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Derek

Twin cam head for the L6 from Derek at Datsunworks

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Derek    46

So looks like the head is about done....When does the aluminum block project start?

 

I wish.

I'd love to do that project some day but that may be a few years off if ever. We'll see how well the heads sell.

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Tony D    143

Re: "Tiny Combustion Chambers"

 

Remember the volume of the OSG, optimized for 2.8/3.0's was 35cc's. If you work at it, reeeeeally carefully, you can make them 40cc's. That's it.

 

You can do the math from there what CR is available from what displacement using simple flat-tops.

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Derek    46

Re: "Tiny Combustion Chambers"

 

Remember the volume of the OSG, optimized for 2.8/3.0's was 35cc's. If you work at it, reeeeeally carefully, you can make them 40cc's. That's it.

 

You can do the math from there what CR is available from what displacement using simple flat-tops.

 

I saw a post on the Tomitakau site that he CC'd his head at 30cc's. I don't think he expected that and could be chalked up to surfacing. Also if the chambers were as cast then hand finished there could be some discrepancy from head to head. That was all through google translate though.

 

on this build I'm shooting for a NA chamber size of around 43cc's. The motor that V2 is going on has a Rebello stroker kit in it. According to the Ozdat engine calculator it will put him right around 11: 1 CR without a piston change.  All that extra meat in the combustion area is going to really make things nice as far as customization.  

 

Derek

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Derek    46

Speaking of V2.

Starting to chug along. The head has been held up waiting on radiology testing so I've been working on other components.

 

20170707041732-5603ead3-me.jpg

 

 

So I bit the bullet and decided to try my hand at making cam towers. They are machined out of 6061 T6 and match the factory specs except for the cam bore size. I opened the bore up to 1.25" since I have a nice Sunnen hone and the smallest it will go is 1.25". I increased the cap thickness accordingly.

 

I also changed the design on the cams a bit. The front is the same as a KA24 and matches the cam gear. I'm doing away with the adjustable hubs and replacing them with multiple dowel holes and a drilled gear. With this combo I'll be able to have 1.25 degrees of adjustment with 2 dowel pins. Stronger, cheaper, better.

 

I'm also incorporating the thrust bearings into the cams and having Crane grind them to size when they do journal #1. The main reason for this was it let me increase the diameter of the camshaft at the end. Mucho stronger.

 

20170707041742-ee4a7779-me.jpg

 

 

I made a fixture plate to bore all 7 towers at a time but for right now I'm only doing one at a time. I bore each opening without moving the table switching the towers in and out. This way the bores are all in line. Went a lot faster than I thought it would.

 

20170707041727-ffc7b3de-me.jpg

 

20170707041723-01340e25-me.jpg

 

 

The bores came out wicked smooth. Much better than the used towers I'm running on mine.

 

20170707041737-1f6537d8-me.jpg

 

SMOOOOOTH

 

20170707041739-53a18987-me.jpg

 

 

Hope to have my hands on the head next week to start machining.

 

Derek

Edited by Derek

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Derek    46

So Derek can the rest of the Datsun community expect to see a four cylinder version of this head in the future?  Seems the vast majority of the work is done on the six cylinder version for what would be needed to make a four cylinder version.

 

I'll make anything if there is demand but it just seems like there are really decent 4 banger options out there. I was easily convinced by myself that a 6 cylinder version was a good idea. A 4 cylinder.....Not so much. Now if someone wants to donate a 2 door dime for "development" purposes I may be swayed:)

 

God Derek stop forcing my hand!!!! You're making me have really bad thoughts about spending LOTS of money!!!

 

It's still cheaper than an OSG:)  

That should give you some comfort.  

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JavelinZ    0

This just keeps getting better. Did machining your own caps also allow you to eliminate the gap between the rocker arms and the cam towers (due to difference in bore spacing) so that those spacers you made will no longer be necessary for positioning the rockers over the valve stems? 

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Derek    46

This just keeps getting better. Did machining your own caps also allow you to eliminate the gap between the rocker arms and the cam towers (due to difference in bore spacing) so that those spacers you made will no longer be necessary for positioning the rockers over the valve stems? 

 

Thanks

Yes. It made it tricky because now if I screw up the machining on one in the later stages then it's a specific location. Fortunately 2, 5,and 6 are the same. 4 is the odd bird and 1 and 7 are specific because they are front and rear. Bottom line...Don't screw up the machining:)

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Tony D    143

The CC's figure I used was for an OSG build currently underway. PMC took extreme pains to get the CC up to 40 from where it was when he got the head.

 

At 18 degrees total advance, the CR can be a bit higher than you think... I'm throwing those numbers out for reference as it's difficult on a non-pent-roof chamber to run that kind of compression without racing gas...but you also need 37 degrees of total advance to get peak cylinder pressure at the proper point.

 

Fast-Burn heads always tolerate more compression on pump gas than most people will think...

