DIY competition exhaust sytem!

[petrolhead]

Hello Comrades of the Old skool brotherhood,

 

Some of you may have already followed my thread and vid on the DIY manifold that I made:

which liberated a few extra ponies. But I was always aware that although I had got rid of one bottle neck, another remained - the Ashley Exhaust system.

 

So I decided to do my own. I had one day (when I'm not working I'm normally looking after the kids), my drive and a budget of about £120. This is how I did it (the good the bad and the ugly)....

 

1) What size 2" or 2.25"? There seems to be a lot of disagreement so I did some research and when in doubt rely on Vizard. He came up with an equation (I can pm if you are interested) the long and short of it is this:

 

Up to 150bhp use 2" OD pipe

150-190bhp use 2 1/8" OD pipe

190+ use 2.25" OD pipe

 

2) I went for 2 1/8" pipe as I am aiming for 150bhp but I suggest most of you go for 2" as it is much easier to get, cheaper and you will keep real world torque.

 

3) Materials needed:

2 x 1m lengths of your chosen size tube (2 1/8") in thick 16 guage steel

1x 0.5m length of the size larger (2 1/4" for me) for making external sleeves.

1 x Universal straight-through silencer, I used the Jetex BIG 51 (£70) but the smaller one is more like the Ashley original and is cheaper.

 

Its important to get 16 gauge as the larger tube forms perfectly fitting sleeves for the Joins

 

Using this external sleeve technique (ie the tube fits over the exhaust manifold rather than inside it means that there are no internal lips or narrowing at the joins this means higher gas flow rates.

 

The first metre length stops halfway down the car, you need a slight (3') angle for the second pipe to go upwards but still under the axle. I kept a 1" gap under the axle and almost inline with the welds on the diff (I'll explain why later)

 

 

Once I was happy with the fit and where the mounts would go I welded the two lengths together

 

My silencer was needed to slant upwards as well,

 

I used a 10degree cut and that 2 1/4 to create a sleeve for the join (note If you are making a 2" system this silencer is designed to slip over 2" pipe.,

 

I made a skid plate for the forward edge of the silencer, I made a hole at the lowest point of the skid plate to stop water collecting and rotting out the silencer.

 

For the mounts I used a stainless bolt for the middle one and a piece of steel rod for the silencer. Excuse the welding on the silencer, I had gas problems but perservered because I was short on time:

 

 

So with a nylok nut the middle mount bolts on. The kink at the end of the rod welded to the silencer means that it can only fit on if it is rotated 45' then slipped through the mount

 

Use quality heavy duty Mikalor clips to stop it rotating or better stll make another mount on the boot floor to support both sides of the silencer (I can't bear to drill holes in my shell)

 

 

Finished article finished in Plastikote Hot Paint (superb paint)

Excuse the mud-splattered look, this is after 800 miles of driving. 400 of it across challenging Welsh roads. Even though it goes under the axle it sits higher than the Ashley exhaust and is even slightly quieter!

 

Dyno results?

*With ashley manifold and exhaust 137bhp

*With Wardspeed manifold and Ashley exhaust 140bhp @6600rpm, 124lbft@5000rpm

*with my manifold and exhaust 149bhp@7000rpm and 118lbft@5600rpm

 

The last result was not on HT's dyno, so I will re dyno it in Oct for a fair comparison but early indications are good and it definitely drives much better. Although I seem to have lost torque, on the graph average torque and the torque curve is higher and flatter which is good.

 

Remember, if you copy this it is at your own risk. I've just put it here for inspiration. You can buy a badly fitting exhaust off the shelf or for similar money produce a better performing custom one.

 

cheers

 

Petrolhead Matt

[Copey]

nice one

 

best thing you have done is take it under the axle, will be much better flowing now

 

looks spot on

[Slammed]

again another cool guide matey and thanks for sahring the info

 

 

i shall attempt this, i say attempt

[emu]

Spot on

 

How you have done that is almost identical to mine.

 

Only differences being I bent my pipe with oxy-ace(cetalyn???), used VW style exhaust joiners and used a volvo silencer for the back box.

 

(which I suppose means mine isnt really anything like yours at all is it!! )

 

As you say, still has good ground clearence, is much cheaper, and doesnt knock everywhere.

 

Some nice power and torque figures you have there too

[petrolhead]

That's a great idea, if you can find a good second-hand silencer of straight through design you can make a massive saving.

[vibrating_Cake]

you just use the single silencer???

how loud is it..?

is it louder than the inlet+will it be quiet enough for trackday regs (96-100db)????

 

very interested with this!!! and whered you get the pipe etc? links

 

also... do you HAVE to weld? sounds silly but could you get away without...

and any explinations on the 10degrees angle you needed, i dont see why that was needed? also is your car on lowering blocks or de-cambered leaf springs, the axle sits nice and high

 

ta in advance for the answers... also... if i were to get a 2" pipe with a "flexi joiner" just after the manifold exit, to tuck the pipe up to the bodywork, whats your views on this method... also helps reduce stresses on the welds.

