Jump to content
SAU Community

Recommended Posts

I ask because I currently have a 9.0:1 3L VL, with max power at 5200rpm and am looking forward to 7000rpm when I install the rb25 head, etc. I'm just concerned about how much boost I will eventually want to run, and the lag I'll experience with the low CR. The extra revs will mean I could stroke the engine and still increase the redline. I was originally looking at building a high CR N/A engine but the expense has led me to aim at forced induction from the start :)

Link to comment
https://www.sau.com.au/forums/topic/48074-rb30-stroker/#findComment-968772
Share on other sites

Sorry, I realise this, but I have always planned on throwing the twin cam head on my engine, therefore installing new cams into my current engine would be a waste of money. When I build the engine I will rebuild the block as well as the head, which means when the head goes on, the higher possible revs will be acheved at the same time. I am talking more about piston speed when I ask about stroking the engine. I'm not so much worried about the cams or engine rpm at this stage.

Link to comment
https://www.sau.com.au/forums/topic/48074-rb30-stroker/#findComment-968919
Share on other sites

Sorry Roy, I didn't put that very clearly. The redline of my engine after it's built will be much higher than it currently is, by roughly 2000rpm. This means that when I build the engine, if it was stroked at the same time, it is possible that I could still increase the rev limit over the current 5000 odd. If the engine was stroked, it is possible that it won't rev to 7000ish very happily, but it will still rev higher than it does now. Does that clear it up?

Link to comment
https://www.sau.com.au/forums/topic/48074-rb30-stroker/#findComment-969599
Share on other sites

A bit of RB30 data to start with...

Bore = 86 mm

Stroke = 85 mm

Rod length = 152.5 mm

Rod stroke ratio = 1.793

In order to get to 3,208 cc's you would need 92 mm stroke with 86 mm bore. That's 3mm shorter rods so the rod stroke ratio would be 1.625. Because of the increased angles, the shorter conrods have to be stronger to handle the side loadings. This means extra weight and more stress on the piston skirts and bores.

You have to buy a custom crank (~$4K) and a set of custom conrods (~$3K), plus a set of forged pistons ($2K).

My suggestion (and what we do) is to go for a larger bore, 87.5 mm with the standard stroke. This gives you 3,068 cc's for around half the cost. We rev them to 8,500 rpm with 900 bhp capability. That's good horsepower per dollar. :D

Link to comment
https://www.sau.com.au/forums/topic/48074-rb30-stroker/#findComment-969691
Share on other sites

Thanks for the info SK. The piston speeds must be huge in RB30s doing 8.5 grand?? I couldn't be bothered working it out.

Basically, what I want to achieve is a really strong, flexible street setup, with the option of drag racing and maybe some track work.

Link to comment
https://www.sau.com.au/forums/topic/48074-rb30-stroker/#findComment-971163
Share on other sites

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


  • Similar Content

  • Latest Posts

    • I'm seeing torque specs all over the place for the OUTER tie rod, but none for the INNER tie rod, where it connects to the steering rack. Even in videos, people are just tightening em up as much as they can with a wrench and that's it. Anything tightened down without torque makes me nervous. Anyone know what the spec is for it?
    • Hope you had a great time here in our tiny country.   The JDM scene we have here is quite small, it's mostly BMW, Volkswagen with burble tunes haha. But the few JDM cars we do have in the scene are pretty nice. Some of my friends drive cool s14's too. Both built engines, red one makes abt 500, blue one abt 400 i think?
    • Ye good idea , would have never thought of something like that. Might aswell do it to every pulley and the balancer while I’m there 
    • Use an LS1 or similar, via kit like Frenchy's. But.... It's probably not the alternator. It sounds like belt squeal, which would be because the pulleys are glazed. Rub every groove on the pulleys with 120 grit paper. Report back. Oh, and new belts afterwards too. The old new ones will be shitted up already.
    • Hello all I have 2 r34 sedans , one turbo one na, only recently aquired the na 34.  Man what is with these things.... My turbo 34 started sounding like a super charger, it was screaming at anything above 4000rpm , I took the alternator apart and replaced the front bearing which is the only one I think you can access and it did not fix the issue so presumably the bearing in the rear of the alternator is gone. ( diagnosed it was the alternator by taking off the aux belts one by one to figure out which pulley or bearing it was )  My friend gave me one he had lying around, Installed it , it did not squeal for maybe 500kms and now its started to squeal again briefly on startup  Recently got an na r34 and I replaced the timing belt, water pump + all the auxillirary belts. Runs amazing but it suddenly developed the same squeaking problem but significantly worse, Ive had my neighbour come down screaming at me because it was waking her up everytime I moved the car. It takes a good 2 minutes before it quietens down.  Im yet to diagnose where its coming from but im fairly sure its coming from the alternator aswell. My question isnt about how to fix it but rather where can you get a new alternator for an rb25 neo??? Ive searched everywhere but I havent been able to find a direct fit oem type replacement thats not genuine. All the automotive stores sell an oex one - BXA035 - which I picked up for cheap through a friend with staff discount , got it home only to find the connector is completelty different.... As far as im aware bxa035 is for rb20/30's and after a bit of figuring out the bxa035 has an ev14 type connector, which is tiny compared to the rb25 connector. I actually had an ev14 connector lying around which I was considering just replacing the bigger plug with to get the alternator working but the bxa035 is rated for 70amp vs the rb25 alternators are 90amp ( or so ive been told ? ) That paired along with the fact im about to install an amp + sub in the back and I have the stock sized small battery Im not sure itll do the job unless anyone has another opinion?  I know and have seen all the websites selling the ls1 alternator conversion kit but I am not going down that route, nor do I have the money to. Hopefully I can figure out how to get 2 brand new alternators for both cars. I would buy second hand which there seems to be many of but considering how common this seems to be im sure If I installed a second hand one it would start squealing in no time  Or even better if anyone knows how to fix the issue directly with the alternator itself... Any input appreciated Thank you     Link for bxa035 connector picture
×
×
  • Create New...