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Twin cam head for the L6 from Derek at Datsunworks

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#41 MaritimeRiceburn

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Posted 20 September 2014 - 11:31 AM

I'm assuming that means that a custom gear could not have been machined or found? just seems replacing one gear would be simpler than redoing the timing system



#42 Derek

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Posted 20 September 2014 - 11:37 AM

Larger gear means more teeth which means new gears up top to keep the ratio correct. Also the honda chain is a smaller profile than the L6/KA chain so there might be a strength issue.


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#43 G-E

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Posted 20 September 2014 - 11:47 AM

Awesome job, if you don't mind, I'd like to hear more about the manufacturing end of things, I fully expected printing sand models would be possible, but I'd never heard of it actually being done!

 

I'll pm to keep the thread clean..



#44 G-E

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Posted 20 September 2014 - 11:52 AM

Cometic will stamp out mls gaskets for you for all sides if you order 25 sets btw... might even be fairly economical considering they can just add ports to existing gasket designs for intake/exhaust if you're keeping any of them k-series style...



#45 MaritimeRiceburn

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Posted 20 September 2014 - 12:40 PM

too bad about the timing gear then. Just seems it would be a lot simpler to do this with the stock ones



#46 Tony D

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Posted 20 September 2014 - 04:01 PM

The vavle angles are not really that difficult. Another thing to consider from using the Honda's engineering is this:

The valves are concentric to their pockets. All the pockets are already in-line. Indexing on a 5-axis CMM machine you find your origin off three valve pockets average locations using intake and exhaust.

 

From that point you can sink your valve guide holes. 

 

From that point you can ream your guides to size and from that you have a concentric point for valves and valve seats.

 

From that valve guide hole, since both rocker shaft and cam shaft is in the cam towers, the relative positions of their holes is set by calculation rather precisely.

 

The head bolts are independent of those points, thankfully so that you can get your entire camshaft and valvetrain setup using only the head as a reference. Obviously the cams and rockers, as well as the lines of valves should all be longitudinal parallel lines through a centerline drawn through the head, as would the head bolt holes.

 

Setting of the shuffle pins or reamed taper dowels for locking the cam towers in position is another machining step but once the relative positions of those three intake and three exhaust ports are determined--the relative position of the entire valve train can be determined. EVERYONE here I'm sure has seen valve seats in a head that looked 'off center' relative to the port--welcome to the world of 'casting core shift' --- the relative position really isn't that critical, and with the casting method Derek is now using the relative positioning of the ports, separation from centreline, etc should  be VERY precise compared to an older head made with traditional casting methods.

 

You just have to get the longitudinal axis for the line of valves determined using rough port diameters...you can adjust it quite a bit, relatively, inboard or outboard from centreline of the head to match the cam towers properly, and to make sure the valves are under the cam lobes (or more properly under the rocker arm tips) like they should be.


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#47 Tony D

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Posted 20 September 2014 - 04:03 PM

Cometic will stamp out mls gaskets for you for all sides if you order 25 sets btw... might even be fairly economical considering they can just add ports to existing gasket designs for intake/exhaust if you're keeping any of them k-series style...

That may be what their advertising propaganda says, but their customer service in response to JUST such a request is met with cold shoulders and a resistance of the CSR to contact the engineering department to discuss ANYTHING other than what they already have in stock.

 

Yes, they will cut any gasket you want, but they are resistant far more than you're making it sound.


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#48 Tony D

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Posted 20 September 2014 - 04:07 PM

RE: Derek's response to Alan T.

"Not the market I'm going after. This project is as much about proof of concept as anything else. Patternless casting has arrived. It seems expensive, but for this type of project it's ideal. "

 

What, tax deductible R&D with Advertising Possibilities? Like "BLAKE MACHINE 3.2 DOHC"?

 

Noooooooooooooo.

