Don Terrill’s Speed-Talk

redliner wrote: ↑Wed Oct 04, 2017 10:18 am Hey guys I am getting ready to build a new set of headers. I have a sbc with a 4/7 swap in the firing order and I would like to place the primary tubes in the collector in the order which helps evacuate the cylinders the most effectively. Am I over thinking this or..... I have the pipemax program which has told me the diameter and length needed but I wondered about placing them in the collector in a certain order... These fenderwell headers for my 42 Stude coupe will be 2 " for about 10 " then 2- 1/8" for about 20" finishing with a 16" 3- 5/8" collector.

I was shocked to find out that the 900+ hp ProStock truck 358 was running a primary of 1.625,
I don't know what the step lengths were but It was smaller then I would have ever guessed.

In-Tech wrote: ↑Thu Oct 05, 2017 11:36 am No need for a tool(I've not seen that one you speak of on my windows machines). Shift/Print Screen(look at your top keys to find it), open up paint(in all windows programs under accessories), Ctrl V will paste it, save as .jpg to desktop for ease of finding it. Post here

maxracesoftware wrote: ↑Thu Oct 05, 2017 11:39 am

redliner wrote: ↑Wed Oct 04, 2017 10:18 am Hey guys I am getting ready to build a new set of headers. I have a sbc with a 4/7 swap in the firing order and I would like to place the primary tubes in the collector in the order which helps evacuate the cylinders the most effectively. Am I over thinking this or..... I have the pipemax program which has told me the diameter and length needed but I wondered about placing them in the collector in a certain order... These fenderwell headers for my 42 Stude coupe will be 2 " for about 10 " then 2- 1/8" for about 20" finishing with a 16" 3- 5/8" collector.

I was shocked to find out that the 900+ hp ProStock truck 358 was running a primary of 1.625,
I don't know what the step lengths were but It was smaller then I would have ever guessed.

the main reason why your calculated Header Specs are larger than a ProStock Truck 358
is your Compression Ratio is only 11.5:1 -vs- a ProStock Truck 358 's 15:1 + Compression Ratio + the VE% is way less than a ProStock Truck 358
this will cause your EGT's to be higher , making a larger diameter tube necessary .

i ran a 3-Step 1.875,2.000,2.125 3.500 Collector on my 355cid with 13.7:1 CR
so a 2-Step 2.000,2.125 3.500 Collector is very reasonable
i've run that much Header on many 377cid to 434cid with great Dragstrip and Dyno results .

Also you made a mistake on number of Intake and Exhaust Valves per Cylinder
your Inputs should have a value = 1 per Cylinder , but you entered 2 Intakes and 2 Exhaust Valves per Cylinder

Redliner_SBC414cid_7500RPM.png


Redliner_SBC414cid_7500RPM_Headers.png

I see the port centerline length you used was different than mine. Does this make a big difference? I am running a ported Motown single plane intake.

maxracesoftware wrote: ↑Thu Oct 05, 2017 12:10 pm here's a 420cid with Pump Gas and 11:1 CR
that likes a large Header
Headers 2.000/2.125 4.000 Collector

154 cranking psi

http://www.maxracesoftwares.com/forum/v ... p?f=5&t=95

This Pump Gas 420cid 711.3 HP engine
was built for a Customer who didn't want to buy Race Gas
.... sort of like see how much HP you can get me on Exxon 93 prem deal .


.

maxracesoftware wrote: ↑Thu Oct 05, 2017 12:17 pm

I see the port centerline length you used was different than mine. Does this make a big difference? I am running a ported Motown single plane intake.

the Default= 3.200" as its a combination of BBC and SBC centerline lengths average

your Heads are closer to 2.900" Exhaust Port CenterLine Length
so use that Input value

mk e wrote: ↑Thu Oct 05, 2017 11:54 am

In-Tech wrote: ↑Thu Oct 05, 2017 11:36 am No need for a tool(I've not seen that one you speak of on my windows machines). Shift/Print Screen(look at your top keys to find it), open up paint(in all windows programs under accessories), Ctrl V will paste it, save as .jpg to desktop for ease of finding it. Post here

The program call "snipping tool" does all those sets automatically for you. It started at win 7 I think, just click the windows icon in the bottom left and type snip, it should pop right up....its really handy.

RevTheory wrote: ↑Wed Oct 04, 2017 12:04 pm I've heard you want them to hit the collector clockwise but who knows...

mk e wrote: ↑Wed Oct 04, 2017 5:38 pm

redliner wrote: ↑Wed Oct 04, 2017 5:33 pm

mk e wrote: ↑Wed Oct 04, 2017 5:24 pm
That sounds like a winning plan!

Programs like dynomation5 (just ordered my copy of dynomation6) or the designs I've seen from places like burns have having at all about order in the collector, but the flow bench and dyno sure say bends matter!

What do they say about the order of the pipes in the collector for my 4/7 swap I'm wundrin...

They don't care about the order of the pipes in ANY setup of any kind. Get the sizes right, use the biggest bends you can and you'll have a good header no matter what order they get plugged into the collect.

ptuomov wrote: ↑Fri Oct 06, 2017 8:26 am

mk e wrote: ↑Wed Oct 04, 2017 5:38 pm

redliner wrote: ↑Wed Oct 04, 2017 5:33 pm

What do they say about the order of the pipes in the collector for my 4/7 swap I'm wundrin...

They don't care about the order of the pipes in ANY setup of any kind. Get the sizes right, use the biggest bends you can and you'll have a good header no matter what order they get plugged into the collect.

The order in itself doesn’t matter but the merge angle probably does matter. I think you want the shallowest or most acute angle of the flow merge for successively firing cylinders. That way, the positive blowdown interference pulse from one cylinder does the least damage to and the flow creates the lowest pressure for the cylinder that’s in overlap. (90 degree blowdown interference at high rpms.). Rotating collector pipe order accomplishes this, because of how the collector angles work. But if you push that thinking further, you’ll end up with 4-2-1headers. Just my opinion.

77cruiser wrote: ↑Fri Oct 06, 2017 8:46 am Easier to build too. 2-6 & 4-8 1-3 & 5-7, I think just opposite of standard firing order.