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 Turbo Head Or Non Turbo Witch 1 - serious ??  

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**Skillz**
  • **Skillz**
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  • Joined: 26-January 08
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  • From: brisbane
Post #1 post 26th October 2008 - 02:31 AM
ok if u were building a rb25/30 combo right witch head would u use

rb25det turbo head

or

rb25de non turbo head

we have been informed by heaps off different people to use a the non turbo and other are telling us to use a det turbo head
and others are telling us to use a rb20det head


witch one would u choose and why please help


NOTE] every one is tellin us different things so we are confused on itch one to do wats ur opinion ???

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pipster11
Post #2

check on the r31 site i forget what its called now but google it

its wiki.somethingr31.com (something like that)

and look for the tutorials/info section is has how to build one of these motors

rob_88_
Post #3

the rb25de and rb25det heads have the same part number from nissan. But I'm pretty sure the cams are different. Also the rb20 heads dont bolt up.

eddie_xr6
Post #4

There is alot of prep in putting one of these heads on it's not as easy as just bolt it on also alot of dollars.

The only dif between non turb head and turb head for memory is valve's and springs aswell as cams.

Have fun if you got alot of money to spend on head!!!!!

iamhappy46
Post #5

Do not use the RB20DET head as the oil galleries do not line up properly and there is modifications required. The smaller bore combustion chamber also bumps up compression a LOT which can cause detonation.

RB25DET and RB25DE heads are the easy way but it depends on what compression ratio you are chasing.

Are you using stock pistons/rods from the RB30 or is it being rebuilt to suit the RB25 head?

**Skillz**
Post #6

umm the whole motor is being built we are just waiting on a list off parts there will no doubt be forgies and lots off dollars goin into motor cheers guys


OH AND THANKS EDDIE I DIDNT THINK U WOULD WANNA HELP

iamhappy46
Post #7

Use the RB25DE head if your rebuilding the bottom end smile.gif

MR2Mark
Post #8

For those of us who dont know much about nissan RB engines why would you use a RB25DE head rather than DET head? What is the difference that makes the DE worthwhile? Id imagine they would be quite similar apart from maybe camshaft duration/lift?

iamhappy46
Post #9

Cam duration and lift is slightly better taking into account the RB30 blocks extra capacity. Nothing wrong with fitting the RB25DET head but the DE head is mildly superior on a 3L block.

The above is another reason why the RB20 head is not a good choice, smaller inlet and exhaust valves due to the smaller bore means it does not flow as well on a 3L block.

Of course, if you want the ultimate head the RB26 head flows a lot better.

09ONE
Post #10

QUOTE(MR2Mark @ Oct 27 2008, 10:29 PM) [snapback]1283061021[/snapback]

For those of us who dont know much about nissan RB engines why would you use a RB25DE head rather than DET head? What is the difference that makes the DE worthwhile? Id imagine they would be quite similar apart from maybe camshaft duration/lift?



There is really no advantage/disadvantage of using either head, you just need to slightly change a few things.

RB25DE head doesn't have VVT. This means you don't need to weld up the oli feed for the VVT. Also the RB25DE head has a slightly different port design to RB25DET, so the inlet runners (the second part of the two part inlet plenum) are different aswell because it's port design is the same as an RB20DET. The valves are also slightly smaller on the DE head but not by a great deal.



The rest of the differences are the commonly know ones that everyone else has mentioned such as weaker valve springs (never designed to handle boost) and different cam profile/duration/lift and 25DE and 25DET cams are not interchangable.

P.S. I have 2 x RB25 heads that I need to moves out of the garage for cheap smile.gif

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