Carby On A Rb

[johan.p.g]

ok b4 i start i du know its a wierd idea but would i b able 2 make a custom plenum and fit the carburetor whyle still running the factory ecu faving disconnected the injector signals and afm and oxy sensor etc so its only function is 2 control the timing and tell me what the engine is doing on the factory dial cluster (i dont like big after market dials)

the reason is to try something diff i want 2 try it on a high comp rb25

[andylaurel]

its doable with the right tools and carbys.

you'd need to trick the ecu into thinking all the fuel inputs were functioning correctly, eg AFM, TPS, Air Temp sensor etc.

you'd be better off running a microleb or EMS or something

[johan.p.g]

il just have 2 make up the manifolds and try it du u know of any 1 who has managed it

[WITTIES]

good idea hope it works out for ya

[mid life crisis]

i used too run the inlet manifold off a nissan patrol with a 500 holley on a rb30 at speedway yrs ago not sure if it will bolt up to a rb25 tho worth investigating

[Greg]

what are the advantages of a carby on an rb? or is it purely for the challenge of it?

[CEF11E]

I had thought about getting a RB30e decking the head so you get a 10:1 comp ratio. then putting on 6 throttle bodies from a GTR and retain injection

250 for the motor

300 for the throttle bodies

few $$$ for fabricating

you would need to do away with the AFM and work out some way to read air volume like a MAF.

[342Four]

a carby engine usually revs harder and quicker

but mainly prob for the challenge of it

[V8skylineMAN]

talk to a guy on here by the name of prince, he usually frequents the classic skylines area. he's done it to an rb20

[32vspecII]

dont disconnect the o2 sensor and maf , the ecu will need them even for ignition timing

also rb24s and rb30s were factory carbd , if you could find bits from those it might help

[WTF-33R]

Povo pack GQ Patrol used a carbie RB30, see if you can find one and see how the timing is managed

[killaniss]

Povo pack GQ Patrol used a carbie RB30, see if you can find one and see how the timing is managed

the gqs use a vacum advance in the dizzy, all the fuel injection stuff bolts up to a gq, so i cant see why the carby gear wont bolt up to a skyline. try looking on some of the 4wd forums you should be able to find a carby manifold fairly easilly, ive threw a couple out over the years.

try http://www.outerlimits4x4.com/index.php

[johan.p.g]

iv tried looking for patrol parts but cant find any i thought they were single cams which would mean the manifold wouldnt fit a twin cam head also this means that the dizzy has nothing to attache to as the single cams dizzy is recessed into the head and runs of the cam shaft

the reason for the conversion is for the revs but also the sound (iv heard that a carby rb sounds insane) and i also enjoy a challenge

regarding the maf sensor i didnt think it affected the ignition. what does it do?

[32vspecII]

my understanding is if your ingition maps come from rpm vs load (afm value) your going to need the afm to figure out when to fire those spark plugs

unless you change your ingition system to something else or you go programable aftermarket managment then you could get load from something else , tps , map sensor

Edited February 15, 2007 by arkon

[johan.p.g]

so as the air flow increases does the ignition advance or dellay also would it work if i were to confuse the ecu telling it that there is a set ammount (not chanjing) of air entering the engine throught out the rev range (i know hot 2)

[Kaido_RR]

why go carbies? when you can go 6x throttles body!! rev rev!

or why not use an rb25 block and smash a rb26 head onto it!

[32vspecII]

so as the air flow increases does the ignition advance or dellay also would it work if i were to confuse the ecu telling it that there is a set ammount (not chanjing) of air entering the engine throught out the rev range (i know hot 2)

when load and rpm increase the ecu advances ignition

you could leave it static but it would run like a dog

you could go to a mechanical ignition system (dizzy) if you wanted . these have mechanical systems to advance ignition timing as load and rpm increases usually some sort of manifold pressure advance or wieght system adjusted by rpm

the whole thing is not realy worth it though theres a reason we abandonded carbs and distributors , they are old tech , unadaptable and inefficient .

an rb26 revs to 8500 with ease , how much more revvy do you need ? try and adapt the rb26 head to your n/a perhaps ?

[andylaurel]

its funny coming from an AE86 background to listen to this talk of revs!

doesnt matter how big your cams are, how high your compression is or how many throttles or carby's you stick on it: RB30's wont rev high because of their bore/stroke ratio.

you wanna build a tough, hot sounding NA screamer inline six? Slap an RB20 crank in an RB25

Destroke it to 2.4 and use a twin cam head capable of the revs you want.

(or just use a turbo engine you pansies)