Injector Flow Rates......? : V-Twin Forum: Harley Davidson Forums

ktwillys · 08-30-2009, 08:23 PM

When doing my last build I figured that I would go with a bigger fuel injector to reduce my risk of running at the limits of the injector.
So I got a couple of injectors from Drag..
I have done the calculations and come up with some numbers that dont make sense to me so I thought I would see what you all came up with..
I have the Drag injectors

1022-0009 FITS: 01-05 FXST, FLST, 02-05 FLT and 04-05 Dyna models, REPLACES: OEM #27609-01 - (high flow, 47 lb. per hour) $192.95

This item appears on page 338 of the Fatbook

and am trying to figure out the grams per second..
I know that the 04 stock injectors are at 4.22 gps
but the numbers I come up with for the drag injectors is
6.9 gps.. if this is correct boy did I go over board for my build...

jerry34208 · 08-30-2009, 08:59 PM

Quote:

Originally Posted by ktwillys

When doing my last build I figured that I would go with a bigger fuel injector to reduce my risk of running at the limits of the injector.
So I got a couple of injectors from Drag..
I have done the calculations and come up with some numbers that dont make sense to me so I thought I would see what you all came up with..
I have the Drag injectors

1022-0009 FITS: 01-05 FXST, FLST, 02-05 FLT and 04-05 Dyna models, REPLACES: OEM #27609-01 - (high flow, 47 lb. per hour) $192.95

This item appears on page 338 of the Fatbook

and am trying to figure out the grams per second..
I know that the 04 stock injectors are at 4.22 gps
but the numbers I come up with for the drag injectors is
6.9 gps.. if this is correct boy did I go over board for my build...

47#/hr = 94.83 grams/second

OK I'll admit I got a differenet answer the first five times I tried to figure this out but I think I have it now.

If I am correct you have one hell of a big injector there.

ktwillys · 08-30-2009, 10:06 PM

Quote:

Originally Posted by jerry34208

47#/hr = 94.83 grams/second

OK I'll admit I got a differenet answer the first five times I tried to figure this out but I think I have it now.

If I am correct you have one hell of a big injector there.

Thanks Jerry....the numbers should have come out something like a 4.22 gm/sec
I came up with 6.9 gm/sec.. 94.83 gm/sec would be huge.. I sure hope you are not right.. or man I really screwed up..

according to the DTT site it shows a calculation of:
Some companies rate injectors in lbs/hour, Delphi uses a metric rating of gm/sec. The appropriate conversion constant is 1 gm/sec = 7.93 lb/hour.
Using this calculation I come up with 5.9 gm/sec.. it still seems to large for my motor

rodriguc · 08-31-2009, 06:26 AM

This flow calculator equates 47 lbs/hr to 5.92 grams/sec.

http://online.unitconverterpro.com/u...ow---mass.html

ktwillys · 08-31-2009, 08:31 AM

Quote:

Originally Posted by rodriguc

This flow calculator equates 47 lbs/hr to 5.92 grams/sec.

http://online.unitconverterpro.com/u...ow---mass.html

very cool conversion page.. I knew it was out there but couldnt find it..

thanks..

jerry34208 · 08-31-2009, 09:23 PM

I gotta git me one a them

Snaps · 08-31-2009, 11:19 PM

The way I always do it is to convert pounds to grams and hours to seconds.

That way, 47 lbs/hr = 21318.84 g/hr x 1 hr/3600 sec = 5.92 g/s

jerry34208 · 09-01-2009, 04:09 AM

I was thinking 454 g/ounce. Dummy, it's 454 g/Lb, 28/oz. Just needed to divide my answer by 16.
Hell that's close enough aint it?

Back to the original question. I don't know the answer. Ha ha. If I had to guess though ... In order to use them I would reduce the fuel setting by the percentage of difference from the max flow rate of the new compared to the old injector's flow rate. This would get you in the ball park. Then tune from there.

In this case use 71.3% of the current setting for the new and larger injector. (4.22 is 71.3% of 5.92)

Hey, it makes sense in my world anyway.

ktwillys · 09-01-2009, 04:02 PM

and that makes it a sensable world....

Steve Cole · 09-02-2009, 02:10 PM

For those of you with Mastertune there is a injector calculator built in that let's you converter g/sec to lbs/hr and more. You will find it in the "Tools" menu.

barrybasinger · 09-02-2009, 02:35 PM

As to whether it's too big: I don't have my PC (Excel spreadsheet) with me, but I use 31 lbs/hr for 95 horses at no more than 83% duty cycle. Yours seem
like overkill to me. Problem when they get way too big is getting them to deliver small doses at idle.

ktwillys · 09-02-2009, 04:31 PM

Quote:

Originally Posted by barrybasinger

As to whether it's too big: I don't have my PC (Excel spreadsheet) with me, but I use 31 lbs/hr for 95 horses at no more than 83% duty cycle. Yours seem
like overkill to me. Problem when they get way too big is getting them to deliver small doses at idle.

I wasnt attempting to overkill. I did a quick calculation and figured it to be a 4.9 to a 5.0 injector.. I got a good price on them and it wasnt until I started checking on why I seem to be running rich that I questioned my calculations.. which I off by a decimal point in the calculation..
I am running about 105 horses so the 4.89 injector is the one that I wanted..

Steve Cole · 09-02-2009, 08:42 PM

If you can calibrate the idle fuel properly then it should be fine with what you already have. Are they a little big for what you need.............. sure, but as long as idle can be setup your fine.

ktwillys · 09-02-2009, 11:28 PM

I am running the Tmax with autotune and have no problems with my idle.. it seems to work very well..
the only problem I have is that I cant find where in the software to find out which injectors are used in the map..
of course TMax is way to busy to answer their phone.. 30 phone calls and not answer from the tech line and the front dest will only transfer you to the tech line..
I also have sent 3 emails over the last couple of weeks and again no answer..

got to love customer service... not good

rodriguc · 09-03-2009, 08:14 AM

You may find this RB Racing fuel injector calculator useful (bottom of page). Assuming a fuel pressue of 43.5, if your 103ci engine were putting out 110 hp, you would only need 34 lbs/hr to feed the beast for a duty cycle of 80%. Your 47 lbs/hr jectors have a potential of up 150 hp at 80% duty cycle.

http://www.rbracing-rsr.com/fuelinjectors.htm