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cylinder head molding prossess


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Guest Anonymous

I think changing the block to use the Skyline cambelt pully would be a better idea that changing the head to use a chain?

 

I've got an RB20 head in my garage, I'll try and get a digital camera later on tonight and take some pics and show you what the differences I've noticed have been and what I think would need to be done.

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Guest Anonymous

Okay, here we go, sorry about the size of the pics but I think its necessary if you want to see any of the detail

 

Standard L28 block

L28Block.jpg

Underside of the RB20 head

RB20Head.jpg

RB20 head + L28 head gasket (there are L28 headbolts in each corner to line up the gasket

RB20HeadHG.jpg

Closeup of timing end coolant passages, notice the large one at the bottom (just below the head bolt) that would need a lot of work

Closeup1.jpg

Closeup of the other end, notice the coolant passages at the bottom semi-lineup but would also need work

Closeup2.jpg

A long shot just to show how well the cylinders line up

Closeup3.jpg

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Why on earth wouldn't you just plop in an RB26 engine? It sounds like the end-goal is more to have a DOHC 24valve Z car than to have a very expensive (in terms of time and money), but possibly worthwhile learning experience. If the primary goal is increased performance, I wouldn't even consider attempting something like this. There are several MUCH cheaper, quicker, and similar- or better-performing alternatives. Hey, SOMEbody's got to be the voice of reason here;)

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Hey DJ33 is that really a RB20 head? Also would you consider selling it? Or do you know where I can get one for a desent price?? Please let me know soon I would like to have that hed for the idea also to make it work then I will have to change the timming chain cover so I can block off the belt and then allwo oil to make it to the Oil pump or I can use a different oil pump or just go with chains but I do like belts over chains if I can get a way with it.

 

 

tbs

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yah guys I found a head for the BR26DETT and was shocked when the price was converted to USD about $2400 shipped (3900AUD) for just the head. I decieded against that head and am on the search for a RB20DET head since the whole motor cost about $1000 USD I figure that just the head won't be to expensive plus it would be able to work on any zcar because of the spacing and the fact that it was a 2.0 liter., if I'm right I did see some pics of a stock gasket on a RB20 head and it's almost perfect I just need to know which holes were ment for oil so I can relocate them I really want this to work for us. Also if anyone can post me some pics of the timming belt tensioners I might go that route But I need to see some first. The problem at had is the oil pump and distributor if I go that route but I would really like to use the belt.

 

 

tbs

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Guest DaneL24

Dan does have a point, a SOHC L6 head with the right cam can provide flow to the engine at very high RPMs. If you have SOHC 2 valves per cylinder, why not get a better cam grind to deliver power at higher RPMs. The L6 heads perform pretty well as they are, an L24 with E31 head hits peak HP at 6,000 RPM with the stock cam. If it didn't flow well, how would the motor develop power at 6,000 RPM?

 

I'm not against the DOHC project, I just believe there are ways to get great performance out of the L6 SOHC as well. In the end, you could probably spend your money on head work and a better cam for an L6 head and get just as good of performance as you otherwise would have after the RB head swap.

 

If you really like the idea of the crossflow DOHC head though, were behind you...

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Hey daneL24 I agree with you but with out spending mega bucks in head porting by rebleo racing your head will run out of flow and on a turbo car that will come back and bite you. I believe that if you combine a DOHC head with a 3.0 stroker bottom end you'll have a beast strait from the depths of hell. If you look into it the best motors that are produced are a stroker with DOHC motor. EX: 4G63(Eclipse and lancers), 2JZ(Supra), RB26DETT(Skyline). Note we don't have that and you always have to compromisse something when you deal with a single cam duration and advace and retard must be set at a happy medium to get a good set up and in a DOHC its independent you have more control over that and the abillity to produce more power that to me is better off.

 

 

 

tbs

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Personally TBS, I think it's a cool idea. The fact that the headbolts and cylinders line up makes the swap thinkable, and with a little plumbing work and front cover work it would be a beast. I'm not sure how you'd rig a tensioner up, but either a belt or the chain would be do-able. A good fabricator wouldn't have any trouble making motor mounts for a full RB swap, but a drop-in L28DET would be one of a kind.

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I think it's worth a try. I would be concern about the bottom end because you'll need to turn the motor more than 7k rpm to get the # like RB26's HP. VE sucks on the SOHC because the valvetrains are so heavy compared with DOHC head. (one large valve vs. two small valves) Just a thought.

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I'm sorry I didn't make myself clear in my last post. I ment that in a stock head with a cam and springs you can make power to past 7k and people rev there motors to this high rpm range, heck the motor was built for topend not lowend you can tell that by the stock dyno tests. And I know people that rev them that high the only thing that I should be worried about is the crank pully seporating and breaking the crank but If I get to worried to always be reving it that high I'll have it rebalanced and thanks to Jeffp I can just buy a solid one piece crank pully plus the bottom end on these cars are almost bullet proff, the can take a lot of beating look at Norm he beats the heck out of his,seriously he does and a lot harder then the anyother z driver I know, and it held untill the crank pully spilt and broke his stroker crank.

 

 

tbs

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Can you be a little more in depth about the crank difference of a 10 and a full I would like to learn about them to get a better understanding of it. Can you enlighten me out yo2001?

 

tbs

 

There was a rather lengthy discussion on crankshaft dampers and harmonics in this thread:

 

http://www.hybridz.org/phpBB2/viewtopic.php?t=18731&postdays=0&postorder=asc&start=0

 

This link was referenced in that thread, and is a very good reference:

 

http://www.dinanbmw.com/html/danger_of_power_pulleys.htm

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ok I read about half of it and started to fall asleep I did get the idea of Jeffps crank dampener but if what you say is true about the skyline crank dampener, then if you've seen the ones on the RB20 they match ours so no problems which ever cost less The RB20 or the one that jeff had that company design. I know I can get the head idea work work but to get the whole set up to work will take some time.

 

 

 

tbs

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Guest Anonymous

Yeap its a real RB20DET head from a 1991 GTSt Skyline. I was surprised the first time I saw it at how similar the heads actually are. I haven't had a chance to look at one but I'm sure you could use most of the valvetrain bits from an RB20E or 30E in a Z engine.

 

To me converting the head does look possible (with a lot of work, the RB20 had much better cooling than a Z one, look at the pics for the water galleries) but is probably a waste of time, it would make using the standard Z drivetrain easier but an RB engine is definitely the way to go.

 

I can take some more pics if theres anything else you'd like to see on the RB head in detail.

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