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upgraded injectors

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988541312_accelerationtestat60psi.thumb.jpg.e44b066788f289c5e8f5b4a24bffb8af.jpgBit the bullit and sourced bigger injectors.

I will get my Emerald ECU to run just on these new Bosch 0280 156 211 's and delete the use of the secondary injectors.

This is the difference in flow between the original Rochesters in the middle and the new Bosch ones either end.

Acceleration mode at 60psi.   Quite a difference, 42%

However, all other modes of testing show approx 24% increased flow ???


Edited by alanlambert
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17 hours ago, alanlambert said:

I will get my Emerald ECU to run just on these new Bosch 0280 156 211 's and delete the use of the secondary injectors.

Hi Alan,

I`m pretty sure those injectors are not going to be big enough to run as your only source of fuelling.  They are only marginally higher flow than the stock injectors at 267cc/min  and are typically used as replacements for the stock injectors when keeping the secondaries in place (secondaries are 550cc/min)

Of course it all depends on your power target but even at 400bhp, you would need something up around 8x 360cc/min.

There is a rough injector size calculator on the RC Engineering website

RC Fuel Injection > Technical


1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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A quick rundown of what I think may be instructive, as follows. An ECU such as the Emerald will issue pulse commands to the injectors measured in terms of pulsewidth, i.e. milliseconds. This, in concert with the system fuel pressure and the flow capacity of a given injector, determines the quantity of fuel delivered for each trigger event. In the case of fully sequential injector triggering such injector events are once per 720 degrees crank (for each cylinder) , the duration of each cylinder's 4 stroke cycle. This is the typical state of injection during steady state engine conditions, eg. idle, full throttle, steady cruise. When the driver goes full Wellie from idle or light throttle there will be need for additional enrichment momentarily as transitory plummeting inlet tract vacuum will result in fuel particle dropout en route to the cylinder. This enrichment can take the form of either/both extended pulsewidth or additional trigger pulses per cycle. The latter are correctly termed asynchronous AFAIK, due to being off the basic clocking of once per engine cylinder cycle. Mike is the expert, in any case.

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Posted (edited)

Thanks Mike.

I had seen that calculator but i thought the recommended injector rating which was at 43.5psi had to be adjusted for the higher pressure i run.

Just realised the adjustment is in the calculation allready.

Looks like i will be keeping the secondary injectors after all 🤨

Also as the fuel pressure rises with boost, should the final pressure in the table be running pressure (65) plus boost pressure (10) i.e.75psi ??


Edited by alanlambert
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