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24 Valve DOHC head almost done!


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Guys give me about 1 month and I'll have pictures of the custom head for the L6. Note that won't be a complete set up just the head and valve train finished. Cams, timing and manifolds will need to be fabricated later. So far the total cost of this head will be about 120 bucks! Top that! I'll report more on the progress of this project when time comes nearer to completion. Also I'll see how things goes but if I can I might bring the head to the West Coast Nations this year, if I don't I'll bring it next year complete and running in my Z.

 

 

tbs Productions

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ok at least give us some hints or clues or something here. We had to wait this long its only fair to get a little info. Congrats on the progress. I remember talkin to you on the phone when you were working on adapting the rb head. Cant wait to hear whats up your sleeve now

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I thought that had be previously ruled out though maybe Im wrong. Sure would be pricey to get cams made for it though lots of custom parts are probably gonna get that price up in the air.... Still cant wait Im up for some fabrication album_pic.php?pic_id=2875 Here is the ka24de head but it is from an altima so it may differ from the earlier 240sx heads although I dont think so.[/img]

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What are the plans as far as manifolds go? I guess seeing how it is going to be cross flow i assume, the intake is usless, but what about the exhaust manifold? Also, is it set up more for a lower compression turbo set up, or will it be designed for a higher compression motor such as the KA?

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Manifolds will all be one off, custom peices. but, a header doesnt cost taht much to make, neither does a weld el turbo manifold! :D the combustion chambers on a KA head are 47cc's, i think. or somewhere close anyway. which is actually good for both N/A and turbo. The difference will be in flat top pistsons or dished. I've been behind the 2 heads into one thing from the beginning, its really cost effective if you think about it. Plus, its all stock nissan stuff as far as valves, lifters, springs, retainers crap like that. just no big bucks for the machine work and welding plus I was looking at the SOHC to keep things simple, but the DOHC will actually work far better.

 

McAdam

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OK guys I plan on building the headers for this set up I'm not sure if I want individual trottle bodies or a conventional type with velocity stacks in it. Also I'll be using the CAD software to design a Equal length Exhaust header for turbo and maybe one for non turbo. And yes the 1.5 KA = 24DOHC head. yes I did at first rule this out and now that I have all the tools at my disposal I'm doing it also I talked to an engeneer last year about welding two heads together and said it wasn't possible but I've learned that 99% engeneers out there know nothing about metelergy. Also to use this head you must bore the motor over for valve to cylinder wall clearance. I'll keep you guys up to date on this project. ALso I'll most likely be building the cams and turning them out on the CNC.

 

 

 

tbs

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I would like to hear more discussion about welding two heads together. We are talking lots of stress and accuracy is critical. How reliable would a head that is welded together in that fashion be. Im not being a pessimist at all I love the idea and am praying that it works. Just curious

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I bet 99% of engineers do know how to SPELL "metallurgy";)

(ok, probably more like 80%)

 

Best of luck and godspeed, but this doesn't seem to be realistic. Is it really possible to acquire two KA heads, cut them, jig and weld them together, machine the weldment, for $120?

 

Aren't the bore spacings on the KA kinda goofy, like 96, 98, 96?

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he is using cyls 2&3 and 1&2 and 3&4 kind of like nissan did with the block, going from 4 cyl to 6 cyl. cut one head in half, then take the middle cylinders out of another head and weld the halfs on tho the ends of the middle chunk. As far as stress and welding 2 heads together, there really isnt any. Once you bolt the head to the engine, wheres the stress? Only real stress is up (cyl explosions) and down (head bolts) there is no stress trying to tear the heads apart (side to side). Unless you count heat of the expading heads, but the head bolts will keep everything in check as they do for other heads. welding it is merely a way of sealing the colant and oil passages.

 

As far as accuracy.... If you build a jig, you can do it.. Another thought for accuracy was to bolt a camshaft across the weld lines of the 2 halves (or thirds in this case) when you are welding the bottom and sides. Then, when you are done, a simple, minor align bore and a custom CNC cam blank.

