Mandrel exhaust shop

[DoubleDingo]

Ahhh. Being from the racing world, mandrel really is unnecessary for 99% of street vehicles, that's why I asked. Even with a 572, especially in a truck, you wouldn't notice any difference in a crush 3" and a 3" mandrel as long as there wasn't any really tightly bent/pinched areas. But I get it, mandrel is nice. I'd eventually like to take my truck to a guy local here that does full stainless, mandrel, tigged exhausts in your choice of size and polishes it all up if you want. But that's a pipe dream

I see what you did there...lol...

 

[DoubleDingo]

I feel really dumb for asking this but what is a mandrel exhaust shop?
Just an old regular exhaust shop with a tubing bender? Or is it a special machine? Just trying to understand lol

No crimped bends, no crushed bends. It basically the same diameter all the way.

 

[squaredeal91]

No crimped bends, no crushed bends. It basically the same diameter all the way.

Oh so more like roll cage tubing bender for exhaust. I think i got it. I know that even smashed headers still flow good lol

 

[TotalyHucked]

Oh so more like roll cage tubing bender for exhaust. I think i got it. I know that even smashed headers still flow good lol

Yep, the difference in a crimped bend and a mandrel bend would only show in a max effort, all out run. Like if you're trying to squeek out that last 2mph at redline going 240mph at Bonneville

 

[Catbox]

It looks prettier for most things it is installed upon.
My kit was dirt cheap, so I jumped on it.

 

[DoubleDingo]

It looks prettier for most things it is installed upon.
My kit was dirt cheap, so I jumped on it.

So it's best for three things:

Preference
Car shows with undercarriage mirrors
To eek out that last 2mph at 9,000 rpms

 

[Catbox]

So it's best for three things:

Preference
Car shows with undercarriage mirrors
To eek out that last 2mph at 9,000 rpms

It could also be better is your exhaust is undersized.
When I brought my truck home its 454 was exhaling through dual 2 inch tail pipes.
It was a weak feeling engine at best that would barely spin the tires.

 

[DoubleDingo]

It could also be better is your exhaust is undersized.
When I brought my truck home its 454 was exhaling through dual 2 inch tail pipes.
It was a weak feeling engine at best that would barely spin the tires.

GM didn't want that beast to breathe. Too big of pipes can cause mileage to go down, so there is a tipping point on pipe size. A big block being a bigger air pump needs to be able to move more air, for sure. A 350, 2 inch all the way is good as long as it's free flowing. My '81 is 2 inch y-pipe into 2.5 intermediate, and is 2.25 over the axle. No lack of power at all like that.

 

[legopnuematic]

I didn’t see it mentioned so I’ll throw it out there. The advantage of mandrel bent over crush bent or other bends is when doing fabricating, if you cut a mandrel bend square to the center point of the bend, you get an almost perfect circle.

You can take that cut and mate it to another mandrel bend or a straight pipe and it fits.

Now if you did the same with crush bent, you will have an elliptical (or oval) cross section, which will not mate to a straight piece or other cut bend.

It can allow for more complex geometry and to do so in a small area. Being able to buy u/j bends allows a lot of freedom and flexibility compared to part store crush bends.

Hopefully that makes sense.

And they look nice.

 

[Bextreme04]

I didn’t see it mentioned so I’ll throw it out there. The advantage of mandrel bent over crush bent or other bends is when doing fabricating, if you cut a mandrel bend square to the center point of the bend, you get an almost perfect circle.

You can take that cut and mate it to another mandrel bend or a straight pipe and it fits.

Now if you did the same with crush bent, you will have an elliptical (or oval) cross section, which will not mate to a straight piece or other cut bend.

It can allow for more complex geometry and to do so in a small area. Being able to buy u/j bends allows a lot of freedom and flexibility compared to part store crush bends.

Hopefully that makes sense.

And they look nice.

This is also what I was going to say. I buy the bends in mandrel bent form so that I can cut and weld them as needed easier to get the smooth bends I want.

 

[TotalyHucked]

I didn’t see it mentioned so I’ll throw it out there. The advantage of mandrel bent over crush bent or other bends is when doing fabricating, if you cut a mandrel bend square to the center point of the bend, you get an almost perfect circle.

You can take that cut and mate it to another mandrel bend or a straight pipe and it fits.

Now if you did the same with crush bent, you will have an elliptical (or oval) cross section, which will not mate to a straight piece or other cut bend.

It can allow for more complex geometry and to do so in a small area. Being able to buy u/j bends allows a lot of freedom and flexibility compared to part store crush bends.

Hopefully that makes sense.

And they look nice.

That's a very good point. Since I can't weld tubing, I've not really thought about the fab part of it

 

[Radiohead]

I didn’t see it mentioned so I’ll throw it out there. The advantage of mandrel bent over crush bent or other bends is when doing fabricating, if you cut a mandrel bend square to the center point of the bend, you get an almost perfect circle.

You can take that cut and mate it to another mandrel bend or a straight pipe and it fits.

Now if you did the same with crush bent, you will have an elliptical (or oval) cross section, which will not mate to a straight piece or other cut bend.

It can allow for more complex geometry and to do so in a small area. Being able to buy u/j bends allows a lot of freedom and flexibility compared to part store crush bends.

Hopefully that makes sense.

And they look nice.

Makes absolute sense to me. For all the reasons posted.

 

[Old Guy Bill]

The manufacturer I work for has a nice hydraulic bender, it’s used for steel tubing such as hand rails etc… I’m not sure how many dies it has, but you can bet if it can be used for a custom exhaust system I’ll be all over it!

 

[Ricko1966]

Mandrel bending the have a die inside the tubing when they bend it to keep the pipe round,similiar,but better than filling tube with sand before bending. I believe the die they use is a string of ball bearings. I've never owned or run one. Investigated them about 1994? But out of my price league,and beyond my needs. So memory is a little fuzzy,butI think it was a string of ball bearings.

 

[squaredeal91]

Mandrel bending the have a die inside the tubing when the bend it to keep the pipe round,similiar,but better than filling tune with sand before bending. I believe the die the use us a string of ball bearings. I've never owned or run one. Investigated them about 1994? But out of my price league,and beyond my needs. So memory is a little fuzzy,but zi think it was a string of ball bearings.

That reminds me of a similar thing. A friend told me about and described something like maybe a few large ball bearings like you say to straighten out dented intake runners on gm tuned port.