Flex Pipe Question

So while looking online for exhaust pipe, I keep running into this stuff called flex pipe or flex connector. Is it really 'flexible'? Can it be bent to account for slight misalignment of DIY exhaust systems? Could it be bent for say a 45 degree angle? For that matter is it even bendable at all?

Speaking of 'bendable' pipe, I emailed one reseller and asked if their 'bendable' pipe was really bendable and the answer was no. I then asked why it was called that, still no answer.

Yes, it’s bendable. Very similar to radiator flex hose. A 45 degree...sure, but don’t expect a SHARP bend. It’s best for a slight misalignments, and of course better to avoid it altogether.

Depends on what pipe you actually are looking at.

I know of two styles and they are bendable to some extent. Neither are real good for smooth flow, imo.

Dynomax 46975 for example, spiral wound steel tube basically.



Bellows style, all one piece.

I have seen these on turbo set ups

Those braided style flex couplers come OE on a lot of FWD cars. They usually use it between the manifold and the rest of the exhaust. Since those engines are transverse mounted, the exhaust has to absorb some fore/aft movement. A solid pipe won't work in that situation. I can remember back in the late 90's when a car came into the shop with a bad flex coupler like that. We replaced it with another flex coupler. A few months later, the car was back with an exhaust leak. The new coupler was bad. Turns out that the car had a bad engine mount and there was excessive fore/aft movement which took out the coupler.

Some short sections were OEM on new Kenworth’ up at the turbo area for the same reason—engine movement.

Don’t like seeing that stuff on vintage muscle though.

We used that stuff back in the early 70's when a properly done exhaust was not in the budget. It would last a couple of months and then unravel LOL.

Any flex tubing for exhaust I've seen usually has a pretty short life expectancy. The replacement flex exhaust used on FWD vehicles only lasts about 2-3 years under the best conditions. The other flex exhaust has a much shorter life span. Gene

Someone should build a flex pipe that also dampens a specific “drone” noise.

The existing bellows style seems like it could be “tuned” to eliminate drone.

Not my original idea because I have read about “dimpling” exhaust pipe, including PVC pipe, to reduce exhaust noise.

That is the truth right there. I only used it once when I swapped a 360 in place of the 225 in my Dart and I needed to save up for a dual exhaust. Used the donor car's Y pipe and in the trunk of the donor was a new muffler and piece of flex tubing. Lasted till the next payday and in it went for duals.