 

The KA intake manifold has LONG runners and is built for a long stroke, torquey motor. I wonder how it would behave on a short stroke high RPM motor? It is feasible to make a 6cyl KA intake using the same method as building the head. I think a custom intake built for some side draft mikunis to start out with for simplicities sake would be the best route.

 

the cost issue is cheap for him because he is in a school where he has access to all of these things and tools for free. but, on another note, KA heads can be had VERY cheap. Hell, whole motors go for $150, with motor, trransmission and wiring and ECU.. they are swap leftovers when everyone wants an SR. also, KA's came in EVERYTHING! Altimas, 240sx's frontiers.... lots of stuff. Heads in junkyards at U pull It yards gor for about $30. once he gets the procedure down, as long as you can find a shop with a full CNC setup and a well skilled heli arc aluminum wleder, the cost really would probably be cheaper than having an "Ultimate P90" built from say, sunbelt or rebello. seriously, how much are people on this board spending for a head that flows 250cfm?

 

McAdam

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You know I almost forgot that I'm the engineering student building the head and not my friend MACK. I'll decided what to do with manifolds for sure when the time comes but I know I'm not going to use the factory KA ones I can't stand them. I still have a few passages to fix and reroute before I can make it a bolt on. This project will take me time and right know I'm more concerned with getting the two heads welded together and showing you the mocked up head with chains and cams up on a bare block. Dan I know my spelling is bad give me a break, that’s not my strong asset. And yes I can do the head for 120 about because that’s with my college helping. With me machining the parts out and having the welding instructor weld them together. Note I can’t say anything on heads after this I bet I’ll have to out source the welding jobs. Stress there is not much I can garrote here on that part but I do know that the head bolts are help. Although I'm going to make it mandatory that if anyone want to attempt to this head that they use ARP head studs. I know the Factory L6 heads like to warp in the middle so I'm going to ask if we can stress relive the head, possible temper the head to get back some of the ductility. I'll be posting the complete process with pictures and write-ups of how it goes. Dan one last thing yes the bore spacing is weird on the KA but so is the L6 because of the thrust baring that is in the middle of the block the same holds true for the KA, that’s why I'm using the middle of that for the middle of the L6 head. Don't worry I still haven't given up on a billet head for the L6 I've started laying in the ports and am not sure if I want to make the port like the KA or like the OS head. I think the OS ports are better because of less turbulence and more velocity.

Alright I've got work to do and will answer any more questions you might have or if you feel that you want more of an explanation I'll give you a call and talk this out over the phone.

*Also* OS Giken has a web page FINALLY http://www.OSGiken.co.jp sorry no email yet but I'll keep trying with them I want the Z's to have a nice head even if I'm not the builder for them. I'm trying my best to give you guys your option of what kind of head you want.

 

 

 

Later

 

 

tbs

 

Sorry I needed to spell check it.

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hey, TBS >>> I am really not trying to steal your thunder, I am just trying to help answer questions with solutions I came up with when I was looking at doing this with the SOHC KA heads. Plus, if other people know whats up, we can have a nice little brainstorming session going on here and help get some more ideas out on the table.

 

Perhaps a solution for releiving the stress in the heads would be to have the finished assembly cryogenically treated? It helps a lot with pistons. When they cryo pistons, it helps them retain thier "round-ness" a lot more when things start to heat up. less distortion. anyway, this is coming along nicely!

 

McAdam

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Guest Nic-Rebel450CA

Curious that you mentioned using autocad to design an equal-length header. Have you found anything to support the necessity for equal-length? In general, there is no benefit from equal-length, and the engines that do benefit, it is normally so negligable that it does not warrant the extra work. Might save some time and money to just make an un-equal-length header.

 

Since this is being made from an existing head, do we already know what the flow rate per cylinder is going to be?

 

Have you considered a running engine endurance test? I think many of us would like to know how well this will hold up under high-rpms and/or high boost.

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Nic-rebel,

I think that the use of unequal lenght headers only really works on 90 degree v8's. Where the firing order discahrges into the exhuast at a equal interval a equal lenght exhuast has got to be better, Particularly on a straight 6.

 

Douglas

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