Header design question?

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?

The total length is from the valve.. not
from the flange.. put your numbers in and
see what you get
EDIT
mine is a older version so I dont have the Y
info

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

I ordered some flanges and a few 1-3/4" mandrel bend pipes from Hells Gate Hot Rod to get a start. Should get them this week.

I'm just going to start on the stock iron head 440 first. I need to replace the engine mounts first, they are in bad shape.

Pipe max is saying the 1-3/4" will be good for the first step, then pipe step to 1-7/8", then merge the "Y" into a 2" then into the collector?

On my 405ci I did the 4 into one.. 1 7/8- 2-
2 1/8 into a 4" collector... myself I'm not
a fan of the tri-Y headers

I gotta ask MR_P_BODY- what kind of valve covers are those??

Those are the Mopar cast covers.. I milled
the logo off and lightened them up... I really
like the cast covers but they are/were heavy...
this is what they look like stock

Those look a little short to me

But I'll bet he some fantastic bottom end!!!!

Joe

Originally, from looking at some of the photos of the GM Tri-Y headers, they looked to have short sections before the first merge, and looked to maybe easier to fit, but the lengths Pipe max is giving me are near 20" to the first "y", and at that point, it may be easier to fit a 4-1 configuration?

Anyone have information on what merge angles to use for the 2-1 merges?
Several look like 45-degree? or would a shallower 30-degree be better?

Love it! Looks awesome!

Are you talking an Interceptor? You will be running primaries below the floors for sure with 36" long primary tubes!!! I have Delta SS headers, they are like a block hugger header with a tipped out slightly longer collector. There are longer primary headers available on the UK Ebay, take a boo..? Or maybe I'm not reading this right..? lol

PipeMax 3.89. For a 505" stroked 440, Trick flow heads, Solid roller 243/249 @ 0.050", 0.616"/0.624" lift, 110 lsa cam installed at 106 icl.

Street header with muffler:
primary total length 41.1 to 44.0" Tube dia in the 1-3/4" range.

Tri-Y street header with muffler:

2-step: First segment 20.6 to 22.0" (1.651 dia), second segment 20.6 to 22.0" (1.776 dia)

3-step Higher RPM: first 20.6 to 22.0 (1.776 dia), second 10.3 to 11.0 (1.901 dia), third 10.3 to 11.0 (2.026 dia), same cpmbined overlength of 41.1 to 44.0", collector about 3", 22.9" long

The Tri-Y race with or without muffler is same overlengths, just slightly larger tube sizes.

That collector sure looks small in dia for
a 505ci
EDIT
What do you have for max HP RPM

After I had already ordered parts, I found trick flow build a 446 with nearly the same size Hydraulic roller cam.

This is trick flows' dyno chart for the 446" engine with a similar sized hydraulic roller (243/247@0.050", 0.600"/0.600" lift, 108 LSA), shows 620 Hp at about 6,200 RPM?

I figure the larger engine will bring the peak HP rpm down a bit, but the wider LSA may extend the RPM?

They used 1-7/8" Hooker Super Comp headers, and open exhaust.

https://static.trickflow.com/global/images/chartsguides/t/tfs-k616-620-576.pdf