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08-27-2011, 11:56 PM | #2076 | |
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Quote:
Please do this math and either confirm or prove I am wrong. (this is bugging me a lot) At 6000 rpm you say there is 20ms IPW total time during the intake stroke alone. That means that on every rev there is 40ms total time. (80 ms total for 4 strokes which is 2 revs) 1 rev/40ms = 1500 rpm You are off by a factor of 4. I am convinced you have this 100% wrong. I am sorry about that, but I do think it is true. PLEASE READ THE MATH I PUT OUT, AND SEE. I would actually love to be wrong. Maybe I will have a duuuuuuuuuuuuh moment, maybe you you will, but I do want this solved. Thanks.
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08-28-2011, 02:35 AM | #2077 | |
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Quote:
If you still have a hard time understanding, read this link from drive magazine. It states exactly that the injectors only open during the intake stroke per cylinder. http://drive2.subaru.com/Spr08/Spr08_whatmakes.htm -Gabe Additional from your last example trying to convert my math back: Your math is wrong @ 6k sating it is 1500 rpm with 20ms intake stroke time. You must convert rev/time to time/rev at the correct point in your calculation. You are not doing this correctly (order of operations). 20 ms per 1/2 rev is what I state. 0.05 1/2 revs per ms (convert ms per 1/2 rev to rev per ms; it must be converted here) 0.1 revs per ms (make it a full rev) 100 revs per second @ 6k (second conversion) 6000 revs per minute @ 6k (minute conversion) However, since we have calculated what it takes for one stroke and two strokes equals 1 rev, we can simply do the addition to state that 40ms per rev or 80ms @ 6k rpm IPW = 100% DC as the camshaft has now turned 360*. If the injector fires during a full revolution of the cam, you have 80ms of pulse width to deliver fuel. That would have the injector open all the time. The RR logger @ 100% DC is a true 1/4 of injector opening time per cam rev. Also, this is why WRX injectors are often a popular v8 swap as many modern v8's run in batch mode (due to intake manifold design, they do not have individual runners). Here is an example: http://www.vividracing.com/catalog/p...z-p-19750.html 380cc injectors for a forced induction 350z???? WTF? Why do we need 550CC injectors then on a 300 hp stock FI engine? What gives? I mean, yeah 6 of those are near the same amount of flow as 4 stock STi injectors, but the 350/370zs make as much power or more than an STi. And these are an upgrade for forced induction on a 350z which puts it into the 400-500 whp range? The 350Z runs their injectors in batch mode. The tuning books out there do not talk about sequential multi port. They were written back when fuel injection worked like your meth nozzle. That is, independent of whether the injector needed to fire only during the intake stroke and was pointed right at the intake valve in a runner. That is why the old saying of 80% IDC is the max you should go. Not on our cars. Our car's injectors never hit 80% true IDC. The cam does overlap a bit (duration) and this is why you can go to 110% logged IDC before the AFRs go wacky on an 07 STi. What interests me is that the AFRs go wacky @ 117% IDC on an 06 STi. My hunch is that the 07 has a shorter duration, higher lift cam. The exhaust cam did change to non sodium filled in 07. Also, I could get more power and tq on a stage 2 tune out of my 07 than my wife's 06. One last edit... If this does not resolve the confusion, lets take the discussion over to RR forums. I can show you some code there. Gabe Last edited by gabedude; 08-28-2011 at 04:32 AM. |
