Inject her

[yankeedoodoo]

Yet another question from a neophyte builder: Utilizing a 2L zetec which should produce 200-220hp what brand(s) of injector is best and in what size(s)? The car will be used for street and track/competition days whenever possible. A jenvey/lumenition TB system with pectel ems is being employed. Thank you for all past and future experience/wisdom expressed on this very excellent forum!!!!!yankeedoodoo

 

 

[Peter Carmichael]

Brands of injector? I thought they were mostly all Bosch.

 

I run Weber picos, because they are small and fit behind the air filter back plate.

 

Basically, you want the smallest size that is just big enough. This way you will get a good spray pattern. If you have sequential injection you can go bigger and the ECU will time it to hit the back fo a hot valve. With grouped you know you aren't aiming to hit the back of the valve, so you just squirt fuel in regardless - a fine spray pattern helps atomisation.

 

The Bosch ones are often known by their colour. Cream will be suitable for up to ~220bhp; green up to ~300bhp at something like 3bar fuel pressure.

 

To get mine to cover the right range I am running 4 bar fuel pressure. This means I am using a small injector, but still have the capacity for 250bhp. The downside is more strain on the pump and more current through the pump circuit.

[AMMO]

Yankeedoodoo.

 

I always recommend the Weber "green" injectors which are suitable from 40 to 75 horsepower per cylinder. These can be used successfully with pressures from 2.5 to 4 bar(apparently also used at 9 bar! with big horsepower Lancia Delta Integrales). Although it is seen by many as a performance injector use for upgrading it is in fact use in quite a few mundane applications as well. Good if you decide to upgrade further at a later date. You just increase the fuel pressure and re-map.

 

I am also very familiar with the Pico injectors that Peter mentions. Ive supplied about 400 modified versions of these to Works Superbike teams. I usually supply ones that are capable of flowing 330 cc per minute at 3 bar as the engines rev to 16000 rpm. For your application from memory I believe there are ones that flow 190 cc per minute.

 

Although the Picos are very trick looking they cost about the same as the standard injector (Around £60.00 + VAT). The standard injectors weigh around 100 grams. The Picos around 40 grams.

 

I can email you a picture of these side by side so you can see the difference in size.

 

AMMO

[yankeedoodoo]

Peter, Thank you very much, that is exactly the information I need. Ammo, Thank you! Looks like I have a few alternatives. I would appreciate the e-mail you offer. yankeedoodoo

 

 

[AMMO]

Yankeedoodoo

 

Will email pics tonight.

 

An additional thought. The systems I am familiar with are all sequential, so the injector only fires every 720 degrees, hence the largish injectors I recommended. They effectively have to supply twice as much fuel in half the time compared to a non-sequential unit. The Pectel T2 you are thinking of using is sequential.

 

Interestingly enough if the cam sensor fails it defaults to non-sequential/grouped firing mode. The duration pulse is then reduced by around 50% as it fires every revolution. You will then get one pulse against a closed inlet valve.

 

Common opinion is that driving the vehicle you cannot tell the difference between the two systems. The sequential systems are supposed to be cleaner from an emmissions point of view.

 

The Weber "green" injectors are not OTT if used on a sequential system but may be too much for group firing.

 

When I go over to fuel injection I will use Picos because they are so cute and save about 240 grams. I will also probably use the Pectel ECU.

 

AMMO

[EFA]

I run the Bosch Cream injectcors at 4.3 bar.

 

Generally the injector cc/min @100% duty cycle in a 4 pot engine equates to the max hp you can generate on 3 bar of fuel pressure. Increasing the fuel pressure value to give an accurate factorisation of the max power available does not actually work however as it is the mass of fuel, rather than its pressure that ultimately dictates this figure.

 

Many cars run at around 80% duty cycle on the injectors as std. Increasing the duty cycle on a grouped system generally results in cleaner power delivery. It is possible on some engines to actually drive the injectors at a duty cycle of over 100%

 

 

 

Fat Arn

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