08-10-2017, 02:46 PM | #57 | |
Drives: 2015 Camaro LT Join Date: Sep 2016
Location: Fox Lake, IL
Posts: 393
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Quote:
And I would keep your old plates on the car as some members have mentioned. You're not going to pass their inspection without putting all the stock parts back on.
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08-10-2017, 07:44 PM | #58 | |
Drives: '13 LS, '09 Forester, '11 HD SGlide Join Date: Jul 2017
Location: Waltham, MA
Posts: 83
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Quote:
I don't hear knock, but that just means I don't hear it. Going to keep this in mind. Thanks.
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2013 Chevrolet Camaro LS - M6
2011 Harley Davidson Street Glide 2009 Subaru Forester - M5 |
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08-10-2017, 09:18 PM | #59 | |
Drives: 2015 Camaro LFX A6 Join Date: Nov 2015
Location: Elk Grove, CA
Posts: 675
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Quote:
I don't have all of my stock parts.
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Cold Air Inductions CAI : Apex Air Scoop / WW Relocate Kit : JacFab Intake Manifold Spacer : Overkill 80mm Throttle Body : Overkill Tuned : MagnaFlow Cat-Back Exhaust : Elite Engineering Catch Can : ZL1 Strut Tower Brace : Custom Tunnel Brace : JPSS Caster Locks : JPSS 32mm Rear Sway Bar : JPSS Billet Radius Arm Bushings : Pegasus Solid Sub Frame Bushings : 1LE Brembo Conversion : B&M 70273 Trans Cooler
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08-10-2017, 09:23 PM | #60 |
Drives: 2015 Camaro LFX A6 Join Date: Nov 2015
Location: Elk Grove, CA
Posts: 675
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Actually. I don't have ANY of my stock parts.
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Cold Air Inductions CAI : Apex Air Scoop / WW Relocate Kit : JacFab Intake Manifold Spacer : Overkill 80mm Throttle Body : Overkill Tuned : MagnaFlow Cat-Back Exhaust : Elite Engineering Catch Can : ZL1 Strut Tower Brace : Custom Tunnel Brace : JPSS Caster Locks : JPSS 32mm Rear Sway Bar : JPSS Billet Radius Arm Bushings : Pegasus Solid Sub Frame Bushings : 1LE Brembo Conversion : B&M 70273 Trans Cooler
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08-11-2017, 06:55 AM | #61 |
Might want to consider leaving dear old Commiefornia.
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08-11-2017, 07:13 AM | #62 |
Drives: 2014 2LT RS Summit White Join Date: Apr 2017
Location: Cincinnati
Posts: 622
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Well, now I am going to have to run a few tanks of 93 through. Need to fill up tonight after work; current tank of 87 I got 19.6 mpg, avg. speed around 31mph. I will run a few tanks of premium and see if anything changes in mileage or feel of car.
Last edited by KenKat; 08-14-2017 at 08:19 AM. |
08-11-2017, 09:13 AM | #63 | |
Drives: 2012 2SS/RS, 1968 SS Join Date: Feb 2012
Location: Southeast, PA
Posts: 2,093
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When it runs knock free for a while, it will try to push timing again, and if it knocks it stops. So when you switch from low to high octane, pull the battery for an hour to reset that, or just run it with high octane for a while until the car takes the time to relearn everything. Or just sell the car in 7 years. CA sucks for any modifications. My buddy who lives out there deals with all of this crap with his Corvette and Impala. He can't even buy a CAI because none of them are CARB certified. Companies won't even SHIP him parts because they aren't certified for use in CA. It really stinks to live out there and be a car guy.
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LS3 Crate Engine Swap | CSP Custom Cam 232/240 .615/.615 113 +3 | Stainless Power LT Headers | Z28 Intake | Borla S-Type Exhaust | FTI Triple-Disc Billet 3200 Stall
2012 Camaro 2SS/RS | 1968 Camaro SS | 2020 Cadillac CT5 Premium Luxury | 2021 Spark LS |
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08-11-2017, 10:07 AM | #64 | |
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08-12-2017, 11:51 AM | #65 |
Drives: 2011 2LT RS Victory Red Join Date: Oct 2015
Location: Southington, Connecticut
Posts: 45
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Hi Guys/Girls,
Great discussion on fuels. I'm a little new to the game and am old school for sure. In the 1960's all those big block Chevy's and others "HAD" to run premium fuel. From the factory they would push anywhere from 325HP to around 435HP. I went through alot of premium fuel. In my 2011 2Lt/RS Camaro that's rated at 312 HP I'm able to run regular gas. From my point of view it was one of the reasons I went with the V6 and NOT the V8. I run ONLY Mobil 87 octane and have never heard a knock or a ping as we used to call it. Thoughts, comments? |
08-12-2017, 01:26 PM | #66 |
Drives: 2012 2SS/RS, 1968 SS Join Date: Feb 2012
Location: Southeast, PA
Posts: 2,093
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Just read through the thread again. This is the argument, and we are showing the very reasons why these engines still need premium. You don't HAVE to do it, but the data is at least there for you to make an informed decision on the matter.