 

and... where you located and you fancy making some beer money =o)??? haha

[Fiesta Steve]

also is your car on lowering blocks or de-cambered leaf springs, the axle sits nice and high

 

 

Lowering your car will not alter the height of the axle !! Only the tyre size can alter this, and they look like 175/50's so that'll be as low as it gets.

 

As for the noise levels, pipe diameter plays a huge part in this. With 2 1/8" bore I don't think Matt will have any trouble with noise regs.

[vibrating_Cake]

also is your car on lowering blocks or de-cambered leaf springs, the axle sits nice and high

 

 

Lowering your car will not alter the height of the axle !! Only the tyre size can alter this, and they look like 175/50's so that'll be as low as it gets.

 

As for the noise levels, pipe diameter plays a huge part in this. With 2 1/8" bore I don't think Matt will have any trouble with noise regs.

 

ohhh yehhhh... buhhh!!! i must have been thinking of something else lol

[petrolhead]

So many questions, lol. Answers below:

 

1) Just a single box which is slightly biger than the Ashley back box

 

2) It is definitely quieter than the twin box Ashley system it replaces. Prabably due to thick gauge steel, bigger back box, bore (as Steve mentioned) and modest 2.25" tail pipe (Ashley was a chavvy 3")

 

3) Don't know about dB levels, it is louder than the intake, see answer 2

 

4) You could minimise the welding by using slot together parts from the Jetex Universal Parts Catalogue (google it) but you would still need to weld the mounts and heat the pipe to bend it slightly.

 

5) The angles bend the system upwards at the back, you can kind of see this in the last photo. If you didn't have any angles it would get progressively further away from the floor and exit 9" below the rear valence rather than a snug 0.5" below it that I have.

 

6) I had to double-think about what Steve said about lowering blocks and he is right. I have 175/50's on.

 

7) Flexi joins seem like a good way to reduce vibration stress but if the exhaust is mounted properly it shouldn't be a problem.

 

Finally, I'm sorry , I would love to help but I have started a new job with 12 hour days and after my family I have very little spare time. I can advise though so feel free to ask.

 

regards

 

petrolhead matt

[emu]

also is your car on lowering blocks or de-cambered leaf springs, the axle sits nice and high

 

 

Lowering your car will not alter the height of the axle !! Only the tyre size can alter this, and they look like 175/50's so that'll be as low as it gets.

 

As for the noise levels, pipe diameter plays a huge part in this. With 2 1/8" bore I don't think Matt will have any trouble with noise regs.

 

It does make the axle sit 'higher' into the body though, which helps to minimise the amount you would need to bend the pipe to go underneath.

 

 

Vibrating cake - This is the style of joiner that I used, your local exhaust supplier should be able to get them in a variety of lengths and diameters.

 

http://cgi.ebay.co.uk/Exhaust-Pipe-Conn ... 286.c0.m14

[vibrating_Cake]

that for 2" pipe??

 

iirc the output on my manifold is 2 1/4 inch... if i got a 2 1/4 inch pipe (1m long) and get two streight through boxes which sleeve over the 2 1/4 pipe.

 

what would i join the end of the manifold to the pipe with? 2 1/4" to 2 1/4"

 

the two boxes should be easy enough to slip over and clamp. and use the jetix mounts with a cotton reel mounting bush or two to mount it to the chassis (cause im ok drilling into the shell) and those long pieces of metal that look like meccano.

 

then all i need to do is get a flexi for 2 1/4" pipe and get it welded between two small lengths of the 1m long pipe....

 

so...

 

manifold (2 1/4) to

a (2 3/8") joiner to a short piece of 2 1/4" pipe

with a welded on flexi pipe to

a length of (2 1/4) pipe slipped into the first box

another length of (2 1/4) pipe slipped into first box and into 2nd box

onto a 45 degree turn slipped onto end of 2nd silencer

(for the side exit) before the rear axle

 

then use the meccano mounts with cotton reel rubbers bolted into the cars floor. using the flex on the flexi pipe for the 5degrees angle to keep the exhaust level with the floor...

 

would the first join be strong enough?? what would i use for it??

 

 

sorry i need to get rid of my powerflow shite exhaust!

[vibrating_Cake]

as above... 2 1/4" system being 57.15mm

 

manifold to....

 

http://cgi.ebay.co.uk/Stainless-Steel-E ... .m14.l1262

 

with tubing after this joiner to the first box being

 

http://cgi.ebay.co.uk/EXHAUST-PIPE-TUBI ... 286.c0.m14

 

then the box... something like a cherry bomb, low profile but where 2 1/4" slips in and bolts up

 

http://cgi.ebay.co.uk/Cherry-Bomb-Unive ... 286.c0.m14

 

all held onto the shell by

 

http://cgi.ebay.co.uk/EXHAUST-BOBBIN-UN ... 286.c0.m14

 

and

 

http://cgi.ebay.co.uk/Exhaust-Parts-Uni ... .m14.l1262

 

to hold it all tight to the body

[petrolhead]

The list of components generally looks OK but check the sizes. That specific cherry bomb seems to be for 2" pipe or less. Also it is not clear to me if that flexi link is to join 2.25" tubes or is itself 2.25" (in which case it is for joining 2" tube).

