Extending shorties????
After cutting up the shorties, altho it might seem like you've saved some effort by having flanges/collectors with tubes on them, I bet with all the chopping it will have actually taken longer than just starting from scratch.
Good luck tho, and keep us informed on how it works, with pics!
Flanges and collector parts are readily available. There are good parts out there that are alot better than the stuff the shorties come with. For example, the collectors used on the shorties aren't usually worth anything. They're way too short in length to be good for much (the individual tubes don't scavenge well because of the approach angle), so you really don't want to re-use them in a set of long tubes. And the flanges are likely to be thin, and in the case of header flanges, thicker is better.
Another reason I think that starting with a set of shorties and hacking them up will be a disadvantage is that most shorties aren't available in the best tube diameters (usually you see 1.5" or 1.625")for LSx motors (which seem to do well with 1.750" or 1.875" primary tubes). I certainly wouldn't build a set of 1.5" long tubes for an LSx (unless its a 4.8l) because it'd be alot of effort expended for little to no gain.
If you really want to hack and chop on a set of headers, look at the various catalog long tube offerings. The Ford small block headers have about the right spacing (between ports) that you can swap flanges if you can find headers to mostly fit in your chassis. Would certainly be a better starting point than a set of shorties.
If it was me, I'd still be starting with a kit, flanges, collectors, and a box of extra bends.
But it's not me, that's just my $.02. Do what you think is the best solution.
'JustDreamin'
oops! I guess I should have read the above post. We make the same point
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I learned to use stainless as it lasts forever. If you use mild steel and decide to wrap them they just crack and break.
Very time consuming but on one application (SBC Volvo) I gained 40 hp. over a set of block hugger shorties. The difference was HUGE.
Try to keep lengths somewhat equal though not a MUST. More important to keep merges, collectors smooth. A "Y" merge works much better than a "T" merge.
We are just now realizing the LSX stuff likes big primaries. At least 1 3/4" even 1 7/8 if room allows.
I've used stuff from STAHL for mild steel
STAINLESS WORKS for stainless
A complete system for my car front to back including 2} 3 inch Magnaflows and Dynaflow junk Cats was 1500 bucks just in parts and around 80 hours of fab time.
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