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08-28-2011, 09:23 PM | #2078 |
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A while ago I used a spreadsheet to calculate injector flow requirement based on airflow that the engine/turbo is ingesting. It came up with:
At ~270g/s (typical STI flow rate at sea level), the fuel flow required is ~2020cc/min. With 4 injectors, I would need ~505cc/min from each. This would be the full capacity of the injectors and data logs also show ~100% IDC. Am I missing something here? |
08-29-2011, 03:23 AM | #2079 |
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I don’t understand where you are getting .05=1/2rev. .05 is what? When 20ms=1/2rev I also come up with 1500rpm. 1rev/40ms=.025rpms=25rps=1500rpm
Correct me if I am wrong I am also having a hard time understanding how you are coming up with your results. Last edited by tobywongg; 08-29-2011 at 04:56 AM. |
08-29-2011, 08:14 AM | #2080 | |
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Quote:
Is anyone reading the link from drive magazine or wikipedia? Look at the manifold design and tell me how exactly you could pool fuel in that runner for 3/4 of the time. Spray pattern would not even be important at that point. Maybe a log will help. Code:
TIME AFC1 AFL1 AFS1 ATP WTMP LOAD RPM FBKC FLKC ILTC IPW IAM IGN IDC IAT VVT NCA KSUM MRP MASG MASV WGDC TOA VSPD LC1 368609 0 0 12.49 14.07 189 1.5 3350 0 0 1.0392 9.73 1 30 27.43 111 14 2.76 9 1.25 86.37 2.98 46.67 100 40 12.44 368722 0 0 11.99 14.07 189 1.62 3384 0 0 1.0248 10.75 1 30 29.94 111 15 3.15 9 2.27 94.24 3.04 46.67 100 40 12.01 368833 0 0 11.22 14.07 189 1.73 3438 0 0 1.0272 11.52 1 30 33.28 111 15 3.51 9 3.25 101.51 3.1 46.27 100 40 11.91 368928 0 0 11.02 14.07 189 1.85 3506 0 0 1.0225 12.29 1 30 36.28 111 16 3.92 9 4.6 110.13 3.2 46.27 100 40 11.73 369041 0 0 11.02 14.07 189 1.97 3564 0 0 1.0225 13.31 1 30.5 39.86 111 17 5.93 9 5.79 118.71 3.28 45.88 100 40 11.82 369153 0 0 11.02 14.07 189 2.15 3592 0 0 1.0102 14.85 1 31 45.09 111 18 9.25 9 7.35 131.89 3.42 45.88 100 41 11.44 369250 0 0 11.02 14.07 189 2.4 3686 0 0 1.0562 16.64 1 31 52.46 111 20 13.37 9 9.01 148.09 3.56 45.49 100 41 11.2 369361 0 0 11.02 14.07 189 2.7 3744 0 0 1.0418 19.46 1 30.5 61.82 111 22 13.81 9 11.15 169.89 3.74 45.49 100 41 10.92 369474 0 0 11.02 14.07 189 3.09 3810 0 0 1.0465 22.78 1 29 72.85 111 23 14.82 9 14.23 201.97 3.9 45.1 100 41 10.85 369570 0 0 11.02 14.07 189 3.45 3914 0 0 1.0465 24.06 1 28.5 85.52 111 23 15.06 9 17.26 226.47 4.04 44.31 100 41 10.73 369682 0 0 11.02 14.07 189 3.82 4014 0 0 1.0538 27.65 1 27 97.15 111 23 15.43 9 19.97 261.1 4.18 44.31 100 43 10.51 369796 0 0 11.02 14.07 189 4.19 4123 0 0 1.078 30.46 1 26.5 107.99 111 22 15.3 9 22.72 299.04 4.26 41.18 100 43 