FP 71HTA / S2's / E85 / 459 & 402 @ 24PSI / RRE "Sam" Tuned
Feb 8, 2018, 02:05 PM
#32
Good news is (from what I can find), your RC 1000cc injectors are rated at 43.5 psi (my RC1200cc injectors were rated at 55psi, which means they are really 1090cc at 43.5 psi). So if we look at 43.5 psi, your injectors are rated at 4,000 cc/min. 1 gallon=3785.41 cc, so your injectors can flow 1.0567 gallons per minute. So for 1 hour, your injectors can flow 63.4 gph. Lookat your pump flow at 12V. I'm reading 57-58 gph. If your pump is actually getting 11V, you can be getting 52-53 gph.
Now, you're boosting 24 psi, so your injectors can flow more since fuel pressure is around 67.5 psi. But look at what your pump is pushing. If we look at the 12V curve, it's around 48 gph. That's like an equivalent flow of 700cc injectors running at 67.5 psi.
Now, you're boosting 24 psi, so your injectors can flow more since fuel pressure is around 67.5 psi. But look at what your pump is pushing. If we look at the 12V curve, it's around 48 gph. That's like an equivalent flow of 700cc injectors running at 67.5 psi.
Feb 8, 2018, 02:32 PM
#33
Don't just watch your AFR. Watch your IDC too. Personally, I feel that anything over 95% is pushing it much because cold nights will runs injectors over 100%. I'm not even sure if it is possible to run over 100%. My taeget is to run 90% IDC max because my tune at 99% ended up 104% at night where temps are 20 degrees lower I think it was mid 50s that night). What if it was 40s or 30s? Scary thought.
I don’t think cold nights will be an issue for me
You can go over 100%. Obviously, you’ve done it.
Not saying you should, but people have definitely ran it.
Feb 8, 2018, 02:54 PM
#34
Log shows 100%+ but I'm not sure it's possible. I'll need to calculate how many milliseconds my intake valves are open and compare with injector pulse width to see if all the fuel gets inside or does it pond for next cycle. The fuel pump and injector flows were more calculations than I wanted to think through. Lol
I was lazy when I let others select and install for me. I'll take a look at the calculations later. I think my brain is still cramping from thinking about our fuel pumps.
Ok, to start, let's think about 4 stroke engine. To go through one cycle engine crankshaft goes through two revolutions.
Let's start at 1000rpm idle. 1,000rpm ÷ 60 sec/min = 16.67 revs per second. Inverse gives us 0.06 seconds per revolution. If valves are open 1/2 of revolution every other revolution, so they're open for 0.03 seconds (30 miliseconds).
So at 7000 rpm, we only have 4.3 ms? Yikes! Let me check my log...Log shows 18 (I assume this is in ms) when I'm at 100% IDC. Now I'm really confused!
So injectors has continue spraying when intake valves are closed. At 8000 rpm, there's only 15 ms between each full cycle whete valves open. So spraying over 100% shouldn't be possible since injectors just stay open. At 6000 rpm, 100% IDC is 20 ms. At 8000 rpm, 100% IDC is at 15 ms. Just checked my log and the numbers match. So even if log shows over 100% IDC, injectors are static open.
I was lazy when I let others select and install for me. I'll take a look at the calculations later. I think my brain is still cramping from thinking about our fuel pumps.
Ok, to start, let's think about 4 stroke engine. To go through one cycle engine crankshaft goes through two revolutions.
Let's start at 1000rpm idle. 1,000rpm ÷ 60 sec/min = 16.67 revs per second. Inverse gives us 0.06 seconds per revolution. If valves are open 1/2 of revolution every other revolution, so they're open for 0.03 seconds (30 miliseconds).
So at 7000 rpm, we only have 4.3 ms? Yikes! Let me check my log...Log shows 18 (I assume this is in ms) when I'm at 100% IDC. Now I'm really confused!
So injectors has continue spraying when intake valves are closed. At 8000 rpm, there's only 15 ms between each full cycle whete valves open. So spraying over 100% shouldn't be possible since injectors just stay open. At 6000 rpm, 100% IDC is 20 ms. At 8000 rpm, 100% IDC is at 15 ms. Just checked my log and the numbers match. So even if log shows over 100% IDC, injectors are static open.
Last edited by 2006EvoIXer; Feb 8, 2018 at 04:48 PM. Reason: Calculation update
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MinusPrevious (Feb 8, 2018)
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2006EvoIXer (Feb 8, 2018)
Feb 8, 2018, 06:29 PM
#38
Evolving Member
Glad to see the HTA71 showing great results. I'll be pushing an HTA71 myself with a 2.4L, Walbro 450, 1650's, Jun264 cams, ATS triple carbon clutch, lots of STM goodies, & E85 in my Evo IV. Also converted to a full VIII longblock as well. Can't wait to have mine done. Car has been down since April 2017. 
Feb 8, 2018, 07:01 PM
#40
Just had a chance to flog it today. Takes some getting used to. The S2's really rumble & I can feel the loss in some low end, but it screams & carries high into 6K to low 7K range
Got a funny chugging sound at idle & does not happen all the time. Called Sam (Tuner) & he thought it might be the idle control valve on the throttle body.
Anyway, the car is pig dirty & feels like its been in the shop
Got a funny chugging sound at idle & does not happen all the time. Called Sam (Tuner) & he thought it might be the idle control valve on the throttle body.
Anyway, the car is pig dirty & feels like its been in the shop
Last edited by MinusPrevious; Feb 8, 2018 at 07:47 PM.
Feb 8, 2018, 07:08 PM
#41
Chugging? Like a train?
Just had a chance to flog it today. Takes some getting used to. The S2's really rumble & I can feel the loss in some low end, but it screams & carries high into 6K to low 7K range
Got a funny chugging sound at idle & does not happen all the time. Called Sam (Tuner) & he thought it might be the idle control valve on the throttle body. Anyway, the car pig dirty & feels like its been in the shop
Got a funny chugging sound at idle & does not happen all the time. Called Sam (Tuner) & he thought it might be the idle control valve on the throttle body. Anyway, the car pig dirty & feels like its been in the shop
