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DOHC head... more progress...


Guest young frankenstein

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Guest young frankenstein

hello guys... i was referred here by people from zcar.com. they said u might be interested in my little project! lol lol lol i think this might be the site for me. ive lurked for a few days, u guys seem a lot more technical and into the mechanics of the cars. just a bit more serious i guess. anyway.... the pics..

 

 

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to tell the truth, i havent sealed up the passages inbetween the sections yet. im worried about welding it and having it warp, i want to keep the cams turning freely! ha ha ha! i was thinking about cutting grooves for o rings around the water and oil passages and then just tack welding it together in cetrain areas 4 strength, what do u guys think?

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I think most of us are aware of your project, someone had posted a zcar.com link with this recently. Looks awesome BTW. I'm at a loss as to how you'd weld it, but my first thought is you can do any straighteing by a combination of heating the whole thing up and bending it back along with milling it.

 

EDIT: as for the cams, maybe you could mill the caps down and align bore them?

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Guest JAMIE T

Welcome! When I saw your post on Zcar, I wondered why you bothered posting that there anyway. I only looked at your post becuase someone here linked to it! ALOT of us don't even bother going to that website. It's useless if you ask me... You are at the right place for ultimate performance Z cars. Your progress looks great. Great job on tackling such an ambitious task. Please be forwarned, I noticed you wouldn't elaborate on details on Zcar.com. Our group of guys here are the most helpful you will find, and I'm afraid they would be hesitant to provide much information without knowing more about you progress and technical information. Being intentionally secretive is not the way to get information from these guys.

 

We can be very helpful though!

 

I think your O-rings will eventually fail. EVENTUALLY. It could be years, could be months, but not having a way to replace them other than cutting you tack welds and re-welding them. I AM an aluminum welder, not sometimes, but everyday.

 

My recommendation would require alot of cutting and welding from the inside out. Basically, cut the mating surfaces so that they come to a point so that they look like this }{ instead of this ][.

 

Make it so you have just enough room to get your TIG torch in there and work your way out. Replacing the material (pieces of alum to be welded in place) where it needs to be to form the oil passages and water jackets. It would require sterdy jigging and machining afterwards to the deck and probably to remove the weld seem on the outside. I would completely trust that method if I were doing it.

 

FWIW, I have an RB26 going in my car and you can look at the post in the RB forum to see the head I'm porting. It looks strikingly similar your head in the combustion chamber and intake port shape.

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I'll be in Fargo at the end of next week. Perhaps I could stop by for a "refreshment" and have a look at your project.

Bernard

 

Yeah, and when you get back you can tell me if people in Fargo really talk like they did in the movie. Actually I always thought the people in that movie talked with a Steinbach accent.

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Well there is a head that will DEFINTLEY out flow mine, I think I read somewhere that the KA head flows 250 CFM at 500 lift and at a pressure of 25" of water. To where my head only flows about 210 at that pressure and lift, not even to mention that the crossflow design will purge the cylinder much better.

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Don't know the fascination with keeping an L28, seems like alot of work when there are many fairly cheap and better alternatives (1JZ, RB25). Once you get the head done what are you going to do for manifolds and a front cover, and sealing of the valve cover to front cover.

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Gosh...getting a cast made for this DOHC head would cost an INCREDIBLE amount of $$$...but really that would be the only way to ensure that there was no integrity and strength sacrificed. Eventually you would more than make back your money as potential buyers would feel very comfortable knowing that the heads are cast and not two welded KA heads with questionable internal welding.

 

A very well ported and polished P90 flows some really impressive numbers..I remember seeing a L28 with a P90 pick-up almost 30wheel hp just by switching heads and same cam..very impressive and this was on a NA motor.

 

Naturally your head will still outflow a really well manicured P90...but there is alot of testing that you would need to do to make a potential buyer feel confident about spending the $$ on your DOHC head and the unique intake as well. On ZCAR you said that the ball park would be around the $5G mark...that is more expensive than buying a RB26 motor, tranny, harness and ECU. Actually you could probably get a RB25 Skyline front cut for close to that - not trying to sound negative or disuade you and your excellent work.

 

A fully rebuilt and extrmely very well ported and polished P90 will run about $1100.

 

Hope to hear more from you and updates on your great work.

 

Regards - Yasin

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