gokussx4

iTrader: (3)

These are advertised as 42lb injectors at 3bar. Maybe I am crazy but please help confirm

Bosch says 0280155968 is 310 g/min @ 3bar (43.5 psi) which is also 310 c3/min or cc/min however you want to label it.

When I run that through any of the calculators I get a 37.1 lbs/hr injector at 4 bar or 58 psi.

How is it possible that this bosch green giant is known to be a 42 lb injector at all?

I must be missing something here. Please help!

JakeFusion

iTrader: (7)

What's the conversion you're using?

I see two for g/min to lbs/hr. One says divide by 10.5 (RC Engineer) and it gives me 29lbs/hr. And the other says to multiple g/min by 0.132277465211 and that gives 41lbs/hr.

lol?

gokussx4

iTrader: (3)

yea thats why I am so confused. For example:
http://www.witchhunter.com/injectorcalc1.php

If i punch in 310 cc/min that gives me the 10.5 division and an outcome of 29 lbs/hr. Bosch's docs are in g/min. My search says 1 g/min = 1 cc/min.

Google tells me one thing with its built in calculations and the calculator designed specifically for conversion from cc to lbs says another.

lol and here I thought the math was easy

usdmholden

310 g/min is only 310 cc/min when the specific gravity of the fluid is equal to one.

Gasoline specific gravity is not 1, it ranges from about .68 to about .78 depending on the fuel being used. Most unleaded gasolines have a specific gravity of about .72 to .73. Unless you know the SG value used by Bosch, we will always only be guessing at their rating conversion.

From my calculations, 310 g/min converts to 41 lb/hr.
310 g/min * (60 min/hr) / (454 g/lb) = 40.97 lb/hr

310 g/min divided by SG of .73 = 425 cc/min, and according to the witchhunter website you linked, calculates to 40.5 lb/hr.

gokussx4

iTrader: (3)

Thanks for the math! What did you use to arrive at 454 g/lb?

usdmholden

1 pound = 453.6 grams. It's easier to type 454, and since we don't know the SG which Bosch actually used, the difference in calculated values between 453.6 and 454 is irrelevant.

Also, at 58 psi it should be a 47.3 lb/hr injector.
41 * square root(58/43.5)

usdmholden

So actually according to this data sheet
http://www.bosch-motorsport.de/pdf/c..._Valves_en.pdf

It appears as if Bosch uses a SG value of .744 for gasoline.

This changes the volume flow calculation to:
310g/min / .744 = 417 cc/min

It's still a 41 lb/hr injector.

gokussx4

iTrader: (3)

Excellent answer and reference! Really appreciate it, makes much more sense now.

gokussx4

iTrader: (3)

For those that are curious I found this calibration sheet which will help with tuning:
http://www.boschdealer.com/specsheets/0280155968cs.jpg