how to route exhaust pipes

Sammy · Post by **Sammy** » Thu Oct 23, 2008 2:09 pm

ok i need some advice from those who have done it ... i guess either with a v6 or v8 .....

ok first things first, i want to run a single exhaust pipe out the back of the ute, weather its before or after the diff i want one only ... not a fan of dual pipes .....

the original plan was for custom extractors into 2 x stock commodore v6 cat converters, then from there into 2 x mufflers then somwhere between the mufflers and the rear of the car it would join into one single 2.5 inch exhaust.
I pretty much can't do anything after the diff as far as joining the two into one and before the diff is useless with the tailshaft there so it has to be done up near the gearbox.

SO ... i've been looking at what my options are as far as fitting mufflers in under the car etc and this is where i stand at the moment.

so my thoughts were as follows:

1. cut the left (in the picture) pipe off just after the collector and swing it hard right to go under the bell housing and across to the right hand pipe then join them into a 2.5 inch pipe which will then go into a cat then muffler .... and out the back ....

2. swing the current left hand pipe over to the right hand side after the gearbox crossmember which has pretty much the same clearance as the bellhousing area then join into 1 and then be as above.

as i see it - disadvantages:

1. swinging the pipe over at the bellhousing is well and truly doable however the bend is going to have to be a quick 90 degrees down and then 90 degrees right and then another 90 over on the right hand side to get it into the other pipe.

2. having it here is probably going to mean the cat converter and muffler are further back than in 1. which might mean less room to move for exhaust options, also means the left pipe joins the system after the oxygen sensor (which is how it would have been with the current twin cats anyways).

so i'd like to see pics of peoples exhausts how they have handled this if there is anyone out there who has done a cross over like i'm suggesting or just peoples thoughts and maybe some advantages/disadvantages that i may not have thought of .....

i'm tending towards the bellhousing crossover only because it will be better having the cat closer to the motor and i'd prefer to have the oxygen sensor reading both banks!!

oldnek · Post by **oldnek** » Fri Oct 24, 2008 11:30 pm

Sammy wrote: I pretty much can't do anything after the diff as far as joining the two into one and before the diff is useless with the tailshaft there so it has to be done up near the gearbox.

You could run the pipe return just under the rear extension housing

so my thoughts were as follows:

1. cut the left (in the picture) pipe off just after the collector and swing it hard right to go under the bell housing and across to the right hand pipe then join them into a 2.5 inch pipe which will then go into a cat then muffler .... and out the back ....

I wouldn't do that, the transmission and engine temps are hot enough, without the need of the exhaust keeping the oil temps up even more.......

2. swing the current left hand pipe over to the right hand side after the gearbox crossmember which has pretty much the same clearance as the bellhousing area then join into 1 and then be as above.2.

Thats what I would do.

Regards John

P.S I'm not really a fan of Duals on 6's either

mrs ratbox · Post by **mrs ratbox** » Sat Oct 25, 2008 6:43 am

re: the temps, don't they run where sammy said from the factory other than they run right to left, ie. right hand pipe crosses over to left pipe, i do beleive the autos do run hot which is a drama when towing but being a lighter car may help

Sammy · Post by **Sammy** » Sat Oct 25, 2008 8:31 am

the pipe on a commodore runs along the passenger side so if i was to cross over at the bellhousing and go one pipe down the passenger side it would be the same as a commodore

i'm hoping the big oil cooler i have will resolve any tranny heat issues!!

i've had alot of people keep telling me i should go the two mufflers then dump it at the diff and just run a balance pipe between the two!

of course if i was to do that i'd need to see what the engineer has to say about the pipes like that, but being a ute i don't think there should be too many problems.

mrs ratbox · Post by **mrs ratbox** » Sat Oct 25, 2008 10:23 am

only thing with that i've never heard a 6 cylinder especialy a v6 that sounds good with a dual exhaust
as to tranny cooler this is just what i've heard, heavy towing is not a good thing but to overcome the problem fit a big tranny cooler so i'de say you'll be on top of it

Sammy · Post by **Sammy** » Sun Oct 26, 2008 10:09 am

yeah me either, thats why i wanted to go the single ....

i've been thinking, it might be worth trying the twins first with a balance pipe because if its no good asleat i can just remove it and put a single pipe on later .... and it means the bit i've already done will stay as it is which i would prefer not to change

i've got a decibel meter on its way too so i can see what she reads with the mufflers on it .... everyone tells me it'll be quieter than 96db but i'd like to know exactly how loud it is.

i guess if its crap at the end of the day i've only wasted a few hundred dollars of mufflers which i can probably use elsewhere down the track anyways!

Malcolm · Post by **Malcolm** » Sun Oct 26, 2008 6:28 pm

Sammy,

Make sure if you cross the pipe over under the bell housing you can get the gearbox out without dropping the exhaust down.

Will make it a lot easier to get the box out when the shitbox Holden 4 speed auto shits its self, or say, maybe you cant keep it in 4th gear.

mrs ratbox · Post by **mrs ratbox** » Sun Oct 26, 2008 9:52 pm

is the box still no good mal

i think it's nearly time for a clutch pedal

Malcolm · Post by **Malcolm** » Mon Oct 27, 2008 12:03 am

Hey RB, box is still out, have been told now it will be another $1200 to hopefully fix it. Taking it to $2500 in total.
Looks like I'm paying for experience here.

FB MAD · Post by **FB MAD** » Mon Oct 27, 2008 5:12 pm

I'd be chasing a better experienced auto trans repairer than the one you've been using to date especially since he's asking more money for a job he should have fixed before.

Just my thoughts,

Sammy · Post by **Sammy** » Mon Oct 27, 2008 7:47 pm

Mal, i'm thinking if i go the twins i'll be making the balance pipe at the rear of the gearbox and then it will make the two tail pipes into one piece then have the flanges that bolt to the cat converters before the crossover sorta a H shape...

as for the auto, anything is possible with it after the floods .... it only had a few drops of water in it and so im hoping its alright ... i know it has first and reverse hahahah

i tend to agree about your box too, if you take a box to someone and it comes back $*#@ then they expect you to pay for the repairs that crap.

either they knew there was a problem and rebuilt it anyways in which case thats there fault, or if they didn't know what they were doing then they shouldn't have taken it on in the first place.

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