RB25 turbine on VR4

[keong_MIRAGE]

danny,

hmmm... you need to mod the RB 25 turbine in ur VR4,cost a lot or not?
well, RB 25 with 1 bar should be alright, i afraid later you tak tahan and boost more then that! :lol: RB25 fast respond but fast finish also... hmmm... sell both to our bro, vteckiller lor... ask him whether he accept trade in or not! go for TO4S or TO4E lar... future no need to change turbo liao, just upgrade your engine to push the turbo! ;)

 

[f8.]

i think high boost in itself is not the cause of ceramic turbine failing, it is high boost and high air flow which occurs at high rpm.

say at 2bar for a 2L engine, this compressor can support the air flow at 3000rpm at this boost for this engine size, if you try to hold the same 2bar on this engine at 6000rpm, in the simple case you are doubling the air flow already. to keep up with the air demand of the engine at 2bar 6krpm, the turbo will need to spin faster to keep up. this is over-revving of the turbo, and as rotational speed goes up, the centrifugal stress os the blades rise until they let go, thus the story of ceramic turbo's losing their fins.

sometimes i talk to a wall in zth because no one seems to bother taking the time to even try to understand what i have taken the time to try to explain. i wonder why i even bother in the first place. as you can see from the original poster's response after this post, he hasn't got the slightest clue what i'm saying here. i might as well be speaking timbuktuan. moijkotozu zambata kon. turbo jeriwa engeok. perhaps those wanker lights will help. *shrug* help me, help you. help me, help you. help me, help you....

i would say, high boost is fine as long as its in mid rpm but you taper your boost off judiciously at high rpm's. to a limit any turbo can support whatever the torque you want more easily through boost, but it can only flow enough air for a certain hp that the compressor was designed for. high torque at low rpm is not necessarily high hp, but even medium torque at very high rpm is very high hp. and this, if you demand of the turbo, will mean over-revving. even steel turbo's will fail like this sooner or later. in other words, use the turbo as a constant power item, so have as high a torque(boost) you want at low rpm and lower it at high rpm as long as you don't exceed the hp rating.

on the other hand, also be careful how fast you allow high boost to build up. if the engine is not yet consuming enough air flow for that high a boost(say at a lowish rpm) then you will get compressor surge, which will kill the turbo too. in most cases, we don't operate anywhere near the danger regions so it is fine, but when you start pushing things you need to be careful.

 

[Danny]

keong, don't tempt me la...hahaha...I shall try to live with 1 bar. Main concern here is to have a hassle free or little hassle engine. Maybe after half a year or a year of running in successfully then I'll consider other upgrades like td06,microtech,bigger intercooler,injectors etc etc. Now my car control also not that good yet, don't really dare to tekan during corners...straight line ok la.

the rb25 needs some mods on the piping thats all. It also comes with tomei ecu (first time I heard of this ecu for vr4) so I'm going to use that as well.

 

[devious17]

f8,hahahahahahahah.....I konw the flineeg. It has hpapened so mnay temis taht I jsut dno't crae aomyrne epxcet I jsut wnat to let it out.

Timbuktoo koo koo waa waa

 

[ramsing]

hehehehe......f8, dun la speak timbuktooan. i think the problem here, is that u didin't join the planta gang. once u join them, then eveyrthing will be slippery smooth. u see devious17, he's now a high ranking member in the planta society. everone loves his slippery way'in...ehehhehe

 

[Danny]

f8, it's not that I don't understand, I was merely replying to keong's suggestion n keeping yours in note.

What you suggest is that if it is running at low rpms it will be fine at high boost, but high rpm + high boost = broken ceramic fins. However it's not practical to use a turbo and keep your revs at 3000rpm during activation. Sorta defects the purpose of a turbo does it not? Also, to taper off boost at high rpm without engine management, how do u do it, besides letting go of the pedal and keep looking at the boost meter? (in which u take your eyes off the road).

Since high rpm is mentioned, what is considred high, 7000?

