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09-22-2010, 06:37 PM | #26 |
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I have a block in the grage that looks exzactly the same. it is def the leanness on #3. this is a problem with the stock fuel rail. because #3 injector is at the end of the line it is the first one to go lean. I would recomened going to a after market fuel rail and this problem disapears. I learned the hard way too. if you ant to test my logic try watching the EGTs on each cylinder. this will show you if your in the danger zone.
mine happened at about 19psi climbing a hill. no cel, no warning, just long enought on the power to get to the melting point.
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09-23-2010, 08:25 AM | #27 |
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How did you rule out everything else to only be left with the determination that the oem series fueling setup was the cause of your failure? I think it's well known that #3 runs leaner and hotter, but wouldn't that just be the first cylinder to go if there were a bigger problem?
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09-23-2010, 11:50 AM | #28 |
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I understand what's behind the theory. However, I read so much last night on here about #4 and #2 having the highest EGT/ failure rate and it either being due to an exhaust manifold design or the block's cooling design. But there never seemed to be a real conclusion.
I am considering the DIY fuel mod to make them equal length. I don't see an issue if you keep the same diameter hose as factory. |
10-01-2010, 09:38 AM | #29 |
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My motor finally got torn down...
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10-01-2010, 12:51 PM | #30 |
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Ouch. How does the cylinder look?
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10-01-2010, 12:57 PM | #31 |
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10-01-2010, 04:19 PM | #32 |
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Vehicle:... 02 and 04 WRXs! 2020 G70 3.3T RWD |
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10-01-2010, 04:58 PM | #33 |
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Looking at where the piston melted. I'm going to say your exhaust temps were running really high. It could have been that your car was running lean as well. The melting spot however is right next to the hottest area a piston would see. I'm think a little of both. Not enough fuel for it. Well really actually if you were running a **** load of fuel this would not of happened. So yeah not enough fuel and probably too much boost for the amount of fuel it was getting. 19lbs I think is high for stock block anyway(some people disagree of course).
I think to avoid this issue, in the future you may want to go with a different tuner for one. Also you may want to use some high temp steel sheets. APS uses inconel sheets for their exhaust system. Not much price for the sheets considering the effects heat has on the #3 cylinder. Wrap it up tight ( use a stronger steel for headers, as these can crack when you don't let the heat out). People say you can use any stainless steel but they are wrong. Go with a higher grade steel so you can let them get really hot without the cracks. Also if you stay with stock internals just keep your boost at 17 or lower. No reason to turn it up if the stock parts don't like it. They weren't made to go much higher anyway, so don't play with it above that unless you start upgrading the internals. |
10-02-2010, 12:05 AM | #34 |
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Detonation in that cylinder, look at all the pitting on the piston dome. probably cracked a ring land and it was burning oil. When you burn oil with your gas you end up with very little octane, which would cause the cylinder to start to run super hot and melt.
Check your knock correction range, if it was around the stock setting of 6100 and you were revving to say 6800-7k that's about 1k rpms of no knock control, so it would not pull any ignition, or show a knock count. Not to mention it would be in the range were the td04 is pushing some seriously hot air which would tend to detonate a lot. What was your timing and wideband AFR.. Hopefully you had a wideband or were tuned with one at least. Lots of timing or very lean tune or both.. Look at your number 1 piston as well.. Same corner nice and shinny. Your EGTs were probably pretty high when that melted. If it was a bad injector only 1 piston would look like it took some serious heat. |
10-02-2010, 11:27 AM | #35 |
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Time for a new tuner
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10-02-2010, 06:43 PM | #36 |
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Dang who tuned your guys car? Got any logs before it blew?
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10-03-2010, 04:49 AM | #37 | ||
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Quote:
Quote:
(I don't think it's possible, but I like to ask questions in cases like this...) |
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10-03-2010, 09:46 AM | #38 |
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I'm not going to name names here to throw someone under the bus, but I will say a well known tuner here on NASIOC who has made a lot more power with plenty of other cars they have tuned. Yes I realize everyone is human and makes mistakes, but the tune on this car seemed pretty simple compared to most.
*edit* I hope you realize you're looking at two different engines. I'll post up pics of the other cyls from mine later today. |
10-04-2010, 04:17 PM | #39 |
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Bump for more pics.
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10-04-2010, 05:22 PM | #40 |
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More pics
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10-05-2010, 11:45 AM | #41 |
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10-05-2010, 11:45 AM | #42 |
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10-05-2010, 12:15 PM | #43 |
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#3 is the hottest
#4 is the leanest (on stock series fueling setups) |
10-05-2010, 12:59 PM | #44 |
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10-05-2010, 01:45 PM | #45 |
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Last edited by yaya20; 10-05-2010 at 02:31 PM. Reason: disclaimer |
10-05-2010, 03:54 PM | #46 |
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your knock correction range.........
I thought this would be throughout the rpm range. Where in the map is this located???? I have read from various sources that the stock fuel system (when cars are modded) don't distribute fuel evenly to all cylinders. Due to the design of fuel rails. Namely not equal runs of fuel lines to rails. Perrins website has info. Did you do any upgrade to your fuel system??? Last edited by sackytar; 10-05-2010 at 04:12 PM. |
10-05-2010, 04:07 PM | #47 |
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Lean mixtures produce hotter combustion gases than a stoichiometric mixture, so much so that pistons can melt as a result. Rich mixtures produces cooler combustion gases than a stoichiometric mixture, primarily due to the excessive amount of carbon which oxidises to form carbon monoxide, rather than carbon dioxide.The chemical reaction oxidizing carbon to form carbon monoxide releases significantly less heat than the similar reaction to form carbon dioxide.(Carbon monoxide retains significant potential chemical energy. It is itself a fuel whereas carbon dioxide is not.) Lean mixtures, when consumed in an internal combustion engine, produce less power than the stoichiometric mixture. Similarly, rich mixtures return poorer fuel efficiency than the stoichiometric mixture. (The mixture for the best fuel efficiency is slightly different from the stoichiometric mixture.)
