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Skyline vs LS1 vs Soarer dyno day 17th May

Martin Donnon

By Martin Donnon,
in South Australia

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Martin Donnon Mentor

Martin Donnon

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Originally posted by whatsisname

I don't know the full details yet. I'll let you know when I do.

Reason I say this Matt is because AFAIK the Microtech doesnt have individual cylinder fuel trim control, hence 6 would be running the same pulsewidth as 5 and as 4 etc. etc. As for air distribution in an RB manifold? Generally 6 will receive LESS air than cyls 2 and 3, making it inherently richer. You will more than likely find that 6 has been running physically hotter than the other cylinders, due to the Skyline cooling system design, which has pushed it over the detonation threshold. Ie. it detonated to death, rather than 'leaned out'. I may well be wrong though.

whatsisname Grand Master

whatsisname

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Yep your right mate, the LT12 doesn't have individual cyl control. What you've explained, re 6 running hotter & leading to failure, sounds quite feasible. I'll post up the exact findings when the motor is apart.

Freebaggin Proficient

Freebaggin

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Could the cause be a high pressure drop across the factory fuel rail and therefore no. 6 injector gets less fuel pressure and may have pushed it over the safe AFR edge? I would say the harder you push the fuel pressure, the greater the pressure drop.

Martin, what ECUs has individual injector control? Have you seen high pressure drops across RB25 fuel rails?

I've seen on a number of tune shop designed items, the fuel feed line is in the centre of the rail, thus ensuring more even fuel delivery for each injector.

I will be thinking serously about a better fuel system when I bolt a bigger turbo on I think (as per Martin's HPI story some time back re RB25 injectors). Either straight fit SARD or new/better rail with whatever injector we come up with.

Sorry for hijacking thread, should be in Matt's rebuild thread!

Freebaggin Proficient

Freebaggin

Posted
Posted

Hang on guys, the problem with Whatsisname's motor was nothing to do with the Microtech.

I just asked, what other ECUs have individual injector control?

What if it did, how would you measure AFRs for each cylinder anyway?

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