Hey Guys,

Was looking for some advice and maybe a few pictures of peoples exhausts. Had a search but couldn't find too much information about actually making your own extractors and exhaust system.

I have an XH and was going to whip up a set of extractors and a 2.5" system.

Just interested in some technical advice.

Engine is basically stock.

With the exhaust,

Was thinking..........2.5 system - Catalytic converter, smallish muffle before the diff and a largish muffler after the diff with very little pipe after the 2nd muffler - Have heard this helps to minimise reasonance issues in the Ford plus gives a nicer sound?

For the extractors,

Two options - 2 into 3 into 1 setup - this could get a bit messy though - would be paring 6 with 1, 2 with 5 and 3 with 4, this was the advice I got from a few exhaust shops for probably the best design for a set of extractors, anyone else got an opinion on this?

Or,

3 to 2 to 1 - this would be a bit simpler to make and would be just pairing up the first 3 cylinders and the back 3 cylinders. This seems to be the model used by Pacemaker and some other off the shelve brands I have managed to find pics of.

Making the stuff isn't concerning me - just like a bit more theory about what will actually be the best setup would be appreciated.

This thread has a few pic's of some custom extractors as well as some off the shelf sets, might be of some use to you..

ford-4l-and-6-cylinder-f1/show-us-your-pipes-t90445.html?hilit=pipes

Mine are the ones from show us your pipes and the design is 6-3-1 all tuned length and mandrel bent, they work great but will be really expensive to get made but best case is your very skilled and have a lot of time on your hands.

Feel free to ask questions if you want.

What do you intend to do to the engine and what do you want out of it in terms of performance? (i.e what rpm do you want it to perform best at/where are you willing for it to suffer).

I would go 6-3-1 set up with the pairing as you said. In terms of measurements I would use 38mm primaries for mild set up, 39/40 for a medium set up and 41/42 if you want it hot. From here you really need to know the actual set up of the engine so you can figure what rpm range to tune to. The theory behind it is that pulses are created from the opening and closing of valves which travel down your exhaust and reflect (as well as continue) when they reach junctions. The primary purpose of pulse tuning is to create an area of low pressure behind your valve as it opens so that it essentially 'sucks' exhaust gasses out of the cylinder. Then you have collectors/secondaries which use pulse tuning improve efficiency of primaries for lack of a better term.

The fun part is that from an open end (ie a junction) your reflection inverts and you get a negative pulse running back up your primary, but from a closed end (ie a closed valve) it stays the same upon reflection (negative pulse will reflect as negative pulse, positive as positive). You can use generally up to the 4th reflective wave for tuning, although your first 3 are the most important.

Sh"t Dorman AU.....................that is elaborate! You make that yourself?

Guess with something like that you would tack the runners together and then pull it all apart, weld up the tubes, than throw it back onto the exhaust flange. As long as you were able to do this off the car, i.e. a spare head and you could flip the thing around so you were in a suitable welding position (particulary if it is TIG'd together) It would be fairly straightforward, time consuming as all hell though !

What is the gain from that design Dorman AU?

Got any more pics ?

So what you have is a my first option, i.e. the 2 ports into 3 collectors and then into 1 collector? But with extremely accurate runners with perfectly equal length? Don't think I would probably go to that extend, but try and get them as close to equal as possible without spending 8 weeks on it !


Don't suppose you know why your exhaust was done this way (not the equal length runners) but the lay-out of the collectors?

What does the rest of your exhaust system look like?



Lots and lots of low to mid-range power - not to fussed if I lose power up top for this. Was even thinking of going down the turbo route and putting on a little Gt28, but is a lot easier to just make a set of extractors and do a cam compared to properly turboing a car, even poorly turbo'ing car is very expensive compared to a set of extractors !

Anyone got an opinion on my exhaust, as in the placement of the mufflers?

Cheers

Tony

Mandrel bends or crush bends in the sports exhaust???

How do I use that particular piece of information in designing a set of headers ?

Sorry just realised I gave you the wrong formula, will put the proper one in when I get home tonight.

I didn't make these extractors but being a boilermaker I under stand how much has gone into this. The runners are all tacked together and then all the flange pieces are individual so would have been welded while in a spare head. I would have use a joined flange as when the stainless pipes have shunk its made it hard to put some bolts in.

I'll have a look for some more pics.

After the extractors I have a redback cat and redback 2.5in mandrel bent with one middle straight thru muffler and a hotdog resi. Cruising at 100 ks it can hardly be heard with the radio very quiet it is louder then the exhaust, boot it then she comes alive.

Also to add on the car is very slow under 2000 then just picks up and goes and goes till redline. Std cam to.

Your not wrong mate! Have to do it out of the car and would have to bolt it to a head to try and avoid warping, which would be almost impossible - so just have to keep it to a minium - start by locating the collectors, then start trial and errorring routing of the tubing, tack it all up, pull the individual runners apart, brace them, weld them up - but not to quickly to avoid warping and so on - then start assembling them back onto onto the manifold flange - reckon the welding alone would take you a day !

They are very cool looking extractors mate - love to see more pics!

Where are you mufflers located - one before the diff and one after close to the a£s of the car?

What kind of HP/Torque are you making?

Yeah a muffler before the diff and resi in the normal spot next to the tyre well. Not sure about power yet but thinking about the 125 to 135 rwkw mark. Getting a tune in next few months so ill let you know.

With the flange start off with 12mm and once its all welded get it milled so its true.

I have off the shelf Pacie 4480's, but after that is custom made. I got a new BMW CAT ( damaged in transit ), cut the ends off, made my own cones for it ( it's as long as the g'box ), into a twin ,side-by-side 2&1/4" exhaust into the muffler ( custom made too ), then a single 2&1/2" after that.
It isn't loud, about the same as an original EF/EL XR6 system, and it doesn't drone.
I'm making 150 rwkw at momment, with some more fine tuning to come.

Why did you use the BMW cat mate? Better flow?

Why did you go the twin route?

Going to grab an VY (I Think) SS exhaust of a friend and it has a similar arrangement (Nice cheap mandrel bends to cannibalise ), It has dual exhaust's, running into seperate mufflers, then the twin pipes go into 1 big muffler at the rear and the splits into a dual tail-pipe.

I am best off to just replicate the placement of the mufflers of my current exhaust? I am building this thing from scratch and will have the materials - any point in running a dual system ?

I used it coz it was free.....and it was new.....and has a s/s outer casing, so made s/s cones for it.
The twin route.....no drone.....heaps of flow, without the noise. It is only twin into the muffler.
Have a look at the EBII XR6 exhaust ( factory type ), they were twin till over the diff, then single, much like a V8 system.

Here's a pic of the CAT from my car. I had it out today to weld in a socket so as to fit a wideband O2 sensor. Thats a 600mm steel rule next to it for size.
It has 2&1/2" in and twin 2&1/4" out. Here's a close up of the insides.

 

 

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