 

To join 2 1/4" tubing you can use a 2 3/8" short section of 16 gauge to create a very snug fitting sleeve (see 1st post above, 2nd pic). One side is then welded in place and the other clamped over the mating tube (or you could possibly just clamp either end)

 

http://cgi.ebay.co.uk/2-3-8-60-3mm-Mild ... 286.c0.m14

 

The rest of the 2 3/8" can then be used to make a 60mm tail pipe.

[Fiesta Steve]

 

what would i join the end of the manifold to the pipe with? 2 1/4" to 2 1/4"

 

 

To join these you need pipe of 2 1/4" INTERNAL diameter

[vibrating_Cake]

The list of components generally looks OK but check the sizes. That specific cherry bomb seems to be for 2" pipe or less. Also it is not clear to me if that flexi link is to join 2.25" tubes or is itself 2.25" (in which case it is for joining 2" tube).

 

To join 2 1/4" tubing you can use a 2 3/8" short section of 16 gauge to create a very snug fitting sleeve (see 1st post above, 2nd pic). One side is then welded in place and the other clamped over the mating tube (or you could possibly just clamp either end)

 

http://cgi.ebay.co.uk/2-3-8-60-3mm-Mild ... 286.c0.m14

 

The rest of the 2 3/8" can then be used to make a 60mm tail pipe.

$

 

i was just using the cherry bomb as an example of a centre box, couldnt find what i chose before, think it was a magnex box or something.

 

so...

 

i cant weld and i'd rather use a flexy. but if push comes to shove i could get someone to weld up a flexy with two small runs of 2 3/8" tubes to clamp em.

 

so... if my EXTERNAL diameter of my manifold is 2 1/4"

 

i would need *two of* (2 3/8") 16guage steel sections to sit flush over the manifold end and weld onto both ends of the flexy (clamped up externally over the manifold)

 

on the end of the (2 3/8") 16guage steel tube coming out of the flexy i'd have a (2 1/4") 16guage?? steel tube inserted INTERNALLY (clamped up) ,however long it needs to be.

 

on the end of the (2 1/4") 16guage?? steel tube ill slide over a centrebox designed for a (2 1/4") tube, clamp that up, then repeat for the rear box. (clamped up)

 

out of the rear box i'd use some (2 1/4") tube/bend and to exit use the rest of the (2 3/8") 16guage steel sections (clamped up) to get it to the side or the rear of the car? or just use the rest of the (2 1/4") tube//leave it to exit under the car.

 

then make hangers with the meccano stuff and bobbin rubbers

1. front & back of front box

2. front & back of 2nd box

3. as far back as the exhaust goes right near the tip

 

bearing in mind i would say a minimum of 300mm between flexy-box and same again between the boxes, means it should end somewhere JUST before the rear axle and also have enough "tube" to "flow" rather than, flexy, silencer, pipe, silencer exit., itd have a bit of room to build up flow between the boxes and flexy

[petrolhead]

Yes all of the above looks right. Just to clarify, 2 3/8" 16gauge tube does have a 2 1/4" id.

 

Also have a look at the sleeve I did for the silencer. Put slots in all sleeves so that they can be effectively clamped.

[vibrating_Cake]

 

i will keep you updated!

[vibrating_Cake]

vvv silencer link vvv

 

http://shop1.actinicexpress.co.uk/shops/Rat_Sport/index.php?cat=Ashley&ActinicSID=50a55703ddf5a1d83569b1abeb646ca5

 

ACE04 silencer.... 4 inch body by ashley.... anyone know where i can get any cheaper oval silencer (2 1/4 inch) thats maybe 3 inch deep, 4 inch is really my limit. and it needs to silence a lot as im deciding on a single box... and the ovals seem to silence a lot more with a streight through core?????

 

i dont fancy the cherry bombs as they seem to be really loud... and not silence much! i need to be under trackday regs.... (96/98db @ 3000rpm )

 

ive done an example price for a 2 1/4 inch system including a bolt on flex and 1m of stainless tubing

 

 

EXHAUST

 

FLEXI £22+5.50 = £27.50 ebay

STRIPS £2.20 X 2 = £4.40 ratsports

BOBBINS £2.20+£2.20 x4= £10 ebay

PIPE £14.95 = £14.95 ratsports

SILENCER £57.50 = £57.50 ratsports

PASTE £1.73 X2 = £3.46 ratsports

 

postage £10

 

Total plus postage = £127.81

[lurch914]

i cant weld and i'd rather use a flexy. but if push comes to shove i could get someone to weld up a flexy with two small runs of 2 3/8" tubes to clamp em.

 

you could get of these to sort the clamping issue out

http://cgi.ebay.co.uk/Bergen-3-piece-ex ... 286.c0.m14