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  • dave.g.in.gansevoort
    replied
    Originally posted by SuperBuickGuy View Post

    relying on a fuel pressure regulator is a work around but not a solution. Regulators fail, and in this case, it could cause some pretty severe damage due to the pressures in play. Add to that if you overfill your tank, there could be enough pressure at the tank to cause full pressure to go into your carb...
    Absolutely correct! We did this in a HDD dyno cell, pumping from/to a 55 gallon fuel barrel, in an overpack. Full automatic fire protection, etc,etc,etc.

    Now for the rest of the story as Paul Harvey used to say. We were working with a catalyst manufacturer developing a lean NOx catalyst system. This is very different from the crap selective catalytic reduction converters that came along. The system needs a little extra dose of fuel to light off, which can be done 2 ways: introduce a small amount into the exhaust stream , or with modern electronically controlled engines, by making a randome cylinder run rich, you know just like modern electronically controlled engines in passenger car systems that dither lean to rich around stoic.

    We didn't have that so I bought an aftermarket fuel injection driver, and put an injector in the exhaust before the cat. Over a period of cycles I adjusted the fuel curves to get just enough fuel in the exhaust to make it work. Now there is a down side, about a 2-3% fuel economy hit, but considering that these cats are developed for gasoline engines and work for 200,000 plus miles with no maintenance, I think that it could have been a better choice for trucks than SCR, with the maintenance issues and need for DEF and a complete separate system.

    That's my 2 dollars worth, but what did I know? The upper management had pretty much already gotten in bed with all the various players as they saw SCR as a quicker way to reduce NOx. I think history will show that lean NOx catalysts would have been the correct choice.

    Oh man, I did it again! Off on another windmill tilt...

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  • SuperBuickGuy
    replied
    Originally posted by dave.g.in.gansevoort View Post

    And remember the one experiment where we needed 140 ish psi and series ganged pumps to get there, then regulated by using a bypass like you said. Crude but effective if you need higher pressure. If I remember correctly we used Walbro Nissan replacement pumps. That was almost 30 years ago...
    relying on a fuel pressure regulator is a work around but not a solution. Regulators fail, and in this case, it could cause some pretty severe damage due to the pressures in play. Add to that if you overfill your tank, there could be enough pressure at the tank to cause full pressure to go into your carb...

    Leave a comment:


  • SuperBuickGuy
    replied
    Originally posted by Thumpin455 View Post
    I have had the FiTech on the GTO and sitting on the shelf for a year while I tested/tuned E85 carbs. I used a Walbro inline external pump rather than springing for a whole new tank. The 65 has a very small sender hole, and that tank was brand new when I started driving the Goat. You know me, the budget is always tight. Its been back on for nearly two years running E85 the whole time. I can tune all kinds of stuff, cold start for various temps, after start, the curve to some extent, but the handheld is limited. Haven't done anything with a Sniper, only the FiTech, but I want to get one of the 4500 flange Sniper systems for my 'big' engine.
    there is a way to fix the handheld issue.... use your laptop, instructions below

    Leave a comment:


  • dave.g.in.gansevoort
    replied
    Originally posted by DanStokes View Post
    Todd - don't know if I was following you correctly of not but at EPA we'd often do a back pressure regulator where the pump ran at maximum all the time and the pressure required by whatever we were feeding was adjusted by allowing the extra fuel to return back to the tank such that the regulator was controlling the return line. Depending on the application sometimes we could get along with a simple valve in the return line. If the item we were controlling the pressure to (say, a carb) had varying supply needs we'd put a regulator in the return line. It's a little bulky but works great.

    Dan
    And remember the one experiment where we needed 140 ish psi and series ganged pumps to get there, then regulated by using a bypass like you said. Crude but effective if you need higher pressure. If I remember correctly we used Walbro Nissan replacement pumps. That was almost 30 years ago...

    Leave a comment:


  • DanStokes
    replied
    Todd - don't know if I was following you correctly of not but at EPA we'd often do a back pressure regulator where the pump ran at maximum all the time and the pressure required by whatever we were feeding was adjusted by allowing the extra fuel to return back to the tank such that the regulator was controlling the return line. Depending on the application sometimes we could get along with a simple valve in the return line. If the item we were controlling the pressure to (say, a carb) had varying supply needs we'd put a regulator in the return line. It's a little bulky but works great.

    Dan

    Leave a comment:


  • Thumpin455
    replied
    I have had the FiTech on the GTO and sitting on the shelf for a year while I tested/tuned E85 carbs. I used a Walbro inline external pump rather than springing for a whole new tank. The 65 has a very small sender hole, and that tank was brand new when I started driving the Goat. You know me, the budget is always tight. Its been back on for nearly two years running E85 the whole time. I can tune all kinds of stuff, cold start for various temps, after start, the curve to some extent, but the handheld is limited. Haven't done anything with a Sniper, only the FiTech, but I want to get one of the 4500 flange Sniper systems for my 'big' engine.

    You don't need to get super fancy with the fuel system, the big thing is making sure you don't have leaks with 58-62 psi these things need. When I went back to the carb, I switched the feed from the high pressure pump to a carb pressure pump, and let the EFI pump ride back there hooked to the return on the tank, then the high pressure that was plugged at the carb. I used the carb feed as the return for the EFI, and simply connected the carb and low pressure pump to that line.

