3" Exhaust

[MacQuigley]

Im wanting to run a 3" exhaust on my 454ci 62 stepside but am having some difficulty routing the pipes.

I had hoped I could fit single boxes under the cab and take the pipes out just in front of the rear wheels but its just too loud for road use over here.

Of course Ive the added difficulty of getting round the X member in the frame but I wondered if anyone else has a similar set up that they could post some pictures of.

The truck is lowered but its only a 3" static drop, I can run the pipes below most of the frame. I would like to add a 2nd box on each leg though to try and quiet it a bit, but ultimately I may have to drop to 2.5".

[LVPhotos]

2.5 with Pypes tunnel X rear axle dump and a shot of out the rear.

[MacQuigley]

Originally Posted by LVPhotos

2.5 with Pypes tunnel X rear axle dump and a shot of out the rear.

I meant to ask, where your pipes form an X and are welded together are they open between the 2 legs of are they just welded together for strength?

Ive been told if you join the 2 legs together wither by an interconnecting pipe or in an X you get an additional sound reduction by doing that. I don't fully understand why, I assume it slows the gad down further, but if it works Im willing to give it a go.

[vin63]

The X-pipe helps to balance the exhaust pulses, maintaining a smoother flow...this in turn helps to reduce the decibels. The H-pipe configuration, not so much.

[LVPhotos]

Or if you can snake the pipe out side frame rail put mufflers in front tire.

[MacQuigley]

I like the look of that and it definitely gives me some ideas. Id still rather go 3" but that may still be a bit tight. That said Ive plenty of spare pipe to mock it up.

[vin63]

I don't have room to the inside of the frame, so I ran my 3" exhaust to the outside. I was able to keep it above the bottom of the frame.

[MacQuigley]

That's almost the setup Ive got at the moment (all be it a temporary setup) the only difference being I put the muffler under the cab floor about 16" from the header collector.

It does sound great, but it will never pass and MOT (the same as your inspection) as there are limits to how much noise and exhaust can put out. Unfortunately those limits are not exactly specified and a lot of it is down to the MOT tester on the day but I believe its 100db at 3900rpm and although Ive not tested it at that speed I am pretty sure Id not make it. So, Im hoping a 2nd muffler on each branch will solve that but I need to take the pipes out the back to get the space.

[vin63]

The muffler under the cab would be very annoying to me with the drone. Try putting a muffler as far back as possible, so that you can pass the sound test and then just remove it after.

[MacQuigley]

Originally Posted by vin63

Try putting a muffler as far back as possible, so that you can pass the sound test and then just remove it after.

Will it make a significant difference if I increase the distance between the headers and the muffler? I can certainly mock it up just to see what happens.

[AcampoDave]

Originally Posted by MacQuigley

That's almost the setup Ive got at the moment (all be it a temporary setup) the only difference being I put the muffler under the cab floor about 16" from the header collector.

It does sound great, but it will never pass and MOT (the same as your inspection) as there are limits to how much noise and exhaust can put out. Unfortunately those limits are not exactly specified and a lot of it is down to the MOT tester on the day but I believe its 100db at 3900rpm and although Ive not tested it at that speed I am pretty sure Id not make it. So, Im hoping a 2nd muffler on each branch will solve that but I need to take the pipes out the back to get the space.

Doesn't running a second muffler on each branch kind of defeat the extra flow gained by the larger pipe?

[MacQuigley]

Originally Posted by AcampoDave

Doesn't running a second muffler on each branch kind of defeat the extra flow gained by the larger pipe?

It probably does but with at least 450BHP available Im not too fussed if I lose a few horses as a result. I want the look and, to some degree, the sound of the 4" pipe. Im not racking the truck so power isn't necessarily the goal.

I guess I could always install a pair of cut-offs somewhere and operate them electrically should I ever feel the need.

[LostMy65]

My 65 is on a 62 frame.
Mine is ran the same as LVPhotos

[sirJim]

Not 3" but shows the way I routed it.
Works great with the 283 60 over.
And we have the same problem with inspection.

