I have the PipeMax software and have been running some numbers through it, and the total lengths are coming up at what seems pretty long, around 40"? It this from the valve (subtract the exhaust port length from the 40"), or is that 40" from the header flange?
I am looking for mid range torque from the 440 in the Jensen, and looking at a Tri-Y design.
Pipe max lists a two step, and a three step Tri-Y?
Is the first step of the three step, just a pipe step before the "Y"?
I think the paring for the "Y"s are 1&5, 2&4, 3&7, 6&8?
Yes. Knowing which version Pipemax will help. Also Larry has a forum for Pipemax. It's worth checking out.
I'll try to answer in reverse order:
* Yes, Normal pairing is as you posted - the ports next to each other except 5 and 7 because they fire immediately in sequence.
*In version 3.98
> 2 Step is 1st segment of Y off of head, then second step is merged segment of Y.
> 3 Step is a stepped primary. So the segment off of head has a first step, and a second step before the merge. The third step is the merged or secondary going to the collector.
* In both 3.98 and the previous version, the pipe length is just that. It is adjusted based on the exhaust port centerline length you entered.
* As far as 40" length goes, experiment with your input numbers. See what happens when you change target rpm (which is based on max hp rpm that you enter), VE and estimated Hp. Most of the time we're ballparking unless the engine has already been run on a dyno.
As much as I like pipemax and respect Larry's work, realize he is working from mostly 1/4 mile, and also has done more with 4 into 1 than tri-y.
I will say this, we were surprised that the room for a tri-y was exceedingly tight for an LA in an A-body on the passenger side. In retrospect, a 4 into 1 would have been the better path in terms of difficulty to make fit. Granted a Jensen will be different and the B and RB have higher exit ports so that should make it easier. But just be forewarned that the driver side may not actually be the more difficult side.
We used pipemax for some things like crossover placement, but relied more heavily on Calvin Elston's guidance.
I think you will find Calvin's approach interesting and useful if you're pursuing tri-y; and especially for uses other than drag strip or standing mile.
Elston's Blog
Exhausting 101 at Speedtalk. First time header build pages 3-4, 11 and more.
What is Exhaust Blowdown Length? page 2
and for FWIW the development and build for my headers are in this thread (its a 340 not a 440!)
http://speedtalk.com/forum/viewtopic.php?f=1&t=42702
