Anyone have a good calculator for this?

What would a 60# equate to at 58psi? 62psi?

Thx!

 

I think with an adjustable FPR you can get them to act like 83's, mightymouse was talking about this in one thread

 

You have to be careful when cranking the fuel pressure up with injectors.

If you are running big HP and intend on turning up the fuel pressure, it is always a good idea to flow the injectors at that fuel pressure.

FWIW, most injectors are designed for around 45-50 psi fuel pressure. If you start turning it up to 70-80 psi, some injectors don't balance well at all.

The calc for injector sizing with fuel pressure changes is:

New Flow = Old Flow * SQRT(New Fuel Pressure / Old Fuel Pressure)
New Flow = 50 * SQRT (58 / 43.5)
New Flow = 57.7 lb/hr

 

Thx!

 

PMed You
Kyle

Guess not your inbox is full so ill ask it here.

Kevin,

I have the 60's myself and i am making almost 500rwhp thru my stock 10 bolt and my 4L60E. Im running 6-7 psi now on my built motor and i noticed last night under WOT that my FP does drop a little. My base is set at 56 psi and my REG does have a 1:1 rate rise but im not using it. FP drops to almost 50 psi and im running a external Bousch 420L pump, with -8an feed line and Nasty Performance rails. Will that pump and Injectors be enough for my goal of 600rwhp with my new FMIC and 3.4" pulley? 3.7" blower pulley now. Should i raise FP or hook up the REG.?? I tried that last night and it dropped my Base FP to 50 psi and FP rose at the beginning of WOT to 56 psi, but then fell 2-3 psi as the motor climbed to my 6800 rpm shift point. Does the car have to be tuned different also for a lower base FP?? because it idles way wierd and wanted to die at stop lights witht the boost ref hooke dup on the reg. Sorry if this is so long........ you know what your talking about and i wanted your advice.
Thanks
Kyle

I know this goes in the Fuel section but i know i would get a response here. Thanks and feel free to PM me if you like.

 

Motoron 60's used at 58/60 psi will supply 72 pounds.

Dave

 

Just some quick notes that I've found from my discussions with the Sales/Support guys on their Mototron 60 injectors. It is clear that they've been successful accross a wider operating range than most injectors because the 60s were designed and built from the ground up to perform that way. Their spray pattern and control is consistently good. They are not stock design that have been hogged out, tested, given new specs and been repackaged to operate at a higher flow.

It's to the point that when you hear references about the Mototron's high impedance 75lbs injectors, you're talking about this very same 60lbs injector running at 68 PSI.

They have customers that are running these up into the 80 PSI range for racing and off shore power boat applications. They do get feedback from those customers and have been very pleased by their success in that kind of extreme range. The other interesting thing they are finding is that the injectors can tuned down to shorter pulse widths than LS1-Edit can support. The finer control of their spray pattern is making it pretty easy to tune that low and to offer a fairly linear flow curve that makes them perdictable for tuning where some of the other designs can be more challenging to tune.

Rick

 

So what your saying is i should raise my base Fuel Pressure?????? set at 56 psi right now with my 60's.
Thanks
Kyle

 

Figure your cars fueling requirments

Cylinder HP = RWHP + Driveline Loss + Supercharger Loss

I don't have enough information to calculate you drive loss on the supercharger, so I am just going to guess around 140 HP, which should be pretty close anyways.

Cylinder HP = 600 HP + 60 HP + 140 HP
Cylinder HP = 800 HP

This means that the equivlant HP that you care is going to be producing at the cylinders is 800 HP. This means your fueling needs to meet an 800 HP requirement.


Size the Fuel Pump

I'll use a BSFC of 0.65 to be on the safe side and assure proper size of the fuel pump. Your actual BSFC will probably be closer to 0.60

Required Flow' = Cylinder HP * BSFC
Required Flow' = 800 HP * 0.65
Required Flow' = 520 lb/hr

Include a 10% safety margin. Remember that a pumps discharge volume decrease with the required discharge pressure. Most manufactures don't include a pump flow map, so it is best to add a 10% fudge factor to ensure that you aren't buying anything twice.