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Derek    46

The CC's figure I used was for an OSG build currently underway. PMC took extreme pains to get the CC up to 40 from where it was when he got the head.

 

 

 

Any reason why you wouldn't dish the piston as opposed to working the chamber? Seems you could machine the outline of the combustion chamber into the piston. The quench areas would stay the same. If you wanted to be really anal you could cc each chamber and change the depth of each dish to match the chamber. Removing 1mm of depth at the perimeter of my chamber changed it from a 53cc to a 44 cc chamber.

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Derek    46

Look I'm starting to buy in bulk:)

 

20170707041745-fc5d929e-me.jpg

 

Got the valve covers on Friday. This time the firing order filled great but there was a short run on one of the ribs. Nothin that a little tigging won't fix.  I have to do a little more work to the pouring basins as they are having trouble keeping it choked up with metal. You wouldn't beleive how much math and Voodoo goes into designing a pouring system.

Edited by Derek

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Derek    46

If I end up with one of these babies I'll let PMC have a fiddle I think. Sounds like fun.

 

Keep up the amazing work Derek!!!

Based on his instagram  account he seems to know what he's doing. The OSG head he's restoring is amazing. 

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Tony D    143

Any reason why you wouldn't dish the piston as opposed to working the chamber? Seems you could machine the outline of the combustion chamber into the piston. The quench areas would stay the same. If you wanted to be really anal you could cc each chamber and change the depth of each dish to match the chamber. Removing 1mm of depth at the perimeter of my chamber changed it from a 53cc to a 44 cc chamber.

 

When you make your own head, you can do what you want. When you work with what exists, you gotta do what you can with what you have. There are some advantages to having a large combustion chamber in the head... and in most cases you have to match the CC on the head with the largest chamber anyway. It wasn't uncommon on VW's to machine individual pistons to get CR equal on each hole.

 

There is always the angle that a simple flat-topped piston is delivered on a stocking order and at a lower price than one with a dish machined into it...or a custom machined matching chamber-profile dish in it.

 

Everything you say is possible, indeed.

 

I just saw the 'small combustion chamber' comment, and wanted to give a real-world L-Engine Head example of a comparable aftermarket head: the OSG. It's a 35cc chamber, and takes a lot of work to get to 40CC's (which is important on a 3.4L engine, as how deep a dish do you really want to make?)

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effing matt    0

So, I guess I finally worked up the nerve to ask:  How much is this going to cost me?

 

Or is it still at the "If you have to ask what it costs, you can't afford it" phase?  I dream about two "Baby" EFR turbos on this setup.

 

I am just happy someone is giving OSG some competition, you've done an awesome job Derek!

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Derek    46

So, I guess I finally worked up the nerve to ask:  How much is this going to cost me?

 

Or is it still at the "If you have to ask what it costs, you can't afford it" phase?  I dream about two "Baby" EFR turbos on this setup.

 

I am just happy someone is giving OSG some competition, you've done an awesome job Derek!

Not so much if you have to ask and more like I'm not sure yet:)

 

Here is what I do know.

 

Raw castings, head, valve cover, timing cover.  $4500.00

 

Machining all of that so that an automotive machine shop can do their thing. At least $1500-$2000. I've only done one so far. I'll know better after V2.

 

Camshafts. Better figure $2000.00 - 2200.00 for the pair finish ground ready to go.

 

Automotive machining basic. $1500.00 - $2000.00

 

Parts:

 

These are prices I banged together working off of the internet.

 

Valves $200.00 - $500.00

Springs and retainers $500.00 - $800.00

Exhaust guides $75.00

intake guides $75.00

valve seals $60.00

12 rockers  $28.00 each  $336.00

exhaust shafts  $75.00

intake shafts $75.00

 

Better add another $1000.00 for stuff that I can't remember right now.

 

Plus you need induction and exhaust.

 

Better have $15000.00 in the bank or plan on using used stuff like I did or working deals. 

 

V2 is a paying job with all new parts so I'll have a much better idea of pricing.

 

Cheaper than OSG but still freeking pricy. Plus you'll actually be able to get one as I don't plan to be stingy:)

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effing matt    0

That's far more reasonable than the numbers that I have heard for the OSG deal.  I am interested, but I am in the very beginning of my money pit  and nowhere close to needing to start the engine guild at this point.  But it's nice to know it will be available when I am ready.  I can't wait to see the numbers one a max effort turbo build lays down!

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Derek    46

Got V2 back from radiology and it looks great. The changes I made to the gating and risers solved the bad shrink porosity I had in the front.

 

Got it all set up in the mill.

 

20170707041750-7cdd02ca-me.jpg

 

 

If it aint crashing it's clearance.

 

20170707041753-91fd2073-me.jpg

 

 

Won't be many updates as it's basically the same as last time. If I see something interesting while I'm machining I'll post a pic.

 

Derek

Edited by Derek

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