe section that connects to the manifold.

This will be because they don't do a de-cat pipe b'cos your supposed to have one due to fuel emmision's by law, if the car was fitted with one. Car's are usually fitted with one after 93' but you do get the odd occasion when there is one on an earlier model
Your best bet is to have a look underneath your car and see if you can see the lambda sensor in the pipe, look's like a spark plug (Usually got a heat shield round it) with a plastic coat lead coming off it. It's got 3 wire's inside it; 2 white & 1 grey. If it has'nt got this you can, by law, change this pipe. The manager who sold you the exhaust would have had the same diagram up as we've got up now and would go by the part number's on his screen so would not beable to get hold of the exhaust.
Other than that, go somewhere to get it made up.

[Gwynleym10]

Just to note the pictures are from the online ETK which is often incorrect.

I think the parts for the lambada probe etc are for US market cars which probably don't apply for uk cars.

However the front pipe is where the CAT would be, but its just a normal box in the UK i assume.

If they haven't replaced front pipe, then you could argue that they have onl given you a "CAT Back" system rather than a full one.

I would talk about down pipes as there isn't one as such as they are kinda inbuilt to the tubualar manifold.

[E30Mark]

The middle pic is your catalytic convertor. You will have to get a Cat back exhaust or get a de-cat pipe to replace it and then add the rest of the exhaust.

It's not a CAT!!!!!!!!!!!!! unless you have the lambda probe fitted. This CAT thing comes up quite often with the 318iS, I've never known anyone to have a CAT fitted, it's just a resonator.

The definition of 'front pipes' is a bit dubious here i suppose.... technically the pipe that comes off the manifold should be called 'the front pipe', but it's not just a pipe in this case as it has the front resonator attached to it...

So I'd say the down pipe includes the front box, therefore the if your changing the exhaust after the down pipe this will be the last two boxes only.

Considering i have never seen a 318is exhaust and am going by the diagram i am saying this IS a CAT!!!!!!!!!!!!!!!!!
As it does have a Lambda Sensor!!!

wooooo chill dude, what i was saying that the 318iS doesn't need to have a CAT and very few do, as the iS were only available in late '89 to early '91 before the CAT became mandatory.

The easiest way to check of you have a CAT is to grope under neath the battery tray, if you find a capped off connector then you don't have a CAT.

As the M10 man said, the ETK pictures aren't necessarily correct.

I'm sure your exhaust could make a straight through pipe to eliminate the front box, but it will sound like hell on earth IMHO. What size back box did you have put on?

I've had the two rear boxes removed from mine, and just one large box replacing them. I got them to use the largest box they could to reduce the noise, i like my exhaust, very subtly louder than standard, but not in your face.

[dark_sounds]

likewise mines quite a large rear box, and ive got a smallish mid box. deep but not too loud and mental,

265 x 410 is the size of the back box...

that alone cost 100 quid? does that mean if i went for a loud rubbishy chaved up MEEEEERRRR in ur face exhaust it would cost cheaper??

what if i replaced the front box with a small box like the mid box so it stilll stainless and bit quiter....


what effect on sound will removing the front box and replacing with pipe have??