Building an exhaust

[Behold81]

So I'm about to build a H-pipe for the Holden. It's part one of building my 3inch system.

Should the H be 3 inch too or thinner?

Also as I have no cats and don't need cats. Should I move the H Pipe nearer the headers? Is there a calculation for that?

Thanks

[j666eds]

http://www.superchevy.com/how-to/exhaust/1504-x-an...

[OverSteery]

Behold81 said:

So I'm about to build a H-pipe for the Holden. It's part one of building my 3inch system.

Should the H be 3 inch too or thinner?

Also as I have no cats and don't need cats. Should I move the H Pipe nearer the headers? Is there a calculation for that?

Thanks

Can't help much, but please keep us updated.
I assume this is for the GTS? I don't know the history of my system, but its seems a quality job and sounds wonderful, say of you want me to take photos of the routing etc for you to consider.

Why no Cats?
Are you going to fit a cut-out

[Behold81]

j666eds said:

http://www.superchevy.com/how-to/exhaust/1504-x-an...

Perfect! Thanks.

[Behold81]

OverSteery said:

Can't help much, but please keep us updated.
I assume this is for the GTS? I don't know the history of my system, but its seems a quality job and sounds wonderful, say of you want me to take photos of the routing etc for you to consider.

Why no Cats?
Are you going to fit a cut-out

Yes for the GTS. There is nothing wrong with my Wortec 2 1/2 inch system other than I want to have a H Pipe for sound reasons and my headers are 3 1/2 inch exit. If I'm going to build a new section I might as well go 3 inch. much larger is not needed and clearance becomes an issue. at the moment I have it in quite mode (centre boxes in) buy I have an idea for a varex bimodal system.

Using these http://parts.parts.s3.amazonaws.com/106304/VMK16-3...

This will allow a single pipe to be straight through or silenced with out being dual sided like the newer monaro's and VXR8's are. once built I can sell my Wortec system and probably break even at least. I will likely still have a rear box (although we will see how the centre boxes perform) for now its just the H-Pipe. Baby steps.

You don't need cats legally on the GTS unlike the monaro as it was never sold in the UK so was not EU Approved. this means it is not tested as an EU regulated car with CATs but as an import. as it was imported in such small numbers it is not on the MOT DB and has no emission to be tested to. this means it will be tested as a PRE cat car. Some centres stick it under monaro tests and they need to be educated! I have a good tester that I use so its not an issue.

on a side note I have also had a copper stop me saying that if he got under my car he could impound it for not being a BS stamped exhaust. I told him he is right it is not BS Stamped but it does not need to be. the conversation when on for a bit before he realised its an import and he should just move on before I report him for time wasting. To be honest he also didn't question his ANPR that though my car was a Renault 5.

[OverSteery]

Hmm this thread is full of goodness....

VAREX is new to me, and I am thinking a rather more pleasing solution than a Cut-out.

I have yet to MOT my car. I know a 'good man' who often can help me through emissions tests and I was wondering if I would need his help, but clearly not.

you say "it was never sold in the UK so was not EU Approved". How did LSV manage the process foe the 60 odd GTS(R)s that they sold? was it through SVA or something? Obviously its too good for the rest of Europe.

What was your copper talking about? Did he actually mean BS as in British standard? Whilst regretful, the world doesn't now show such respect of our institutions.....

My car appears to have a couple of cats thanks to H5V VE (he's a bit sensitive if I don't show appreciation of his excellent period of ownership and generosity of letting me own it ) and a rear box. Whilst not overly loud, I think its sounds great. Interestingly enough it conforms some of the words of the link posted, having a X cross-over its a more refined and less US V8 sound than I'm used to.

[Behold81]

OverSteery said:

Hmm this thread is full of goodness....

VAREX is new to me, and I am thinking a rather more pleasing solution than a Cut-out.

I have yet to MOT my car. I know a 'good man' who often can help me through emissions tests and I was wondering if I would need his help, but clearly not.

you say "it was never sold in the UK so was not EU Approved". How did LSV manage the process foe the 60 odd GTS(R)s that they sold? was it through SVA or something? Obviously its too good for the rest of Europe.

What was your copper talking about? Did he actually mean BS as in British standard? Whilst regretful, the world doesn't now show such respect of our institutions.....

