Jump to content
SAU Community

Recommended Posts

Hi,

My R32 has a VG30-something turbo on it that came with the car when I bought it. It's had several problems with boost creep and the like, but I've managed to fix that. The problem I have now is that it just doesn't hit boost (only 10 psi) until 4500-5000rpm which makes it unresponsive and shitty lower in the rev range. Obviously this is because it's an RB20 and it's a mismatched turbo for a 2.0L engine, and that's fine. However, I've got the chance to buy a stock RB20 turbo with literally no shaft play for $50. I don't care about the high end power loss, I just want more early-mid responsive while I save for something better.

My question is, should I be able to just remove the VG30-something turbo and replace it with the stock one, or would the conversion to the VG30 turbo have required modifying something which would stop me from doing a straight swap back to the stock turbo?

Sorry for the nooby question, but I'm still learning as I go. Don't want to buy the stock turbo, pull everything apart, then find out that I can't put it on for some reason. ;)

Cheers,

Tom

Edited by Incurafy

A couple of points....

1) The VG30DET turbo is very very similar to the stock RB20 turbo. The turbine is actually the same turbine. The turbine housing is a little bit larger (hence why it can make a bit more power and hence why it can slow down the boost response). The compressor wheel is a little bit bigger, hence the extra power capacity.

2) A VG30DET turbo when installed on an RB20 will barely add any extra delay in bringing on the boost. Maybe up to 500 rpm. I've personally driven them that felt like they came on at least as well as the stock turbo.

3) If you have yours not coming on until over 4500rpm, then something is wrong. Either turbo is crook, or something else is crook. The most likely candidate is that the wastegate is not tight shut.

But the answer to your question is.....yes. Straight swaps. About as easy as it is possible to get.

What ECU do you have? You won't know what you have till you get the turbo off.

I have the stock R32 ECU. I know what the turbo is because I was told that buy the guy I bought it off. I also checked the stamp on compressor housing when changing the dump pipe. :)

A couple of points....

1) The VG30DET turbo is very very similar to the stock RB20 turbo. The turbine is actually the same turbine. The turbine housing is a little bit larger (hence why it can make a bit more power and hence why it can slow down the boost response). The compressor wheel is a little bit bigger, hence the extra power capacity.

2) A VG30DET turbo when installed on an RB20 will barely add any extra delay in bringing on the boost. Maybe up to 500 rpm. I've personally driven them that felt like they came on at least as well as the stock turbo.

3) If you have yours not coming on until over 4500rpm, then something is wrong. Either turbo is crook, or something else is crook. The most likely candidate is that the wastegate is not tight shut.

But the answer to your question is.....yes. Straight swaps. About as easy as it is possible to get.

That's interesting. I was under the impression that the RB25DET turbo was slightly larger than the RB20DET and added around 500rpm to the spool time, while the VG30DET turbo was even bigger again and took a lot longer to spool? At least, that's what I got from reading the threads around here.

While I've got your attention, my turbo has 45V1 stamped on the compressor housing, and from what I've found on these forums, that is a VG30 turbo. Sound right to you?

Regardless, I think I'll swap it over and see what difference it makes. It will be easier for me to wrap my head around a diagnosis of any problems if I can see the difference between the stock turbo and the VG30DET turbo (never driven a stock one).

Cheers mate!

Edited by Incurafy

I have the stock R32 ECU. I know what the turbo is because I was told that buy the guy I bought it off. I also checked the stamp on compressor housing when changing the dump pipe. :)

That's interesting. I was under the impression that the RB25DET turbo was slightly larger than the RB20DET and added around 500rpm to the spool time, while the VG30DET turbo was even bigger again and took a lot longer to spool? At least, that's what I got from reading the threads around here.

While I've got your attention, my turbo has 45V1 stamped on the compressor housing, and from what I've found on these forums, that is a VG30 turbo. Sound right to you?

Regardless, I think I'll swap it over and see what difference it makes. It will be easier for me to wrap my head around a diagnosis of any problems if I can see the difference between the stock turbo and the VG30DET turbo (never driven a stock one).

Cheers mate!

The VG30DET turbo is actually the same turbine housing as the RB25DET Neo (this is the OP6 housing). This is slightly bigger than the 21U housing on the R33s, which is slightly bigger again than the RB20 turbo.

But let's be very clear......they're all basically the same turbo. The RB20 compressor housing is noticeably thinner than the others though.

The 45V1 is actually the marking on the R33 turbo. So it may not be the VG30 turbo you've been told it is. If you get it off and the turbine housing says 21U, then that's your answer.

And without a Nistune or am ECU [or a bender like a SAFC} gains are minimal for any turbo swap. Also you have an RB20, so low down torque is not going to improve probably as much as you would be looking for.

Same ceramic turbine , three different compressor wheel sizes . Late RB20DET smallest comp , BB VG30DET then RB25DET . From memory early BB RB20DET was same approx same as RB25DET but with smaller compressor housing casting .

VG30 and R33 RB25s use same compressor housing machined for native wheel , RB25 with anti reversion groove in snout .

The throat size in RB20 and 25 turbine housings isn't great but the 25 to VG30 is a bit more significant .

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

    • For DBA, check out their guide table here. https://dba.com.au/wp-content/uploads/2023/01/Direct_Replacement-Guide-2021.2.pdf   Additionally they have some other guides and info on how to make sure you choose the right pad.
    • Sorry, just assumed that talk of coloured pads meant EBC red/green/yellow/shit stuff. I don't know the DBA pads, but it's a reasonable bet that they will be OK. DBA make good stuff generally. Those 4000 series rotors I linked to are very good. I may well replace the RDA rotors I have with those when required.
    • The average previous owner for these cars were basically S-chassis owners in the US. Teenagers or teenager-adjacent. I often tell people that neglect is easier to fix than something that was actively "repaired" by previous owners.
    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
×
×
  • Create New...