10.33 369888 0 0 11.02 14.07 189 4.37 4268 0 0 1.066 30.21 1 26.5 109.26 111 21 15.03 9 23.59 306.89 4.28 37.65 100 43 10.69 370002 0 0 11.02 14.07 189 4.27 4446 0 0 1.0538 29.44 1 26.5 110.07 111 19 14.85 9 23.77 315.43 4.3 37.65 100 43 11.38 370096 0 0 11.02 14.07 189 4.07 4644 0 0 1.0562 27.9 1 27.5 111.24 109 17 15.07 9 23.38 312.01 4.28 37.65 100 47 11.73 370209 0 0 11.02 14.07 189 3.93 4868 0 0 1.061 27.39 1 28 113.99 109 14 15.12 9 23.02 314.41 4.36 36.47 100 47 12.07 370321 0 0 11.02 14.07 189 3.83 5149 0 0 1.0443 26.88 1 28 118.21 109 10 14.97 9 22.88 324.98 4.36 34.12 100 47 12.35 370418 0 0 11.02 14.07 189 3.73 5394 0 0 1.049 26.11 1 29 119.36 109 6 14.21 9 22.41 332.14 4.38 29.41 100 47 12.57 370531 0 0 11.02 14.07 189 3.62 5623 0 0 1.0588 25.09 1 30 119.42 109 1 14.06 9 21.64 337.37 4.38 27.06 100 47 12.58 370640 0 0 11.02 14.07 189 3.51 5758 0 0 1.0538 24.58 1 30.5 119.61 109 0 14.06 9 20.59 335.44 4.38 25.88 100 52 12.48 370736 0 0 11.02 14.07 189 3.46 5840 0 0 1.0588 24.32 1 30.5 117.96 109 1 14.06 9 20.16 336.74 4.38 24.71 100 52 12.39 370848 0 0 11.02 14.07 189 3.48 5783 0 0 1.078 24.06 1 30.5 113.45 109 1 14.06 9 19.7 334.14 4.32 27.06 100 52 12.35 Code:
Calc RPM/2 IRPM/60 ISPS/1000 1/ISMS 1000.00 500.00 8.33 0.008333 120.00 1500.00 750.00 12.50 0.012500 80.00 2000.00 1000.00 16.67 0.016667 60.00 2500.00 1250.00 20.83 0.020833 48.00 3000.00 1500.00 25.00 0.025000 40.00 3500.00 1750.00 29.17 0.029167 34.29 4000.00 2000.00 33.33 0.033333 30.00 4500.00 2250.00 37.50 0.037500 26.67 5000.00 2500.00 41.67 0.041667 24.00 5500.00 2750.00 45.83 0.045833 21.82 6000.00 3000.00 50.00 0.050000 20.00 6500.00 3250.00 54.17 0.054167 18.46 7000.00 3500.00 58.33 0.058333 17.14 7500.00 3750.00 62.50 0.062500 16.00 |
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08-29-2011, 08:18 AM | #2081 |
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Order of operations, read the previous post. I'll explain more tonight.
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08-29-2011, 09:40 AM | #2082 | |
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Quote:
3000cpm/60=50 cycles per sec 1sec/50cps=.02 sec per cycle .02spc*1000=20ms of the cycle that injector can be opened 16ms ipw/20ms (100% time)=80%idc (time) I don't see what is so complicated with that equation? |
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08-29-2011, 03:21 PM | #2083 |
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Makes perfect sense. I have read several tuning books over the years and have been basing my understanding off of the information in them. Thanks for clearing that up, and thanks gabedude for taking the time to educate us.
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08-29-2011, 10:20 PM | #2084 |
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Just remember that some cars still do fire in batch mode or a variation of batch, but not many (mainly v6s due to firing order). For the calculations airboy mentions, the wikipedia link I posted has example formulas for sequential fuel injection to calculate pulse width, injector sizing, etc. In the formulas you can clearly see the calculations are for sequential injection as they are calculated on the intake stroke of the otto cycle.
