what bhp are Siemens 55lb, 72lb and 83lb injectors rated for and do they need a special fitting kit. Also what resistance are they supposed to be? 2.8 Ohms????just wondering as i can get hold of some fairly cheap and was wondering which ones would be good for about 400 bhp with a view to upgrading later for more power but dont want to have to buy more injectors.They are for an escos.

 

just buy the biggest....they can be mapped to suit power levels me thinks

 

72lb injectors are in the region of 735cc IIRC

And should be good for 450 easy, 500 bhp at a push.

Not sure on the others, but if you want 400 now and 450 eventually then 72s will be fine for the job.

Si

 

Your question is like asking "What sort of insurance is a Ford, high or low?"

The injectors are available in varying impedances and chassis types. Siemens are just teh manufacturer and they make hundreds of different injectors, just like they make hundreds of different car parts, ecus, sensors, etc.

As a guide to work it out for yourself:
Multiply LBPH x 10.2 to get an approximate rating in CC's.

When choosing an injector to suit power output, its sensible to leave 30% injector pulsewidth free for "ultimate reliability" but this normally requires excessively sized injectors. (Assuming BSFC of 0.62)

As an example.
For 500bhp you will need a 100lb per hour injector if you wish to leave it OEM reliable with the full 30% free. This however is not what i personally prefer to work with and i find 15% acceptable. That makes your 72lb siemens a 450bhp injector if pushed to 15% when assuming a BSFC of .55.

For teh same 450 engine you will need a pump that can flow 170 litres an hour at the same fuel line pressure as you expect to make the BHP if you want to retain a nice 30% safety margin, and you should. On Most YB engines that pressure is 5.5bar absolute if running 2 bar boost to achieve the power.

Once you have worked out the above, your choice is no longer complex, but the big problem is working out your BSFC as it can vary wildy from 0.45 - 0.70 and it makes a HUGE difference to the injector and fuel pump rating.

Alternatively, you could just pay tuner prices for your injectors and let them choose for you, thus safeguarding your engine...

 

it's just the £200 difference in price thats making me think of ordering them and all three different sizes are the same price. Im just trying to get the parts together before i fit them and get the car mapped

 

£200 difference Seems a lot?

A set of 55lb Siemens are £300 retail here inc vat and import duty.
To be fair though, most tuners will be happy for you to supply your own anyway, i certainly am because they are a common item of failure and can take the engine out if they are imbalanced, which means its totally down to you when it happens.

 

Bet you wish people supplied their own oil pumps etc too

 

Do i fooking ever mate, that took me months to recover from.

 

it's on the five o website that they are selling them and with the exchange rate at the moment they come to £133 for a set of 4

http://www.fiveomotorsport.com/Injec...DS.asp#siemens

im just looking into all the options at the moment.

 

Wounder indeed!!