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05-06-2008, 01:48 AM | #1476 |
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Cold starting issues are due to the basic physics of ethanol. It does not produce a flammable mixture with air below about 55 Deg F. At low temps you are depending entirely on the gasoline component in the fuel to get the initial ignition to start the engine. Once the engine gets some heat in it the problem goes away.
So you need to do things that improve the flammability of the fuel air mixture during cold start. One procedural trick is to turn the ignition on and let the fuel pump build full fuel pressure before you crank the engine over. That ensures that the fuel injectors produce a high quality fuel mist when they first spray fuel into the intake. I also in very cold weather hold the key in the crank position just a fraction of a second longer as the engine fires so the first crank or two is starter assisted. That helps a lot in very cold weather. Good ignition helps light off a lean fuel air mixture so wider spark plug gaps, good quality spark plugs (probably want to change them out a bit sooner than you would on gasoline) and a nice strong battery that will crank the engine fast and still provide good voltage to the plugs makes a difference. Adding a little extra ignition advance at cold cranking rpms will give the mixture more time to get burning before the piston runs off and leaves it behind, since lean mixtures burn slowly in a cold engine. One step warmer plugs in the winter is another work around. Anything that adds heat to the intake air will also help. In bitter cold weather putting a drop light under the hood at night will hold air temps under the hood up in the 30's - 40's even in subzero weather. Pulstar plugs work, they improve cold starting and allow the engine to pull better at very low engine rpms. My car will pull a load about 200 rpm lower with them than I can on conventional plugs, but they are not magic and will not fix all starting problems. They do illustrate how important a hot spark is to cold starting though. I like them but for folks that have high power setups they may not have the heat range choices folks want. I think new conventional plugs would work just about as well. Years ago it was very common for folks to install new plugs in the fall to ensure good starting when the weather got cold. The most practical solution in very cold weather may simply be to throw in an extra 2 gallons of gasoline just before a cold snap. Larry
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05-06-2008, 02:53 AM | #1477 |
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Working a 12hr night shift so lots of time to catch up on all the posts, not dedicated enough to read all 60 pages though...so sorry if this has been asked before...
Would it be worth the effort to run higher compression pistons with the e85? say 9:1 or even 10:1. Would the higher octane of the e85 permit the same levels of boost without detonation? Or I guess along the same line of of thinking, maybe less boost, but same power levels? I'm assuming this would offset the lower thermal energy of the e85 mixture vs gas Just curious, as I do not run e85 as Virginia has only 1 station that is publicly accessible. And it is no where near me... |
05-06-2008, 03:44 AM | #1478 |
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To a point yes!
It would help off boost economy and power, as long as the base compression ratio is not too high. 9:1 - 9.5:1 would help and not hinder your boost too much. 10:1 and up would give better fuel economy and daily driver performance, but might limit your max boost slightly. Since E85 allows 30-40 psi boost on 8:1 compression ratios I doubt most folks would really see any useful limits. I have an 86 Subaru GL-10 with the 1.8L NA block (9:1 compression ratio) that I run on high blends of E85 and about 6 psi max boost. It is a very pleasant daily driver and almost as much performance as a stock WRX. The main reason for limiting the boost is to keep a clutch in it, as the guy I bought it from had smoked the stock clutch running over 13 psi boost. I have not had time to do a full conversion on it yet but I will eventually. Larry |
05-06-2008, 04:16 AM | #1479 |
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On 100% Ethanol, the Saab AeroX prototype was running something like 12:1 compression and 14.7 psi of boost.
With the right quench design on the combustion chamber, and a really good intercooler, as well as radiator/thermostat (alcohol fuels being more intake/coolant temperature sensitive), you could probably get close to stock boost limits even with 10:1. Nevermind those of us with 91 octane. For us, 10:1 with 105? octane, would surely be better than ~8.0-8.4:1 with 91 octane. |
05-07-2008, 01:47 AM | #1480 | |
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Quote:
The argument is that the 8:1 compression ratio is too low to take advantage of the fuel... Out of curiousity, I may search and see if any e-85 powered acura RSX-S (uses compression to get a factory claimed 200 something hp out of a 2.0) |
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05-07-2008, 02:07 AM | #1481 | |
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NWIC
Location: Tweakin your ECU-Portlandia
Vehicle:2015 WRX WRB |
We all love E-85 in Colorado. There are so many of us running E-85 I have twice been at a gas station filling up E-85 with another converted Subie. I have only been running E-85 for 3 months. More and more people are converting all the time.
Subaru's are perfect for this. Turbocharged engines that really use it's potential. Larger injectors are just a dremel tool away. We have cheap reliable open source tuning available. It's really not hard to tune for either. Now with gas prices climbing out the ceiling I am starting to save a little bit of money. My first tank I felt like I was stealing. I am getting a little less mileage but only like 15% less. I don't even have it all dialed in yet. Quote:
Last edited by eminehart; 05-07-2008 at 02:13 AM. |
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05-07-2008, 05:11 AM | #1482 |
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Vehicle:2002 WRX Silver |
Just a quick check and there don't seem to be many offerings for high compression pistons for the ej20 saw 8.5:1 and maybe a 9:1 but that was about it.
What other pistons fit the ej20 block? I guess form the NA side would offer higher compression? I'm coming from honda's where lot's of stuff is interchangeable, not sure how that is with subie's, only had mine for a few months now... |
05-07-2008, 04:05 PM | #1483 | |
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Quote:
http://wac.addr.com/auto/obs/turbo/ejcalcs.html The JDM 2.0 L engine had some stock compression ratios up near 9.0:1 but I am not sure of the exact number off the top of my head. The easiest solution is to call Ron at http://www.raw1performance.com/ (formerly known as Axis power), he can get you CP pistons in just about any spec you want as I understand it. Larry |
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05-07-2008, 04:14 PM | #1484 |
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I have 9:1 CP pistons, and I run E85, it doesn't hurt anything, but it doesn't do that much for power either (the compression increase vs. other similar E85 STis). But, it is only a small increase in compression over stock perhaps a greater increase would yield bigger gains.
