CK5
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The Willomet Charger
- Thread starter AgDieseler
- Start date
A desecration to Mopar nuts everywhere, this is my protouring, LS-powered, 1970 Dodge Charger; built at my shop, Willomet Motor & Fabrication.
I'm curious to see how well that tubing miter works on the swag table. I have the same one, but my dewalt bandsaw doesn't tend to cut straight, so I have to eyeball it.
Overkill is good enough2" primaries seem a little overkill for engine size
2" primaries seem a little overkill for engine size
I thought the same thing at first because it's an LS and not a big block, but when I put a 427 cylinder in my math at 7200 RPM redline it says 1.98" for 16 ga tubing or 1.95 for 18 ga tubing, both of which are closest to 2". He is not prioritizing low end torque for a road racing/street vehicle, so the larger tubing makes sense. You could do a stepped 1 7/8 - 2" if the port will fit it, but if he already has the tubing just roll with it.
Headers are very rewarding when you are done. You can weld better than I can, so I expect works of art, no pressure.
The Dynasty does make it easier though allowing you to tailor the pulse to get more heat in a shorter burst. I just started finish welding a set of headers I am working on for a customer, for my butt welds I make zero gap, and use no filler with pulse, however I always add filler for the lap joints. I don't use pulse on the lap joints because I find a move slower and then you end up with more heat anyway. I always back purge, its really bad inside if you don't. I never used the pulse on the 220 because you couldn't adjust the pulse percentages, it was just on or off and frequency. Your welds are so pretty you'll probably figure out a better way than I did. I'll post some pics in the photo a day thread of what I'm working on now, I won't clutter your thread.
As for header design, I tend to gravitate toward easier to work on than all out max power at peak RPM. I prioritize spark plug access and installation and if they look right, I don't go for equal length and in a chassis you can't always make them so the collector rotates evenly with the firing order either, which is the next step after equal length. Equal length does make more peak power if you tune the primary length to your RPM, but other tests have shown that unequal length can produce a flatter power curve, as the cylinders peak at different RPMs, like dual plane intakes. If you want to go for peak power since it's a road race engine I can put your engine into my pipemax software for you. My app I wrote just calculates diameters, but this software calculates ideal lengths for the primaries and exhaust to shoot for, and some to avoid.
I use a swag table and handcut the tube for my headers. I had a friend start trying to cut curves on my milwaukee bandsaw and then it started not cutting straight, a new bearing kit fixed that pretty much, but it's still not perfect. I always finish the end of the tube after the cut on a 6" belt sander for a nice flat surface and zero gap. If I have any saw marks left I sand more until it's 100% sanded flat.
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That's how 2" was selected. Heath does the maths, David makes the toobs.
The saw blade has to be crisp and sharp for the cut to be right. Anything with some wear on it will wander.
That's the ticket for sure. Cutting 180s has always required some "dressing" to make the joint super flat. I have a bunch of super nice 90s and 120s from Vibrant, and they're easier to fit.
This is going to be a lot of fun trying the triangle waveform pulse. I'm setting up some test material to try and dial that in. I've always used 35A continuous, and my instinct for pulse is about 85A peak, 55%/15%, 1.0-1.5PPS.
I'm going to go get the LS7 today or tomorrow, and get it in the car.
David
Good point, it is worse on the 2nd half of the 180 in the J bend than the first half. You kind of have to squeeze the end round in the vice soft jaws before you sand it flat. The SPD J bends I've used before were a little better than these J bends I have now.
I figured you would have some good ideas. Are you using 18 ga?
I haven't tried the triangle pulse yet, maybe I should, it would be the ideal case for it to weld easier without overheating the SS and discoloring it more, I am not used to how much capability this thing has. If I have too low of power I go too slow and then I overheat the joint and then it loses the nice looking shine.
Yesterday for the butt welds I was at 100A peak, 1.2 PPS, 25%/25% square. I didn't always use 100% pedal as the outer part of the bent tube is thinner than the inner part. And for the lap welds I was at no pulse, 55A max, not always full pedal either. I use a #12 ceramic cup with a large gas lens, gives better looking welds than a #8 on SS. I tried the expensive large pyrex cups and broke one way to easy so I rarely use them.
16ga 304. That's where my 35A continuous baseline comes from.
12 and a good back purge is the sweet spot. The bigger 17s devour gas and don't substantially improve coverage. That's been my experience for stainless, but it could be effective on Ti.
For the length of the primaries, my plan is to build the crossovers for 6/5/4/3, measure, and then work 1/8/7/2 to match. I shouldn't have a problem getting to at least 32" in length, which seems to be the average for 2" LSX long tubes.
Heath - I am curious of the exhaust pulse timing separation cylinder to cylinder. If #1 exhaust valve opens at X degrees, when does #8, and then #7, and then #2, and so on. If their spacing is even, then equal length creates equal pulses at the 4:1 collector. Something tells me there's a 120 degree separation somewhere in there, and that means one or two runners need might need an extra inch of length.
David
After reading the above discussion, you guys would be soooo disappointed in pigeonrats exhaust. 
I'll take a look at the bearings. I've been using it a long time, and I've certainly abused it.
Can’t be worse than mine. Passenger side exited at the axle. Driver side under the seat. All hung with rebar tie wire.After reading the above discussion, you guys would be soooo disappointed in pigeonrats exhaust.
Le Pigeónrat has logged miles. Several of them. My garbage sits.
