RB20DET head swap?

Post by **uvamosk** » Wed Oct 03, 2007 4:34 pm

Well I searched but the button won.

I was wondering if by chance the Rb20det block can have a 25det head mounted to it?

I know people mount 25det heads to 30e blocks and I heard the 20det head fits on the 30e block also. Thus I correlate that the 20det block can have a 25det head mounted on it.

Although some facts always get distorted and people lie so I figured I would check it out with my Rb family.

O anyway I ask because I hate the RB20Det intake design and its not so good flowing head. If it doesn't swap for a 25det head then I'm forced to buy and do a port,polish,3angle valve job with 1mm over valves on my rb20det when i get it.

Post by **AxiOn419** » Wed Oct 03, 2007 6:08 pm

I do not know the answer to your question but I just saw that intake for sale on ebay or http://www.japengineshop.com/i...e=777

Post by **l0nestar** » Thu Oct 04, 2007 1:30 am

This is not a 100% answer, but you CAN put a 20 head on a 26 block (along with the rotating assembly -- but that requires some machining) I'm not sure about a 25 though. I do remember that the 20 / 26 are very similar (like exhaust port flange design). HTH.

Post by **uvamosk** » Thu Oct 04, 2007 3:18 am

Yeah, I found the manifold on EBAY. I kinda don't really care where it comes from. I was just wanting something to get rid of that horrific contraption that comes on the Rb20det. I know its long runner design is for Trq but its pain in the *** to deal with for intercooler piping and it looks cleaner with out it.

well I do know that the Rb26dett and the Rb20det for some reason have a connection that the Rb25det does seem to share. For instance I have read 26dett and 20det have the same Collar bearing Issues and a few other small things.

I have read that the rb20det head flows really bad thats why I was wondering about the head swap.

Any other suggestions. I think just porting and polish and 3angle on the rb20det head useing that manifold might be my easiet choice not to mention that I can do a valve train upgrade while im in there ^_^. My goals are for 300 to 400whp any where in there. So Its not Like i need to go all out with Titanium and everything.

Post by **uvamosk** » Thu Oct 04, 2007 3:21 am

I just question is Flow charistics.. When I was looking at making a custom intake manifold for my Ka24det i was building. I was told that intakes have to be the correct volume, leangth, and created the correct harmonics or they could hinder more than they help. Just because it looks like it would be better doesn't mean that in the physics world it works. Thought I'm no engineer nor claim to be so I really do not know.

AxiOn419 wrote:I do not know the answer to your question but I just saw that intake for sale on ebay or http://www.japengineshop.com/i...e=777

Post by **Carl H** » Thu Oct 04, 2007 5:19 am

while it might fit with some mods to the oil and water jacket holes the answer is no you cant simply due to the significantly larger bore size of the 25/26...

Post by **uvamosk** » Thu Oct 04, 2007 7:16 am

Thanks Carl H, I was going to check when i got home from work tonight what the bore was on the 25 and compair to the 20det. I should have done that in the first place but I didnt think about it till I was on the way to work today. I figure such. The 2.0 I6 has to have a smaller bore than the 2.5 i6 though i as i guess thinking maybe the 2.5det stroke was what added the Displacment.....

Post by **uber95** » Thu Oct 04, 2007 8:06 am

A quickie Wiki (that's funny )The stock dimensions for the RB engines;

RB20 - 2.0 L (1998 cc, bore: 78.0 mm, stroke: 69.7 mm) RB24 - 2.4 L (2428 cc, bore: 86.0 mm, stroke: 69.7 mm) RB25 - 2.5 L (2498 cc, bore: 86.0 mm, stroke: 71.7 mm) RB26 - 2.6 L (2568 cc, bore: 86.0 mm, stroke: 73.7 mm) RB30 - 3.0 L (2982 cc, bore: 86.0 mm, stroke: 85.0 mm)

Post by **craz4240** » Thu Oct 04, 2007 10:21 am

correction the bore for the rb24 is 82mm...

Post by **uvamosk** » Thu Oct 04, 2007 10:39 am

Yeah thats what I figured. Hmmm... Is the 20det, 25det or 26dett blocks the same block just different bores? I'm sure you know what im getting at?

though from 78 to 86 would be a big jump in bore Im sure there isnt that much extra room around the bore on a 20det block they have to have a smaller block.