Last edited by `04AlpineWhite; 05-08-2008 at 05:54 PM. |
05-08-2008, 03:19 PM | #1485 |
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Had a thought or two on the Cold Start Issue....
Why not raise the CL Delay Minimum Coolant Tempature up from 10 degrees F to say 30-45 maybe higher, that way, when its cold out, it will help force the ECU into open loop- which will then refer to the Primary Open Loop Compensation scale which you can add fuel into for a richer start up. Now, I swear, even at 30-40 degrees outside, my ECU already looks at the Primary Fuel Compensation table when it starts... at least for the first 30-45 seconds, before it switches into CL and starts hunting... so I'm thinking this wouldn't even be needed. Just some thoughts... I have some of my CL/OL delays zeroed out already to force my ECU to refer to the primary fuel map as to decided when to switch from CL or OL, maybe that has something to do with it. thoughts?? |
05-09-2008, 01:35 AM | #1486 |
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SCIC
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Vehicle:2017 SWP BRZ PP, FXT 2002/2003 AW/PSM WRX |
Make your own ethanol. Im sure they have DIY kits posted online, but its cool to see a company come out with a complete kit.
http://www.popularmechanics.com/blog...s/4262690.html |
05-09-2008, 11:36 AM | #1487 | |
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Quote:
The concept is very interesting. |
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05-09-2008, 11:54 AM | #1488 |
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Distilling ethanol is illegal in most places. Better check with local authorities and possibly the ATF before setting up a still in your backyard.
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05-09-2008, 04:14 PM | #1489 | |
Scooby Specialist
Member#: 14141
Join Date: Jan 2002
Location: [email protected] @ 5800 ft on 13T
Vehicle:2002 Impreza WRX |
Quote:
Larry |
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05-09-2008, 04:18 PM | #1490 | |
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05-21-2008, 05:36 PM | #1491 |
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MAIC
Location: annapolis Md
Vehicle:2002 wrx,EVO3 big16g WRB 4.444fd Enginuity,E85 |
I was having a problem with misfire codes and couldnt figure it out, turned out my fuel filter was the culprit, changed it and all is good. so remember change that filter after the first 500 miles on E85
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05-21-2008, 10:39 PM | #1492 |
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Too put 100% E85 in your tank what modifications do you need to make for an 2006 STi. What performance gains do you get from making the change?
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05-21-2008, 11:37 PM | #1493 |
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TXIC
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Vehicle:2005 STI aspen white |
i have an 05 that has been converted for about three months now and it is great!!! i doin an 06 with a 35r tomorrow. basically you have to be able to add fuel across the board so a programmable ecu of some sort. walbro pump 800+ injectors and that is it. performance is wild the tq is phenomenal and you can run major timing your basically running a race fuel setup from the pump so expect the same gains plus more tq as a race gas tune.
Last edited by MRX WRX; 05-21-2008 at 11:38 PM. Reason: spell check |
05-22-2008, 01:48 AM | #1494 | |
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Quote:
Larry |
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05-22-2008, 09:59 PM | #1495 |
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I'll be trying E85 in the Baja over the next week. We don't have E85 where I live, but on a trip we're taking there are stations. Since the Baja uses STi injectors, there should be plenty of capacity for the ECU to adjust. I'm going to start slow (~30% to maybe 40% total alcohol) and if there are no troubles I'll go to straight E85. If the E85 is not significantly cheaper than the gasoline, I'll probably only try a tank or two, but I'm still going to try it. Thank you, hotrod, for this thread.
Hotrod, I did want to ask you re: cold starting: If ignition only needs 55F, why does compression not give you all the heat and much more needed to ignite even in cold winter temps? |
05-22-2008, 11:26 PM | #1496 |
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Location: The land of E85
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You shouldn't run straight E85 without a reflash or FPR or something.
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05-23-2008, 06:05 AM | #1497 | |
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Vehicle:2006 TR E3-16G'ed Running E85! |
Quote:
Btw I ran 320 highway miles from a full tank of northern NY E85 (probably E75) down to the light. |
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05-23-2008, 07:28 AM | #1498 | |
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Location: [email protected] @ 5800 ft on 13T
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Quote:
That is probably why some tuners have found adding a few degrees of ignition advance in cold cranking situations seems to help cold starting in some cases. Larry |
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05-23-2008, 12:58 PM | #1499 |
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THe best thread ever. I got some crucial info's. Ive been contempleting on running my 03 wrx for a while. and now im for sure gonna start doing it. and the availibity is a issue of E-85 unless, you buy a ethanol making distiller kit from ebay and make ur own fuel.. great experiment idea. im interested in trying it out. no more filling up my tank for $4.20 a gallon.
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05-24-2008, 09:08 PM | #1500 | |
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Quote:
I'm planning to fill with straight E-85 from almost totally empty this evening unless this will be a really bad idea. This time, it'll be around-town driving and a little Oregon (aka slow) highway driving over the next couple days. As an aside, I tried the first tank (~40-50% total alcohol) yesterday as part of our trip. MPG was down nearly 20% from the previous tank of premium (mixed brands amounting to ~5% alcohol) in all-freeway driving. Didn't have an opportunity for several driving cycles to allow the ECU to adjust slowly. I just went through town after filling and straight onto the freeway. No CELs or drivability issues. |
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