How do you finish primary tubes inside a collector?

Eric68 · Post by **Eric68** » Mon Oct 06, 2008 9:18 pm

Getting ready to build my second set of headers in a couple weeks and wanted to ask you guys how you should finish weld the primary tubes inside the collector. I have dimensions from Pipemax -- 1-7/8 primary tube 30.4-33.3" long with a 3.5" x 8.5" (or 17") collector.

What kind of angle should the tubes join at? Should the exit be at a flat 90* angle or tapered and smoothed (like below)? Anything to be gained (or lost) by doing this correctly?

Here is how I did my last set (my first attempt).

JBrady · Post by **JBrady** » Tue Oct 07, 2008 11:50 am

Transition from primary to collector is an area where gains can definitely be made. The goal is to reduce turbulence and create the smallest collector area possible that results in the desired outlet diameter. This is what merge collectors are designed to do. The picture you show is in the right direction. Examine the designs at burnsstainless.com or any site with good internal pictures of merge collectors to get more ideas.

JBrady · Post by **JBrady** » Tue Oct 07, 2008 11:59 am

If you do some searching you can find examples to copy or purchase.

Here is a reasonably priced merge collector

For less money here is a stamped/swaged/formed collector that at least tries to reduce volume.

jfholm · Post by **jfholm** » Tue Oct 07, 2008 12:23 pm

Nice looking work! I like what you did on that first set. From what I can gather each application is different. From what I can gather, and please correct me if I am wrong, merge collectors and a set up like the Pro Stock headers are good for a higher RPM with a narrow RPM band. If you were doing street headers then that is a whole different ball game.

John

Eric68 · Post by **Eric68** » Tue Oct 07, 2008 5:18 pm

Thanks guys. I like the idea of pre-bent collectors and will definitely shop around to see what there is. Not sure what is out there that doesn't cost an arm and a leg in 304.

I am building this next set out of 304 stainless and I expect that grinding will be more work than the mild steel set I did before. Just want to make sure that what "looks nice" actually performs. LOL

FYI. The application is a bracket car that may make a trip on Drag Week and an occasional heads up or indexed type event. Running a full 3" exhaust with X pipe if that matters.

1989TransAm · Post by **1989TransAm** » Tue Oct 07, 2008 5:46 pm

You might want to take a look a www.coneeng.com for header parts. They may have what you need at a "reasonable" cost. I'm using their parts to build my set of headers. I envision by headers to look like your first example.

Update: Cone sells the center spikes, bullets or what ever you want to call them. I just had mine welded up and they came out real nice.

RL · Post by RL » Tue Oct 07, 2008 5:57 pm

The trick is to buy 4(I think 15º) elbows and you do a cut parrallel with the straight part but offset 5mm, spin 90º and do another cut offset 5mm and this will give you the long centre spike when goined

Do a side on drawing first to make sure it looks right and it will give you the angles

Ozonkiller · Post by **Ozonkiller** » Tue Oct 07, 2008 11:43 pm

The pieces from S&S are pretty nice and if your time is worth anything, they are priced really right

n2omike · Post by **n2omike** » Wed Oct 08, 2008 1:13 am

Edelbrock sells nice looking merge collectors for only $99/PAIR through Summit! Available in various sizes. Below is 1-3/4" x 3"

http://store.summitracing.com/partdetai ... toview=sku

Follow the link below to the Edelbrock site for more information, and to see what all sizes are available. Call Summit or Jegs with the part number to get the price for that size.

http://www.edelbrock.com/automotive_new ... tors.shtml

Good Luck!

TORQUE INC · Post by **TORQUE INC** » Wed Oct 08, 2008 1:47 am

Do they have a spike in them ?

In looking they seem to be well made kinda wish they made a 2-3.5 id use em on the headers i have manufactured

JW

Tobbe1 · Post by **Tobbe1** » Wed Oct 08, 2008 2:24 am

i got mine from cone to
here are a pic still have one headers to build ...
http://www.forum.shraboras.se/download/file.php?id=8

RL · Post by RL » Wed Oct 08, 2008 6:42 am

How the pros make merge collectors, notice they are elbows sliced in 2 planes

Eric68 · Post by **Eric68** » Wed Oct 08, 2008 8:01 am

Good stuff guys. Thanks for the links.

I noticed on the cone eng site there are different angles for the primary pipes coming into the merge. How do you know which angle to go with?

Post by **3V Performance** » Wed Oct 08, 2008 8:41 am

The angle will change depending on pri pipe size to get the cone back to center. Cone should be able to help with the right one.

coneeng · Post by **coneeng** » Wed Oct 08, 2008 1:02 pm

1989TransAm wrote:You might want to take a look a www.coneeng.com for header parts. They may have what you need at a "reasonable" cost. I'm using their parts to build my set of headers. I envision by headers to look like your first example.

Update: Cone sells the center spikes, bullets or what ever you want to call them. I just had mine welded up and they came out real nice.

I had to come take a look since we were getting so many web hits from here! Great site! I think you'll like this new way of building merge collectors and the prices as well.

Eric- Each tube diameter has a taper specific engineered collector and merge bullet. Users can also tweak on them a little bit to further tune them based on their particular needs. Your primary tube coming into the collector can also be angled unlike a welded merge to save lots of space.

Since they are welded in place (you can make them into a slip fit also if so desired) you get much better sealing than with a traditional welded merge collector. You can also easily polish the bullets after they are welded in place and before collector is welded on, unlike a welded merge that you have to try and reach inside the collector from the little outlet opening to work. Complete build instruction with pics here: http://www.coneeng.com/weld_on_collector_kit.html that whole kit shown retails for $115 in MS and $150 in SS.

Check out the dyno results on the home page to compare a high-end welded merge to a Megs Merge.