My car appears to have a couple of cats thanks to H5V VE (he's a bit sensitive if I don't show appreciation of his excellent period of ownership and generosity of letting me own it ) and a rear box. Whilst not overly loud, I think its sounds great. Interestingly enough it conforms some of the words of the link posted, having a X cross-over its a more refined and less US V8 sound than I'm used to.

I'm not a fan of cutouts. I know a lot have them and yes there a great way for the great sound. I just like my fumes to all come out where the exhaust exits.

the varex box normally is single in twin out. one is silences the other open. when the second pipe is open the exhaust comes out the path of least resistance. but for us single sided blokes its no use. I found they do these so want to try them. about 500 for a pair.

my HSV sounds racy not burbly enough. hoping the H will solve that.

You might find you have a Wortec. it was the main system most of these were fitted with. you might have the centre boxes in and need the loud mode pipes (just no boxes)

and yes British standard mark! his partner was giggling behind him each time I called him out!

[ARAF]

Behold81 said:

I'm not a fan of cutouts. I know a lot have them and yes there a great way for the great sound. I just like my fumes to all come out where the exhaust exits.

Technically, even with cutouts the exhaust gasses come out where the exhaust exits - it's just an earlier exit.

I do know what you mean though, which is why ours exit behind the rear wheels, and with the shorter cab of the really big-boot model we don't get any exhaust gasses coming in the cabin.

[Wolfracer]

I think the force at which mine are squirted towards the tarmac is plenty for them to not hit the body work. I cut out just on the bend before the rear boxes on the vxr8.
Been in over a year now and still make me smile when I click the button!

[H5V VE]

OverSteery said:

My car appears to have a couple of cats thanks to H5V VE (he's a bit sensitive if I don't show appreciation of his excellent period of ownership and generosity of letting me own it ) and a rear box.

Quite right too !

I am pretty sure that it's a Wortec system if that helps and the cats are only 12 months old (or thereabouts - receipt will be somewhere in the mound of paperwork or Andy can confirm) so I would hope that part of the MOT won't be a problem

[ArnieVXR]

Behold81 said:

Also as I have no cats and don't need cats.

Correct, but you still need to pass the non-cat emissions test. I looked into it with my VT2 GTS. Section 7.3 of the MOT manual states that personal imports are tested against their age at first use. The non-cat test is normally only for cars first used up to 31-July-1992. Even then, the visual only test is for pre-1975 vehicles and Q-plates.

The flow chart in section 7.3 page 9 clearly shows that vehicles first used between 1992 and 2002 that have no match in the database should be tested with the non-cat test. They need to have CO <= 3.5% and HC <= 1200ppm.

Interestingly, if you fit an old engine (and can prove it's old) you get tested using the age of the engine, not the car. Must be time to buy a snotty old big block from 1974 and slip it into the engine bay

[Behold81]

Yeah exactly it still has to pass it never struggles with it. Passes fine on that basis.

[2woody]

I built an entire 3" system - and was surprised how easy it was.

I put two sets of flanges in at approximately where the cats would have been, so that I can have a separate piece with a cross-pipe.

[Behold81]

2woody said:

I built an entire 3" system - and was surprised how easy it was.

I put two sets of flanges in at approximately where the cats would have been, so that I can have a separate piece with a cross-pipe.

Any pics?

[MyM8V8]

Behold81 said:

OverSteery said:

Can't help much, but please keep us updated.
I assume this is for the GTS? I don't know the history of my system, but its seems a quality job and sounds wonderful, say of you want me to take photos of the routing etc for you to consider.

Why no Cats?
Are you going to fit a cut-out

Yes for the GTS. There is nothing wrong with my Wortec 2 1/2 inch system other than I want to have a H Pipe for sound reasons and my headers are 3 1/2 inch exit. If I'm going to build a new section I might as well go 3 inch. much larger is not needed and clearance becomes an issue. at the moment I have it in quite mode (centre boxes in) buy I have an idea for a varex bimodal system.

Using these http://parts.parts.s3.amazonaws.com/106304/VMK16-3...

This will allow a single pipe to be straight through or silenced with out being dual sided like the newer monaro's and VXR8's are. once built I can sell my Wortec system and probably break even at least. I will likely still have a rear box (although we will see how the centre boxes perform) for now its just the H-Pipe. Baby steps.

