00:00:00.030 hello everyone and welcome in this video 00:00:02.03000:00:02.040 I'm gonna be explaining how an octane 00:00:03.59000:00:03.600 rating can affect an engines performance 00:00:05.48000:00:05.490 the octane rating of the fuel now the 00:00:08.05900:00:08.069 cool thing about this video is at the 00:00:09.32000:00:09.330 end we're actually going to have an 00:00:10.12900:00:10.139 experiment conducted by shell which 00:00:12.35000:00:12.360 actually shows on a Volkswagen Golf TSI 00:00:14.91900:00:14.929 how the octane rating will actually 00:00:17.18000:00:17.190 affect that car's performance so very 00:00:19.91000:00:19.920 cool test uh but before we go into the 00:00:21.74000:00:21.750 test you need to understand the theory 00:00:23.47000:00:23.480 so a higher octane fuel allows for you 00:00:27.17000:00:27.180 to advance your ignition timing now why 00:00:29.68900:00:29.699 would you want to advance your ignition 00:00:31.33900:00:31.349 timing 00:00:31.88000:00:31.890 well ignition timing is all about a 00:00:33.56000:00:33.570 balance so let's look at the two 00:00:35.24000:00:35.250 different cases if you spark your 00:00:38.33000:00:38.340 mission to light the air fuel mixture 00:00:39.92000:00:39.930 within your cylinder too early you're 00:00:42.35000:00:42.360 going to have wasted energy so here 00:00:43.97000:00:43.980 we've got that example you've got your 00:00:45.77000:00:45.780 piston coming up you've ignited too 00:00:47.93000:00:47.940 early so you have this flame front 00:00:49.61000:00:49.620 you're burning the air fuel mixture and 00:00:51.08000:00:51.090 you're pressing down on that piston as 00:00:53.20900:00:53.219 it's still on its way up before it even 00:00:55.34000:00:55.350 reaches the power stroke and starts to 00:00:57.41000:00:57.420 move down to provide useful work so you 00:01:00.11000:01:00.120 don't want that to happen so you want to 00:01:02.18000:01:02.190 have the timing a little bit later but 00:01:04.16000:01:04.170 you don't want to work the timing too 00:01:05.96000:01:05.970 late because if you have the timing too 00:01:07.39900:01:07.409 late you'll waste work so here's that 00:01:09.77000:01:09.780 example so you've got your piston it 00:01:11.30000:01:11.310 comes up and then it starts to go down 00:01:13.60900:01:13.619 and then as it's going down you ignite 00:01:15.98000:01:15.990 the spark and so that flame front is now 00:01:18.46900:01:18.479 chasing the piston so that work isn't 00:01:21.28900:01:21.299 yet usable until you've expanded the 00:01:23.12000:01:23.130 pressure enough to actually start 00:01:24.53000:01:24.540 pushing that piston down so you've lost 00:01:26.63000:01:26.640 potential work because you didn't have 00:01:28.78900:01:28.799 that pressure when that piston was up 00:01:30.92000:01:30.930 closer to the top when you could force 00:01:32.53900:01:32.549 that piston down much earlier with a 00:01:34.85000:01:34.860 much greater pressure so there's a sweet 00:01:37.46000:01:37.470 spot in there and your problem is if you 00:01:40.03900:01:40.049 go too early to get that higher pressure 00:01:42.62000:01:42.630 to have the piston moving down with a 00:01:44.89900:01:44.909 higher pressure then you could run into 00:01:46.52000:01:46.530 knock if you're using low octane fuel so 00:01:50.06000:01:50.070 here's basically a curve that I've drawn 00:01:52.13000:01:52.140 out to explain this so here we have our 00:01:54.05000:01:54.060 pressure and your peak pressure is going 00:01:56.03000:01:56.040 to be around here and that's kind of 00:01:57.64900:01:57.659 what you want when you want to have that 00:01:59.56900:01:59.579 ignition is to create that peak pressure 00:02:01.81900:02:01.829 