Jump to content
SAU Community

RB30/25 Build Query

WalkyHR31

By WalkyHR31,
in General Automotive Discussion

 Share

Recommended Posts

WalkyHR31 Enthusiast

WalkyHR31

Posted
Posted

Hi Guys, 

I currently run and HR31 with RB25DET making 270 RwKw. Had my engine builder do the bottom end and I did the rest. Great engine and been running it for last 6 years at the track and roll racing without any dramas. Runs 20 psi boost no problem and revs to 7500 RPM still making power. Spends a lot of time in the 5000-7500 range as I do a lot of track days etc. Rest of time just an odd w/e driver. Runs and R33 box and R200 LN diff with 3.7 gears.

However, time for more torque and KW as sick of getting blown away at RR by HSV's (S/c of course) and Datto 1200's etc!!

Have been planning an RB30/25 for some time now and finally went to my engine builder this week with all the parts to get started. He depressed me by telling me that the RB30 is not the engine to turbo due the high Rod:Bore ratio meaning it will sit too long at TDC and under high boost melt/break pistons etc. Says a 3.4 stroker will work Ok but not interested in that as too expensive and car won't handle it. Will be using good forged rods and pistons and crank collar..

Never heard of this being a problem before as there are heaps of these RB30 engines around making awesome power. This will be more a track engine than road so will see high RPM (max 7000). Looking at making around 330-350 Kw at the wheels at 20 psi. I am not a drifter and rarely hit the limiter.

So my query: is this Rod:Bore ratio a problem or not?  What has been other's experience with this combo using it for track work/roll racing etc?

Thanks guys. 

 

 

Link to comment
https://www.sau.com.au/forums/topic/482044-rb3025-build-query/
Share on other sites
WalkyHR31 Enthusiast

WalkyHR31

Posted
  • Author
Posted

Thanks for that but 1. when you say stock I assume factory piston not forged and 2. what boost did this engine run? 3. Could this have been a tuning issue with a standard piston rather than the supposed Rod:Bore ratio problem? I suppose hard to know. 

 

Rusty Nuts Experienced

Rusty Nuts

Posted
Posted
17 minutes ago, Ben C34 said:

Rod bore ratio is not a problem

Exactly, and this is what Rob from R.I.P.S  said about RB30 GTR's over ten years ago.

"I think the only guys who knock a 30 or genuinely prefer a 26 for a strong street car obviously have not been in a good RB30 GTR, there is just no comparison, we've proven 9000-10,000 is not only possible, but to date, has been 100% reliable (in a street/drag situation at least) the response is better, the driviblility is better, the slow cruise is better, the top end can be just as good, if not better, there really is no down side as far as I have found.

As far as rod/stroke ratio's go, it seems from the little I have looked into it, that the 26 is actually considered pretty poor and the Nissan RB30 is considered ideal.

Each to their own and I don't think there will ever be a 100% right or wrong, its just personal choice and you can't really blame a guy who has only ever been in big single turbo 26 GTRs for thinking its the "nuts", one day hopefully he'll experience a good all round RB and move up in cubes, one thing is for sure, I don't know of anyone who has had or been in a good 30 car and then said they prefered a similar spec 26.

  • Like 1
WalkyHR31 Enthusiast

WalkyHR31

Posted
  • Author
Posted

Thanks guys, appreciate your input but was hoping to hear from someone who may actually have an RB30 turbo engined track car that they could tell me what boost they run, rev limit they use and its reliability etc.

Murray_Calavera Mentor

Murray_Calavera

Posted
Posted
1 hour ago, WalkyHR31 said:

Thanks guys, appreciate your input but was hoping to hear from someone who may actually have an RB30 turbo engined track car that they could tell me what boost they run, rev limit they use and its reliability etc.

Have you tried speaking to workshops that are building RB30's? Your like a 30 min drive from CRD, why not pop in and have a chat with the boys who are regularly building RB30 powered skylines?

WalkyHR31 Enthusiast

WalkyHR31

Posted
  • Author
Posted

Yes that was option 1 but motor runs all stock gear - rods, oil pump, balancer, head, cams etc so wouldn't take too much more to reach breaking point! Anyway, already have 2 RB30 blocks, cranks, a head etc ready to go. 

