[RallyBob]

Originally Posted by heimue This is freakin' awesome! For those of us who want to learn from the Opel God, what is the best way to ensure that all the header pipes are equal in length, besides designing them in 3D CAD?

I am so non-high tech, I use equal lengths of welding wire (in this case 32") to visualize the tubing lengths and routing, and then build it from there.

What is an acceptable length tolerance (in percentage from the nominal length) to still consider all pipes an equal length, e.g. for a turbocharger setup? Dieter

Unless you are going for max power with a turbo...don't even bother! Go for shorter lengths for faster spool-up time. Equal length runners for a turbo (IMO) are great with large turbos, big cams, high rpms, but generally don't matter much on a low boost/small turbo street engine. Even for an N/A engine, if you are within 1-2", you are doing GREAT. Most headers are horribly unequal-length. In the case of this Sportwagon header, I got it within 1/2" of being dead-nuts equal. Good enough for me...

Remember my racing turbo header for my Manta? 8000 rpms and 500 hp capability made me decide to build it that way. But my 1971 Ascona wagon is getting a small GT25 turbo and I built the manifold with packaging and spool-up as my main concerns.