Engine and Transmission Tech

I'm starting on my header fabrication for the Vega this week. The empty engine and trans go back in for the fourth time tomorrow night. I got a bunch of parts from Stahl Headers:

[www.stahlheaders.com]

Click on "Bending Mistakes". It takes you to prices for a box of random bent tubes in 16 and 18 gauge of different sizes. I got a box of 1 3/8" tube for the primaries and a couple collectors with 2 1/2" exits.

I'll post what comes in the box when I get it.

Nix-

I would like to see how the engine & transmission look in your Vega. I am toying with the idea of using one of the many Rover 3.5 V8s and 5-Speeds to install into a Vega. I have found a brown 1977 or 76 Vega coupe for sale for $800.00. I am a Triumph TR8 guy but for some reason the Vega Rover sounds very appealing. One of the TR8s I have worked on has a Rover 5.0 liter with Buick 340 heads had custom headers (4-1) made that flow really well compare to the typical headers (4-2-1) configuration. What are you going to fabricate; 4-2-1 or 4-1?

-Mike

I'm building 4-1 headers. I don't have current enough pix of the engine and transmission with the customized crossmember for the trans. I'll be putting it back in tomorrow and I'll post some pix then.

I think the Rover v8 is the best swap for the Vega. It's light and powerful if built right. GOod stuff.

What ever happened to Ed Henneman..
"Headers by Ed".

His website has been down for some time now.

He was in south Minneapolis nick.

I tried calling a couple times but no answer. I don't know what happened to him. Weird. That was why I ended up going with Stahl.

I periodically try the url to see if it's backup but no luck. Sad.

He is there but hard to get on the phone. I thought about stopping in for parts since he is only about 40 minutes away. Hmm, my wife only works about 5 minutes from his place of business.

-BMC.

Nice! Where is it? Is it still the same address?

What a character. GOod advocate for header performance.

OH man… I f'ed up and bought the wrong diameter tubes! AAHHHH! I meant to get 1 5/8" tubes and ordered 1 3/8". GEEZ! SO that process is about to start over. Damn.

I would think that 1 1/2" primaries would be plenty for a 215/3.5. I am using 1 5/8" on my 400hp Camaro.

Too late. I already changed the order. They were really coool about it. They are sending me a new set with a return label. COOL! Looks like I'll get 400 hp then!!! SWEET! That was easy.

No. I got that number from Des Hammill's book on the Rover V8. He's saying minimum of 1 1/2" for lightly modified 4.0/4.6L Rovers with stock heads. 1 3/4" for full race engines with 7k redlines. I figured 1 5/8" was a good compromise. We'll see.

OK on that topic. I was planning on making my primaries 40" long. Any input here? Thanks Team!

> I would think that 1 1/2" primaries would be plenty for a 215/3.5.
> I am using 1 5/8" on my 400hp Camaro.

The primary diameter should be based upon what the exhaust port flows.
David Vizard wrote a couple of good articles ("Exhaust Science Demystified"
Popular Hot Rodding, May 2005 and "No Loss Exhaust", Drag Race Monthly) in
which he presents simple design equations for header and muffler sizing.
I use his equations as starting points for Dynomation iterative simulations
so I wrote a little routine to calculate the parameters. The equations are
based what the exhaust port flows at your maximum exhaust valve lift:

OID = SQRT (Ex_CFM * 1.27/FD)
CDiam = 1.75 * OID

where:

OID = optimal internal diamter (inches)
Ex_CFM = exhaust port flow (CFM) at 28" H20
FD = flow density (around 80 CFM/square inch @ 28" H20)
CDiam = collector diameter (inches)

I have tested several sets of Buick 215 and 300 aluminum heads on a local
flow bench and ran the exhaust flow numbers through Vizard's equation:

Buick 215 unported 85 CFM (1.3125" exhaust valve)
Primary ID (inches) = 1.16
Collector ID (inches) = 2.03

Buick 300 unported 116 CFM (1.3125" exhaust valve)
Primary ID (inches) = 1.36
Collector ID (inches) = 2.38

Buick 215 home ported 129 CFM (1.48" exhaust valve)
Primary ID (inches) = 1.43
Collector ID (inches) = 2.50

Buick 300 pro ported 153 CFM (1.5" exhaust valve)
Primary ID (inches) = 1.56"
Collector ID (inches) = 2.73

The above CFM numbers are exhaust flow at 0.5" lift and the diameters are
ID's (internal diameters). You have to add your tubing thickness. Vizard's
rules reflect bank separated 4-into-1 headers on 90 degree V8's with dual
plane crankshafts. For most applications, primary lengths should fall
between 24 to 36 inches with shorter lengths favoring higher RPM. Likewise
collector length should fall between 12 and 20 inches (good for up to 8000
RPM). Of the two, the collector length is much more important than the
primary length. On engines like ours, longer collectors are generally
better. To not pose a serious restriction, mufflers should flow 2.2+ CFM
per HP (the point at which there is a 1% difference between mufflers and
open pipes). In my own limited experience, mufflers can have a big effect.
I dyno tested a 475 HP small block Ford V8 street motor (made peak power
at 5500 RPM) that lost 50 HP through the stock mufflers compared to open
headers with an 18" extension. Installing a pair of 3" inlet/outlet
Magnaflow mufflers, it got all but 1 or 2 HP of that back. Interestingly
enough, there was little difference in peak power on that engine between
headers with 1 3/4" and 2" diameter primaries but the smaller primary
headers (which also had longer collectors) made a bit better torque below
3000 RPM.

