Sheet metal intake manifold help please

[Motolife313]

Ok ya that a good theory. The area is bigger at the plenum so the area has more mass of air craning it into a smaller and smaller area going down the tube. The wait and volume of the air probably push harder. The out side runners are dead straight also for me. I tryed looking on google and found not much for the vw diesel. I like fabing stuff tho and welding! Is it really worth it to go through alot of work to taper runners?

[ProPower engines]

Ok ya that a good theory. The area is bigger at the plenum so the area has more mass of air craning it into a smaller and smaller area going down the tube. The wait and volume of the air probably push harder. The out side runners are dead straight also for me. I tryed looking on google and found not much for the vw diesel. I like fabing stuff tho and welding! Is it really worth it to go through alot of work to taper runners?

I worked in our wrecking yard for 30+ YEARS so I seen a few things that made sense to adapt to other engines.

But yes the tapered tubes are the best way to go.
Our hilborne injection uses a 2 3/16 restrictors in the bottom of the 2 5/8 ram tube for just that reason
If the restriction is placed at the top it does not allow as much volume of air into the engine compared to the bottom above the throttle plates which are 2 5/8
and the tube length is also important depending on the engine and RPM etc etc.

We played on the dyno and the results were dramatic varying the locations!!

I am just suggesting that you take advantage of some engineer's work saving you test time trial and error.I like building stuff as well but there comes a time where having the machinery to do this stuff to get it correct is retardedly costly and to pay to have it machined is almost as much at time.

You may also be able to buy the tubes pre-made in a similar sizing you need as entry angle and size matter here.
You may also want to mill the side of the head at a improved angle to help with directing the air flow into the ports. Milling the head thinner on the valve cover side on the port to angle your intake upwards to start with to get a straighter shot towards the back side of the valve allowing you to raise the roof of the port without making it too big at the entry of the port to help keep air speed up all the way to the valve.
Or weld the floor and raise the port roof with an adapter plate to direct air to the port.
Many ways to do it. I have been working with iron heads lately with the port floor brazed up and roof raised on both intake and exhaust to help get air in and out. It would be time consuming to do but from what I see in results of the finished products the power gains are significant compared to a std. port simply in stock location.

I am involved with a experimental Nissan head project similar to what I described and so far all the improvements have been seen when the air speed is maintained through out the port to help fill the cylinders.
This is the short story but size and shape and location is everything.


The head design you are using while obsolete by today's standards of head design but if you look towards some of the newer V-6 heads they are using and using similar theories you can build something from the older head that will work very well.
casting thickness is your worst enemy and you may find fluid before you are where you need to be but its easy to weld up and carry on and add material where you need to and grind off what you don't.

[Motolife313]

So your engine would lose power if you took out the restrictors from the intakes? I just hope it will work good after putting time into it. Not much money tho mabye 90 bucks that's if I get it surface right. Could just belt sand it. I'm just hoping it won't warp to much when welding. I'll bolt it to the head. And these tubs are .200 smaller then my head runners

[Motolife313]

Just remebered the stock intake port was 75cc and I put it to 90 or 91cc. I didn't lower the floor at all. This is kinda a raised runner head. And I already dowel pined my intake manifold. If I layed back the intake face area or welded my runners on at a angle is does point it at the valve better. I can even see the valve better but it would have a change in direction. Wouldn't that be bad?

[Motolife313]

This port is way to small it's like around 1.3 or 1.4 average CSA. I've seen little 1.2 liter engines have ports this size. So I think these ports will be just fine. My motor is 2.5 liter

[Sparksalot]

If you are working with 6061 tubing as raw stock it is likely in the T6 heat treatment condition. It will indeed crack if much plastic deformation is required to fabricate your parts. If you anneal it before forming operations it will be much softer and far less prone to crack even with severe bending and forming work. Anneal, form as you wish, weld with the proper filler and it can then be heat treated back to high strength if you wish.

