HarleyTechTalk

Dyno & Tuning Zone => AFR & Tuning Zone => Topic started by: 838 on March 06, 2019, 02:18:18 PM

Title: 5.3 or 6.2 injectors?
Post by: 838 on March 06, 2019, 02:18:18 PM
117" 11:1 with cr575i. Rush wrath pipe SE 58mm with heavy breather.

Do I need 6.2s or are 5.3 injectors right?
Title: Re: 5.3 or 6.2 injectors?
Post by: Kllongbrake on March 06, 2019, 07:09:37 PM
5.3
Title: Re: 5.3 or 6.2 injectors?
Post by: Durwood on March 07, 2019, 04:51:53 AM
Quote from: 838 on March 06, 2019, 02:18:18 PM
117" 11:1 with cr575i. Rush wrath pipe SE 58mm with heavy breather.


Is this a typo? If not, that's too much compression for the CR-575.
Title: Re: 5.3 or 6.2 injectors?
Post by: 838 on March 07, 2019, 05:03:53 AM
It's a REALLY good tune ;)

Edit: CR595i
Title: Re: 5.3 or 6.2 injectors?
Post by: itsafatboy on March 10, 2019, 04:23:35 PM
Im sure 5.3 are fine , I use the 6.2 on my 116" and crunched the fuel reg, to get more pressure , my opinion and could be wrong is I like the shortest duty cycle I can get , since shared intake get fuel in quick and shut off, same with cams low overlap , thats why I like the woods tw8g ,  but this is just me ,

Title: Re: 5.3 or 6.2 injectors?
Post by: N-gin on March 30, 2019, 05:34:32 AM
5.3
Got them in a 120 well into the 150hp range.
To big of an injector will cause idle issues.
Title: Re: 5.3 or 6.2 injectors?
Post by: rageglide on April 02, 2019, 09:37:15 PM
What N-gin said  :up:
Title: Re: 5.3 or 6.2 injectors?
Post by: To The Max on April 09, 2019, 03:44:00 AM
HI, I have a m8 with a 117 with a SE 55 mm manifold . I have just done a data log and im seeing 19 ms on the inj pwm I think its to much. im thinking bigger injectors , if so what size? sory for just jumping in ,was just about to start a post when I saw this one Max
Title: Re: 5.3 or 6.2 injectors?
Post by: kd on April 09, 2019, 05:15:48 AM
I am using 6.2's in a 120 with no "too much for idle issue" and many others are too.  It's all in the tune and can be handled from there.
Title: Re: 5.3 or 6.2 injectors?
Post by: Barrett on April 09, 2019, 06:27:17 AM
www.5250performance.com/blog/fuel-injector-upgrades-when-is-bigger-better

This guy says go one size larger than what you expect you need.
About the opposite from cams...
Title: Re: 5.3 or 6.2 injectors?
Post by: Ohio HD on April 09, 2019, 06:47:37 AM
5.3g/s will be fine with that 117" motor.

I ran SE 5.3g/s for 40k + miles in a 117", never an issue. Made great HP and torque, with a lot hotter set of cams than you'll be using.

Best thing top do is ask your tuner guy what he thinks.   
Title: Re: 5.3 or 6.2 injectors?
Post by: To The Max on April 09, 2019, 03:58:01 PM
Thanks guys , my objective is to get the maximum inj pulse width down to 12 to 14 milli seconds max .I think ohio hd is on the money. if any one else has any idea's they would be welcome. Max
Title: Re: 5.3 or 6.2 injectors?
Post by: lonewolf on April 10, 2019, 08:00:55 AM
Quote from: To The Max on April 09, 2019, 03:58:01 PM
Thanks guys , my objective is to get the maximum inj pulse width down to 12 to 14 milli seconds max .I think ohio hd is on the money. if any one else has any idea's they would be welcome. Max

