Whose Done The 26/30 N/a Conversion?

[ahh 33 s2]

rb25 rods are to short racespec is selling forged rb30 rods for 1800 atm with forged pistons. 25de pistons would be the way to go for a higher CR.

just my 2 cents worth

Dan

[R31Nismoid]

There is a RB30 in SA with around 200rwkw from memory, N/A also (in a 31).

It might even be above that, cant remember as i rarely visit the 31 site

[Silhouette-R]

Yeah I'm a member of the R31 Skyline Club and no one has posted anything higher then 177rwkw and that's in NSW, but in saying that, the bloke with this 200rwkw figure probably isn't a member.

Are they an SAU member cause I would love to have a chat, cause my end goal is 225rwkw(100HP/L), I've got 140 now.

Just wondering, what type of rwkw gain if I did this:

Old System: Hurricane Tri-Y equal length Headers, 3" steel cat, 2.25" press bent piping, and 2 Straight through mufflers.

To this

New System: Hurricane Tri-Y equal length Headers, 3.5" stainless 200cfm cat, 3" stainless steel mandrel bent piping and 2 straight through mufflers.

[Bond]

Good build up.

You have heaps of room for improvement there as your peak power is still fairly low (5700rpm). Lift the torque curve up another 1000rpm and it will start to liven up a bit more.

[Silhouette-R]

Well the car is booked back in for early November to have cam gears put on + the re-tune, and with a little bit of luck that should see me past the 200 HP mark at the treads.

I'll be heading to Putty Rd cruise this weekend so if people are keen on having a gander than they are more than welcome, I spent enough for not to be hiding under the hood the whole time, lol.

[JasonG]

Any updates on the power you are putting down? I'm very interested to see the progress in this thread.

Also, another question, concerning the RB26 head. If I wanted to run the intake as an open ITB setup with trumpets, would it just be a matter of cutting off the surge tank and welding on some trumpets? Of course I'd have to switch to a MAP sensor, could I pick up an RB26 GT-R Power FC D-Jetro and have it remapped for N/A?

[GTRsean]

Cut the plenum chamber and weld on some trumphets.

No probs with running map, tuning is more involved though due to the multiple throttle bodies. Levi's is MAP sensor based.

Using a de jetro pfc and getting it tuned to suit should be possible.

[Silhouette-R]

Not much has happened with the old girl, it was supposed to get cam gears and a re-tune about a month back but the gearbox ate itself quite nicely.

If the work had been done it should have pulled up near the 200rwhp/150rwkw mark.

I'm sure you can actually buy proper trumpets, and bolt them on but you would have to build a plenum around them so the motor would not be sucking in extremely hot air.

Hopefully when I go back to QLD over christmas i'll try to get a stainless 2.5" mandrel bent exhaust put on. But the diff is on its way out so i'm going to have to put some coin away for that when I get back to sydney.

Also does anyone know of someone that has recently thrown a RB30DE/T configuration into an R34???

[666DAN]

I like threads like this, it backs my comments about a certain females RB25DE that's claims to make 130rwkw with next to no "actual" mods, here we have 0.5L more displacement and a GTR head with some real mods and power not much further than claimed elsewhere.

Some more work and this engine will be sweet, good luck

[nizmonut]

the compression on the 26 head is too low for a rb30 block without turbo charging it, thats why it would only make 150 odd rwkw.

the rb25de vvt head on the other hand makes a staggering 267kw at 8700 rpm with raised compression, cams and uprated injectors and a 3l v6 nissan maxima afm..

they make even more too when you custom the intake manifold and put triple downdraft carbies on it, its just a bitch to adjust all three equally.

but really if youve gone to the trouble of buying a rb30 block and a rb26 head you might aswell stick a big fat hair dryer on the side of it and call it 400 rwkw.

nissan did bring out a factory rb30de in japan in the late eightes for some odd ball racing class they had over there, but there rearer than the autech rb26de.

