My Long Tube header build

[xnamerxx]

Originally Posted by malibuguy

the motor mounts in our cars are incredibly soft & these motors go all over the place. a flex joint at the end of a 3-4foot long 'lever' would not be adequate.

to get an idea of how much front scratchers (FWDs) boucne about. go to your local test-n-tune with all the kids beating the fuck out their cars...its quite alarming.

the flex joint NEEDS to be located as close as possible to the motor to reduce the leverage on the rest of the exhaust, period. the further away it is, the less its able to absorb.

I've measured a touch over 2.5",on the rev limiter, of movement. With that being said it doesn't matter in my case since my roll mount will have been taken care of.

Yep, but you can't package a a flex joint in the location it needs to be in with joints that are a proper diameter.

[Viperoni]

Originally Posted by xnamerxx

I've measured a touch over 2.5",on the rev limiter, of movement. With that being said it doesn't matter in my case since my roll mount will have been taken care of.

Yep, but you can't package a a flex joint in the location it needs to be in with joints that are a proper diameter.

I've already got the 2-1 section of my header welded up, and it's mostly made up of a pair of 10" long, 1.75" ID flex pipes. Should allow for tons of flexibility, right where it's needed.

[xnamerxx]

I'm tired of arguing this point. There is lots of math and formulas to determine the best length and diameter for a header. The formula I use specifies something different than what you chose to use. With the dimensions I chose I cannot package a flex pipe on the secondaries and wouldn't do so because laminar flow is substantially worse through a flex pipe than a tube. If you look inside a flex pipe there is a series of baffles which make it behave similar to that of a crush bent tube.

[xnamerxx]

Originally Posted by xnamerxx

it doesn't matter in my case since my roll mount will have been taken care of.

I'm not using the stock dog bone spring bolts flex joints are all irrelevant. The only reason I'm even considering a flex joint is to reduce exhaust noise slightly and help remove thermal growth caused by the catalyst.

My comment about the flex joint is that the bellows cause friction in fluid flow which causes turbulence which reduces flow. For that alone I wouldn't want to run them in my primaries where any slowing of gas flow can have drastic consequences.

I've done the math, run the simulations and calculated the load and stress points. I'm very confident in my design that I don't feel its going to suffer a fatigue failure.

[Bluevitz-rs]

Originally Posted by xnamerxx

I'm not using the stock dog bone spring bolts flex joints are all irrelevant. The only reason I'm even considering a flex joint is to reduce exhaust noise slightly and help remove thermal growth caused by the catalyst.

My comment about the flex joint is that the bellows cause friction in fluid flow which causes turbulence which reduces flow. For that alone I wouldn't want to run them in my primaries where any slowing of gas flow can have drastic consequences.

I've done the math, run the simulations and calculated the load and stress points. I'm very confident in my design that I don't feel its going to suffer a fatigue failure.

Dude, you're so worked up you can't even read what I typed. I said SLIP JOINT. Not FLEX JOINT.

This is a Slip Joint.

[xnamerxx]

I skipped over that point as I assumed you thought slip joints are a way to control exhaust flex.
Yes I did consider a slip joint originally as a way to join the 2 sections of pipe but chose against it for various reasons. The biggest reason I chose against it was that slip joints are weak. In my situation there is still load traveling through the second set of pipe even though there is minimal engine movement in the exhaust its still carrying the load from the 30 lbs of exhaust and that load is effectively being distributed through only one of the pipes which doesn't have a ton of bearing area. If I was mounting the second section of pipe lower down I would probably go to a slip joint, it wasn't appropriate in my situation.

[tooter]

Would one of these help?

[xnamerxx]

I don't know maybe. I prefer to stiffen the dogbone rather than add weight somewhere else.

[Jason@SportsCar]

I think some of you guys are loosing focus on the big picture... Build a prototype, get it on the car and see if it makes power. If needed issues like a flex joint, ball joint or the engine support can be addressed when a production piece is made.

[malibuguy]

Originally Posted by xnamerxx

my comment about the flex joint is that the bellows cause friction in fluid flow which causes turbulence which reduces flow. For that alone I wouldn't want to run them in my primaries where any slowing of gas flow can have drastic consequences.

that is true if your using a low quality flex-joint. Ones like the premium Vibrant units feature a very smooth liner that is not restrictive at all.

Im glad you got it all done & i cannot wait to see the results!