but in order to have the timing to do 00:02:04.28000:02:04.290 that you can't use a low octane fuel 00:02:06.56000:02:06.570 because well for in this example we're 00:02:09.10900:02:09.119 going to say that knock is going to 00:02:10.16000:02:10.170 occur 00:02:10.62000:02:10.630 some point around if you have your peak 00:02:12.42000:02:12.430 pressure occurring here based on your 00:02:14.31000:02:14.320 ignition timing so what a higher octane 00:02:18.24000:02:18.250 fuel does this allows you to advance the 00:02:20.22000:02:20.230 timing a little bit earlier preventing 00:02:22.68000:02:22.690 that and allowing you to have that peak 00:02:25.32000:02:25.330 pressure a bit higher and create more 00:02:28.44000:02:28.450 power ultimately so if you haven't yet 00:02:30.87000:02:30.880 watched my videos on octane rating on 00:02:34.95000:02:34.960 nock and on ignition timing you may want 00:02:37.95000:02:37.960 to check those out so I'll include links 00:02:39.87000:02:39.880 in the video description now so what 00:02:44.40000:02:44.410 she'll has done and this is actually a 00:02:46.08000:02:46.090 really cool test is they've got this 00:02:47.91000:02:47.920 four cylinder engine two of the 00:02:50.25000:02:50.260 cylinders are going to be running on one 00:02:52.56000:02:52.570 fuel and the other two cylinders are 00:02:54.84000:02:54.850 gonna be running on a different fuel and 00:02:56.40000:02:56.410 these fuels are going to have different 00:02:59.16000:02:59.170 octane ratings one's going to be low 00:03:00.48000:03:00.490 one's going to be high and so the engine 00:03:02.79000:03:02.800 is going to run this is a single 00:03:04.05000:03:04.060 cylinder bank this is a four cylinder 00:03:05.97000:03:05.980 engine the engine is going to run with 00:03:08.28000:03:08.290 these two different fuels in the two 00:03:09.84000:03:09.850 different cylinders so each of these 00:03:12.09000:03:12.100 cylinders is going to have a pressure 00:03:13.35000:03:13.360 gauge and the pressure gauge will 00:03:15.24000:03:15.250 measure the peak pressure and we can 00:03:17.13000:03:17.140 actually look at the average of these 00:03:19.32000:03:19.330 two cylinders versus the average of 00:03:20.88000:03:20.890 these two cylinders and one will have a 00:03:22.62000:03:22.630 higher octane fuel and we'll see if one 00:03:25.32000:03:25.330 can actually get higher pressures and 00:03:27.87000:03:27.880 thus create more power so let's go ahead 00:03:30.45000:03:30.460 and check out the test so we have here 00:03:32.73000:03:32.740 two separate high-pressure pumps and 00:03:36.26000:03:36.270 each pump is feeding two cylinders we 00:03:40.02000:03:40.030 have special fuel pipes here so that we 00:03:43.44000:03:43.450 can have an external fuel supply as you 00:03:46.20000:03:46.210 see on the right and on the left so at 00:03:48.24000:03:48.250 the moment two cylinders are running 00:03:50.13000:03:50.140 from the right red can which is in that 00:03:52.98000:03:52.990 case shell v-power and on the left side 00:03:56.76000:03:56.770 two cylinders are running on regular 00:03:58.89000:03:58.900 shall unleaded fuel so 95 from fuel 00:04:03.11000:04:03.120 during the 00:04:06.26000:04:06.270 we will run this engine on the same time 00:04:08.78000:04:08.790 with those two fuels that we measure the 00:04:11.60000:04:11.610 difference in cylinder pressure so we 00:04:14.66000:04:14.670 have each cylinder has a pressure sensor 00:04:17.06000:04:17.070 where we directly can see the pressure 00:04:19.10000:04:19.110 from the cylinders and then we will swap 00:04:21.92000:04:21.930 the fuels from the right if you like 00:04:24.95000:04:24.960 right bank to the left bank and vice 