Rb25de With Carbs

[JasonG]

If I install an RB25DE with carbs in an early Skyline with an upgraded ignition system can I completley eliminate the ECU and wiring harness? Because it seems like the only things the ECU really needs to control is timing (which will now be handled by the ignition system) and air/fuel ratio (now controlled by the carbs).

Thanks!

[342Four]

yes its a possibility

here in australia there was an early model Nissan Patrol ('88-90 i think) that came out with the RB30 but in carby form

if you could get hold of an intake manifold it could be possible to install a big holley 350 double pumper or something on it

[teng]

Pic of RB30S from a R31 4-dr skyline. Very rare indeed even in my country. Most of them came with the CA20S Engine.

[GTS4WD]

The Dirty Thirty just got dirtier..

[donut_kng]

Pic of RB30S from a R31 4-dr skyline. Very rare indeed even in my country. Most of them came with the CA20S Engine.

thats crazy, interesting to hear what that would sound like..

[SKiT_R31]

thats crazy, interesting to hear what that would sound like..

... shit...

lol

feed it triple trumpeted webbers or even SU's and it would be allright though

Wouldnt be hard to custom make a manifold, would be better to start fresh, and make a short runner manifold feeding diectly to carbies instead of modifying the dirty 30 manifold to suit a 25

Edited November 25, 2008 by SKiT_R31

[MBS206]

The question would be, WHY?

Even if transplanting, the engine is still from a "new" vehicle, and hence, when being engineered, needs to meet the Emmision levels of the engine.

Hence, going Carby, you will not meet these emissions, so I'd really have to ask WHY you want to do it?

If you get a whole loom, plus ECU, it really is only around 5 or so wires you need to modify to make it all fit. Much easier the customising manifolds.

[CEF11E]

induction noise, throttle response and better breathe-ability having 6 throttle bodies and no plenum if you were to use 3 side draught webbers, dellotos or so on.

[daisu]

Completely remove ECU and wiring harness...

but replace with custom inlet manifold and multiple carbies, you'd also need to use a different fuel pump as the EFI pump will have too much pressure for the carbies?

Potentially, yes it could be done, but question remains why you'd want to when you could get better tunability, resulting in more power and probably less fuel consumption, not to mention safe guards of things like knock sensors.

If you want induction noise, throttle response and better breathe-ability, you could make a custom inlet with individual throttles but still retain fuel injection.

[MBS206]

induction noise, throttle response and better breathe-ability having 6 throttle bodies and no plenum if you were to use 3 side draught webbers, dellotos or so on.

Make a custom throttle with ITB, with individual air filters.

Same throttle response, same induction noise, no plenum, better tuneability, more reliable and consistent through varying weather patterns.

I still need to ask why you want to remove the ECU, considering, placing it in any car in NSW would make it illegal with ECU etc removed.

[SKiT_R31]

last time i checked, running an aftermarket ecu was also illegal.....

I would much prefer ITB's + MAP, but i can see why you would want carbies... and the induction/exhaust noise would be different, and you cant say for sure that you would get more power out of EFI, maybe economy and drivability and flexibility (weather, atmosphere etc) but it can be cheaper and a whole lot easier with carbies. Esp if you were to have some rediculous cam setup, aswell as other modifications, where you would need a damn good tuner to get good power (and lets face it, its hard to get a tuner so passionate to sqeeze every last kw out of a car by spending hours dicking with injector timing etc.)

Edited December 1, 2008 by SKiT_R31

[Bliksem]

The question would be, WHY?

Even if transplanting, the engine is still from a "new" vehicle, and hence, when being engineered, needs to meet the Emmision levels of the engine.

Hence, going Carby, you will not meet these emissions, so I'd really have to ask WHY you want to do it?

If you get a whole loom, plus ECU, it really is only around 5 or so wires you need to modify to make it all fit. Much easier the customising manifolds.

I still need to ask why you want to remove the ECU, considering, placing it in any car in NSW would make it illegal with ECU etc removed.

It says he's from Japan so our laws won't mean anything to him LOL

Edited December 1, 2008 by MintR33

[mid life crisis]

when i run modifird production in speedway the rules said we had to use a 350 holley altho it could be converted to run methanol.

a few of the guys running vl's at the time used the nissan patrol manifold with a methanol holley and made good power out of them .

problem was finding the manifolds it was a problem back then and prob even worse now

cheers mid life crisis

[blind_elk]

If I install an RB25DE with carbs in an early Skyline with an upgraded ignition system can I completley eliminate the ECU and wiring harness? Because it seems like the only things the ECU really needs to control is timing (which will now be handled by the ignition system) and air/fuel ratio (now controlled by the carbs).

Thanks!

What's going to tell the "modified ignition system" to fire the spark?

The ECU does more than simply "control ignition timing".

If you are after the carby induction sound, you can run injectors in a weber-style manifold fitted with trumpets (have a look on www.efihardware.com). That way, you get the fuel efficiency of EFI with the induction "roar" of Webers.