 

You mean trying to KEEP your money to do thing that are cool for your car  isn't a thought? C'mon people, there are MANY reasons to do this project if you are in the casting business, other than an altruistic self-sacrificing love of the marque model of Sir Lawrence. Consider this more like good old Mr. Raffles, what!

 

Man, I gotta go find some Sapphire and Tonic... the mosquitoes here are oppressive. What was it that the Dutch drank out of Batavia? Bloody hell, I'm not having any of that Civet-Crap Kopi!


Edited by Tony D, 20 September 2014 - 04:08 PM.

Misanthropic Anthroparion Class 5 Hoarder, aspiring to posthumous fame as my containers are cut open and the market floods with crap I've squirrelled away over the years! I endeavour to persevere...

#49 MaritimeRiceburn

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Posted 20 September 2014 - 05:10 PM

I don't understand any of this^

 

Hope this goes well, i really want to see this thing running



#50 Derek

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Posted 20 September 2014 - 05:11 PM

 

 

EVERYONE here I'm sure has seen valve seats in a head that looked 'off center' relative to the port--welcome to the world of 'casting core shift' --- the relative position really isn't that critical, and with the casting method Derek is now using the relative positioning of the ports, separation from centreline, etc should  be VERY precise compared to an older head made with traditional casting methods.

 

Exactly. The combustion chambers, ports, water jacket and the front and back of the head are printed in one piece. If you look at the bottom picture of the casting you will see a tab on the front and a tab on ...well half a tab on the back. It short ran. Anyway on the front tab you see 2 pins. Those are hardened ground steel dowel pins that are cast in place. There should be 2 in the back, and that will be fixed on the next ones. Those pins will slide into a fixture on my rotary table. I'll then probe various points on the head to find the center of the casting. You then average out from there. I do this pin trick on all the larger castings I do. Makes life  little easier for the machinest. You know how cranky they can get.

 

When I modeled in the cam tower and rocker, the valves that I had modeled in previously didn't line up with the rocker. I tilted the valves .5 degree pivoting at the bottom of the valve guide and it lined up. 

So the difference between lining up and not lining up is half a degree.  Now I could drill from the top like the factory and wherever the valve seat ends up well thats where it ends up.  If I had a head to scrap this would be a simple fix as I will get the angle right after a couple tries. Trying to get it right on the first hole will be tricky.


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http://datsunworks.com/page3/page4/


#51 Tony D

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Posted 20 September 2014 - 06:55 PM

If only you knew someone with a Rottler Valve Machine and the index reference points for the K20.

If one (Number 1 or Number 6) is in the same relative position as it is on a K20 that Rottler can sink guides, valve seats per factory specs and then moving on from there is pretty easy rather than starting from scratch.

Boy, would it suck right now if the site crashed and we lost this thread...hahaha
Misanthropic Anthroparion Class 5 Hoarder, aspiring to posthumous fame as my containers are cut open and the market floods with crap I've squirrelled away over the years! I endeavour to persevere...

#52 roger280zx

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Posted 20 September 2014 - 07:47 PM

I love the valve cover, you are the man Derek!



#53 NewZed

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Posted 21 September 2014 - 11:35 AM

 

After talking with Jeff about his testing on coolant flow I decided to get the most out of the 3D sand printing process as I could. I designed a water jacket that would be pretty hard to duplicate traditionally. There is a lot of surface area so hopefully there will be large improvements in cooling.

 

Some computerized flow analysis seems like a good idea.  I thought that the big problem with the L6 head is the flow, not so much the surface area.



#54 Derek

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Posted 21 September 2014 - 11:48 AM

 

 

I thought that the big problem with the L6 head is the flow, not so much the surface area.

I believe you are correct. Tony pointed this out to me but it was too late in the process as the molds were already printed. Version 2 will have access to the water jacket above each exhaust port. If you want to get to it you mill through the head. This way if you have a high heat turbo build you can exit the water at each port tied to a single tube with thermostat. Personally I won't need it for my NA build but it will be there for those that need it. The OS Giken is this way.