 

[bujang_hensem]

before you upgrade to any bigger turbo make sure you upgrade your fuel system maaa...not enough fuel kabooommmmmm hahaha that the first step before any upgrade

 

[Danny]

done already earlier thanks for the advise, using evo 3 fuel pump + tank & safc for air/fuel ratio.

 

[bujang_hensem]

aiyo...evo3 fuel pump + 450cc injector ar??? not enough maa for more than 1 bar boost on tdo5h 16g/rb25det ..it will go up near to 100% for boost more than 1 bar...unless you bump the base fuel presure to eg 50 psi...but if fuel presure high eg boost 1 bar=15 psi+50psi (base) = 65psi....i don't think your evo3 fuel pump enough to supply enough fuel on that kind of presure....if using boosh high presure fuel pump maybe...but again stock fuel injector will come to limit....that why vr4 rs or evo are using bigger injector with bigger turbo eg 510cc or 550cc


some more you have to upgrade you air flow sensor to 2G eg evo,v6tt because it flow 29% more air compare stock one...or you can hacked stock air flow sensor....


bigger turbo + more boost = bigger money man.... not just up boost with RM6.00 ikan to 2 bar and then kaboom hehehe :lol:

 

[lekalo]

Setuju with bujang hensem.

And the most important key is management. How is your engine managed? is it getting the appropriate air/fuel mix at various operating conditions? Is it at optimal tune?
Best if u can control just abt every operating parameter that the engine can take.

 

[Danny]

isn't that where the safc comes into play? you can set the hi throttle settings for higher fuel ratio. There is a setting under hi throttle where you can add up to approx 50% extra fuel depending on what rpm and what percentage throttle.

 

[bujang_hensem]

yes you can increase fuel using SAFC, but again you will reach fuel cut (100%-injector pulse) sooner compare stock setting....eg

high trottle + 10% = injector cycle will go up to 100% about 10% sooner compare to stock....and if you try to lean in how much you can go? maybe up to -5% only...too lean kaboom.....the bigger advantages for having safc when you upgrade bigger injector eg 550cc then you will have about 18% extra fuel.for high boost..because at SAFC high trottle you set it to -ve 18%


maybe you can used this sheet as fuel guide tuning

http://203.82.67.196/~abgabas/vr4_ecu/DSM_Tuning_Sheet_v2%5b1%5d.1.xls


hope this will help

 

[Danny]

thanks for the link! very helpful indeed. On the graph it mentions cars with 1G and 2G, what is 1G & 2G?

 

[bujang_hensem]

1G (1987-1992) = mirage,vr4, eclipe etc or 6 bolt flywheel screw engine

2G (1992-1999) = evo1,evo2,evo3,v6tt etc 7 bolt flywheel screw engine



G mean generation :D

NT mean non turbo

 

[vestax]

eclipse also has 2G which almost has the same stuff with the evo's , 8.5 compression , same air flow sensor , 7 bolts , smaller intake ports , smaller tb and etc etc .

 

[Itab]

which generation does GSR belongs to then?

 

[bujang_hensem]

2G lor.....

 

[Itab]

ic....thanks for the info man...ahaah...me quite blur one :P

 

[vteckiller]

hey danny...
how is your super tomei engine and rb25 turbo doing? all done already or still pending..make sure when ready bring us all for a super ride yah!
lets feel the G... so u and jovan can fight pick up la.. jovans one is 220bhp and your vr4 200 with all the goodies..wow can't wait to see your monster in action.
Hey go force jovan go for track day on sunday la... his car can ma..

 

[Danny]

hahaha...sure jovan win la... his driving skills much better. Like comparing schumaker and alex yoong only. His car already modify blow off valve to sequential, sounds like bird chirping kind! Now only boosting 0.6 bar but the response feels like 0.9 bar. Mine stock vr4 only, no monster la. Yea, should go track day... then can really test the cars in a safe environment. Which sunday u all go?