Jump to content
SAU Community

Recommended Posts

Guys thanks for the discussion.

As stated in my first post, i am running a adjustable HKS actuator. I have tensioned it up and we saw a peak of 17.8psi on the dyno in the middle (around 4300rpm). It then slowly drops off as revs rise and severly drops off over the 6000rpm range. It bottomed out at too 12.5psi.

So possibly there can be no boost leak as the i am using no boost controller and only one hose from the intercooler to the actuator which is tight as buggery and has been changed.

I have come to the conclusion that the 2530 is too small for the Rb25. I have compared the 2 side by side and there is only millimetres difference in size. I would still doubt whether a 2535 would hold the same boost up high and i am willing to experiment in this.

If i can gain an extra 1psi up high i would try. At the moment know more boost can be added as the standard computer is holding me back.

  • Replies 46
  • Created
  • Last Reply

Top Posters In This Topic

hey guys, ive had a 2530 on my car for some time and had the same problem as robos. ive tried everything that had been suggested here and you just cant get the boost to hold. Im no turbo expert so i cant tell you exactly why this happens, yet from what ive heard the turbo is too small to support the amount of air required by the rb25 to maintain the boost levels. I also said in a post ages ago that i had also concluded that its too small for an rb25, but then thats all subjective really. The car was damn fast even with boost dropping off, running repeatable 12.5's at 115mph with 2.1 60footers, considering such a small turbo.

so saying its too small depends on what you want out of it. For most street applications id still say its a great upgrade, providing stomper torque that hits hard early.

in your case robos, 12.5psi is slightly lower than what mine dropped off too, but only by about 0.5psi or so. If you ask me its not worth chasing a little extra boost, as you are obviously wanting a good strong top end, get a larger turbo and do it much easier because the 2530 will never give you a big kick up top! its just too small. Even tho the 2535 may only be mm bigger on visual inspection, see what results people have got, i know there is at least 1 user on here with a nice 240rwkw from a 2535.

cubes, i will answer your question to nacho, the turbo is simply too small for the rb25, hence why whatever boost control method u choose to use, it wont change that fact. throw it on an rb20 however and see a great top end, pulling madly as far as 8000rpm (i have been in an r32 with this setup, and the turbo behaves completely different up top)

cheers.

PS robos: look into a GT-RS!

hey guys, ive had a 2530 on my car for some time and had the same problem as robos. ive tried everything that had been suggested here and you just cant get the boost to hold. the turbo is too small to support the amount of air required by the rb25 to maintain the boost levels. (so Nacho, there is your answer to Cubes) I also said in a post ages ago that i had also concluded that its too small for an rb25, but then thats all subjective really. The car was damn fast even with boost dropping off, running repeatable 12.5's at 115mph with 2.1 60footers, considering such a small turbo.

so saying its too small depends on what you want out of it. For most street applications id still say its a great upgrade, providing stomper torque that hits hard early.

in your case robos, 12.5psi is slightly lower than what mine dropped off too, but only by about 0.5psi or so. If you ask me its not worth chasing a little extra boost, as you are obviously wanting a good strong top end, get a larger turbo and do it much easier because the 2530 will never give you a big kick up top! its just too small. Even tho the 2535 may only be mm bigger on visual inspection, see what results people have got, i know there is at least 1 user on here with a nice 240rwkw from a 2535.

so the turbo is simply too small for the rb25, hence why whatever boost control method u choose to use, it wont change that fact. throw it on an rb20 however and see a great top end, pulling madly as far as 8000rpm (i have been in an r32 with this setup, and the turbo behaves completely different up top)

cheers.

PS robos: look into a GT-RS!

Sorry to bring it up again but I've been doing some investigating. :rofl:

I really don't like simple 'No it doesn't work' answers. I like to know why, what and where.

When I don't understand and others can't explain why with detail that answers, questions it frustrates me.

Robo,

I've since found a compressor map that is apparently almost identical to the HKS2530.

The 2530 pretty much max's out with a PR of 2 and ~30lb/s of air which is ~320hp.

The old golden rule of the HKS turbo's being conservative by approximately 15% would push the power up to approximately 370hp.

220rwkw + 60-65rwkw drivetrain loss = 280kw = ~370hp. Fairly close.

370hp = ~33.6lb/s of air.

The RB25 with a VE of 90% & 17psi uses approximately 30lb/s of air at 5500rpm.

By 6000rpm it is using ~33lb/s worth of air, over this and boost theoretically should start to drop off and airflow will plateau. Which it appears to do so. :rofl:

If you drop the VE to 85% at 7000rpm (which is where it is most likely at) you have an airflow of 33lb/s at 12psi.