    I went with steel lines on the 65, but from now on I plan to use the nylon stuff, lots easier to work with and get fittings. That stuff feeds high HP supercharged EFI engines so it should work for what we are doing. If you need more than that, you probably need a -8 or half inch line to feed your engine. The TBIs have a 10mm feed inlet, so larger feed line still necks down to go in them.

    Those EFI pumps aren't like the carb pumps, they won't like being stuck behind a regulator that knocks it down to 5-7psi even with a return, dead head they REALLY won't like it and it will die a horrible death within a few miles.

    Interesting thing I noticed since I got into these 99-07 Silverado and GMC trucks, the 03 and up have the regulator at the pump, so its a simple feed line to the injectors, rather than the FPR (pressure regulator) being on the rail like the 02 and earlier systems. If you could make one of those tanks or pumps work in your vehicle, that would be a kick ass way to go, all self contained other than the vapor recovery system. Something to look into.

    I'm using a 2005 system on a 6.0 with 706 heads for a bit more compression to test heating ethanol before the fuel rails/injectors in my 76 C10, which is why I noticed the FPR being in tank with the pump, don't want 200F fuel going back to the tank where it can expand can cause a pressure problem.

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  • Russell
    replied
    Dad has a high pressure pump on his carb engine. I think they used a high pressure regulator with a bypass and ended up keeping the regulator that was on it will the old noise maker pump to get it low enough.

    Leave a comment:


  • anotheridiot
    replied
    Originally posted by SuperBuickGuy View Post
    I suppose the other option would be to plumb something like this in, then simply sell it if you don't like EFI

    https://www.summitracing.com/parts/edl-36032
    I have one of those, did not cooperate with the sniper, there was a variable signal on that one for vehicles that use that to vary the speed (pressures the pump was putting out) when it was running. You leave your fuel pump on the motor and it fills that little sump and there is a high pressure pump in the plastic tank that feeds their estreet package. We went to the intank pump pretty quickly.

    I plan to use that if I ever set up my mechanical injection on the 36, as a prime tank.

    The e street problem was you have no chance to tune anything, the sniper problem is it seems to have one solution which is add fuel. Even with their distributor, that is controlled by their computer, its a simple solution, add or take away lead where its too rich or lean instead of adding fuel and leaving lead alone. It has an end for the learn cycle, and each time we try to let it learn on its own, jump on it to black smoke out the exhaust.

    That is why I think it will work for you since you have a "mild" cam. Ours idles like a funny car, which is her personality, that is why I am more interested in if your duration cam is a good match before we buy another one.

    Leave a comment:


  • SuperBuickGuy
    replied
    I suppose the other option would be to plumb something like this in, then simply sell it if you don't like EFI

    https://www.summitracing.com/parts/edl-36032

    Leave a comment:


  • anotheridiot
    replied
    I would just make sure what range the regulator has when you buy one. Sniper has its own regulator you need to plumb in so adding a connector on the feed line where you might want to put a regulator later in the general area of the return line would probably be enough during your trial basis.
    Hopefully you will keep us posted. Our cam is over 310 duration, its not a good match. Need to see how "tame" we have to get to make the sniper happy. We have never just set it up, go back to a clean tune and just drive in all conditions so all the software always wants to do is add fuel constantly.
    There is also a 250 some dollar O2 sensor they are suggesting now.

    Leave a comment:


  • cstmwgn
    replied
    my 2 cents - if you plumb it with a return line and regulator, then you can change the spring in the regulator to flip between 45psi and 5 psi.

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  • SuperBuickGuy
    replied
    pressure is the difference, 45 psi v. 5 psi. With that said, aeromotive (and others) make high pressure and low pressure versions the in-tank pump.
    That said, you won't change it. I have that system on my Corvette and love it.

    Leave a comment:


  • milner351
    replied
    I picked up a barely used sniper, I plan to use it on a mild 393 stroke 351W with AFR heads and a 254 duration at .050" lift hydraulic roller cam backed by a TKO 5 speed.
    It will either work, or be replaced with a carb.
    What I'm worried about is the fuel system, if I set it up for EFI, is there a fuel pump that will work with EFI and a carb? or would the pressure requirement difference between EFI and carb be so vastly different
    - I'd have to swap the pump (planning to run an in-tank pump) will a regulator in the engine compartment with a return line be able to manage that kind of difference?

    Leave a comment:


  • anotheridiot
    replied
    I did get a brand new sniper from Holley. I called to ask them if I can send ours in to get checked since we already lost one injector and went thru 3 IAC motors. Then I heard about a spark plug wire, called Magnacore that is supposed to handle the interference the sniper gets from plug wires (like that has ever been brought up before). Say to route the cables around the back and under the headers to stay as far away from the sniper internal computer as possible. Just got the car back in the paint booth after our 4 bar subframe and subsequent tubs and quarter panel replacement, along with 5 speed installation, so hopefully we will get some answers.

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  • Shep48COE
    replied
    I suggest having all information, including tire size, rear end gear, tranny, engine, camshaft, and vehicle weight. There are some very knowledgeable people on Holley sniper site and at comp cams that have helped me. If all that sounds ok, you will probably asked for a copy of your mapping from computer.

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