2013 vs. 2007 injectors - effects on duty cycle

[fullboogie]

Yesterday I installed 2013 injectors in place of my stock '07 injectors because my FP and injector duty cycles are way too high. If you've ever wondered how much head room 2013 injectors will give you, here is my data:

Stock Injectors:

4,000 rpm: injector duty cycle 68.7%; FP duty cycle 71.8%

5,000 rpm: injector duty cycle 84.1%; FP duty cycle 82.0%

6,000 rpm: injector duty cycle 97.1%; FP duty cycle 96.2%

6,200 rpm: injector duty cycle 99.1%; FP duty cycle 98.7%


2013 Injectors:

4,000 rpm: injector duty cycle - 66.9%; FP duty cycle 72.3%

5,000 rpm: injector duty cycle 79.1%; FP duty cycle 80.0%

6,000 rpm: injector duty cycle 94.3%; FP duty cycle 91.3%

6,200 rpm: injector duty cycle 94.0%; FP duty cycle 91.4%

Keep in mind, this is just with an initial tune that is running very rich (11.0 AFR) at WOT. Once tweaked, the numbers will come down a tad. The tune with the stock injectors is after remote tuning on a chassis dyno and multiple revisions. End result is that while I expected a tad more, after a tune revision I should be fine - particularly since it is as cold as it is ever going to get in Houston. In warmer weather, I'll have plenty of head room. I hope this info is helpful.

Seteup is 2013 TVS, 2.39" upper, 123mm CAI, 63.5 TB, 17.5V BAP, and axle backs. It makes around 625-640 hp depending on the day its on the dyno.

 

[Ninjak]

Thats some good info

 

[jml1521]

My duty cycle is at 95% with 13 injectors and no bap with similar setup aside of a 66l&m throttlebody I hope a bap will bring it down some

 

[1320 Junkie]

theres a lot of ways to gain DC on injectors on these new cars...do you happen to know what both stock and 13 injector rail pressures were? that makes a huge difference...also the BAP will gain you a ton of DC surprisingly. Im jumping to 80's myself this winter and selling my 13 injectors to a buddy.

 

[IronTerp]

Excellent information Boogie. Interesting that you can get a dual benefit of Injector AND Fuel pump duty cycles with the addition of these injectors. Looks like that up to 650-660 RWHP with the 07-09' GT500's, upgraded injectors can satisfy increased fuel demand without the need for a BAP?

 

[Van@RevanRacing]

What was commanded fuel pressure before and after? Same or changed? Incomplete analysis.

 

[fullboogie]

What was commanded fuel pressure before and after?

Good point - I hadn't thought of that. Fuel pressure with stock injectors was between 58 and 60 psi. Fuel pressure with 2013 injectors was 50-52 psi. So I take it that is good. Lower duty cycle on injectors and pumps with less fuel pressure.

 

[fullboogie]

Looks like that up to 650-660 RWHP with the 07-09' GT500's, upgraded injectors can satisfy increased fuel demand without the need for a BAP?

I don't know about that, Terp. I guess it depends on what is safe. I would think that without a BAP, I'd be back up into the high 90% even with the new injectors.

 

[me32]

I don't know about that, Terp. I guess it depends on what is safe. I would think that without a BAP, I'd be back up into the high 90% even with the new injectors.

Bap is a good safety net.

 

[PistolWhip]

I thought you could lower the injector DC by raising the line pressure slightly (within a certain limit of course), am I wrong there?

 

[fullboogie]

I thought you could lower the injector DC by raising the line pressure slightly (within a certain limit of course), am I wrong there?

You're right. Justin was able to lower fuel pressure with the new injectors to take some strain off the pumps. Looks like it worked, since everything went down. I'm sure if pressure were still at 60lbs, injector duty cycle would be even lower, albeit at the expense of pump duty cycle. Bit of a balancing act, I suppose.

 

[IronTerp]

I don't know about that, Terp. I guess it depends on what is safe. I would think that without a BAP, I'd be back up into the high 90% even with the new injectors.

I didn't pay close enough attention to your sig and now see that you are running a BAP with your setup. I'm running a stock fuel system at 595 RWHP and am at 95% FPDC so am predicting that by switching out to higher flowing injectors could get some extra cushion?

 

[PistolWhip]

You're right. Justin was able to lower fuel pressure with the new injectors to take some strain off the pumps. Looks like it worked, since everything went down. I'm sure if pressure were still at 60lbs, injector duty cycle would be even lower, albeit at the expense of pump duty cycle. Bit of a balancing act, I suppose.

Yeah, that's the way I understood it. I wish I would have logged my DC's last time I was on the dyno. Maybe next time.

 

[Silver_Serpent]

Does your fuel pump duty cycle really matter unless it is a high duty cycle combined with a low pressure? Really, couldnt you have the pumps at 100% while the car is idling (pressure would be high) ... would not mean your pumps are maxed out.

 

[jml1521]

With a Tvs on an 07 and 13 injectors installed my dc is at 95% I will be installing a boost a pump for added ins hopefully it will drop my dc I am curious to see how much

 

[IronTerp]

With a Tvs on an 07 and 13 injectors installed my dc is at 95% I will be installing a boost a pump for added ins hopefully it will drop my dc I am curious to see how much

Well, based on Boogie's research, it should drop your FPDC by about 6-8%.

 

[jml1521]

Doesn't seem like much????

 

[fullboogie]

Doesn't seem like much????

Well, if you're near maxing out your pumps and/or injectors in the 99-100% range, and a BAP and/or injectors brings you back down into the 92-94% range, isn't that worth it?

 

[jml1521]

I'm at 95% now was hoping hi 80s with bap

 

[- Aj -]

Sub'n for good info