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| 10 Degree Advanced Camshaft Pulley | |
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| Tweet Topic Started: Nov 4 2009, 09:55 AM (6,124 Views) | |
| Cobb | Nov 11 2009, 11:51 AM Post #31 |
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Although my engine is toast, I do not notice any pinging. The dizzy is at full advance before and after upgrade. Just to correct what I said earlier, its only the cam shaft gear. It lowers the power band so you can shift earlier. As is the the power band is fairly high, like most small engines. The newer ones with vvt have it adjusted automatically to broden it out over a wider range, not to mention earlier in the revs. Having said that, you could buy a box to add to the 06 scion xa I use to own to further advance or retard the cam timming or fix it, so its not moved withthe rpms. |
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| mwebb | Nov 11 2009, 12:56 PM Post #32 |
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FOG
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many posters have recommended advancing base ignition timing "all the way, then back off if needed as needed to eliminate ping " my contention is that there is no benefit to doing that and that in fact on my car with the +10 cam gear and the 3tech economy cam this caused fuel economy to get worse . not better . my test results over the summer with summer fuel NOT winter blend are consistent with current dogma / theory as preached / taught to those in the automotive repair world . with NYS blend E10 shell 93 octane Edited by mwebb, Nov 11 2009, 01:00 PM.
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| Cobb | Nov 11 2009, 01:31 PM Post #33 |
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My understanding was the only the oem cam in a non xfi benefitted from the 10 degree wheel. Otherwise no more than 6 degrees advance on the cam for xfi or modded cam. |
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| starscream5000 | Nov 11 2009, 01:49 PM Post #34 |
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Got 70 MPG?
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That's too bad. There's isn't E10 in our shell gas around here. I've also noticed that my car gets it's best MPG around 8-10 degrees BTDC. Anything more than that just got me a little more power with some rattle and less MPG. |
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| Woodie | Nov 12 2009, 06:43 AM Post #35 |
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That's a very good point, maybe it's something about the cam or the 10 degree advance that makes it a different thing. mwebb states that all the way at the end of the slot is 27 degrees, he's got a 10 degree pulley, so that means that the end of the slot is 17 degrees on a stock engine. This fits in nicely with the fact that most stock engines run best near the end of the slot, I've seen 14 degrees listed by numerous people as the place where the ping comes in. |
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| 3tech | Nov 12 2009, 09:06 AM Post #36 |
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That is only for the xfi cam. All others can go +10 |
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| mwebb | Nov 12 2009, 11:18 AM Post #37 |
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FOG
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this can get confusing but for reference base ignition timing is set with relation to crankshaft position not camshaft position and base camshaft timing is set to crankshaft position at TDC . so if ignition base timing is 8 degrees before TDC that value is with respect to TDC on the crankshaft it will have to be adjusted if camshaft timing is changed to maintain the same value .............................. so our collective knowledge and experience seems to show ; the best fuel economy is obtained with base ignition timing around 8 to 10 degrees btdc using 87 octane top tier fuel without ethanol if possible . slight seat of the pants (untested and unquantified ) power gains possibly may be obtained by advancing base ignition timing until "ping" is heard then backing base ignition timing off slightly . BUT- this will result in mild to substantial loss of fuel economy depending on how far out of the above specification base ignition timing is set to the need to use of premium or regular fuel to obtain better results in regard to "increase in power" with base ignition timing advanced has NOT been addressed here ........................................................................... if there are test results to dispute what is above lets have them , please o please . if we agree on what is above - please o please make it a " sticky " so no no else wastes time and fuel thinking that using premium fuel and advancing base ignition timing will improve fuel economy like i did .... because it appears that we all agree that it really decreases fuel economy . |
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| starscream5000 | Nov 12 2009, 02:00 PM Post #38 |
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Got 70 MPG?
