The only mods on the car are Cantrell AIS, K&N drop in filter, Comptech headers, and a NA2 OEM exhaust.
Sale pending, my first project (should be a good one)
- Thread starter L_RAO
- Start date
Props to you Loc.
Here is a video showing the RDX injector spray pattern:
http://www.youtube.com/watch?v=bmy8bZHugRA&feature=player_embedded
Also, I sent in the OEM injectors to RC Engineering for inspection, flow testing, and, if necessary, cleaning.
http://www.youtube.com/watch?v=bmy8bZHugRA&feature=player_embedded
Also, I sent in the OEM injectors to RC Engineering for inspection, flow testing, and, if necessary, cleaning.
I have to admit I've been one of the skeptics as to this mod, but I must admit I'm impressed. Assuming the above-VTEC richness issue can be smoothed out, this looks like a promising mod. 30 wtq on the NSX is no joke.
I'm still waiting to hear a plausible explanation of cause and effect that says larger injectors make a difference based on the evidence presented. The charts show an extremely strong correlation between higher A/F and torque. Well duh. As I've stated, if you lean it out, you make more power. News flash: you don't need larger injectors to run less fuel. What knock-down factor was used for injector duration between the 2 runs with stock and larger injectors? And I'm not sure what definition of "rich" we're clinging to here, but running 3 A/F points leaner than stock at the top end isn't exactly running rich in my book.
Daedalus,
The purple line (RDX injectors + ProSpeed ECU) shows a AFR well below 11 in VTEC. Is that not running rich?
My interpretation is that, if anything, there is more power to be had since the (stock) and (ProSpeed ECU only) lines were running lean (non-VTEC) and in the sweet spot (near 13.5) in VTEC, whereas the RDX injectors + ProSpeed ECU line was just slightly rich (non-VTEC) and very rich in VTEC.
The purple line (RDX injectors + ProSpeed ECU) shows a AFR well below 11 in VTEC. Is that not running rich?
My interpretation is that, if anything, there is more power to be had since the (stock) and (ProSpeed ECU only) lines were running lean (non-VTEC) and in the sweet spot (near 13.5) in VTEC, whereas the RDX injectors + ProSpeed ECU line was just slightly rich (non-VTEC) and very rich in VTEC.
Yes it would be the opposite of what Daedalus mentioned. I'm glad to see you are being thorough and having the injectors tested. I'm still surprised how lean the stock ECU was going and how all over the place the AFR's are. My other car's stock ECU is pretty flat until ~5750 where it gradually dips down a point.
Does anybody else have charts with AFR's on an NSX with a stock ECU? I couldn't find any via searching the net
Does anybody else have charts with AFR's on an NSX with a stock ECU? I couldn't find any via searching the net
Sorry, I misread the purple A/F as stock. I'm surprised the stock injectors are in fact running that lean. If you're getting more power while running richer, especially if timing wasn't touched between the last 2 runs, then I'm a believer. Trail well blazed--Congrats on your solid gains.
Another thing I'll add, if it means anything, is that Brian (ProSpeed) did mention that in his research, he felt that the OEM injectors were pretty close to maxed out for a typical I/H/E setup.
Last edited:
This is my stock ECU, but bypassing cats. You can see I was pretty darn near 14.7:1 until VTEC kicked in and then it went right to 13:1. It reached a tad lean at 15:1 from 4k-5k RPM. Besides VTEC, it's also interesting to see the distinct change VVIS made at 4800RPM too.
I believe the injector spray pattern can help improve power and efficiency like you're doing L_RAO, but I think the gain in power around 4k RPM is because your OEM ECU is extremely lean at that point. Something doesn't look right with your OEM ECU. 16:1 is just too lean, even taking into account Bisi's potential wideband O2 measurement errors/uncertainties.
Those AFR's are just all over the place. Something is not right at all, old or new injectors/tunes.
Keep up the good research! Like I said before, I think we can get some better results going with newer technology. Our archaic piston design is also another area for improvement.
