'72 K5 - Greg's @MightAsWellK5 Build

[folkenheath]

First off I think the headers are looking awesome, keep it up! They look saweeet!

I do have one question, are you eliminating that square tube right behind the collector? Because it looks like it is right in the way. If you plan to use a large pipe radius there, keep in mind the bend radius of a large pipe is huge compared to the bend radius of the small tubes. Also, the collector takes up considerable length. You might want to get that collector figured out before you spend too much time routing the tubes or you might have to start over.

Also, the tire looked pretty far away straight, but what happens when you turn right, is it still far away?

 

[Greg72]

As always, this build makes me shake my head at how dedicated you are to building EXACTLY what you want. So freaking cool Greg. [emoji144]

This guy once described my build as:

"...attention to detail combined with near-retarded levels of awesome..."

I felt that was a pretty apt description.... Ultimately "I want what I want" and I'm stubborn enough to work and fight for as long as it takes until I get there. That recent quote from Jesse James on FB about never accepting "good enough" really says it pretty well also. It takes a stubborn and disciplined guy to build for more than 7 years without getting any sort of payoff.... and I've still got a couple more to go before any of this work pays off in the traditional sense. Of course I've said many times that "the process" of building is something that I get a lot of enjoyment from, and I know a lot of guys just don't GET that...they just want their truck to be FINISHED so they can go back out and drive it.

First off I think the headers are looking awesome, keep it up! They look saweeet!

I do have one question, are you eliminating that square tube right behind the collector? Because it looks like it is right in the way. If you plan to use a large pipe radius there, keep in mind the bend radius of a large pipe is huge compared to the bend radius of the small tubes. Also, the collector takes up considerable length. You might want to get that collector figured out before you spend too much time routing the tubes or you might have to start over.

Heath,

That 1x2" block is just a spacer to keep the collectors away from the floorboards. It gets removed once the mock-ups are completed.

Good point about the bend radius for a 3.5" collector! It's going to be a tight-squeeze getting the next section of exhaust through that tiny cab-support area (I'd say it's probably less than an Oreo's worth of clearance....maybe a Thin-mint or Lorna Doone?), but I think I can do it... I have some flexibility to slide the actually merged-collector part up a few inches if I need to so that the bend in the 3.5" tube happens in a clean part of the tube instead of where all those 1-7/8" tubes are getting crushed together and reshaped into the large single exhaust outlet.

I'm so stoked about getting that 4th primary tube in tonight.....I can't wait to see it!!!!


EDIT:

I think you might have been asking about the 2x2" square tube.... here's the diagram of how that needs to resolve itself:

It's going to be tight. That red circle is the "through hole" for the collector, and the yellow lines define the rockslider / A-Pillar mount that is not moveable. I might be willing to put a small cresent notch into the top if it ends up being necessary, but obviously I don't want to do too much to weaken it structurally.



-G

 

[blazinzuk]

Heath does bring up a good point about collector length though. They do take up some room

 

[Greg72]

Heath does bring up a good point about collector length though. They do take up some room

You guys always make good observations and suggestions. I'm glad you guys stop by to save me from making time-consuming mistakes!!!



-G

 

[dremu]

A thought maybe use PVC pipe instead of cardboard? Assuming you can find it in exactly the right OD to fit snugly, of course, but the stuff is cheap and stiffer than paper products.

-- A

 

[Greg72]

A thought maybe use PVC pipe instead of cardboard? Assuming you can find it in exactly the right OD to fit snugly, of course, but the stuff is cheap and stiffer than paper products.

-- A

A lot of "real" builders do just that...

For me it was more a function of starting my work each night at 8PM and not feeling like driving across town to Home Depot to buy PVC. You're right too, unless it's a PERFECT fit to the I.D. of my current exhaust tubing it's not really going to save much time.

What's nice with the paper tubes is that they can be slid into those template steel tubes easily and adjusted for length over a very wide range of values. So when I'm trying to get the first bend transition lined-up on a path that will get it up to the head flange, being able to "telescope" that paper tube really allows for some quick experimentation.

I think at some point it just comes down to personal preferences, and no matter what tools you use none of them are going to be 100% perfect and will have certain limitations.... even those $1400 plastic LEGO kits!!


-G

 

[miniwally]

Greg,

Building your own headers is something that has always been intriguing to me. Good work.

My only concern for you is clearance to the strut in all suspension positions.

Otherwise also don't be afraid to look at "odd" shapes of exhaust pipe to meet your space needs. We needed a large dia. vent for our fuel cell in the race car, however where we needed it to go didn't allow for a large dia. Solution was to make "oval" pipe for that section out of electrical conduit, now a 1" cross section pipe fits were a 5/8" pipe fit.

 

[Greg72]

Greg,

Building your own headers is something that has always been intriguing to me. Good work.

My only concern for you is clearance to the strut in all suspension positions.

