What was the formular for injector sizing ie...

cc's per bhp..

is it 1.xx???

with custom rails could cosworth greys be made to fit or are there different impediances (sp) between injectors?

David

 

cosworths ones are wrong impedance

440cc phase ones available v.cheap
others for phase 2 also available.

mail me with what you want to do, I can tell you where to shop.

paul

 

YHM..

Formular?

 

Quoted values vary - 1.3cc / BHP using four injectors is an estimate. Depends on what IDC, what brake specific fuel consumption you assume, how lean you run it, charge temps, ignition timing etc. I think everyone agrees that 440s at standard fuel pressure get a bit daft above about 320-330 BHP. I would hope that 550s should be adequate for your plans unless you are stark raving bonkers and if you are can I have some too please

 

I am bonkers...

 

Andy Forrest rewrote the rules on this, but he was running 7 injectors at high pressure at one point I believe so maybe his equivalent would be 740s?? I wonder what IDC Mr Trout is getting these days with his donut king turbo?

 

Cossie greys also cause bad idle etc on cossies, so would you realy want them?? They are only about 500cc as far as I remember anyway, so not that big..

 

I've seen 550s with an uprated pump running 380 - 400bhp @ 78% duty cycle iirc.

 

cossie greys are not 500cc.

i think they are 380cc. they are definitley the wrong impedance though and are top feed not side feed but this is no problem.

I have never heard of them causing idling problems. I hope not since I am running 8!

 

Yep...

.....when it comes to your car

I am interested in what injectors i would need.

Paul YHM

Steven

 

Guys,

I know it's Friday, but REALLY

So you need 1.3cc's of fuel per 1 bhp, do you ????

440 x 4 = 1760

1760 div' 1.3 = HOW MANY BHP

Mark.

 

Adam,

Cossie greys are theoretically 503cc's. Greens are 380cc's.

400bhp out of 550cc injectors @ 78% idc !!!! and what "virtual" RR was that on.

78% of 550, is less than a 440 running at 100% !!! (97.5%)

On average, running a sensible AFR expect 5.25~5.6cc's per 1 bhp.

Mark.

 

or 1.3cc/min per hp per injector (ish)

SO for 550s at standard pressure

(550 * 0.85 IDC)/(1.3cc/min/hp) = 359HP

Which looks a little more sensible that 1700hp and not alot different from:

(4 * 550 * 0.85 idc)/(5.25cc/min/hp) = 356HP

pay attention at the back of the class please!

Paul

 

so 440's with slightly increased fuel pressure should see me ok for 340ish bhp?

David

 

So therefore say 5.6cc per bhp, so 350bhp would require

350 x 5.6=1960

1960/4=490 injectors, therefore 550 injectors.

or 440 x 4=1760
1760/5.6=315BHP

So i will need bigger injectors then?

 

Sir!

Can you go through that again please, but this time with 440 injectors as your guide.

<Hate friday afternoon double maths>

DARLEY

 

fuel pressure can be raised fairly cheaply. easily an extra 1 bar giving 15% more fuel, possible another 1.5bar which gives 22% more fuel (standard fuel pressure is nominally 3bar)

Not sure what the pumps are good for flow wise at pressure, but their general rating is 6.5-7bar (possibly at very low flow though). Fuel pressure is above manifold pressure, so raising pressure to 4bar nominal at 1.5bar boost, means 5.5bar at the pump.

Might be worth pushing for 1.5bar more, giving 6bar at the pump, maybe someone can say if the pump is good for the required flow at this pressure?

Using 5.6cc/min/HP, 440s at 4bar would be good for about 360hp at 100% duty cycle, but only 324hp at 90%idc (pushing it by all accounts)

Due to the interest in cheap 550cc and larger injectors (I get about 6 emails whenever I mention it), I am enquiring about getting some in sensible numbers from a variety of my sources.

Paul

 

 

i deffo want four I think..

 

here you go paul
walbro 255 ltr/hr pump like we have is 'GSS341' as shown in the key below:



ian

 

fan tastic!

 

360hp is about 2 litres per minute

pretty much 4.5litres per gallon

so 360hp = 26 gallons per hour.

4.5 bar fp + 1.5bar manifold pressure (a lot with a big turbo, more likely to be around 1.35bar)

6 bar total = 87psi say 90psi at the pump (possibly more)

at 90psi we can run 34 gallons per hour, enough for 430hp

so running 6 bar total fuel pressure for 360hp looks possible, with a little headroom, interestingly the bosch pump is significantly better when looking at high pressures.

Assuming 5.6cc/hp

running 550s at 4.5bar would flow about 671cc/min giving 407hp@85%idc
running 440s at 4.5bar would flow about 537cc/min giving 326hp@85% idc

Assuming 5.2cc/hp

running 550s at 4.5bar would flow about 671cc/min giving 430hp@85%idc
running 440s at 4.5bar would flow about 537cc/min giving 344hp@85% idc

running 380s at 5bar! would flow about 490cc/min giving 314hp@85%


To be running less fuel means getting rid of det in other ways, like lower intake temps, meaning FMIC, bigger turbo.

please don't take the above as gospel, your fuel engine may wel be different, if in doubt, get the biggest injectors you can.

Paul

 

so this pump, with 550's, and upped line pressure should be fine for my engine then?

 

looks that way..

David

 

apologies, getting my greens and greys mixed up again.

 

so If im running water or water / methanol mix I would need less fuel wouldnt I?

Not that Im thinking of being cheap...

550's or 740's here I come...

Paul sort me some out, and Im not using phase 2 rails!

David

 

that's what you think!

Only have cheap phase 2 compatible ones available, possibly get s/h fuel rails for a phase 2 engine. Otherwise it's a good excuse to get busy with the tig welder on stainless.

Paul

 

Mark I did say for FOUR injectors (as in size of EACH injector) since most of us are using that number it makes the sums easier

 

Paul/Mark/David/Anyone else

Am i right in thinking that to fully exploit my forthcoming setup i would be best with 550 injectors or higher.

Paul can you sort me some ASAP please, if that is the case.

Mail me cost please, and anticipated delivery times please

Steven

 

see thread in drivetrain.

am working on it.

paul