So yeah the engine was running hot, the reason the #3 cylinder melted was because it was close to the exhaust. Run rich and it would never melt. Other problems would occur but melting would not. |
10-05-2010, 04:15 PM | #48 |
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Thats true. Personally I think no-one should be getting in their car if their car is tuned without having a Wideband in at all times. If anything just for piece of mind.
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10-05-2010, 04:20 PM | #49 |
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It seems though that the AFR by itself can't be a save all. If the avg of all 4 cyls is fine that tells nothing about one running hotter than the others. This article was posted on the thread about this in the built engine section, its a really good read. http://www.streetrodstuff.com/Articl...ne/Detonation/
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10-05-2010, 04:27 PM | #50 |
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Also two other sources to help out here.
First from member Unabomber Fuel Rail FAQ What are fuel rails? Aftermarket fuel rails are designed to increase the internal diameter of the stock fuel lines as well as convert the OEM fuel rail set up from series to parallel. The theory behind these two changes is to increase fuel flow and equalize fuel distribution. When are fuel rails needed? This is a very hard question without a clear answer. Two very reputable tuners and NASIOC Vendors do not believe they are necessary. god of Godspeed Inc. and nmyeti of TurboXS recently posted that they are not needed for additional fueling or fuel distribution equalization, which is the rumored cause of particular cylinder number failures. Another view by nmyeti. That being said, there is no real downside to fuel rails for people who believe they may provide an extra level of protection. Who manufactures fuel rails? APS Aeromotive Agency Power BDL Industries Crawford Performance Outback Motorsports Perrin Performance Rocket Rally Rails Subydude TurboXS Ultimate Racing Vishnu Boomba Racing Is there a "fuel rail mod"? Yes. Many have modified their stock (series) fuel rails into parallel fuel rails. scoobymods.com instructions supporting/supplemental NASIOC thread supporting/supplemental NASIOC thread Are their other fuel rail mods? Yes. As detailed in this thread, Ultimate Racing offers fuel injectors that mimic fuel rails by being flow matched for each individual cylinder. These injectors are specifically matched so that each cylinder flows the exact amount of cc's using the stock fuel rails. They also have flow matched units for parallel or aftermarket rails as well. How hard is it to install fuel rails? Allow around six hours for install time. Professional installation, depending on your area, is around $400. This vehicle modification is more difficult and time consuming than most "bolt on" installations. How do I install fuel rails? Refer to the fuel rail manufacturer's instructions. For fuel rails without instructions, below are some links to installation instructions: Perrin's instructions Perrin's instructions APS's instructions Vishnu's instructions Mike Egan's instructions Jorge's instructions AND a comment by member nmyeti The solution is not to be had in the fuel rail, or not in available aftermarket rails, as I doubt anyone that has "designed" them in the aftermarket has access to several million dollars worth of fluid dynamics modeling equipment that would be required to correctly predict and balance the flow to any greater effect than the stock pieces when put in the dynamic conditions of the under hood environment. [Rant on] Rails, as with most machined AL components are very cheap to manufacturer. With their inexpensive manufacturing cost and outrageous selling price aftermarket fuel rails offer a substantial profit. If we didn't have a conscience we would build/ sell them, as TurboXS owns the required machine tools, and would have very little trouble acquiring the correct bar stock. The fact is that vendors claim these rails will solve all your problems and cook you breakfast, but in the real word it doesn't play out quite that way. In the real world, of the two things that are being mixed in your cylinders, O2 is by far the most easily disturbed. The intake and exhaust manifolds are much more likely to be the source of the "lean run" problem, and almost all data I've seen tends to point in this direction. I know more than a few people who have had one cylinder run lean after installing a set of aftermarket fuel rails. The evidence isn't conclusive by any means, but it's more than enough to keep me from hawking a part designed to play on consumer fear as a quick way to make a buck. I have tuned many cars with and without rails and never once noticed that we could run a leaner overall air fuel ratio or slightly more ignition advance before detonation set it. It happens when it happens, and more often that I can count people have installed rails to solve some problem with the way their car runs only to find that their wallet is lighter and their car runs basically the same. In addition, we did a compression test on Phil's motor today. This block has been horse beat for over a year, with copious amounts of N2O and insane levels of boost. It has put down 411hp on the dyno, without n2o, and stood up to the last 4 or 5 months of 25psi (note most of the time much higher) daily driving. This car has had stock rails installed for its entire life. The compression test showed that the motor was not just in spec, but also near perfect on all cylinders. The stock fuel rails seem more than adequate in this case. So in the very end, the car was run lean. Maybe injectors were not up to the job. Maybe the tune was lean to begin with. In the end the car ran lean. If your cylinders melt, it's lean. It's just that simple. your exhaust temps would never get hot enough to melt the cylinder if the car was ran rich. It doesn't work that way. The lean state caused extra temps from the exhaust. If are cars were setup so the exhaust temps did not add any head to the block then we would see the engine heat to the point where all the cylinders would of started to melt at around the same time instead of just one area. |
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