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LS3 Crate Engine Swap | CSP Custom Cam 232/240 .615/.615 113 +3 | Stainless Power LT Headers | Z28 Intake | Borla S-Type Exhaust | FTI Triple-Disc Billet 3200 Stall
2012 Camaro 2SS/RS | 1968 Camaro SS | 2020 Cadillac CT5 Premium Luxury | 2021 Spark LS |
08-14-2017, 07:47 AM | #67 | |
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I've been running 93 since Jun 30 and while I'll have to look at my previous data to be absolutely certain, it appears I'm getting about 3MPG more than I was with 87. Think I'm on my 4th tank of 93. It needs way less pedal to get going and runs much stronger with the AC running. The more I run 93 the more convinced I am to keep running it, even though it's a bit more expensive and I'm not sure the increased mileage will counter the expense. The car runs better when it's drinkin' the good stuff. |
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08-14-2017, 09:56 AM | #68 | |
Drives: '13 LS, '09 Forester, '11 HD SGlide Join Date: Jul 2017
Location: Waltham, MA
Posts: 83
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The more I read about it, the more I myself go back and forth. It boils down to the cost difference. It's about $6 a tank or more. Now - IF I got 3 mpg more, the cost per mile is almost a wash (1 penny per mile higher). I track my mileage, so this could be a real world experiment. Taking into account it's really the previous fill-up.
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2013 Chevrolet Camaro LS - M6
2011 Harley Davidson Street Glide 2009 Subaru Forester - M5 |
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08-14-2017, 10:54 AM | #69 | |
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While I'm not gonna pretend to know what's an optimal detonation point in the compression stage, I imagine it's at that point where the ratio achieves its designed 11.5:1, I do know that's what adjusting the timing does. Not sure if the LFX has variable valve timing or not but if the intake valves open to soon or remain open to long can also contribute to "knock", which is detonation of fuel/air outside the point it's supposed to be exploding and is not good for the motor. Pistons and valves are in the wrong place when it happens. The lower the octane rating of a fuel usually means it can be fired simply by compressing the mix, think diesel engines, the higher it is requires external stimuli to achieve explosion. So, the car is designed to give it's full power within a single cylinder with a air fuel mix containing 93 octane when the piston has compressed it all to that 11.5:1 ratio. Putting 87 in it causes pockets of the A/F mix to detonate before or after the ratio is reached. When the computer senses it happening it adjusts the timing which will change the compression ratio the A/F mix gets to when fired. Either before, at or after the piston reaches top dead center (TDC). I don't know which way it adjusts but I'm sure someone here can tell us. In my experience, however limited, retarding timing makes the engine output less power while advancing the timing has the opposite effect, up to a certain point. If the timing is advanced to far the spark will not hit the A/F mix during any amount of ignitable compression and the car won't run. Just thinking about it, I wouldn't think you'd want the explosion to hit while the piston is traveling up. TDC probably isn't really all that good for the rods or crank either, but, it can't be very far past TDC on the down stroke or you lose the compression ratio needed. Alright, I've probably rambled ignorantly on long enough. Still about 4 1/2 months away from the end of my 6 month 93 octane study. |
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08-14-2017, 12:25 PM | #70 |
Drives: Miss Con Ception Join Date: Aug 2016
Location: Chicagoland
Posts: 2,998
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Advancing the timing does mean beginning the burn before TDC. So by the time the piston is passing TDC the majority of fuel is burning.
It isn't as if all the fuel explodes in an instant. One of the most important aspects in engine design is the burn pattern. Air and fuel are still being introduced to the chamber when ignition begins and the way it swirls determines the rate and efficiency of the burn. Higher octanes burn slower and thus ignition can begin earlier. This allows more of the fuel to burn, thus increasing power and MPGs. Anyway, with direct injection, the computer controls when and how much fuel is introduced along with the spark timing. Thus detonation can be avoided by delaying the introduction of fuel. But this means there is less time to add fuel and still expect it to burn effectively. Resulting in lower power and lower MPGs. The main way to control the burn and the way the air/fuel moves involves the shape and length of the intake and exhaust ports, the placement and size of the valves, the rate and height and time at which valves open and close, the size and shape of the combustion chamber, etc. And that is a simple explanation As you can see, it is quite involved and it used to be all trial and error. With the advent of super computers and dynamic equations much of the guess work can be avoided, but it still comes down to building and testing, tweaking, repeating. Of course, cost and reliability are always factors affecting the final product. There comes a point of return on investment. The masses do not want to spend another $1,000 on a car for 0.1 more MPG or 1 more HP.
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