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted
14 minutes ago, WalkyHR31 said:

Yes that was option 1 but motor runs all stock gear - rods, oil pump, balancer, head, cams etc so wouldn't take too much more to reach breaking point! Anyway, already have 2 RB30 blocks, cranks, a head etc ready to go. 

Stock RB25 with just headstuds only will do 350kW all day on E85 at the track.

  • Like 1

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Borci88
      Borg Warner EFR Series Turbo's V 2.0

      By Borci88 · Posted

      Not a problem at all Lithium, I appreciate your help regardless. I've pulled a small part of a log where the target pressure was 28psi and it spiked to 36.4psi. I've only just begun using Data Log Viewer so if I'm sending this in the wrong format let me know.
    • Lithium
      Borg Warner EFR Series Turbo's V 2.0

      By Lithium · Posted

      Sorry had a bit of a week and haven't had heaps of time to follow this, so apologies if I've missed something - any chance of showing a log with the rpm, turbo speed, MAP, and wgdc all in one view? Definitely an "interesting" problem, and while it's definitely worth noting that there was a similar issue with the twins I'd not completely put all bets on the root cause being the same thing.  Keep an open mind, follow the data.
    • Borci88
      Borg Warner EFR Series Turbo's V 2.0

      By Borci88 · Posted

      I built this engine approximately 12 years ago so my own head (brain) is a little grey on the exact hardware in the RB head, however what I recall is. Stock RB25 NEO TURBO Intake Camshaft HKS 260 degree Exhaust Camshaft (R34 GTR) RB25 NEO Turbo Springs  I ported/removed the exhaust stud humps found in the RB25 head so theres less turbulence but it wasn't ported/polished properly, just a hump removal. I've attached two pictures of the before and after to illustrate.     The ECU gets its boost reference from the nipple on the rear of the head on the intake side, behind the fuel rail. The wastegate gets its boost reference from a nipple on the cooler pipe immediately after the comp cover.  Could a decent pressure drop across the intercooler cause the wastegate to be seeing a higher PSI than what the ECU is seeing, and thus it can't control it accurately and quick enough?   We ran a line to the actuator and watched it open and close using an air compressor, while we didn't have a gauge on the line to see when it was cracking open, it was opening smoothly.  I just removed the gate now and even though the documentation says you need to open it in a vice due to preload (which I did), there wasn't any preload on the cap, which is something we noticed straight out of the box as well when new. This silver cap internally is threaded to the actuator rod that runs out the bottom of the straightgate. Not sure how I'm supposed to get this spring out to be frank.. Potentially but everyone else doesn't appear to have to stop at 500kw because of 6boosts design.  I would, but I think I'm getting to that point where if I'm going to do the head and make another 100kw, then I'm going to need a fancy gearbox and quite a few other things and 10k becomes 20k becomes 30k within a few months. I'm not necessarily sold on the idea just yet that the head is restrictive at 4000rpm (and what.. 300kw?) and yet doesn't seem to be restrictive at 7000rpm when it's making 500kw, however I'm obviously not closing the door on that theory.
    • Kinkstaah
      Mistakes were made, my R34 Story

      By Kinkstaah · Posted

      Yeah - Half the problem is I know this sensor actually goes to 150C.. I'm pretty certain it is min of 11C. So still more data required I suppose. It's really quite hard to get the oil temp to 100+ then immediately pull over and take a reading before the temp drops. Annoyingly I suppose the range I really 'want' is likely 80 -> 120C. TBH the ecu can't really *do* anything with it, and the gauge itself is very visible... ...but you know how it is.
    • The Mafia
      Borg Warner EFR Series Turbo's V 2.0

      By The Mafia · Posted

      My EFR 8474 Black, made 800awhp on a roller dyno. at 25-26psi. E85. Shaft speed was around 106,000rpm 1.01 rear. The rear is maxed.  6 boost Turbosmart 60mm gate 3.5inch exhaust  Head is worked to the shithouse. Bain racing. VCam. 272 exhaust. RB28 - RB26 foundation.  You have an intake issue. Start getting proper data and I mean go back to the simple things.  - Pressure test your intake - Block off the Turbo BOV, you don't need it.  - Test pressure before and after your intercooler If your head is pretty stock, that is your issue. Especially if it is NA.  Take it off and spend $10k on it. 
×
×
  • Create New...