At the other end, idle and low end if you get into the non-linear area of the injector you may have a tough time tuning it. You will ask for more fuel and get less and vice versa. Open exhaust plays into it as they usually don't like lots of fuel down low. I don't think there is an issue with seeing 80%+ duty cycle.
Title: Re: 5.3 or 6.2 injectors?
Post by: Don D on April 10, 2019, 08:13:57 AM
I think the injectors on the smaller side and running at a high duty cycle is a better plan. You will not lose power but you will gain resolution down low
Title: Re: 5.3 or 6.2 injectors?
Post by: To The Max on April 10, 2019, 03:29:19 PM
Quote from: lonewolf on April 10, 2019, 08:00:55 AM
Quote from: To The Max on April 09, 2019, 03:58:01 PM
Thanks guys , my objective is to get the maximum inj pulse width down to 12 to 14 milli seconds max .I think ohio hd is on the money. if any one else has any idea's they would be welcome. Max

At the other end, idle and low end if you get into the non-linear area of the injector you may have a tough time tuning it. You will ask for more fuel and get less and vice versa. Open exhaust plays into it as they usually don't like lots of fuel down low. I don't think there is an issue with seeing 80%+ duty cycle.
so your both thinking the 5.3 injectors ?. about 15-16 ms
Title: Re: 5.3 or 6.2 injectors?
Post by: joe_lyons on April 10, 2019, 08:20:35 PM
15-16 at what rpms?  Calc up duty cycle and try to keep it under 85-90ish.
Title: Re: 5.3 or 6.2 injectors?
Post by: To The Max on April 11, 2019, 03:41:16 AM
Quote from: joe_lyons on April 10, 2019, 08:20:35 PM
15-16 at what rpms?  Calc up duty cycle and try to keep it under 85-90ish.
Hi Joe, at 3800 rpm im seeing 19.71 on the front and 19.22 on the rear. and im seeing 17.00's right through to 6000 rpm. Max
Title: Re: 5.3 or 6.2 injectors?
Post by: To The Max on April 11, 2019, 03:56:44 AM
Joe, did the calc at 6200 rpm and 17.02 ms and got 88% you think that will be ok ? Max
Title: Re: 5.3 or 6.2 injectors?
Post by: To The Max on April 13, 2019, 03:18:48 AM
Because im so impatient I decided to fit the 5.5 oem injectors at 3600-3900 am seeing 18.80 ms and at 5700 13.00 ms cant say the bike feels any different. Max
Title: Re: 5.3 or 6.2 injectors?
Post by: itsafatboy on April 20, 2019, 02:20:40 PM
Maybe because I use a thundermax not sure but I have the 6.2 on a 116" and have no idle issues even with a little higher fuel pressure(crunched the spring)  but bike idles great even at 896 rpm.  so what is wrong with the way I think that the shortest pulse width is best on a shared runner ,  don't you want the fuel to get in fast as possible so its not spraying on a closed valve or am I not thinking right on this .   I always thought open get it in then close same as cam that's why I loved the TW8G lowest over lap quick ramps .
Title: Re: 5.3 or 6.2 injectors?
Post by: hdfat2002 on May 19, 2019, 01:44:13 PM
16ms would have you at 80% duty cycle at 6,000RPM.

Rule of thumb is to stay below 85% at max.

-Brown
Title: Re: 5.3 or 6.2 injectors?
Post by: scotman623 on August 27, 2019, 11:35:22 AM
Personally I would stay with the 5.3.. Just my opinion and what I have done..
Title: Re: 5.3 or 6.2 injectors?
Post by: jjdalynh on September 06, 2019, 04:33:16 AM
i'll just add my $.02, not sure if it will help but just another example....   i have 5.3gps in a 11:1 107" with TW8 cams, at 6K i'm at about 15ms PW WOT.  Additionally, i've reduced my injector sizing in the map to 4.89 to keep my displacement from going too far (it's at 121.7 after bumping a couple times from the initial 113" i had it set at).  I'm sure if i'd just let the displacement increase (at one point it was pushing me for 134") the PW would be down a couple more ms.