Dave
Dave,
Doesn't Lean = Power up to the point where you (pre-)detonate?
If anything, going from really lean to ideal (solid green line) should make less power, right? Since going from ideal to lean would make more power at the risk of detonation.
Edit: Oh wait, the dotted line vs. the solid green line proves otherwise.
Doesn't Lean = Power up to the point where you (pre-)detonate?
If anything, going from really lean to ideal (solid green line) should make less power, right? Since going from ideal to lean would make more power at the risk of detonation.
Edit: Oh wait, the dotted line vs. the solid green line proves otherwise.
Last edited:
I think the 16:1 is too lean at the point the OEM ECU was pulling timing and reducing power (perhaps due to knock?). That's perhaps why even at 13:1 AFR, there were some gains in power with the new injectors. Some of the gains were probably due to the better injector spray, but the 20ft-lbs difference at 4k RPMs may not just be due to the injectors. It's almost like the fuel pump wasn't kicking into high speed at the programmed 4k RPM 
I searched for a long time how to interface with the OBDI OEM ECU and monitor programmed fuel, timing, etc to no avail. It was when I was playing around with fuel mixes and wanted to confirm what the butt-dyno felt.
Below is an extremely interesting thread, and I'm curious like DDozier on how the stock ECU handles knock:
http://nsxprime.com/forum/showpost.php?p=1514211&postcount=103
Dave
I searched for a long time how to interface with the OBDI OEM ECU and monitor programmed fuel, timing, etc to no avail. It was when I was playing around with fuel mixes and wanted to confirm what the butt-dyno felt.
Below is an extremely interesting thread, and I'm curious like DDozier on how the stock ECU handles knock:
http://nsxprime.com/forum/showpost.php?p=1514211&postcount=103
Dave
Slight update. Got my OEM injectors back from RC Engineering:
(Note: I did not label the injectors when I pulled them off the car, so these are in order that RC tested them)
Before:
#1: 240 cc, good pattern
#2: 237 cc, dripping
#3: 244 cc, good pattern
#4: 239 cc, good pattern
#5: 245 cc, good pattern
#6: 234 cc, fair pattern
After (all had excellent spray patterns):
#1: 250 cc
#2: 249 cc
#3: 251 cc
#4: 250 cc
#5: 251 cc
#6: 249 cc
(Note: I did not label the injectors when I pulled them off the car, so these are in order that RC tested them)
Before:
#1: 240 cc, good pattern
#2: 237 cc, dripping
#3: 244 cc, good pattern
#4: 239 cc, good pattern
#5: 245 cc, good pattern
#6: 234 cc, fair pattern
After (all had excellent spray patterns):
#1: 250 cc
#2: 249 cc
#3: 251 cc
#4: 250 cc
#5: 251 cc
#6: 249 cc
We are set to meet up again and re-dyno on 1/30.
In the meantime, I wanted to throw this out there and see if I could get some brainstorming going: Any thoughts as to the value of adding an adjustable fuel pressure regulator and trying different fuel pressures?
From what I've been able to find online, it seems like the RDX injectors "like" fuel pressures greater than the NSX's OEM 38-44 psi.
In the meantime, I wanted to throw this out there and see if I could get some brainstorming going: Any thoughts as to the value of adding an adjustable fuel pressure regulator and trying different fuel pressures?
From what I've been able to find online, it seems like the RDX injectors "like" fuel pressures greater than the NSX's OEM 38-44 psi.
I'm by no means an engine mgmt expert but it looks like you're on your way to needing a full on Engine Management System.
Keep the updates coming!
Ryu,
I am doing everything in my power to avoid a full EMS. I want to explore all "low-budget" possibilities before going into the big time.
Next dyno day (1/30) looks very promising. I'll leave it at that. :biggrin:
I am doing everything in my power to avoid a full EMS. I want to explore all "low-budget" possibilities before going into the big time.