A classic fabrication shop floor method is to coat the aluminum to be worked with carbon with straight acetylene from a torch, then heat the aluminum evenly with a soft oxy-acetylene flame until the carbon disappears from the surface of the aluminum and let it cool in the air. The aluminum can then be worked until it's finished or if it work hardens too much to proceed, do the carbon coat and heat cycle again to proceed further.

If you have the facilities for it annealing can be done in a heat treat furnace, simply heat to around 800 F and let it slowly cool.

If you want to restore hardness and high strength it needs solution heat treatment and aging but that's beyond the problem presented.

[mk e]

If you are working with 6061 tubing as raw stock it is likely in the T6 heat treatment condition. It will indeed crack if much plastic deformation is required to fabricate your parts. If you anneal it before forming operations it will be much softer and far less prone to crack even with severe bending and forming work. Anneal, form as you wish, weld with the proper filler and it can then be heat treated back to high strength if you wish.

A classic fabrication shop floor method is to coat the aluminum to be worked with carbon with straight acetylene from a torch, then heat the aluminum evenly with a soft oxy-acetylene flame until the carbon disappears from the surface of the aluminum and let it cool in the air. The aluminum can then be worked until it's finished or if it work hardens too much to proceed, do the carbon coat and heat cycle again to proceed further.

If you have the facilities for it annealing can be done in a heat treat furnace, simply heat to around 800 F and let it slowly cool.

If you want to restore hardness and high strength it needs solution heat treatment and aging but that's beyond the problem presented.

+1
I usually use the black with acetylene then heat until it's clean method, but I've found it's best to heat from the opposite side or the torch may just burn off the carbon long before the part is hot enough. Sometime when I want to bend a specific area I just run the tig torch along the planned bend line to anneal a stripe.

[ProPower engines]

If I were you I would weld up the port floor and the outer portion of the head above the port then angle mill the head to make the entry angle nicer.

Even if you must re-drill the mounting holes its still better then trying to turn the air there and give a better shot to the valve.

[Motolife313]

Would I need to pull the seat out first? Wouldn't they pop out when welding? I already got a valve job.i did add .300 high of clay on the floor and tapered it down to the short turn. to make it like a D port head on a 1020 flow bench I know it's the biggest one. And gained 1 or 2 cfm up to .400 then lost about 6 cfm.

[pcnsd]

I have had good luck (so far) welding in alum chambers with the seats installed by using a set of sacrificial (old) valves and springs. The valves help to transfer the heat away from the seats. I also preheat the assembly to 275 - 300 F before welding and allow to cool insulated from the welding table with a thermal blanket cover (my welding jacket). I have never tried it after the valve and seat cuts were finalized.

[Motolife313]

Ok thanks. Ya a little sketchy doing it after the valve job it was only 80 bucks tho. Did you get in the port with a small 24 torch or a wp20 with a long cup or stick out?oh I guess you said chambers sorry

[Motolife313]

Ok I actually think chamber welding is a good idea. Not much quench in this head besides about 1/4 all the way around the hemi head. I was think of welding in the 2 marked areas. And the red line in front of the short turn is about the center of the port. Does this look like a good area to weld? I can radius the side into the ex seat

[Motolife313]

I have another head I can practice on. Is it ok to sand blast the head before welding or do I need to use other cleaning methods?

[pcnsd]

1. I have not successfully welded further than about an inch into the port from the side furthest from the valve and never from the valve side. The stock ports in my application start at hopelessly too small but can be pushed to almost big enough. If you try this you need some insulator to protect the valve guide. The guide draws the high freq to it otherwise and makes for an unstable arc and an ugly guide.

2. Welding quench pads is do-able. Add more material than needed and finish to final. Other than the cut to make the surface flat for me it is all hand work with a lot of fitting and claying to get it right. I have grit blasted before welding and I am less than comfortable with it now. I can't say for sure but I think it made for greater porosity in the welds. (My base material can be porous to begin with, so it is hard to say with certainty) If you choose to blast, I will suggest final cleaning using a fine wire brush followed by an acetone wipe.



Paul

[Motolife313]

So did you weld that Harley head with the head bare? I was just at baislys shop yesterday. I see alot of that kinda stuff over there. Ryan the weldor gives me good tips too.