Edited December 25, 2008 by nizmonut

[drive2slide]

The RB30DE you're referring to was brought out in the Tommy Kaira MR30 and it was made up of an RB25 head and an RB30 block. Very sexy engine bay it was!!

[JonnoHR31]

nope. was called a M30 and had a redtop 20 head on a 30 block, no such thing as a 25 or 26 at the time

[Silhouette-R]

Thought I would do a small update. Had adjustable cam gears and a re-tune done on the old girl.

It is making 137rwkw (yes it has lost some power due cam gears but the benefits out way the loss). More low end torque is evident (comes on nice from 2500rpm, don't have a new torque graph though to show)

Here is the Dyno figure + fuel ratios, it was given some more fuel down low (had a bad flat spot):

Blue line = new setup; Red = old setup

[...Joshwa]

Hi all,

Im in the process of building my 30/25 N/A. . Marc at MRC is also going to be finishing it (tuning etc)

My motor consists of:

Standard crank, balanced

Spool rods and ARP rod bolds, balanced

Custom Hyper Eutectic pistons (havn't ordered yet due to not knowing how deep valve notches should be for 10mm lift), balanced

ACL race series bearings for the big end and main. .

Pressure plate and flywheel are also going to be balanced. .

Head is a standard R33 head with VCT. . I am looking at getting cams around the 270 with 10.2mm lift, would this be fine for the hydraulic lifters and would any head machining need to be done?

I was going to use the RB25DE pistons but due to having to shave around 2mm from the block, that equates to a 4% loss in torque (Torque = Force x Distance)

So I am opting for a set of custom made pistons. .

1. With the RB25DE pistons, what did the head CC in at to have a 12:1 comp ratio, or does it achieve this with the stock head (63cc)

2. Should I get my pistons made to the exact same spec as the RB25DE pistons but have them raised 2mm in the bore. . Therefore it should have exactly the same comp as the RB25DE pistons would have (a bit more) and should be able to fit the same cams as the RB25DE pistons would.

3. Would this be fine for 10.2 mm lift cams?

4. And what else should I look into for the build. . Things such as porting and polishing (how much does this cost?). an aftermarket balancer and would a 90mm throttle body suffice (im using a front facing plenum)

Edited February 17, 2009 by ...Joshwa

[342Four]

u might be pushing it with 10.2mm lift with that compression (major recess out of the pistons to allow clearance....)

i would stick to 9mm lift or whatever it is

[Silhouette-R]

I got recommended on something that size, so I could go bigger if I choose to (which I will) down the track.

I'm keen to see your power output with those cams and the 25 head, it will easily make more power than what mine will but I want to see how much of a benefit the cams are with the 12:1 comp.

[Silhouette-R]

I've had a 4.11 minispool diff put in since the last update and so far have run a best of 15.3 @ 92mph down the quarter and are keen when it gets colder to drop into the 14's later on in the year.

[Gerg_R31]

since the rb series is a straight motor not a v shape and the crank has already been balanced you can balance the rods without having to worry about the crank getting balanced at the same time

knife edging isnt a bad idea, the counter weight slices through the oil preventing drag increasing torque, and reduces weight aswell, but will need 2 be rebalanced

i found with my rb30e the adjustable cam gear only adjusted when the reground cam kicked in no kw gain

speak to malcom at camtech he made my cams for my rb25 head (nearly rb26 head) it has 10.8mm by 280 deg and he has the billets all in stock ready 2 be ground

oh and the cams lobes need a bit of clearance where it meets the head to prevent vapour lock

[Silhouette-R]

Had a proper exhaust system installed in the car, it has a 3" stainless steel cat, 2.5" mandrel bent piping (under the diff), hot dog, and a straight through rear muffler.

the old power was 138rwkw went back onto the same dyno and it pulled 152rwkw so I have officially made 200hp at the treads now, it needs a bit of a tune now so I'm hoping it won't lose to much power when it goes in for a tune.

[GTRsean]

One word for ya........CAMS!!!!!!!!!!!!!!!!!!!!!