[MacQuigley]

Still very much a "proof of concept" but I modified the pipes over the weekend just to prove I could get them to clear the frame and suspension. The photos you guy's supplied helped greatly.

I was able to modify what I already had in order to route the pipes to the rear of the vehicle and although I haven't included any mufflers I now have options to fit them, under the cab, under the bed and under the gas tank.







Fitting the 2 mufflers I do have onto the very end of the pipes there was no noticeable reduction in the noise output as a result of lengthening the pipes (though using a sound meter on my phone there seemed to be a slight reduction, maybe 2db, but Im really not sure how accurate that measurement is). However, as I said above I now have plenty options on where I can fit mufflers to try and cut the noise down a bit.

So I need to buy a few bends a couple of additional mufflers and maybe some additional pipe and a couple of days should see this done.

[LVPhotos]

I got the Pypes tunnel X pipe ,its universal, but Nova, Chevelle are listed. The X is open unlike prior set up. The dual "popping" side to side is gone more of a deep tone but I just went Super 40 Flowmasters big case.
Last 2 pictures are old system no pipe crossover.

[Robert Haas]

With planning you can get it inside the frame and up above the bottom of the frame as well.

3" stainless mandrel bent tig welded with Flow Master super 50's all the way to the rear.

[MacQuigley]

That is a really nice set up!

Not too fussed about getting it inside the frame. Unfortunately living in Scotland its not easy that get such big pipe bent locally (or at all), though now I know roughly what I want to do, I may make some enquiries. We really don't have the numbers of specialist shops in the UK and definitely not in Scotland that you guy's have in the US.

Plus the headers Im using do extend below the frame making that slightly harder again.

My plan all along really was to build a system that wold get me on the road then I can take it to a specialist to get them to build a complete stainless system. Of course Id likely end up playing with it for a bit first but then it would be rude not to!

[Robert Haas]

Originally Posted by MacQuigley

That is a really nice set up!

Not too fussed about getting it inside the frame. Unfortunately living in Scotland its not easy that get such big pipe bent locally (or at all), though now I know roughly what I want to do, I may make some enquiries. We really don't have the numbers of specialist shops in the UK and definitely not in Scotland that you guy's have in the US.

Plus the headers Im using do extend below the frame making that slightly harder again.

My plan all along really was to build a system that wold get me on the road then I can take it to a specialist to get them to build a complete stainless system. Of course Id likely end up playing with it for a bit first but then it would be rude not to!

Big block headers for a 1970 Chevelle will not hang below the truck.

Headman can hook you up.

Flowmaster sells a master build kit that has all the bends and flanges you would need to build a system from scratch. You just cut it to what you need and weld it up. That is what I did.

[MacQuigley]

Originally Posted by Robert Haas

Big block headers for a 1970 Chevelle will not hang below the truck.

Headman can hook you up.

Flowmaster sells a master build kit that has all the bends and flanges you would need to build a system from scratch. You just cut it to what you need and weld it up. That is what I did.

Thanks for that Robert. I will look into it. I am still learning and there is just so much you can get not just for our trucks but for almost all classic American cars. Despite the fact Ive stripped every bit off my C10 and just about every bit off my C3 Ive ton's to learn! Wish Id started playing with these cars when I first had the chance but I was 21 and couldn't afford to (yes that was a long time ago!).

[Robert Haas]

Headman Chevelle headers

[LVPhotos]

Robert,
The truck is a torsion bar X frame. Unlike ladder frames there is not a straight shot down side. On top you got to get around trailing arm.

[MacQuigley]

Anyone ever tried these before?

http://www.xforce.com.au/products/varex-mufflers

[MacQuigley]

Got my exhaust layout altered over the weekend. Not only does it look better but it sounds better, though I think I may still need additional mufflers and I want to get it up over the axle if I can.








And there is still room for a set of cutoff's!