Post by **Carl H** » Thu Oct 04, 2007 4:51 pm

rb24 is a rb26 crank and rods with custom 82mm pistons.

Post by **TenjoTenge** » Sat Nov 17, 2007 2:09 am

Carl H wrote:rb24 is a rb26 crank and rods with custom 82mm pistons.

i think its a rb25 block with a rb20 crank ?! ....

Post by **craz4240** » Sat Nov 17, 2007 9:49 am

rb26 crank and rods and 82mm pitons=rb24

rb25 crank and rods and 82mm pistons=rb23

rb20 crank rb20 rods and 82mm pistons= rb22

RB22 gets my vote.

Post by **jdmser** » Sat Nov 17, 2007 10:02 am

The RB24 their talking about on Wiki is the rb25 block with the rb20 crank which does have the bigger bore and is sohc and carbbed.

Post by **TenjoTenge** » Sat Nov 17, 2007 3:49 pm

jdmser wrote:The RB24 their talking about on Wiki is the rb25 block with the rb20 crank which does have the bigger bore and is sohc and carbbed.

you get it ... but it wouldnt make sence without the eccs and the rb25 head ...

Post by **Carl H** » Sat Nov 17, 2007 4:21 pm

huh?nissan has used eccs on all their engines since the late 80's and only recently changed it for the stricter emissions laws.

TenjoTenge wrote:
you get it ... but it wouldnt make sence without the eccs and the rb25 head ...

Post by **Sky80** » Sun Nov 18, 2007 9:55 pm

Dang! Reading Own Joo Guys, lol... Everyone is correct about the RB24 in this thread... You can take a RB20 block and put a rb26 crank and rods, plus bore it out to 82mm and get an RB24...

BUT

There was also an RB24s that was created and that is what is mentioned on Wikipedia, which was carburreted and didnt have ECCS...QUOTE FROM Wikipedia:

http://en.wikipedia.org/wiki/Nissan_RB_engine wrote:This is a relatively unknown engine, as it was not produced for the Japanese domestic market. These were fitted to some left hand drive Nissan Cefiros exported from Japan new. Mechanically it is made from an RB30E head, RB25DE/DET block and RB20DE/DET crank with 34 mm height pistons. This engine used carburretors instead of the Nissan ECCS fuel injection system. It is able to rev harder than the RB25DE/DET (as it has the same stroke as the RB20DE/DET) as well as being almost the same displacement as the RB25DE/DET. A common modification is to fit a twin cam head from other RB series motors while retaining the carburreted set-up. The standard single cam form produced 141 PS @ 5000 rpm and 20.1 kgf·m (197 N·m) of torque @ 4400 rpm.

Post by **Sky80** » Sun Nov 18, 2007 9:58 pm

Oh and for the original poster, just get a RIPS Intake manifold and be done with it, its been proved and works... You will only be upgrading to it later if you go with anything lesser quality...http://www.ripsltd.com

Post by **ztunelover** » Thu Jun 18, 2009 5:25 am

300-400whp, you can do that quite easily.

Multi-angle valve job would be unneccessary. It will help if you have the budget and are doing it then do it. But if you are trying to save some money, you can skip that process, mildly upgraded valvetrain with a mild port and polish, with a proper turbo manifold, and a properly trimmed turbine unit will give you that power with solid midrange, and like you saw there are intake manifolds. Research on a proven one, use a good 70mm throttle body with it, and you will have a solid 350-380whp with plenty of usable midrange. if you want more torque down low, go rb24. then u can also use the ati super damper pulleys and net some more down low power.

Post by **Carl H** » Thu Jun 18, 2009 5:31 am

uh...welcome to over 2.5 years ago?

Post by **ztunelover** » Tue Jun 23, 2009 3:29 pm

so true wow i didnt even notice that lol. wow. i really have no idea what to say.

RB20DET head swap?

RB20DET head swap?

Re: RB20DET head swap? (uvamosk)

Re: RB20DET head swap? (uvamosk)

Re: RB20DET head swap? (AxiOn419)

Re: (uvamosk)

Re: (uber95)

Re: (Carl H)

Re: (TenjoTenge)

Re: (jdmser)

Re: (TenjoTenge)

Re: RB20DET head swap? (uvamosk)

Re: (Carl H)

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