07-02-2019, 12:47 PM | #29 | |
NOXQCES ZL1
Drives: 2017 Camaro ZL1 Join Date: Mar 2019
Location: Huntsville AL
Posts: 307
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Quote:
https://www.summitracing.com/parts/m...0aAtcMEALw_wcB |
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07-02-2019, 01:32 PM | #30 | ||
Dumb Ass Deluxe
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12.x/1 whether it is a carb, EFI, SFI, or DI feeding the cylinders. (If you want to split hairs, maybe a wee bit more on a carb setup due to variances in wet flow characteristics. Some cylinders will always end up rich and some lean). The computer DOES give you a LOT more control (and immediate self adjustment) of engine requirements for the load it sees vs. carb jets and points timing. I'll give you that. You can take the timing to the ragged edge because you have the KS circuit to pull you back. It still doesn't change the physical principles occurring in the cylinder. Quote:
There isn't any flame front during compression. That means zero effect on pre-ignition. It *might* have an effect on detonation. I'd have to read up on it to see what they are trying to accomplish. On the surface, designing an "air envelope to insulate the flame front" is counterproductive. When controlled ignition is started, you want the flame front to progress as rapidly and smoothly as possible to exert the most force on the piston. Insulating it suggests it is intentionally being slowed down. My guess is it has more to do with flame impingement than anything else. Thinking about it, that makes more sense. The fuel is in the "middle of the chamber and "doesn't have time to reach the chamber edges". Therefore, there is an "air envelope around the metal" which minimizes emissions and wear, but maximizes fuel efficiency and power. It also might be why oil is sprayed on the bottom of the pistons. They are absorbing more heat since they are not insulated (back to fuel dumped on the crown) and take more concentrated heat than the head/cylinder walls used to. But, I will do some homework on it. |
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07-02-2019, 01:55 PM | #31 | |
Dumb Ass Deluxe
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What I am saying is that there is more than one way to skin a cat. We are talking theory here and all trying to learn and clear up misinformation. For me, I'm scouring the boards looking at other people's hard earned knowledge and learning about the specifics of the G5LT1/F-body and how I can fit it into my plans/goal when I pull the trigger and get one. Right now, I'm just trying to give back by sharing what I know. |
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07-02-2019, 02:09 PM | #32 | |
NOXQCES ZL1
Drives: 2017 Camaro ZL1 Join Date: Mar 2019
Location: Huntsville AL
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07-02-2019, 02:50 PM | #33 | |
Drives: 6th gen Join Date: Aug 2013
Location: US
Posts: 3,678
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Quote:
A lot less heat on the crown and edges in the chamber from the last combustion event helps prevent preignition during the compression stroke leading up to the next You can see they’ve blatantly increased compression when moving to di Sorry for the shit posts, I’m on the run today Last edited by 6spdhyperblue; 07-02-2019 at 06:27 PM. |
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07-03-2019, 12:58 AM | #34 | |||
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The coldest are where the water jackets are located. The hottest (edge) is the piston crown. Traditionally, heat has to travel from the crown, thru the rings, to the wall, and then the jackets. Or, thru the wrist pin, rod. Or oil splashed on it from the rotating assy. Now, we have direct oil spray. (As a side note, oil spray is also used in the Duramax engines). "Flame impingement" occurs on the edges (3D wise) in the combustion chamber. Why? it's cold there. This is where HC and CO on your smog test come from. Incomplete combustion. Quote:
What happened? The Smog Nazis, gas shortages, and the unleaded, low octane transition in 1971. Compression (and HP) took a dump. Big cube motors were gone. What we got were, exhaust choking cats, egr valves, smog pumps, etc, in an effort to meet Big Brother's requirements. Mid 80's seen EFI and a resurgence in power. 90's we had the G2LT1/4 with 10.5:1 and 3 way cats. Now we have DI giving us even better fuel economy and less emissions. So, to say that DI is the reason we have factory produced high compression motors is false. DI is the reason we have them back with all the rules and regulations skewing the playing field. No offense taken... Last edited by 95 imp; 07-03-2019 at 03:06 AM. |
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07-03-2019, 06:09 AM | #35 |
Drives: 6th gen Join Date: Aug 2013
Location: US
Posts: 3,678
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I am comparing ls3 compression to LT1
Fueling .89-.88 lambda full load In my experience, these engines are predisposed to knocking more when rich than lean compared to older engines. Car is making power with the benchmark cars here for what it is Edges I was referring to in that last post were edges in the chamber not necessarily the piston. But the area between the rings, ring lands, edge of the piston does seem critical in terms of preignition with DI from all the lspi things we seen. Most seem to think it’s only related to boost but I’m sure it does play some part in NA too |
07-03-2019, 10:04 AM | #36 | ||
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Ok... Ok.. I see your point. What I am saying is the ONLY reason it got the CR bump was due to being able to control emissions. I'm going to guess NOx specifically because that goes up as compression goes up. I do not know if the second cat help clean it up as well. I do know that the D-max had to start using DEF to combat NOx emissions as diesels were targeted by the smog freaks.