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I'll second that as well. I seem the get the same results that you get with a STOCK motor. |
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| Bad Bent | Nov 12 2009, 09:45 PM Post #39 |
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Facetious Educated Donkey
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Excuse me for being redundant here... Using 'How Stuff Works: Octane,' Octane is used to control spontaneous ignition. Compress gas and air and at some point it ignites without a spark. Octane replaced Lead (read unleaded fuel) and the more you add the more you can compress it. Is the engine designed for regular Octane? "the ratio of the volume of its combustion chamber; from its largest capacity to its smallest capacity"-Wiki. or Compression Ratio is fixed and range roughly from 8:1 to 12:1. Our G-10's are 9.5:1. The 9.5:1 is below the mean average of 10:1 and 38% of the range from 8-12. "Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting." (IMO bad sentence structure) Low compression, low power, low Octane and vice versa. OR the low compression 87 Octane explodes under high compression and knocks. So what changes? If the valve(s) close 10 Deg. sooner; that's more time for the compressing until TDC. If the cam has longer duration there's more fuel and air and the valves closes sooner. Not a higher "ratio" but you are jamming more boom in for a longer time....OR Carbon build-up decreases volume and increases compression (engine knocks on 87 Octane) plus altitude, terrain, air temperature, and humidity. Or my favourites; bore the piston, shave the head or shorten the connecting rod to increase the compression ratio. See also: Produce more power wikipedia.org: Compression_ratio |
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| Cobb | Nov 13 2009, 12:55 AM Post #40 |
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Ok, the dizzy is driven from the cam. If the dizzy is set at 8 degrees advance, you roll the cam 10 degrees advance, doesnt that make it 18 degrees or its still relation tothe crank for dizzy timming? |
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| Woodie | Nov 13 2009, 07:58 AM Post #41 |
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I'm not agreeing to that at all, because it is simply wrong. Advancing the ignition timing provides more power, better fuel mileage, lower emissions (except for NOx), reduced carbon deposits in the EGR and exhaust, reduced hesitation, and longer exhaust valve life. This is not just a Suzuki G10 I'm talking about here, this is a generic statement about gasoline internal combustion engines. The Suzuki G10 usually runs best somewhere between 10 and 14 degrees of ignition advance, using premium fuel might allow you to run more without ping, but the added cost will probably not be worth it. The only reason to use premium fuel is to be able to run more timing or compression, using premium fuel without making any adjustments to utilize the increased octane will do nothing but empty your wallet faster, might even cost you performance and mileage. I'm talking about a stock G10 in good condition here. If your car is modified it may react differently. If your stock G10 can be advanced to the stop without ping, there's something wrong with it. |
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| starscream5000 | Nov 13 2009, 08:00 AM Post #42 |
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Got 70 MPG?
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I may be wrong, but I'm guessing the dizzy is related directly to the crankshaft timing and how soon it fires a plug BEFORE the piston reaches Top Dead Center. This is measured in degrees.
Edited by starscream5000, Nov 13 2009, 08:02 AM.
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| Cobb | Nov 13 2009, 10:18 AM Post #43 |
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Thats what I am lead to believe Woodie. Most dizzyless cars have the timing constantly advanced a degree til it pings, then retards it 3 degrees. If more ping is hear it start to lean out. Thats how my tacoma did. Sure it was supercharged, but I also used preminum fuel. When I was in shop class it was believed you can smooth the chamber, piston top and do a 3 way valve job to reduce hot spots so with more compression and timming you can reduce the chances of ping. |
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| mwebb | Nov 13 2009, 11:13 AM Post #44 |
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FOG
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..."I'm not agreeing to that at all, because it is simply wrong. Advancing the ignition timing provides more power, better fuel mileage, lower emissions (except for NOx), reduced carbon deposits in the EGR and exhaust, reduced hesitation, and longer exhaust valve life. ".... ok this is what i am looking for prove that that statement is true in a stock g10 with a distributor . with regard to fuel economy which is what i am chasing , i have test results which prove that my theory is correct and your theory is false so lets see your test results .... |
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| mwebb | Nov 13 2009, 11:20 AM Post #45 |
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this is true although at start MR ECM can and does retard ignition timing 0 TDC to allow the engine to spin more freely in some system s like Nissan Maxima |
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