You don't need cats legally on the GTS unlike the monaro as it was never sold in the UK so was not EU Approved. this means it is not tested as an EU regulated car with CATs but as an import. as it was imported in such small numbers it is not on the MOT DB and has no emission to be tested to. this means it will be tested as a PRE cat car. Some centres stick it under monaro tests and they need to be educated! I have a good tester that I use so its not an issue.

on a side note I have also had a copper stop me saying that if he got under my car he could impound it for not being a BS stamped exhaust. I told him he is right it is not BS Stamped but it does not need to be. the conversation when on for a bit before he realised its an import and he should just move on before I report him for time wasting. To be honest he also didn't question his ANPR that though my car was a Renault 5.

Why did he stop you? Because it was a funny shaped Renault 5?

[MyM8V8]

I assume my YOM 2001 VX2 GTS (Reg 2002 in UK imported by LSV) does not need a cat test then?

[MyM8V8]

OverSteery said:

Interestingly enough it conforms some of the words of the link posted, having a X cross-over its a more refined and less US V8 sound than I'm used to.

That's more to do with the firing order which is not old school V8.

Old 1-8-4-3-6-5-7-2

LS's 1-8-7-2-6-5-4-3.

[MyM8V8]

MyM8V8 said:

OverSteery said:

Interestingly enough it conforms some of the words of the link posted, having a X cross-over its a more refined and less US V8 sound than I'm used to.

That's more to do with the firing order which is not old school V8.

Old 1-8-4-3-6-5-7-2

LS's 1-8-7-2-6-5-4-3.

Unashamedly lifted from the corvette forum:
"Hi Guys,

I'd like to suggest the possibly "correct" reason for the switch.

Chevy, AMC, and others, all used 1-8-4-3-6-5-7-2, because it allowed the use of an easily balanced 90-degree crankshaft. The other option was a more difficult to balance 180-degree crankshaft, present in our LS series engines. Unfortunately, the old firing order presented a problem; look at the the third, and second to last, cylinders firing; 5 and 7. Note that they are right next to each other on the engine block, and obviously, cylinder head. When five fired, its exhaust pulse was still in the exhaust manifold, creating a high-pressure zone for cylinder seven, which fired immediately afterward. This obviously reduced power, and lead to uneven heating, and wear, on the odd side of the cylinder heads. This is why headers showed such a significant increase in power over "log" type manifolds on those V-8s; they separated the exhaust pulses until much later, when the emissions from the exhaust ports had time to open up into a MUCH larger pipe, AKA the collector, which was usually twice as wide (therefore 4x the flow) of the log manifold where the pulses started off. This is also why today's LS motors only see a modest increase in power when equipped with exhaust upgrades. I've heard of guys spending $500 on shorty headers, and seeing an increase of only 5-6 hp - mainly due to this reason. Long tubes, on the other hand, allow more complex fluid phenomena to take place, including transition from laminar to turbulent flow, along with the density increase due to temperature drop occurring later, and therefore at a more opportune time to create an induced low-pressure zone at the exhaust ports than with factory manifolds. However, one point that is missed by many, is that the factory manifolds have a MUCH greater thermal inertia than SS headers, and for that reason, SS long tubes work best when wrapped with insulating material, for as much of the length of the primary as possible - the matter would be ideal if one could wrap the insulation all the way to the collector."

Interesting point about little or no major gains from fancy headers over stock cast logs.

Another thread expounds the virtues (power gains) from wrapping (insulating) stainless steel headers.

[Behold81]

MyM8V8 said:

Why did he stop you? Because it was a funny shaped Renault 5?

Becaus the Renault 5 was untaxed , no mot and uninsured

I proved tax as this was when we still had them on the screen. I had the mot in the car as it was done earlier that week. I explains the tax was only 2 days old and I would have needed insurance. He was adamant I was lying and his DB was accurate.

Then he told me this is a blue Renault 5 and I burst out laughing.
He did not like that! Only just mot'd I knew he would find nothing in the car so I mildly mocked his car knowledge. His partner found that funny!

[Behold81]

MyM8V8 said:

That's more to do with the firing order which is not old school V8.

Old 1-8-4-3-6-5-7-2

LS's 1-8-7-2-6-5-4-3.

That is true but a h-pipe does give some of it back. And helps the more oldschool some. But so does a cam.