Jump to content
SAU Community

Downsizing Rb25 Turbo

sh@un

By sh@un,
in Engines & Forced Induction

 Share

Recommended Posts

sh@un Grand Master

sh@un

Posted
Posted

I need to use my car in traffic a whole heap, and the engine spends most of it's working life under 3000rpm.

I'm craving more torque between idle and 2500rpm or so- Does anyone know if there's a smaller sized 'turb that will direct fit in place of the current one??

It's a non-neo RB25 if it matters.

Link to comment
https://www.sau.com.au/forums/topic/408058-downsizing-rb25-turbo/
Share on other sites
R31Nismoid Grand Master

R31Nismoid

Posted
Posted

3ltr Shaun, just slap your head on a stock-rebuilt bottom end. Get away with it for a couple grand tops IMO.

I know someone else who did a 3ltr into a Stagea, owner loves it. Made a ridiculously huge difference as it's used for towing as well :thumbsup:

sh@un Grand Master

sh@un

Posted
  • Author
Posted

Cutting the back off the car would probably be a bit loud'n'breezy, and reduces security somewhat.

While the big-block idea sounds great, it's sorta more re-engineering and expense than I could be bothered with.

I suspected an RB20 turbo might fit; Sounds a very doable option...

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

RB30 did it for me - but rather than downsizing the turbo get an electronic boost controller and it will come on to boost a little (just a little) earlier.

But seriously if you stick an RB30 block in your set up and change nothing else who is going to know?

discopotato03 Grand Master

discopotato03

Posted
Posted

I know of one person that has a GCG BB Hi Flow based on an RB20s turbocharger , at least I think the turbine housing is from an RB20 . This is on an early auto Stagea .

For torque at low revs cubic inches are hard to beat , it can have torque from lowish revs with a smallish turbocharger and thats fine provided you don't expect much beyond say 5-5500 revs .

I think its a good idea to lose the ceramic std turbo anyway and doing so makes them breath better exhaust wise and makes the engine work as a more efficient air pump .

Aftermarket wise as I said possibly an RB20 GCG Hi Flow or a HKS GT2530 would be the go .

The thing is that most go looking for more mid range and higher end performance and use larger turbos to achieve it . If you want same maximums as std and a bit more low down punch overall the turbo needs a little more exhaust flow than the RB25s Hitachis turbine has but in a turbo that boosts a little earlier .

A .

hypergear Grand Master

hypergear

Posted
Posted

install an electric turbo that sits 3 psi on ideal. lol

Here's a Electric turbocharger that powers the car to 3psi even the engine is at 0 rpm with car key out ignition. lol

boost.jpg

Pretty big difference in torque down low

power.jpg

No its not for sale. Just a hobby I'm building.

Any way, if it is a stock turbo and you find it laggy then it might not have all of its turbine wheel, but assume its fully functional and so's the car then you might consider trade your R33 with some thing high comp NA.

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

    • MBS206
      Recommendation for engine oil funnel spill free

      By MBS206 · Posted

      I thought I'd come back and add something I JUST learned. A Toyota LandCruiser with a 1HZ, mates perfectly with a bottle of Nulon brake fluid. As in, it perfectly screws in. Great make shift funnel when you cut the bottom of it off. This may work for your Corolla.   Unfortunately, tipping a 10L drum is much harder than a 4 to 6L bottle, and they no longer include the easy pour tap which was just perfection to use previously.  
    • EndZee
      Fuel Pump Control Module & Dropping Resistor

      By EndZee · Posted

      Guys since i bought r33 gts25t coupe 1994 automatic a/t(manual swap 350z gearbox)  all i got is problems, always problems. Lets start with that when i turn key into ignition(ON) fuel pump doesnt always works. Sometimes i have to turn key twice Off/on/off/on until it primes. Its new, dw300 - 340lph. My gearbox broke so i did gearbox swap, install different intake manifold, injectors and i take pipes. Car was sitting in garage for more than half a year. I did assembly all not that long ago and when i turn ignition cant hear prime. All of sudden it stopped working. Theres many videos on YouTube how to make relay mod on r33 straight from battery so i did and it doesnt work! 😰 30 - battery positive  87 - positive from fuel pump to relay 85, 86 - one of two wires from original fuel pump wires(light blue, grey) and it didn’t work. so I check on ignition and took original BLUE relays wires from trunk, next to fuses. (I believe it’s IGN+ and ECU pin 18. it didn’t work…  tried connecting (IGN+ from og relay) and (ECU 104 from 1of4 FPCM wires) to my new relay 85/86 and it didn’t work.  I unplug FPCM. Didn’t work. im thinking what’s wrong   fuel pump is working, if I leave IGN+ on 85 and 86 straight to ground it works but it’s just nonstop. Since it getting constant 12v after key in ON. light blue wire gives me 6-8v.  so how this should be connected? What causing ECU not giving — on pin? Or I did sth wrong and that’s why it doesn’t work? I need negative signal on ECU that control fuel pump. What this should be?
    • Duncan
      M35 Brake caliper replacement

      By Duncan · Posted

      You can use your VIN to look up the factory part number somewhere like amayama, and then look to order new if necessary. https://www.amayama.com/en/genuine-catalogs/nissan Depending on price you might want to rebuild instead. @GTSBoy I had an interesting insight into US market parts when the Titan rear calipers were sticking. New calipers were dirt cheap, about 20% more than a rebuild kit....they are just considered throw away maintenance items
    • Duncan
      Most women will agree that parking is the most taxing part of driving

      By Duncan · Posted

      Funny, but really not funny. Thank god (most) f the world has moved on since then
    • Duncan
      Jacks that fit under GTR lips that can reach the subframe?

      By Duncan · Posted

      Lots of votes for driving onto a plank first; that is the quickest way I've found, 25mm is enough for my case but that will vary by car It also depends where you are going for. On the 32 I can get to the rear diff with my floor jack if I do that end first, and get it up on stands. Then I lift the front from either front tow hook as high as needed, also onto stands. Sometimes I need a small lift on the other tow hook to get it level enough If I do the front first I can't get to the rear diff because of the angle of the car Other options are getting to the front mount of the rear subframe from in front of the wheel (if only lifting one side, or just do both which is a bit of a pain compared to one lift from the diff), or also the gearbox cross member mount on the driver's side if you are  just trying to lift the driver's side. I This is the jack I use; it says 75mm clearance but of course that is only on the lower section so if you have to reach too far in like the diff you still get stuck. https://www.snapon-bluepoint.com.sg/category/Floor-Jacks/product/Floor-Jack,-2-Ton-Low-Profile
×
×
  • Create New...