Advice on injector size and brand from experience?

[diesel des]

You would need to be doing something very wrong to get a bsfc of much over 0.6 on an si engine.

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[Pat D]

Using .6 it calculated to about 1800cc for 800hp.

BSFC would increase when generating more power?

Different engine on the graph, but used for an example.

[diesel des]

Bsfc is directly related to efficiency. So as you see when the tt is pushed the efficiency falls like a stone, e.g. the Bsfc goes up. This is due to small turbo, restrictive exhaust with cat, retarded timing for safe running and too rich a mixture for poor quality fuel. The standard manufacture tune for safety, and they don't care for efficiency at max power.

As you see when things are efficient up to 5 k rpm the efficiency is as stated for normally aspirated about 0.4. On a well tuned turbo engine on good fuel Bsfc won't get much above 0.5

I hate those units, I'm used to grams per Kw hour. A good diesel is just under 200 grams per kWh just for reference at peak torque.

So if a 1000cc injector can do 800hp in our cars at 80% duty then a 1200 cc injector will do best part of 1000 bhp Then figure in the correction factor for e85 of 30 to 47% and your still at 700 bhp easy on 3 bar fuel pressure. At 4 bar 800plus.. still at 80% duty.

Maybe 1500cc would be a good compromise. Remember 5 1200 cc injectors at 80% is 5 litres of fuel a minute. And to burn that you would need 2 bar plus boost, so that's 5 to 6 bar fuel pressure. 5 litres a minute at 6 bar pressure is a lot of pumping power...

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[Pat D]

I'm doing the calcs with 800bhp. So in the end with BSFC 0f .5 it worked to be 1050 * 1.47(E85) = 1543cc injector. Apart from risking a poor idle, what other issues may arise from using a bigger injector?

I'm in the process of installing a variable duty cycle fuel delivery system that should be able to supply roughly 500L an hour at 100psi/6.8bar which is about 8.3L a min at 100% duty, this will vary depending on engine load %.

Boost set point will be around 2.5 bar.

[macspring]

I'm doing the calcs with 800bhp. So in the end with BSFC 0f .5 it worked to be 1050 * 1.47(E85) = 1543cc injector. Apart from risking a poor idle, what other issues may arise from using a bigger injector?

I'm in the process of installing a variable duty cycle fuel delivery system that should be able to supply roughly 500L an hour at 100psi/6.8bar which is about 8.3L a min at 100% duty, this will vary depending on engine load %.

Boost set point will be around 2.5 bar.

Hi Pat, when you've finished installing the fuel system as described, can you post a couple of photos, only have one 044 myself which is all I need, but still interested to see your set up.

Are you fitting an auxilary petrol tank ?

Thanks.

[Pat D]

Hi Pat, when you've finished installing the fuel system as described, can you post a couple of photos, only have one 044 myself which is all I need, but still interested to see your set up.

Are you fitting an auxilary petrol tank ?

Thanks.

Will do, I will hopefully have it done in a month or two. If you're refering to a surge tank, then yes. I'm having a custom one made up to fit in the cavity to the left of the battery tray underneath the car