The dirty bird wins.
David
I assumed 18 ga with that amperage, I been mostly using the 1 A per .001" minus 10% for stainless, you are approaching minus half. Are you going for the not full penetration since you don't need full strength or just traveling slower for more precision and still getting full penetration with the back purge?
I agree, haven't welded titanium yet but wondered the same thing. I still have one not broken yet #16 pyrex cup I could try if I ever do.
I tried the triangle pulse, I didn't like it as much as the square wave with the low 1.2 PPS for the butt joints, I think I will try it again with a more normal PPS to see if i like that for the lap joints. I have plenty of scrap to test on after fitting another set of complete headers.
I forgot you were going with the 180 headers with that exotic sound. Math says to make a 2" primary tube 30.7 - 34" long for max top end. Longer is better for low end, shorter is better for top end. If you can keep them all within that range, that would be pretty optimal. My point is, I don't think you will be able to measure a difference in power if they are all exactly 32" vs some 31" and some 33.5" for example.
A 90 degree 4 stroke V8 has a full complete cycle every 2 revolutions for all 8 cylinders, which is also 90 degrees between cylinder events. The is why a 90 degree V8 with a cross plane crank is a very optimal engine, because it doesn't need any balance shafts as the 1st and 2nd order vibrations are naturally balanced out by the other cylinders. Cadillac actually patented the cross plane crank decades ago as the fix for the vibrations in a flat plane V8.
However, the cylinder banks and therefore header collectors split that up with a normal 4 into 1 having one firing in that collector two in a row and the rest have a firing in between on the opposite bank. With an LS firing order 3 & 1 and also 2 & 6 fire immediately after one another in their respective collectors, while the other events have a firing in the opposite bank in between, this means some cylinder firings are 90 degrees, some are 180 apart, and some are 270 degrees apart in each respective collector. This gives the uneven sound that a typical cross plane V8 sounds like.
What you are doing with a 180 header is set it up so the firings are all 180 degrees apart in each collector. An LS has a firing order of 18726543, normal collector is odd and even, 1/3/5/7, and 2/4/6/8. You want it to be 1/7/6/4, and 8/2/5/3. This will give you equal 180 degree spacing between firings in each collector. I think equal length does make more sense on a 180 header to be honest. I remember Comp experimented with uneven valve opening events to work with uneven length intake runners on typical cast aluminum V8 manifolds, but they have not really caught on and I haven't seen those for an LS, most V8 cams the cylinder events occur on an even 90 degrees between cylinders.
You just need to decide which 4 you will cross over, and leave the other 4 on the same side they are already on, this is a chassis fitment decision. You need to either cross over the center 2 or the outer 2 from each side for a 180 header. I would think the center 2 makes more sense, which is what I think you said above, because the front one is naturally the longest. However, since the rear one is naturally the shortest, it leaves that to deal with. I think you will find equal length, difficult to package in most chassis. It has to fit above all else. I typically give the straightest shot with the least amount of bends, for the highest flow and also easiest spark plug access, but it certainly doesn't sound like an exotic sports car and doesn't have the relative rarity 180 headers do.
What I do is after the header flange and the collector are both in place ( like your temporary collector mounts) I build each tube from the collector and from the flange, and meet in the middle. 3 tach welds each joint, every tach weld is on the bench, until the middle one that joins them together, that one is in the car, that's also where I put the step, which makes it a little easier.
If I remember correctly mine had a refresher kit that also replaced a C shaped piece with the bearings, that piece can stretch and leave a gap for the blade to not run true. Look for that piece too, maybe two of them? I bought two kits for when it eventually gets sloppy again, I'll try to snap a pic of the spare set.
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What a fantastic, richly-detailed reply. Thanks for investing that time.
She’s home.
David
Maybe I’m remembering wrong. Stainless localizes heat so much, but you’re right, that does seem low. Now I’m eager to relearn with my test scrap.
Roger. Good copy.
I’ve always thought the center four made the most sense, but that needs some double checking.
She’s home.
David
Thank you, I enjoy this type of discussion.
I agree, as I think if you crossover the corners the front two are going to be really long, it may be easier to add length to the rear two. But maybe that won't be the case depending on where the collector is relative to the engine in your chassis. If you make all the primaries longer it will shift the header's optimal RPM down, if you make them shorter it will raise the optimal RPM. Then you can decide how to proceed. If done right there will be a specific RPM window where the magic happens and all the pulses pull on each other and power peaks, ideally that matches the cam and heads, bore, stroke, etc, which is where the length I stated comes from.
Nice! Look forward to the factory dry sump timing cover/oil pan shots...
It still needs a harmonic damper by the looks of it? I think for your build I would upgrade to ATI anyway even if it did have one.
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Swapsies.
David
David
WOW almost ready to vroom vroom. 180 headers sound like a really cool concept. Question how do they get install remove ? slip joints between sides, flanges ?
“Rock in to jam.”
Had to take the entire rear apart to make enough floor space to do the swap easily, so that’s all back together too.
David
Had to take the entire rear apart to make enough floor space to do the swap easily, so that’s all back together too.
David
How far back is the engine from stock?
My old shortbed desert truck I moved the engine back 15” and down 12”. It had a 50/50 weight distribution with the radiator behind the cab.
My old shortbed desert truck I moved the engine back 15” and down 12”. It had a 50/50 weight distribution with the radiator behind the cab.