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[QUOTE=6spdhyperblue;10561674] Edges I was referring to in that last post were edges in the chamber not necessarily the piston. Usually the water jacket areas are the coldest and the flame front dies off around them because they suck the heat and extinguish the flame. Quote:
No doubt it is in both. It is more frequent and pronounced in boost motors because you are artificially increasing the CR. More squeeze raises the charge temp. |
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09-07-2019, 10:30 PM | #37 |
Retired from GM
Drives: 2017 Camaro Fifty SS Convertible Join Date: Mar 2017
Location: Detroit
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The position taken by the tuners in Florida is an understandable position. It all boils down to what they may or may not know about particular types of engines. Ethanol is corrosive. Running E85 requires valves and valve seats hardened to resist the corrosive nature of ethanol. If the tuners don’t have a way of confirming that the valves and seats in an engine are hardened to support E85, they are smart to walk away from it.
Now, specifically for Camaro, I am pretty sure...90+ %-ish sure, that the valves and seats in LT1 are hardened to support E85. And from what I can tell, the E85 kits that are sold replace a part of the fuel line that might also be impacted by corrosive ethanol, so getting the sensor and tuning for E85 is really all LT1 needs. My background for saying this is that when I was in Powertrain Portfolio Planning at GM, I had an engineer assigned to working with Product Engineering and the people in the company who managed GM’s fuel economy reporting to determine which vehicles using which engines would be planned to use E85. GM’s position was to maximize the credits that could be generated from using E85 capable engines. 3.5L and 3.9L OHV engines were targeted, as were 3.6L FWD (but not RWD) engines. A lot of small block V8s were also targeted, as a lot of the GM truck portfolio was to be outfitted with E85 capability. This is where Camaro and Corvette benefit. With so much truck volume being E85 capable, it made sense for the engine plants producing those engines to use the hardened valves and seats for everything, whether they were E85 intended or not. Fewer part numbers to track and inventory and separate. There was typically additional E85 content that needed to be added at the vehicle assembly plants. Not totally certain what that would be for Camaro, since it was not intended to come from factory E85-capable. I think fuel pump may have been one of them, but I wouldn’t swear to that.
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09-07-2019, 10:42 PM | #38 |
Drives: 2017 2SS M6 Join Date: Jun 2013
Location: WNY
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the heads on all LT1s are the same between the trucks with E85 and cars. part #12678972 . dont know about the components in the fuel pump but all vehicles made since the 90s have had to have PTFE rubber for everything in the fuel system.
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real ZL1 wheels and brakes, 285/305 Michelin Pilot Super Sports, Pray ported Intake manifold, Soler Throttle Body, Rotofab intake, EFI Tuning Flex fuel kit, full American Racing Headers Exhaust, 1 7/8" w/ cats H pipe and mufflers. Full 1LE suspension, with BMR adjustable sway bars and links, GM aluminum cradle bushings, Hurst shifter with lighter reverse spring, TWM shifter knob, Tick level 1 transmission. I should have bought a ZL1
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09-08-2019, 04:19 AM | #39 |
Drives: 2014 Cyclone mustang Join Date: Feb 2016
Location: Port Lavaca,Tx.
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To add my 2 cents, cam guides can corrode in my coyote application, chevy is ahead of the game in my opinion concerning e85. Skinning cats is fun R&D. I enjoy the research.
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09-08-2019, 08:51 AM | #40 |
Drives: like an old lady Join Date: Jun 2012
Location: indiana
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the only honest downsides i can see are making a lot more $80-$100 oil changes and if the car isn’t driven much, the moisture collection. beyond that, properly use ethanol and let your high comp marvel of engine technology eat, figuratively and literally speaking.
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09-08-2019, 05:25 PM | #41 | |
Drives: 2023 CT5 Blackwing Join Date: Sep 2016
Location: Orlando
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Quote:
The 'extra' oil change thing is a myth.
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Sold 2023 Wave Metallic CT5-V Blackwing M6 |
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09-08-2019, 08:26 PM | #42 |
Drives: 2017 2SS M6 Join Date: Jun 2013
Location: WNY
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i plan to do analysis but that wont be till the end of next year
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real ZL1 wheels and brakes, 285/305 Michelin Pilot Super Sports, Pray ported Intake manifold, Soler Throttle Body, Rotofab intake, EFI Tuning Flex fuel kit, full American Racing Headers Exhaust, 1 7/8" w/ cats H pipe and mufflers. Full 1LE suspension, with BMR adjustable sway bars and links, GM aluminum cradle bushings, Hurst shifter with lighter reverse spring, TWM shifter knob, Tick level 1 transmission. I should have bought a ZL1
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