RB25det question

[xclusive240]

What internals need to be upgraded to make between 450 and 540 whp. thanx for the info

[driftingmy240sx]

at that hp level you would need to have the crank sleeved with an oil pump collar. would probably want to put new acl race bearings in the bottom end with maybe some new rods and pistons. you will also want to get a twin disc clutch to prevent the transmission from blowing 3rd gear out. a new ati or fluidyne crank pulley would be wanted also. get a new cometic head gasket and arp head studs.

[s14 2510's]

Getting a twin disk clutch will not save your trans any abuse. It will just cause more. But it will help your car hold that hp without your clutch slipping. The cheap cast shift fork is what blows out 3rd in the trans. The sincros get bad and bam there go's your fork. As for internal upgrades aftermarket pistons and bearings held together with arp fasteners should hold that power. You will also need a crank collar, MLS head gasket, and basic maintenance parts. The biggest thing about keeping this together is just getting a good tune and not maxing your air and fuel out. I don't know how efficient the stock rb25 intakes are either. The rest you can figure out. I wouldn't dump hella money into internal parts unless you have all the parts to make this thing run happy at that hp. - wasnt there a smiley icon with a search sign once?

[Darius]

at that hp level you would need to have the crank sleeved with an oil pump collar. would probably want to put new acl race bearings in the bottom end with maybe some new rods and pistons. you will also want to get a twin disc clutch to prevent the transmission from blowing 3rd gear out. a new ati or fluidyne crank pulley would be wanted also. get a new cometic head gasket and arp head studs.

^^ so many holes in this ^^. WTF is with all these new guys spouting out regurgitated hearsay?? It is getting out of control.

1) Cranks don't get sleeved, blocks do. For any RB25 power level, the block will never need to be sleeved. That is what honda owners do...

2) Twin-disc clutches have nothing to do with the transmission. Like s14 said, it will be more abusive on the transmission.

3) An ATI crank dampener is not necessary. Where the hell did this come from and how does it relate to hp level??

4) Do not get a Cometic head gasket. Period. Any other MHG manufacturer puts out a superior gasket at a marginally higher price.

But to answer the original post, everything in the previous post other than that mentioned in the list above is accurate. Include smaller oil orifices for the block and add ~$10,000 to the list.

[Joe]

Darius = correct

[Cjmartz2k]

I agree with that last two guys. That being said, I am making around 500rwhp with a bone stock motor and headgasket, but I am pushing it, and I can get another motor for $300. The key is tune and the weakest link is you pistons (ring lands). Good tune+forged pistons+arp head studs= about 600hp capable motor that is fairly reliable. You are still going to be wearing out bearings pretty fast at that power level. Mines lasted about 6 months at this power level so far, and about 1 year with 440hp before that.

[l0nestar]

Would GTR rods / pistons help, or would you suggest new CNC'd pistons? (CP, JE, etc.)

I know they are nearly identical in dimensions (25 and 26 rods) but the GTR rods are much heavier / beefier.

Just thought of that as a possible option.

What are you planning for intake / cams? What head-work (if any)? Are you planning on doing an oil-drain mod on the head?

Side note: Do you guys know at approximately what point (flow / HP) the stock intake manifold becomes in-efficient ? At that point, is it mostly attributed to the size of the stock throttle body?

Cjmartz2k, where are you located? are you stationed in Nippon?

[Cjmartz2k]

GTR rods are stronger than non-neo rb25 rods. If you have the motor apart and have access to some, I would use them. The pistons are the glass jaw of this motor. I good set of forged slugs that would knock the compression down a notch would be my #1 thing to do engine wise.

I wasn't planning on doing any oil drain mod or anything, but I just drag, so I don't really think I have to worry about it all that much. Plus, I'm not really to familiar with it.

For an intake, I am putting in a RB26 surge tank with ITB's and an adapter to make it all work. I would recomend the greddy rb25 one, but a friend sold me this set up for cheap. My shop guy is telling me around 550hp is the max you can shove through the stock intake, which is about where I'm at right now. I had asked him about putting a q45 TB on the stock intake, and he said it wouldn't do anything because the intake is more restrictive at that point.

and yup, I', still over here

[driftingmy240sx]

the crank sleeve i am talking about it the oil pump drive gear. those of us in oue little circle hear in md have not broken or dmaged any shift forks since we've put twin-disc's in. also at that hp level it is also very important to replace the mostly damaged and not longer correctly balanced crank pulley. one guy hear with a 700hp rb has not had oil pump problems (and was informed by a race team it was mostly due to having a quality crank pulley). as for using the stock head gasket why would you want to? the aftermarktet head gaskets out there make for cheap insurance that they dont fail.

you may not agree what i have to say but how many people do i see on hear every day giving advise and their rb's dont run. mine does. i found nico club and all its resources after the trial and error i did on my own and used my nissan background to get my car running. i dont ever claim to know alot about the rb and its dfferences between the 20, 25, & 26's or the differences between s1, s2 and neo engines.

if you dont agree with my opinions there is no need to be rude about it.

[Cjmartz2k]

You are talking about a crank collar. That's why people didn't understand what you were trying to say, and yes it's a good idea to get it fixed.

Any type of clutch that will handle more power will also allow the transmission to get hurt more. IF you had enough traction and IF you had enough power, but a crappy clutch, it would just spin the clutch (and trash it) and not put a lot of load on the transmission. If you had a good clutch though, you would be putting more tourqe on the transmission instead of just frying your clutch.

What in the world would the crank pulley have to do with oiling?

I use a stock headgasket because I have no need for an aftermarket one. Would I prefer one? Of course. Am I going to tear my motor apart to put one in when I don't need it? Nope. If my HG blows, I will replace it with an aftermarket one. BTW, I am pushing 1.5 bar (22psi) and making about 500rwhp with my stock headgasket.

[l0nestar]

Cjmartz2k,

Thanks for the confirmations.

I'm also interested in doing the 26 ITB's + surge tank. But much later...

The pistons are the glass jaw of this motor.

If the slugs (or ring-lands in particular) are the 'glass jaw', Then the crank collar (or lack thereof) would be the Achilles heel... :lol

[Chaos the Xile]

where are you purchasing your adaptor for the RB26 ITB setup, or are you making it yourself?

[Cjmartz2k]

I got it used from somebody.

And yeah, I guess that's a pretty good analogy