Good tips. Yah the flex joint is pretty short. The muffler is strapped
to 2 brackets on engine but I'll look into longer flex and possibly 2
of them. That and a 4-1 manifold. Something I should have done from
the get-go, but thought there would be a performance "hit". Likely
I've done more damage to performance with my Frakenstien "Y" collector
though it does drive well. (video soon!)

For laughs I might repair this one. I'll know better when I remove it.
I can very easily see myself burning a hole on the back side if I
patch it, thus rendering the short primaries/Y pretty much useless.

Thanks again Jim.

Neil.

2008/8/14 Jim Akiba <syncrolist@bostig.com>:
> Yeah if you have a 4 to 1 option... I'd go that route.. as you likely
> know by now, dealing with the one tube instead of two makes life much
> easier, will make the assembly more robust, without sacrificing
> anything but the work you've done so far.  Keep anything that moves
> with the engine as tight to the block and as short as possible, and
> decouple appropriately to make sure you can stabilize the downpipe
> without destroying the flex section every 3 months, so not too
> close(welded to the flange would be pushing it, esp since the flex
> couplers are fragile from a welding and corrosion standpoint compared
> to solid tube), and not too short on the flex.
>
> Jim Akiba
>
>
>
> 2008/8/14 neil N <musomuso@gmail.com>:
>> Thanks much for the re-design tips Jim.
>>
>> I think I get what you're suggesting.
>>
>> I guess another flex section is in order.
>>
>> One obviously isn't enough.
>>
>> I guess I have nothing to lose repairing and bolstering the primaries
>> near the flange.
>>
>> And if I understand your suggestion, would it be best to swap to a 4
>> into 1 exhaust manifold?
>>
>> And crack pipe? Only if I ever do this kind of conversion again will I
>> need one of those --- ;^)
>>
>> Neil.
>>
>> 2008/8/13 Jim Akiba <syncrolist@bostig.com>:
>>> I looked at the other downpipe pics quickly again, I think you're
>>> going to find it is a losing battle with cracking in that location
>>> unless you can decouple close to the flange or increase the thickness
>>> of the primaries by quite a bit closer to the flange.  It's through no
>>> fault of the welds really(they appear to be holding) but if you've got
>>> all that length and mass on two .049 or .065 wall primaries and they
>>> aren't gusseted/braced fully(even then I' bet you'd still have
>>> trouble) they will keep on cracking. I would move to a log 2 to 1, and
>>> put a flex section in, then worry about stabilizing a single tube
>>> downpipe instead of a sort-of longtube setup like you have now. You
>>> won't see much of a performance difference between the two in this
>>> application, but you will have a much better chance being free of your
>>> current crack pipe... ha sorry just had to throw that in.
>>>
>>> Jim Akiba