RB26 Crankshaft

[NightKids2]

Correct me if Im wrong but I think Ive heard that you can swap in an RB26 crankshaft into an RB25 to stroke it. My question is, does anyone know where I might can source an RB26 crank, or at least a busted up RB26 I can get to remove it from. Also, what else might need to be done to use this crank.

[themadscientist]

RB26 rods.

[CursedGTR]

Upon my physical comparison with both sets of rods, I did not see a difference in rod length However the stroke is gained as follows RB26 Crank 73.7mm, RB25 Crank 71.7mm hope this helps.

[eh?]

RB26 pistons, not rods.RB26 rods and RB25 rods are the same rod length.

[themadscientist]

I beleive Cursed GTR has a set of forged 26 pistons for sale.

[CursedGTR]

RB26 Pistons and Rods are Identical to RB25 Pistons and Rods. Trust me dude I have double checked this and rechecked it after that.

RB25/6 - Rod Length 121.5mmRB25/6 - Piston Dimension - 86mm Bore 30mm Compression Height, 21mm Pin Diameter.RB25 Crank Stroke is 71.7mm RB26 Crank Stroke is 73.7mm2.7L Crank is 75.7mm (Compression height of piston becomes 29mm and some kits (Greddy) will change pin diameter to 22mm)2.8L Crank is 77.7mm

Anything after 2.8 requires a deck plate (i.e. the Apexi 2.9L Kit) The only kit that changes rod length is the Tomei Kit (Rod Length becomes 119.5mm), the HKS 2.8 will change the compression height of the piston to 28mm and pin diameter to 22mm.

That is all I know off the top of my head right now. Oh and your boy at HAS hooked me the hell up yesterday I got a fully functional Greddy Type R BOV in good condition for 5,000 yen

[CursedGTR]

I beleive Cursed GTR has a set of forged 26 pistons for sale.

Scott over at S-Tec got those off of me yesterday.

[eh?]

RB26 Pistons and Rods are Identical to RB25 Pistons and Rods. Trust me dude I have double checked this and rechecked it after that.

I agreed with you on the Rods. I do not agree with you on the pistons. How are you verifying your info? Head CC is the same on the RB25 and RB26. The larger stroke on the RB26 will further increase the CR of the engine if the pistons were exactly the same Comp height/dome volume. The HG thickness and diameter can not change the CR too much. The only thing I can think of is Dome volume and Comp height.

I used this http://www.csgnetwork.com/compcalc.html and your info does not add up. Correct me if i'm wrong.
Modified by eh? at 12:28 PM 1/19/2006

[CursedGTR]

**** dude you are quick.... I went back to get some info real quick and edit my post, I hadn't even realized this one went up.

You are right the compression height is different (RB25DET 31mm RB26DETT 30mm) and what I was beign told by shops here was just lost in translation. I apologize for the mis info I will work on my memory skills since I did this all about 3 years ago.
Modified by CursedGTR at 4:58 AM 1/19/2006

[CursedGTR]

Oh Yeah and that CR Ratio thing you mentioned jogged my memory pretty good. I'd buy you a beer if you were here but guess you will have to settle for you told me so. I was basing everything on a 8.5 CR and had totally forgotten the RB25DET had a CR of 9.0.
Modified by CursedGTR at 5:29 AM 1/19/2006

[eh?]

It was a pain a few years ago to find out specs for rb25 pistons. The only spec I knew was from actually measuring the head CC with the plexiglass/syringe method. I began calling up all the big names- JE, wiseco, arias, ross, CP . I asked them if RB25 and RB26 pistons were the same- none of them knew. I did my own calculation and I figured there had to be a difference in the piston. Turns out the only one that had correct or any info was Ross. So I ordered from them.

[CursedGTR]

I never got into the weeds like that. I am going to shgut up now so this thread doesn't get jacked.

[themadscientist]

shouldn't you be polishing something B? What was the name of that driveshaft shop. I just checked Nissan and the yoke swap ain't going to happen,

[CursedGTR]

Precision Shaft Technologies is who I am going to Use. However, Scott over at S-tec can get a better deal with a guy in Texas, I will call him and get the number today.

Oh and I am almost done with all of the polish work. Engine should be comlete by March (Only 4K more worth the crap to buy).

[NightKids2]

So, no idea where to get one?

[CursedGTR]

I will let you know when I come across one. Brand New it is like 700.00 from Nissan if I remember Correctly.

[themadscientist]

you do, R33 crank is about $700.00. you must do the write-up on your new ride as we discussed.

[CursedGTR]

I will probably do it tomorrow

[NightKids2]

Thats actually not as bad as I was expecting. Thanks for your help

[NightKids2]

Is there a post on any forum that tells what parts are interchangeable between the motors, such as using RB26 cams and other parts.

[StricNyne]

cams tween 20 and 26 i think, wut specific parts dou wanna kno