4.2 / 4.5 injectors

[a1rak]

I have just stripped apart a 4.2 inlet system and found that the number on the Fuel injector is Bosch 280150744. On various web sites this is rated at 20.7lbs/hr or 220cc/min. This equates to a maximum power of around 280bhp at typical fuel pressures. Can anyone in the know explain how it works OK in the 4.2 which is rated considerably higher than 280bhp.

Also can anyone give me the number of the injector used in the later 4.5 cerbs.

[Jackal83]

Is your Max HP not based on a 4 Cylinder engine?

[cerberamatt]

I was led to belive the 4.2 and 4.5 use the same injectors.

[high52kojak]

http://www.pistonheads.com/gassing/topic.asp?h=0&a... injectors

[a1rak]

Jackal83 said:

Is your Max HP not based on a 4 Cylinder engine?

www.rceng.com web site

BHP=

20.7lbs/hr(injector flow rate) x 6.4 (8 Injectors 8cyl x 80% duty cycle)
_____________________________________________
0.5 (Normally aspirated B.s.f.c.)

I think that comes out at 265BHP. But i was crap at maths.

[brogenville]

Internet info in fuel injectors, in my exprience, can be very misleading and/or inaccurate. The main problem is that when injector flow rates are quoted, they very rarely include the pressure at which the injector was rated at, and the fuel rail on the cerb runs at an unusually high 3.5 bar.

HTH

[clive f]

brogenville said:

Internet info in fuel injectors, in my exprience, can be very misleading and/or inaccurate. The main problem is that when injector flow rates are quoted, they very rarely include the pressure at which the injector was rated at, and the fuel rail on the cerb runs at an unusually high 3.5 bar.

HTH

Quite agree, I found this out myself when building my engine and running it on Joo`s rollers, for instance, if a standard injector is only supposed to be good for lets say an internet based figure of 265bhp why are there so many 4.2 cerbs running at 360 to 380bhp or even more with no problems at all?

I ended up using the bosche 3`s courtesy of Brogenville, with a flow rate of 28lbs/hr, and on the dyno at full wack 409bhp they were running at just under 80% of their flow rate, so must be good for at least 420bhp.....................next years project

[HarryW]

Don't know what bosch 3's I have (4 hole disc type) but they are good for 450+hp with some headroom for more, perhaps my bscf is a little better though