 

 

 

Boy, would it suck right now if the site crashed and we lost this thread...hahaha

 

Yea that would suck. I thought about that a few times. I hope they are actually getting the backup service now.


EDIS Mounting kits are BACK IN stock!!!
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#55 Xnke

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Posted 21 September 2014 - 12:08 PM

Boy, would it suck right now if the site crashed and we lost this thread...hahaha

 

 

"$wget -mR http://forums.hybrid...-1#entry1121013 && http://forums.hybrid...-2#entry1121013 && http://forums.hybrid...3#entry1121013"

 

Fixed that bit for ya.



#56 garvice

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Posted 22 September 2014 - 03:28 AM

Well done mate.

#57 1vicissitude

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Posted 23 September 2014 - 06:21 PM

Just thought I'd throw this in here, efihardware now has much more affordable itbs on ebay. $1200 for three dcoe itbs in either 45mm or 50mm with trumpets, linkage, and a fuel rail. Pretty awesome deal and should help save more than a few bucks over jenevy.

#58 Tony D

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Posted 23 September 2014 - 08:06 PM

If you are considering this modification... a few bucks goes out the window just as fast as 1,000!

For this intake port design, it's not uncommon to find ITB's in the 56-62mm range being used in N/A Applications...

 

When you put lift to these valves, you are close to 400 cfm port flow! 

 

One thing Jenvey has going for them that most of the others don't is that they have selections OTHER than the standard 109mm flange-to-flange distance. On a DOHC head, space to the right shock tower, no matter what you are in, will be at a premium. Competition Torquer Plenums for this intake have 9 to 12" runners to give performance in the 3,000 to 8,200 rpm range. If you think about trumpets and intake tuning, then that's the length you will want on ITB's as well (trumpets) and that will get tricky. 

 

Using Discarded RB26 T/B's might be an idea..

 

Or as Alan T has reminded us: JECS ECGI (Japan Engine Control Systems Electronic Controlled Gasoline Injection) was available in late 1971...

 

Attached File  LY-24-on-ECGI-pre-73-RAC-12.jpg   119.85KB   28 downloads


Edited by Tony D, 23 September 2014 - 08:14 PM.

Misanthropic Anthroparion Class 5 Hoarder, aspiring to posthumous fame as my containers are cut open and the market floods with crap I've squirrelled away over the years! I endeavour to persevere...

#59 HS30-H

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Posted 24 September 2014 - 12:36 AM


 

Or as Alan T has reminded us: JECS ECGI (Japan Engine Control Systems Electronic Controlled Gasoline Injection) was available in late 1971...

 

attachicon.gifLY-24-on-ECGI-pre-73-RAC-12.jpg

 

Nissan's ECGI was made by (HItachi-affiliated) Nissan subsidiary Diesel KiKi, and used Bosch-licensed electronics as their starting point. The throttle bodies themselves were manufactured by Denso. 

 

JECS was formed in 1973, uniting Diesel KiKi, Unisia, Nissan and Robert Bosch Japan with Hitachi as nominated parent company.

 

 

Now back to our usual programming...



#60 Tony D

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Posted 24 September 2014 - 01:28 AM

The work of the indomitable MITI... The later cars had "JECS" decals on the side, I don't know what that particular one had on it...since it said 73 I was assuming the later, even though the identification was "ECGI"...

 

The MAP sensor on the firewall is a dead giveaway, identical to First Generation BOSCH in the TypIII VW, and the Isuzu Bellet.

 

I've got half a dozen of them at home from my VW Days... Would make a nice looking period-correct 'cheater' system for those at the car shows to argue about...


Misanthropic Anthroparion Class 5 Hoarder, aspiring to posthumous fame as my containers are cut open and the market floods with crap I've squirrelled away over the years! I endeavour to persevere...




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