The figures appear to be too coincidental.

But... Always a BUT.. I still have a question unanswered.

It doesn't explain how boost will shoot through the roof if you manually hold the wastegate shut.

A little off the track but i'll mention it anyway.

Increasing the exhaust a/r improves VE due to less backpressure and improved cylinder filling. This then reduces the boost required for the same airflow.

Lower boost = a denser charge as the air is cooler.

A denser charge contains more oxygen which is where the power comes from.

Even though you are running a lower boost with a larger exhaust a/r (Improved VE = less restriction = less boost required) my understanding is now that once you reach the turbo's flow limit the airflow will plateau and boost will drop accordingly. Power should then flatten out.

The VE Figures are guestimates.

A VERY VERY good example of this is this RB25 that underwent a RB30DET conversion. The Turbo was a GT30. Look what happens to the top end when the turbo's airflow limit is reached.

Airflow plateau's and I'm about to send a PM to find out if boost was actually dropping. No doubt it was. :cheers:

If I'm wrong with the above please let me know, bit of a silly statement really as I'm sure you will. :)

Just to note... 33lb/s of air on the rb20 is around 7500rpm with 17psi. So you should see a little boost drop by 8000rpm on the rb20.

Drop boost to 15psi by 8000rpm and that too is 33lb/s of air.

Thats providing the cams are setup to provide sufficient airflow at that rpm.

Generally with the rb20t the VE will drop over 7000rpm which will allow the boost to be held. So you probably wont notice anything.

Which suggests why the 2530 is well known for how well it works with the rb20t.

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

    • Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
    • But first....while I was there, I also swapped across the centre console box for the other style where the AV inputs don't intrude into the (very limited !) space.  Part# was 96926-4GA0A, 284H3-4GA0B, 284H3-4GA0A. (I've already swapped the top 12v socket for a USB bulkhead in this pic, it fit the hole without modification:) Comparison of the 2: Basically to do the console you need to remove the DS and PS side console trim (they slide up and back, held in by clips only) Then remove the back half of the console top trim with the cupholders, pops up, all clips again but be careful at the front as it is pretty flimsy. Then slide the shifter boot down, remove the spring clip, loose it forever somewhere in the car the pull the shift knob off. Remove the tiny plastic piece on DS near "P" and use something thin and long (most screwdrivers won't fit) to push down the interlock and put the shifter down in D for space. There is one screw at the front, then the shifter surround and ashtray lift up. There are 3 or 4 plugs underneath and it is off. Next is the rear cover of the centre console; you need to open the console lid, pop off the trim covering the lid hinge and undo the 2rd screw from the driver's side (the rest all need to come out later so you can do them all now and remove the lid) Then the rear cover unclips (6 clips), start at the top with a trim tool pulling backwards. Once it is off there are 2 screws facing rearwards to remove (need a short phillips for these) and you are done with the rear of the console. There are 4 plugs at the A/V box to unclip Then there are 2 screws at the front of the console, and 2 clips (pull up and back) and the console will come out.
    • So, a bit of a side trip, but one that might be interesting for people with JDM cars and japanese head units. I know @Pac previously posted about a carplay/android auto adapter he installed which used the AUX input, and @V35_Paul put in one of the Tesla style units that replace both screens. The option I went with was a Lsait LLT-YF-VER5.87_2 (https://www.alibaba.com/product-detail/Lsailt-8GB-Android-Multimedia-Interface-for_1601187633672.html). Price was $1,150 for a single unit although they are much cheaper if you are willing to buy 2....$857ea. Make you you get the version 2 not version 1, it is faster and has a better UI - this is the manufacturer listing: http://www.lsailt.com/product/348.html. BTW if you've never bought from Alibaba before, don't be concerned....these guys can't stay in business unless they are responsive, ship fast etc, they were excellent (probably faster shipping than most local places) So, this was my task for a lazy Sat afternoon....looks complex but was all done in a few hours (it probably helps that I had some of it apart before so it was a bit familiar). I also decided to add a HD USB drive recorded at the same time and the unit also supports an aftermarket reverse cam (if you don't want to retain factory) and also AV in and HDMI out It looks much worse than it is, in fact in was genuinely all plug and play (no custom wiring at all). This video was pretty good (skipped a few steps), unfortunately they are an Aussie seller but no longer sell this unit (I guess Carplay/AA adapters are easier to install and much cheaper) https://www.youtube.com/watch?v=T5hJfYOB8Dg
×
×
  • Create New...