The more I read this, the more I like my bottle.
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| Present confusion over injector size. https://www.slantsix.org/forum/viewtopic.php?t=21711 |
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| Author: | Sam Powell [ Mon Feb 05, 2007 4:06 pm ] |
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So 36# should be "safe", and that is what you would expect the dealer to be. I still don;t understand why it all behaves as if they are 24#ers. Tom PM'd me on how to hook up the Paxton fuel pressure regulator I have, and I will do that as soon as the weather gets even slightly cooperative. It was 9 degrees when I got up this morning. Here is what Tom recommended: The regulator is designed to keep everything betweent he pump and the regulator at a constant pressure. The Paxton regulator has two inlets, and one outlet. The pump will get plumbed directly to the fuel rail, and the outlet side of the rail will get plumbed to one of the inlets to the regulator. The other inlet, which is for the second rail of a V-8 I suppose, I plan on putting a pressure gauge on. I am going to find some way to either test this gauge, or simply buy another one. The outlet from the regulator gets plumbed back to the tank. Sandy, I guess this weather might seem balmy to you for winter time. Sam |
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| Author: | Sam Powell [ Mon Feb 05, 2007 4:12 pm ] |
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triple post. For some reason this system is not sending me back to the thread, so it seemed as if the post was not being made. I copied and tried again , twice. Sam |
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| Author: | sandy in BC [ Mon Feb 05, 2007 7:24 pm ] |
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Well the weather here is supposed to go above feezing tomorrow for the 2nd time since Nov 20.....It snowed another 6"last night putting us over the 7 ft mark....only 2.5 ft on the ground though..... I shovel....therefore I am.... (dont worry dear...Ill build that plow truck for next winter....) Sam....right after you get that regulator on I want data logs! |
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| Author: | Sam Powell [ Tue Feb 06, 2007 7:27 pm ] |
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OK Sandy. I will send it to you. Thanks! Eli is flowing my injectors to find out what they really are, and then will have some recommendations about recalibrating everything. I really feel like I am making progress here. Sam |
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| Author: | slantzilla [ Wed Feb 07, 2007 6:11 am ] |
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The more I read this, the more I like my bottle.
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| Author: | Sam Powell [ Wed Feb 07, 2007 9:14 am ] |
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Dennis you would make a great straight man with an opening line like that.  I think there are about 8 jokes that could set up. I will just let it lie though. You don;t want to get a guy with a bottle upset at you. 
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| Author: | slantzilla [ Wed Feb 07, 2007 10:37 am ] |
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Sam, from reading through this thread, the thing that becomes apparent is "Too many cooks spoil the soup".  IMHO, what you need to do is: 1 Verify what injectors you really have. 2. Log what is actually happening. 3. Go from there. Making wholesale changes when you are already lost is never good. Sorry I can't add anything really constructive. I am fascinated by what you are doing, even if it all baffles me.
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| Author: | Sam Powell [ Sat Feb 17, 2007 7:33 pm ] |
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I sent the injectors to Eli at Accel to have them flowed to see what they are. If they are 36 lb/hr, then according to the Mega Manual, the pressure must be down to about 30psi. That is the pressure that would make 36#'s flow like 24#'s. I checked out their plumbing chart for a system with a surge tank, and I will re-plum the fuel line as soon as the injectors get back and as soon as the weather gets and stays a little warmer. It is very similar to the Mega manual's chart without a surge tank, which I think was the source for the diagram Tom posted. The mega manual is just amazing. It is more free, good information then you can buy looking elsewhere. It will become my bible as I continue with this. Thanks again for all your advice. I think I am headed in a constructive direction. I have a technical/theory question I am going to post soon. Sam |
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| Author: | AnotherSix [ Fri Mar 09, 2007 2:52 pm ] |
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Sam you need a chef, not a cook. I realize I am late here and I have not worked with aftermarket ecms. Yes find out what size injectors you really have. The Buick crowd went thru this issue way back, the ratings may or may not be correct. Aftermarket injectors seem to be sold on the "bigger is better" idea. I suspect some of them are rated for static flow at 75 psi. 50 or 60 lb injectors are crazy for this engine. Just like you did not size your turbo for 600 HP and think you could just turn the boost down, it doesn't work that way(I know you know this). You would be at the 450 to 500 HP level just to start using them. Even if you could dial back the pulse width enough the spray pattern will suck and they will NOT run good on the street. Guys deal with them in the buicks because they have to to support really high horsepower engines. You really do not want the fuel pressure too low either for the same reason. The fuel should spray in over a long enough period of time for it to mix with the air flowing by, not one big drop from a huge injector. A BSCF of .5 is a quick and easy number to use to calculate your max HP for your injector size with a turbo engine. 30s are fine for you. 6 x 30 = 180 x 2 =360hp max (or more correctly, divide the 180 by .5 to get the same answer). If you turn it up later then get the right size at that point. Even if they turn out to be 24s they are at the edge but probably more than fine. The flow rate verses fuel pressure and duty cycle is not linear. With some injectors it almost is, the bigger they get the less this is true. I would try to run 38 to 45 psi at the rail with the vac line off. Your regulator should raise the pressure in proportion to boost or it will be really hard to program. The stock ecms I have played with used the number of milliseconds needed to flow one gram of fuel as the injector constant. Very small changes really made a difference. You are probably already closer than you might think. Fine out what you have and make small changes, test. I agree that the fuel reg should be at the opposite end of the fuel rail from the inlet. It will clear any vapor that way and keep the fuel in the rail cooler. |
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| Author: | Sam Powell [ Sat Mar 10, 2007 6:45 am ] |
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Thanks to all for replying. I got the injectors back from Accel, and they are 36#'s. According to the formula my local speedshop guy use, this should provide 350hp at 80% duty cycle, which is probably more than I need, but hopefully not too much. I am in the process of reworking the fuel line to get the regulator after the rail. I am going to change spark plugs to a cooler plug as suggested , and then start trying to get it tuned once the weather gets a little nicer, which seems like it should be soon. If you have read my other post, and subsequent thread about too rich looking like too lean at the o2 sensor, then you understand where I might have been going wrong with my attempts to get it to run reliably through the warm-up cycle. Thanks again. Sam |
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| Author: | AnotherSix [ Sat Mar 10, 2007 7:10 pm ] |
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36# should be fine. Actually I am sure they are small enough to manage nicely. I did make a chip just a little too lean one time. It ran ok until I stepped on it a just a little and then it stumbled and bucked and blew black smoke. It was to lean to fire so after a few rotations without firing it finally did and was too rich. It's an odd symptom but one you may run into. You know it is leaner but is not running right and blowing black smoke. Otherwise that chip was very close to optimum. I was trying to tweak the program a little for the smog test but it did not help. It ended up being fine with what I normally ran. |
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