00:04:26.63000:04:26.640 versa so it's just changed fuels from 00:04:28.52000:04:28.530 right to left and you will see that the 00:04:31.61000:04:31.620 difference we will then as well see in 00:04:33.68000:04:33.690 the cylinder pressure will just belong 00:04:35.54000:04:35.550 to the fuel and not somewhere to the 00:04:37.64000:04:37.650 engine okay so now the car so here we 00:04:47.99000:04:48.000 have the data readout we're going to go 00:04:50.12000:04:50.130 ahead and switch over to the average 00:04:51.32000:04:51.330 pressures for each of the cylinder banks 00:04:53.75000:04:53.760 so if you look on the left here this is 00:04:56.66000:04:56.670 cylinders 1 & 2 an average pressure of 00:04:58.40000:04:58.410 those two cylinders in the center we've 00:05:00.29000:05:00.300 got the average pressures for cylinders 00:05:01.82000:05:01.830 3 & 4 and then on the right we have the 00:05:04.07000:05:04.080 percent difference between the two 00:05:06.74000:05:06.750 cylinder banks so 1 & 2 verses 3 & 4 on 00:05:09.83000:05:09.840 the difference in pressure that you have 00:05:14.73900:05:14.749 so I'm going to go ahead and pause it 00:05:16.82000:05:16.830 here and explain what we're looking at 00:05:18.29000:05:18.300 so cylinders one and two the average 00:05:20.14900:05:20.159 pressure is twenty point three one 00:05:21.46900:05:21.479 cylinders three and four the average 00:05:22.99900:05:23.009 pressure twenty one point one eight and 00:05:25.01000:05:25.020 that gives us a cylinder Delta of four 00:05:28.87900:05:28.889 point one two percent so what we're 00:05:31.85000:05:31.860 looking at is cylinders three and four 00:05:33.95000:05:33.960 have four percent higher pressure than 00:05:36.92000:05:36.930 cylinders one and two and this is 00:05:39.01900:05:39.029 because the ignition timing is advanced 00:05:41.23900:05:41.249 because it can take advantage of that 00:05:43.30900:05:43.319 higher octane fuel and not have knock 00:05:45.98000:05:45.990 so the NOx sensors and cylinders one and 00:05:48.29000:05:48.300 two are preventing it from advancing 00:05:50.62900:05:50.639 that timing anymore 00:05:58.94000:05:58.950 now so that you can trust the test shell 00:06:01.58000:06:01.590 went ahead and switch the two fuel 00:06:03.14000:06:03.150 cylinders so that one and two are now 00:06:05.87000:06:05.880 running the higher octane fuel and three 00:06:07.94000:06:07.950 and four were running the lower octane 00:06:09.53000:06:09.540 fuel and as you can see it creates the 00:06:12.14000:06:12.150 higher pressure in cylinders one and two 00:06:13.97000:06:13.980 which are running the higher octane fuel 00:06:15.83000:06:15.840 so you know it's purely based on the 00:06:18.20000:06:18.210 ignition timing so now let's take a look 00:06:20.18000:06:20.190 at the ignition timing now it's a bit 00:06:22.37000:06:22.380 hard to see but as you look on the Left 00:06:24.14000:06:24.150 you've got a peak in green and yellow 00:06:25.97000:06:25.980 and green and yellow represents 00:06:27.71000:06:27.720 cylinders one in two and then red in 00:06:30.11000:06:30.120 blue which you see on the right peeking 00:06:32.09000:06:32.100 that cylinders three and four and as you 00:06:34.85000:06:34.860 can see cylinders three and four are 00:06:36.59000:06:36.600 firing later 00:06:37.46000:06:37.470 so cylinders one and two using the 00:06:39.71000:06:39.720 higher octane fuel are able to ignite 00:06:41.96000:06:41.970 earlier and have advanced ignition 00:06:44.21000:06:44.220 timing so thank you for watching and if 00:06:46.46000:06:46.470 you have any questions or comments feel 00:06:47.69000:06:47.700 free to leave them below
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