386 replies to this topic

[rodomo]

The improvements to this "budget build" track car were on going with lap times falling each outing. The next step was to fatten up the mixture but it never got there as I sold the car. I still have the engine set-up but it will be going in a road car with a road going exhaust so we may never know?

[Bruiser]

Yeah, I’ve read through your adventure with your white commodore, brilliant stuff. It’s hard to tell what to say caused a gain, or even a loss with things like that sometimes. I’m betting it couldn’t have hurt. Love a great backyard job

Shitstr, the “headers by Ed” site has some more interesting exhaust theories, he seems to go against the grain a bit, and has claims to back his ideas too.
Look in the header design section, there might be something in there for you while you’re designing something different
- If you haven’t seen it already, that is

[Heath]

Just make sure that you don't have any big flat areas on your exhaust (I'm looking at that middle section, triangular in shape on the drawing)

 

Everything has to be curved, or at the very least, bead-rolled, or you'll have structural issues.

That is why my big expansion chamber (V1.0) vibrated apart and why the car has V2.0.

[Shtstr]

Just make sure that you don't have any big flat areas on your exhaust (I'm looking at that middle section, triangular in shape on the drawing)

Everything has to be curved, or at the very least, bead-rolled, or you'll have structural issues.
That is why my big expansion chamber (V1.0) vibrated apart and why the car has V2.0.

I've already thought of that and put a slight fold line down the centre of the flat sections to give it some strength and to stop vibration.
Only raiit 10mm max in the centre but more than enough to give it some ridged strength and stop vibration.

Edited by Shtstr, 10 January 2023 - 01:02 PM.

[Heath]

Sweet. It's hard to know how carried away to get, but mufflers seem to survive forever with a constant radius in the metal, and my flat one lasted less than 100km, so somewhere in the middle is probably fine.

[Shtstr]

Sweet. It's hard to know how carried away to get, but mufflers seem to survive forever with a constant radius in the metal, and my flat one lasted less than 100km, so somewhere in the middle is probably fine.

Fold like is down the centre line so it's rigid and stops it fluttering up and down causing stress on the welds.

[Shtstr]

Well after trying to make the expansion chamber out of 4 peices and not being able to keep it flat and not twist.
I decided toget a flat sheet of stainless steel rolled to make it in one peice to eliminate twist from end to end.
After having no luck finding anyone who could roll it even after they said they could.
I decided to give it a crack on my home made pan brake for the hell of it.
I think it turned out fairly good for a home made pan brake job and not a proper one. I overlapped the seam to get a better weld join. As it will have more strength than a but weld on 1.5mm stainless. If it was 3mm or larger I would have done a butt join full pen weld.
Now to build the exhaust system.

[Shtstr]

Not too bad.
I wedged a bit of alluminium in between the rear 45 bends to hold them in place so ignore that haha.

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[Shiney005]

After having no luck finding anyone who could roll it even after they said they could.
 

Unfortunately, it is hard to find anyone to make custom parts these days. It looks like you have done as good a job of it anyway.

[Shtstr]

Well I managed to get some time in the shed today.
Started tacking the exhaust in place.
Have a bar across under the mufflers to hold it up at the rear atm until I decide to go over or under the diff.
I know under will be easier and less hassle. But nothing in this car has been easy to work out and build so far🤣🤣🤣.
So that's it now till I get some more time in there.

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[Toranamat69]

You could use oval mandrel bends to get 3" tail pipes over the diff a bit easier.

I gained a noticeable amount of power when I ditched the 2.5" tail pipes.

[claysummers]

I vote for flattening the 3" pipes over the axle too. Even if you reduce the crossection height to 2" over a short section effect on flow is negligible. Tidier solution than under slung.

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[Shtstr]

I think I've worked it out.
90 degree from muffler pointing up.
180 degree bend over the top of the diff parrerel to the top diff arm. 170mm inbetween legs
90 degree facing outwtowards towards the wheel.
60 degree bend turning to run pipe parrerel to the side of my drop tank.
Straight pipe back to a 30 degree bend turning towards the rear of the car to exit the rear of the car with a Straight pipe.
Plenty of room and clearance all round. As my tank is different from others as I have a lot of modifications under the car with the awd system and wheel tubs mini tubbed.

[Rockoz]

Anyone considered using donuts for the tight clearance places instead of mandrel bends?

You can get a lot tighter radius using donuts than a mandrel bend will ever give you.

 

Cheers

 

Rob

[Shtstr]

Anyone considered using donuts for the tight clearance places instead of mandrel bends?
You can get a lot tighter radius using donuts than a mandrel bend will ever give you.
 
Cheers
 
Rob

Yes that's true. But you need a minimum of 160mm inbetween the legs down each side of the diff to have clearance. Have found a 180 degree bend that has 172mm between legs so it is perfect for the task at hand. It also happens to contour the diff tunnel almost perftoo. So can set and forget it.
The stainless will expand at a rate of 2.54 inches per 100 feet. So at the length of the exhaust it will expand about 6mm over 10 feet.
It all has to be taken into account for clearance of diff and tunnels.

[Shtstr]

Well the weather is going to cool down a bit on Friday in SE QLD. So hopefully I will be able to get this exhaust finished finally.
So I can move onto the next issue of running the wiring harness in the engine bay to the cabin on both sides of the bay.

[Shtstr]

Got some time this morning to spend some time on the exhaust.
Got one side up over the diff.

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[Cook]

Well done. I'm running a 2.5" system over a 9" diff and I know the exhaust guy had a lot of fun getting it over. Cheers Ron 

[Shtstr]

Best v band clamps I've found by far. Heavy duty and the only one's I've found with a machined recess for your pipe to slip into for a cleaner join and better weld seal/ joint.

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[Shtstr]

And over we go. Twin 3 inch pipes.
Just tacked together atm. Still have to run it to the rear behind the diff but the hard part is done.
20mm between exhaust pipes and body. Roughly 3 inches of suspension travel at ride height. So will set the bump stops to a height where nothing hits.

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[claysummers]

Very well done!!


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[jeffblanco]

Great work,

I wish I had used the V clamps.

It make so much sense.

Hindsight is grand.

There are so many things I've see the guy's on this forum do, that makes me stop and think "why didn't I think of that"

 

Regards Mando.

[Heath]

That is a pretty difficult bit of exhaust work. Nicely done!

 

I'm gonna stick with my reduced droop rear suspension and pipes under the diff hahaha.

[Shtstr]

Got a bit of time over the weekend to finish running the exhaust pipes to the rear of the car.
Twin 3 inch stainless steel with mandrel bends over the diff.
Decide to run it up high at the rear. Will be fine that close to the rail as there will be a mounting bracket to hold it from hitting the rail. There is about 12mm between the pipe and the rail.
Over the diff I have 20mm plus between pipe and floor and 65mm between diff and pipe. So should be fine once I make my bump stops to suit.

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Edited by Shtstr, 12 April 2023 - 04:41 PM.

[jeffblanco]

Great work,

I love the way the pipes follow the shape of the tank.

 

Regards Mando.