Otherwise also don't be afraid to look at "odd" shapes of exhaust pipe to meet your space needs. We needed a large dia. vent for our fuel cell in the race car, however where we needed it to go didn't allow for a large dia. Solution was to make "oval" pipe for that section out of electrical conduit, now a 1" cross section pipe fits were a 5/8" pipe fit.

Thanks Brandon!

I've missed seeing your comments around here lately...


The clearance "seems" good around the strut so far. It's hard to photograph the angles that really show it well, and sometimes a photo can make things look a lot tighter than they actually are. Obviously, the higher up I build the tubes (relative to the upper strut mount) the less I have to worry about clearance issues, since there is almost no appreciable movement laterally the higher up the strut body that you go.

I will definitely do some more cycling tests (and lock-to-lock steering tests) once I feel the design is complete and ready to be built in stainless. This step really should include the correct steel wheels (and hubcaps) that I intend to use for the final product, as well as the new 1.25" wheel spacers... all of that changes the position of the tire in small ways, so I need to keep those sub-projects moving along as well in my copious spare time!

In the back of my mind I'd already started working on contingency plans for oval tubing in case I couldn't get the 3.5" round stuff over the top of that 2x2" skidplate tube... I know I've seen vendors out there who specialize in oval exhaust tubing for the Pro-Touring car guys who's lowered cars don't have enough ground clearance for traditional round exhausts...


-G

 

[ClassicStyle]

Burns stainless has all of the oval tubing, along with the information on sizing/flow to equal its round counterpart. They are expensive but they are the best in the business.

3.5 seems pretty large, I built a system for a 71 split bumper camaro out of 3" it flowed and sounded fantastic and that had a built 454. I'd be concerned with the lack of back pressure going much larger.

 

[Greg72]

Burns stainless has all of the oval tubing, along with the information on sizing/flow to equal its round counterpart. They are expensive but they are the best in the business.

3.5 seems pretty large, I built a system for a 71 split bumper camaro out of 3" it flowed and sounded fantastic and that had a built 454. I'd be concerned with the lack of back pressure going much larger.

3.5" is at the collector... the design is supposed to then get tapered down to a standard 3" tube before it gets to the mufflers.

I think the logic is that the cross-section of going from 4 x 1-7/8" tubes directly to a 3" round is a pretty big choke point (I haven't done the area-of-a-circle type calculations to see how different they are)... so GM wants the primaries to dump first into a section of 3.5" tube and then transition more gradually down to the 3" size.

I forget the official term for it, but companies do sell 18" sections of exhaust that bolt to the 3-hole flange area and will take the exhaust from 3.5" to 3".... I'm getting awfully short on space, so I don't see how I'd be able to transition all the way to 3" before passing through that cab-support area. There's just not much room there to get a smooth transition....


-G

 

[ClassicStyle]

You can get reducers and such, but bringing them into 3" gives you your back pressure, Since space is tight and it would go to 3" anyways I'd get a 3" collector and save the space.
You can tune a engines curve by playing with collector sizes. I've seen 1 7/8 choked to a 2.5 to fit a engines tune. My experience has yielded geat results with 3" collectors. Hell my 8 into 1 went into a 3", and that was a mid 500 hp ls6. Just some food for thought, the set a posted a picture of on my hotrod is 1 7/8 into 3"

 

[blazinzuk]

It's all about velocity and scavenging. The smaller tube will keep the velocity of the gas high. All a compromise

 

[Greg72]

It's all about velocity and scavenging. The smaller tube will keep the velocity of the gas high. All a compromise

....I just don't think I'm going to be able to fit one of those homemade chocolate chip cookies into a 3" collector. The cookies seem more like 3.5" OD....




-G

 

[4X4HIGH]

Greg, looking good. I suggest you tack weld those pieces together and then make sure you can actually REMOVE the header once it's built.

 

[miniwally]

Greg, looking good. I suggest you tack weld those pieces together and then make sure you can actually REMOVE the header once it's built.

^^^
Takes all the fun out this


Greg,
I've been lurking but honestly there are few things that you are doing that you haven't already worked through to the point that I'm of no real help. Your smart enough to have picked up on most of the problem areas quickly.

 

[ryoken]

If you want man points, use a steak. I could die happy if I never ate another cookie for the rest of my life.

Martin

thanks so much for the correction....



Greg, digging the tubes....

 

[kgblazerfive]

I am going back to my prior comment. Tri Y bring two together then into two go where the 4-1 collector is. So it will be a 2-1 because two are already together.

 

[sreidmx]

You should do 8-1 it will sound a lot better.. Plus scavenging will also be much better.

 

[76zimmer]

You should do 8-1 it will sound a lot better.. Plus scavenging will also be much better.

seriously that would be badassery!


I'm sure you've taken into consideration engine movement translating to header movement being magnified outside the framerails?

 

[Greg72]

I am going back to my prior comment. Tri Y bring two together then into two go where the 4-1 collector is. So it will be a 2-1 because two are already together.

Dude, seriously.....

-G