Now, back to the topic at hand, where is Leslie? Is everyone getting similar results road dyno wise with fast poll vs non fast poll? Mine are near identical if logging only rpm and vs on regular mode. |
08-30-2011, 06:04 AM | #2085 | |
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Quote:
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08-30-2011, 09:45 AM | #2086 | |
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Vehicle:02 billet crank pauter rods, pt5857, E85 |
Quote:
2.5ltr=152.6 cubic inches 152.6ci/1728 (cubic inches per foot)=.0883 6000rpm/2=3000 intake cycles per min. 3000cpm*.0883=265 cfm 265cfm*.95 (VE for 4 valve engine)=225.3cfm 225.3cfm*.076 (weight of 1 cubic ft of air)= 17 lbs/min of air 17 lbs/min/4 cylinders= 4.25 lbs/min per cylinder 4.25 lbs/11.0 afr= ((.3863 (target fuel value))) Now take injector size 505cc/min=48 lbs/hr 48 lbs/60= (.8 lbs/min fuel max (100%idc)) Now figure IDC .3863 (target fuel value)/.8 lbs/min max delivery= 48% IDC This is on a N/A calculation. To figure on a forced induction I would use the cfm of your turbo charger to get you in the ball park. So if you used 498 cfm (vf22 at 14.7 psi) with the above equation you will be near 110% idc. The dynamics are great so trying to figure down to the exact % idc is not going to happen but, you can get a ball park figure. Hope this helps... |
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09-03-2011, 10:13 AM | #2087 | |
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Quote:
Gabe |
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09-03-2011, 10:20 AM | #2088 | |
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Quote:
It is useless as a tool IMHO if you cannot get reproducible close to real world numbers. I can get this because I have stock sized tires right now, but once the tire size changes, the logged VS is out the window. FWIW my logged VS matches my GPS, but VS is very slowly updated and reads slow past 120 mph. I would imagine this is because the ECU does even more high priority threads while under load for such a long time interrupting the ssm params. I have a log of some high speeds with fast poll. I will take a look at it to verify this. Gabe Last edited by gabedude; 09-03-2011 at 10:30 AM. |
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09-03-2011, 02:33 PM | #2089 | |
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Quote:
There is a small text box toward the lower right side of the page that indicates the time unit being selected. If it says "seconds" when you are using RR logs, that is the problem. If you go into the macro editor you can change the threshold to, say, 10 and it should fix it. can you send me a sample log? |
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09-03-2011, 03:13 PM | #2090 | |
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Quote:
What do you think is going on here? I am thinking some of the rpms are missed or off because the ECU hits a more important routine. |
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09-06-2011, 01:58 AM | #2091 |
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I wish I could get in on this. After 13 months on the road without a problem, I was "followed home" by our town's finest (three consecutive nights!). I don't think they'd like me at redline in 3rd gear. What is that, about 90 mph for the 5 speed?
Edit- Labor Day Weekend fundraiser probably. |
09-30-2011, 12:42 AM | #2092 |
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My XTi on high boost. 8 less PSI it trapped 127mph @ 3560lbs.
The sample log was a bit short, but I pulled on a 134mph r35 GTR from a roll so im sure it is making some decent power. Stock ej255 07 STI trans/rear/hubs Dw1300s Aero 340 HTA3582 .82 Spearco TMIC E85 Last edited by Junior2JZ; 09-30-2011 at 01:03 AM. |
09-30-2011, 12:54 AM | #2093 |
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How is the torque not dropping? It looks good down low. Can you add the boost curve to the plot?
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09-30-2011, 01:01 AM | #2094 |
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I said the same thing. I think the curve would be pretty flat on a real dyno though, but def have some drop off. I think it may have been because I was still accelerating pretty hard, I pull it to 8k and let off at 7k on that log. Tomorrow I will get some solid logs on my way to the track. I will get the boost plot up when I post the next one. Hope it doesn't let go
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09-30-2011, 01:09 AM | #2095 | |
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11-19-2011, 01:16 AM | #2096 |
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I guess no more dyno.
Last edited by kleedzine; 12-23-2011 at 09:34 PM. Reason: dead thread |
12-22-2011, 06:55 PM | #2097 |
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03-02-2012, 04:31 PM | #2098 |
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Anybody still doing this?
Last edited by banshee04; 03-02-2012 at 07:43 PM. |
05-11-2012, 05:17 PM | #2099 |
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I wish post 1 was updated. There are lots of good turbos in the last few years.
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11-29-2012, 11:59 AM | #2100 |
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It'd be great if the community would have someone continue this
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