Jump to content
SAU Community

Recommended Posts

no skyline here, but a nissan none-the-less.

i guess the first question is whether an rb25det turbo is made by garrett, my whole idea depends on this.

my current setup is a qr25de-t engine with a garrett t3/t04e 57 trim .63 exh .6comp (pics available)

what i'm wondering is if I get a stock rb25det turbo, if that will fit into a t3 .63 a/r exhaust housing.

reason i'm looking to do this is because my t3/t04 setup is rather laggy, i hit about 13 psi at my altitude by like 3700 rpm (6200 redline), so i'd like to try something (cheap is the keyword here) that spools a tad quicker (ballbearings from what i understand) but i don't want to touch my exhaust setup (4bolt vs 5bolt with internal wastegate).

also, as far as compressor flow map, is there a name for this stock rb25det turbo, or a more known turbo which i could find a compressor map for mapping the flow and efficiency with my engine.

i'm looking to run the turbo at around 2.0 PR (i'm at 5000 feet elevation, so i need the 2.0 PR to make around 10 sea level psi max)

from what i hear, the rb25det stock turbo has ceramic turbine wheel, how far have people pushed this without completely destroying them ?

Link to comment
https://www.sau.com.au/forums/topic/100966-inquiry-about-stock-rb25-turbo/
Share on other sites

Gurov , the easiest and cheapest way to get earlier response is to use a smaller trim TO4E compressor wheel which will also need another compressor cover . TO4E's go down below 40 trim in 76mm or 3" diametre . I went to a lot of trouble some years back to get a TO4E 50 Trim from turbonetics because the map looked so good . You should be able to get some turbo shop over there to do this for you cheaply and easily . The std Hitachi's on RB25's are badly short changed in the turbine and housing dept so I would not seek one if it had something easily available . Actually I think Garrett has released some Ball Bearing T3/T4 conversion cartridges they're calling T3/T4R CHRA's .

Getting nagged by the kids again so back with more info later , cheers A .

i guess the question now is will a turbine wheel meant for a t3 .43 a/r fit into a t3 .63 a/r, as long as the chra is t3 ? for ex i have a t3 .63 and i buy another turbo with a .48 a/r, will that fit into my .63 a/r that's already bolted to the manifold/downpipe ?

Back again , discovered you mean QR25 not RB25 and wish to keep your turbine housing and dump pipe .

Garrett has released five new Ball Bearing cartridges designed to replace everything between the housings for some bush bearing turbos .

Over your way there has been a huge craze over TB31/TA34 + TO4E hybrids . Garrett has decided to use the 76 trim TA34 turbine (stage 3 in US speak) and match it with one of four TO4E compressors , ie 57 and 60 trim in the 75mm or 2.950 O/D . The second two are 50 and 60 trim in the 76.2mm or 3" wheel version . My lists of TO4E compressors is not complete but I would lean toward the 50 trim version because it will spool sooner for the given turbine shaft power . My list shows the 76.2mm 50 trim as 53.9mm inducer and 5.2mm exducer tip height , wheel number is 448048-0004 .

Garrett part numbers for these conversion cartridges are 757179-2/-3/-4/-5 for the respective compressor options mentioned above . The 757179-1 I left out is a TO4 PTrim combined with a TO4B 60-1 compressor .

From memory QR25's are long stroke engines so sizing the compressor to support beyond safe revs is pointless . Probably need a 3000 to 6500 rpm range which the 50 trim should handle and not overwhelm the turbine or integral wastegate .

As for boost pressure the best gauges are absolute pressure type which read zero as zero (total vacum) instead of those silly things that only read sea level pressure as zero . Sea level pressure is 1 bar absolute so at 5000 ft it will read something less . If these read 14.7 lbs of boost it will be 1 bar at sea level , 5000 ft or 20,000ft because its pressure above absolute zero . Often with aircraft turbos are there to maintain sea level manifold pressure to their desired service ceiling so that lower atmospheric pressure does not sap performance .

Cheers A .

Back again , discovered you mean QR25 not RB25 and wish to keep your turbine housing and dump pipe .

Garrett has released five new Ball Bearing cartridges designed to replace everything between the housings for some bush bearing turbos .

Over your way there has been a huge craze over TB31/TA34 + TO4E hybrids . Garrett has decided to use the 76 trim TA34 turbine (stage 3 in US speak) and match it with one of four TO4E compressors , ie 57 and 60 trim in the 75mm or 2.950 O/D . The second two are 50 and 60 trim in the 76.2mm or 3" wheel version . My lists of TO4E compressors is not complete but I would lean toward the 50 trim version because it will spool sooner for the given turbine shaft power . My list shows the 76.2mm 50 trim as 53.9mm inducer and 5.2mm exducer tip height , wheel number is 448048-0004 .

Garrett part numbers for these conversion cartridges are 757179-2/-3/-4/-5 for the respective compressor options mentioned above . The 757179-1 I left out is a TO4 PTrim combined with a TO4B 60-1 compressor .

From memory QR25's are long stroke engines so sizing the compressor to support beyond safe revs is pointless . Probably need a 3000 to 6500 rpm range which the 50 trim should handle and not overwhelm the turbine or integral wastegate .

As for boost pressure the best gauges are absolute pressure type which read zero as zero (total vacum) instead of those silly things that only read sea level pressure as zero . Sea level pressure is 1 bar absolute so at 5000 ft it will read something less . If these read 14.7 lbs of boost it will be 1 bar at sea level , 5000 ft or 20,000ft because its pressure above absolute zero . Often with aircraft turbos are there to maintain sea level manifold pressure to their desired service ceiling so that lower atmospheric pressure does not sap performance .

Cheers  A .

eh, yeah, that's not what i really asked, heh. i know about the ballbearing garret cartidges, but it seems like shelling about $700 out for that i could find something from the stock turbos that fits, wishful thinking i guess. i'm just looking for cheap options to replace the turbo or go up/down a size of cheaply-available turbos.

yeah, it's a qr25de. the long stroke 4 cylinder, 57 works nicely, once it spools, it's fine. external wastegate here, hence the desire to keep my housing, most of smaller T3/t04 hybrids i find are in .48 with integral gate,and i don't want to redo too much of my exhaust hardware.

as far as the pressure thing goes, i say 10 psi sea level because that's what my datalogger/wbo2 displays (zt2) , it uses a uncorrected map sensor (3.5bar aem), and just gives me raw voltage to 0-350kpa in PSI my boost gauge/boost controlelr show relative pressure.

Edited by gurov

Smaller Trim TO4E compressor will bring it on earlier . You are using a 57 trim so a 54 or 50 would be the next steps down .

You could even look at usind a TO4B cover and backplate with the Buick Grand National compressor wheel which is actually a TA34 69mm 58 trim 7 blade wheel 410299-0004 that looks like 2/3 of a 60-1 map flow wise . There are 6 blade versions of the old TO4B compressors in 39/48/57/62 and 70 trims , 48 or 57 could work Ok .

Several ways to skin the cat , mainly depends on price and availability of parts .

I would NOT reduce the turbine housing a/r - anything that increases exhaust restriction is a big no no IMO .

Cheers A .

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...