> No. I got that number from Des Hammill's book on the Rover V8.
> He's saying minimum of 1 1/2" for lightly modified 4.0/4.6L Rovers
> with stock heads. 1 3/4" for full race engines with 7k redlines.
> I figured 1 5/8" was a good compromise.

Are your Buick 300 heads ported? Uisng Vizard's formula, my ported
Buick 300 heads which peak at 153 CFM (1.5" exhaust valve) would need
a primary ID of 1.56" inches. 1 5/8" = 1.625" OD which should be
close when you factor in the tubing wall thickness.

> OK on that topic. I was planning on making my primaries 40" long.
> Any input here?

36" is plenty long for the primaries. Make the collectors longer
and don't go too large on the collector diameter.

Dan Jones

I did get a mild port job done, mostly in the pockets. All the rough parts have been polished out of the exhaust ports but no change to volume. I'm using 16-gauge tubing (about 65ish thou wall thickness) so it looks like I'm at about 1.5". I figure I'm flowing a little less than 153 CFM. How about, for argument's sake, we split the diff and call it 135 CFM. What do you think? I should be pretty close to where I should be I figure.

shortening to 36" should help me a bit. It was putting the collectors WAY back. LOL! Thanks again Dan.

Nick, I ended up with 32" primaries (was aiming for 36) and that has worked out great. Remember that you can extend the tube into the collector a little ways to get even lengths if you need to, that can help a lot. I think you will find that these headers you are building will really make that engine scream. There's more to be gained there than most people realize, especially when compared to the block huggers and shorty headers that are common.

Jim

> so it looks like I'm at about 1.5". I figure I'm flowing a little less
> than 153 CFM. How about, for argument's sake, we split the diff and call
> it 135 CFM. What do you think? I should be pretty close to where I should
> be I figure.

1.5" primary ID should be fine. With 135 CFM exhaust flow at peak cam
lift, you'll want:

Primary ID (inches) = 1.46
Collector ID (inches) = 2.56

Dan Jones

Perfect. That works for me.

I'm pretty excited to start fabricating. I'm certain I'll be hating this by the time I finish. LOL!

I started fabricating the Exhaust. I bought a couple collectors and a box of bending mistakes from Stahl Headers in PA. Absolutely GREAT company to work with. I messed up the original order saying 1 3/8" when I meant 1 5/8" and when the parts came and they were the wrong size they took them back and paid for part of the shipping. It was really a great experience. I hope to frequent their business and recommend them as much as I can. The headers are 1 5/8" primaries and 2 1/2" collectors. Here's a pic of the parts:



I started out using "Muscle Car" TV's idea of welding the collectors in place where they should end up. I wanted the primaries to be about 37" long. The collectors ended up right along side the trans in a convenient slot that appears on either side of the trans crossmember mount. The strange thing is it's symmetrical on both sides. It's almost like they planned on the Vega having dual exhaust! Below is a pic of how far down the collectors hang. They are as snug as I could get them comfortably at 1/2" from the floors. Here also is a couple pix of the collector location:





I was able to get two tubes in last night. There is a lot of time just standing looking at the puzzle and planning the best solution. I have to thread the steering shaft through the headers too. You can see that in these pix. Having the rack steering although causing me to have to put the shaft between cyl 6 and 8 actually gave me more room to make the tube's transitions smoother than if I'd had the stock gear box/steering shaft location.

Get yourself some "smurf" tubing.. .......[The blue flexible electrical conduit ]
drill some small holes in the sides and cut them to equal lengths..
snake em around till you get them looking good then apply some foam to the inside of the pipe through the holes to harden them..
Once you have this.... its easier to weld up and form the hard pipe how you want it.



Edited 1 time(s). Last edit at 07/31/2008 04:47PM by hoffbug.

You can also use lengths of bare welding or brazing rod to get the right bend angle. Kind of an old trick but it works. Generally start at the front and work back since it's easier to add bends than to stretch the tube. Looks like a good start. Would you mind telling how much the box of bends cost?

Jim

I've been using a piece of romex I had laying about. You can actually see it in the picture of all the tubes. I've been laying it over the bends to get a handle on how I can piece them together. So far it's a lot of fun.

The bending mistakes came out to $150. It was $140 for me because my order was over $200 with the collectors. Stahl has been really great to work with on this. Even though I messed up on the order they still sent off a return slip and paid for the shipping back. WOW!

I have stahl headers on my chevelle.. they make a great product...