Required Flow = 520 lb/hr *1.1
Required Flow = 572 lb/hr

Your pump is rated in l/hr so I will convert it over so we can compare. The density of premium gasoline is ~6.35 lb/gal

572 lb = 572 / 6.35 = 90.07 gal
90.07 gal = 90.07 * 3.79 = 341.36 l/hr

Your fueling requirement is 341 l/hr. You fuel pump will deliver 420 l/hr. Your fuel pump is big enough to handle the power.


Now we'll figure you required injector size using some of the above data.

Required Flow' = 520 lb/hr

We don't want to run the injectors any greater than 90% duty cycle so we need to add the 10% fudge factor here as well.

Required Flow = 572 lb/hr

Required Injector Flow = Required Flow / Cylinders
Required Injector Flow = 572 lb/hr / 8
Required Injector Flow = 71.5 lb/hr

71.5 is greater than your injector of 60 lb/hr so we need to figure out what kind of fuel pressure you will need to run to meet the demand. 70 psi is considered the ceiling for safe operation.

New Flow = Old Flow * SQRT(New Pressure / Rated Pressure)

We know what we want for flow so we need to solve for the New Pressure

New Pressure = Rated Pressure * (New Flow / Old Flow)^2
New Pressure = 43.5 psi * (71.5 lb/hr / 60 lb/hr)^2
New Pressure = 43.5 psi * 1.42
New Pressure = 61.7 psi

So it looks like you will be able to use your pumps and the 60lb injectors for your goal. Set your fuel pressure to 62 psi and call it a day.

Good Luck

 

Man that is awesome. I'm really learning a lot from your informative posts. Admin, how bout making Kevin a mod here in the FI forum? We can use some direction here in our unruly FI house

 

Thanks.

Wouldn't the .65 BSFC rating take into account the HP loss from driving the Supercharger?

Trying to digest all of this.

 

Nope. That's just how much fuel is required to make a specific amount of "cylinder" hp. Makes no difference what's hooked to the engine...

I agree with frcefed98, make nogo a moderator, if he wants to.... and I also agree that the fi house is unruly (knowing I don't help that aspect at times )

SC-

 

i am beating the crap out of mine and they are working flawlessly and asking for more.
new 'testing ' has shown they are still kicking at 19psi bost and 79psi rail pressure which is around 1kfwhp.

 

I would need to see a flow map to figure what your FWHP is, but I think it is probably somewhere closer to 900. Your turbo is much more efficient than the superchargers that I have been using in the prior calcs.

I'm not saying that you can't run injectors at that high a fuel pressure, but there are defiantly some drawbacks.

The higher psi you flow the injectors from their design pressure the greater the chance that your injectors won't balance. When I say balance I mean that all 8 of your injectors will be at different flows. This happens normally, but at higher fuel pressure this difference between injector flows becomes much more pronounced. This can cause uneven fueling among the cylinders. It is not detectable either being a wideband will take an AVERAGE of what the a/f is among the cylinders.

Addtionally, depending on the drive mechanism of the injector they may not function properly at all above XY pressure. Several injector styles *cough* Lucas *cough* actually pull against the fuel pressure to open. Increases in fuel pressure for these types of injectors can lead to severe balancing issues at high pressures and high loads.

FWIW, most injectors that we send out balance just fine up to 70 psi. There have been a couple types though that I wouldn't use above 55 psi though.

Rule of thumb is just make sure that your injectors can handle that type of pressure before using them at it, because the only indication that you will get that the cylinders aren't balanced is a dead hole.

 

it did @ 920 flywheel at 16.5 psi boost.. figure at least 25hp per # more for 19.

i have talked at length with mototron and have good faith in these babies. mototron makes good $hit.