Next dyno day (1/30) looks very promising. I'll leave it at that. :biggrin:
I totally understand how you feel about avoiding a full EMS. I was the same way and had to go that route when I went Turbo... Things are in the works for larger things and hopefully we surprise a lot of people out there. After getting the AFR right we could squeeze a lil more with timing =) I am impressed so far and I give LOC credit for going out there and testing it out!
That's awesome! It'll be great to have more options. I'm subscribed to this thread!
You just started mentioning fuel pressure so I was thinking.. EMS automatically. It's reflex, I promise! lol If you remove the factory fuel pump resistor and find a way to control the injector pulses then you can up the fuel pressure to improve the spray pattern/atomization on the RDX injectors. That's my shot in the dark at least.
Last edited:
Good man. I hope you, Prospeed and sr5guy combine efforts to give us a RDX injector mod with ecu tune for I/H/E. 
Well, we just finished. Drum roll please...
We peaked at 264 wHP (over 247 wHP baseline) and 209 wTQ (over 196 wTQ baseline). That's +17 peak wHP and +13 wTQ over baseline.
As you can see, we picked up a TON of torque all over the powerband. The car is an absolute blast to drive.
Unfortunately, we did not have a chance to play with fuel pressure; we believe there is power to be gained from running the RDX injectors at 55-60 psi.
In addition, from the vacuum map there is a restriction in the intake; there is more power to be found.
I have included the dyno chart.
I have also include the AFR plots as well as the vacuum plots.
All in all, this is a great bang for the buck mod. The injectors plus hardware should run about $400, and the ECU is $350 plus 1 hour of dyno time. So anyone else should be able to get everything done for about $850-900. 20 wHP would mean would cost about $45 per HP.
We ended up spending 5 hours on the dyno to get this figured out.
Thanks again to Brian (Prospeed), Bisi, and sr5_guy for helping us out.
In the future I'll test out more fuel pressure. I think I will also find some HP in a better exhaust system.
We peaked at 264 wHP (over 247 wHP baseline) and 209 wTQ (over 196 wTQ baseline). That's +17 peak wHP and +13 wTQ over baseline.
As you can see, we picked up a TON of torque all over the powerband. The car is an absolute blast to drive.
Unfortunately, we did not have a chance to play with fuel pressure; we believe there is power to be gained from running the RDX injectors at 55-60 psi.
In addition, from the vacuum map there is a restriction in the intake; there is more power to be found.
I have included the dyno chart.
- Green is baseline.
- Red is ProSpeed ECU + RDX injectors (before we fixed the VTEC maps)
- Light blue is the ProSpeed ECU + RDX injectors (after we fixed the VTEC maps)
I have also include the AFR plots as well as the vacuum plots.
All in all, this is a great bang for the buck mod. The injectors plus hardware should run about $400, and the ECU is $350 plus 1 hour of dyno time. So anyone else should be able to get everything done for about $850-900. 20 wHP would mean would cost about $45 per HP.
We ended up spending 5 hours on the dyno to get this figured out.
Thanks again to Brian (Prospeed), Bisi, and sr5_guy for helping us out.
In the future I'll test out more fuel pressure. I think I will also find some HP in a better exhaust system.
Attachments
Last edited:
Another thing I wanted to mention was that hybrdthry911 was nice enough to put together a "is my fuel system adequate?" app here:
http://www.nsxprime.com/forum/showthread.php?t=149197&page=2
As you can see, the calculations on a stock application suggest that the OEM injectors are undersized even for a stock motor. This was verified by our stock AFR readings; I'm kind of lean and Prospeed has some other stock AFR plots that are even leaner!
Now I am making more power and my car is running a "safer" tune than stock! Win-Win.
http://www.nsxprime.com/forum/showthread.php?t=149197&page=2
As you can see, the calculations on a stock application suggest that the OEM injectors are undersized even for a stock motor. This was verified by our stock AFR readings; I'm kind of lean and Prospeed has some other stock AFR plots that are even leaner!
Now I am making more power and my car is running a "safer" tune than stock! Win-Win.
Similar threads
- Locked
