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Thread: Spittybug - Designs for converting stock setup to EFI

  1. #1
    Back to the Omnipresent! Spittybug's Avatar
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    Spittybug - Designs for converting stock setup to EFI

    I pulled my old manifold assembly (with all the K-Jet pieces attached like some kind of morbid stuffed animal back from the taxidermist) out of the cabinet I now store it in and plunked it down onto my workbench to stare at it. I'm chewing on just how one could possibly modify it to EFI with minimal intrusion and reversibility. I'm sure more mechanically competent minds than mine have tried, but then again I have a stubborn streak in me.

    My "rules" for such a mod would be that it had to be reversible, be more reliable than K-Jet, not required a new manifold, must be safe, perform at least as well as a functional K-Jet, be doable by the average Delorean owner (with some good instructions) and cost under $1000 all in.

    Ideas being kicked around:

    • Our stock injectors (always open) could conceivably be used in this mod by feeding them with a fuel line that is modulated just like a modern fuel injector being opened and closed. Megasquirt opens/closes each bank of injectors at the same time or sequentially and I've not been able to notice a real difference in performance between the two. As Opethmike pointed out, ours are constantly open anyway.
    • Alternatively, the W pipe might present a place to insert one or two large injectors, thus turning our manifolds "wet" and obsoleting our current injectors. Those holes can simply be plugged with a long bolt as several of us do. Large volume injectors are <$100 apiece items and could be plumbed via fuel hose rather than rail. The modification to the W pipe would involve drilling holes for the injector and some form of bracket to hold the injector in place. Whether this could be done at the very opening of the W pipe, under the access cover or not (one big injector), I don't know. It may need to be in the sharp radius which would required a bit more work to reverse if desired. The benefit of doing it in the W pipe would be maximum air flow for uniformity and owners could easily mail in a W pipe for a modification rather than say a whole manifold.
    • If one of the two above could work, there would be no need to find new manifolds, change the stock throttle body or throttle cable or build fuel rails. A pressure regulator would need to go inline, but other than that, the fuel system could remain pretty much intact.
    • Idle air would be an issue. I think the best solution for that would be to machine a small aluminum block into which a standard GM worm gear idle air valve (<$100) would fit. This could be mounted pretty easily in the above mentioned beginning of the W pipe if the injectors were in the elbows. It wouldn't be very big and could be made to screw into the cover plate holes to hold it down.
    • Replace narrow band 02 with wide band. Add in an intake air temperature sensor (could be put into the back side of the stock air filter housing with just a small drill hole), re purpose the water temp sensor in the Y pipe, remove the air deflector plate or block it open, and done. If spark control were desired, the mechanical advance in the dizzy must be locked in place (need to see if that can be done without the little tack weld I used).
    • Megasquirt would then control the system. Wiring into our cars would be comparable to what is in my write up earlier in this thread.

    A user could then remove a lot of the hoses and K-Jet components to clean the engine bay up if they wanted to, but wouldn't have to if they wanted to leave it looking essentially stock.

    The success of a mod like this would appear to depend entirely on the aerodynamics of our stock manifolds and whether throttle body injection rather than port injection would be good enough. If it weren't, I'm sure that we have sufficient brain power in this group to come up with the "master" fuel injectors that could be installed upstream of our existing injectors (sounds like frequency valves or 60 lb/hr fuel injectors minus their spray nozzles) to keep our port injection system.

    Calling all fabricators and tinkers!
    Last edited by Spittybug; 09-24-2011 at 11:28 AM.
    Owen
    Tour the country and visit breweries through the eyes of our two puppy dogs. http://www.twobrewdogs.com
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  2. #2
    Not a DeLorean Guru
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    Location:  Rochester, NY

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    Quote Originally Posted by Spittybug View Post
    I pulled my old manifold assembly (with all the K-Jet pieces attached like some kind of morbid stuffed animal back from the taxidermist) out of the cabinet I now store it in and plunked it down onto my workbench to stare at it. I'm chewing on just how one could possibly modify it to EFI with minimal intrusion and reversibility. I'm sure more mechanically competent minds than mine have tried, but then again I have a stubborn streak in me.

    My "rules" for such a mod would be that it had to be reversible, be more reliable than K-Jet, not required a new manifold, must be safe, perform at least as well as a functional K-Jet, be doable by the average Delorean owner (with some good instructions) and cost under $1000 all in.

    Ideas being kicked around:

    • Our stock injectors (always open) could conceivably be used in this mod by feeding them with a fuel line that is modulated just like a modern fuel injector being opened and closed. Megasquirt opens/closes each bank of injectors at the same time or sequentially and I've not been able to notice a real difference in performance between the two. As Opethmike pointed out, ours are constantly open anyway.
    • Alternatively, the W pipe might present a place to insert one or two large injectors, thus turning our manifolds "wet" and obsoleting our current injectors. Those holes can simply be plugged with a long bolt as several of us do. Large volume injectors are <$100 apiece items and could be plumbed via fuel hose rather than rail. The modification to the W pipe would involve drilling holes for the injector and some form of bracket to hold the injector in place. Whether this could be done at the very opening of the W pipe, under the access cover or not (one big injector), I don't know. It may need to be in the sharp radius which would required a bit more work to reverse if desired. The benefit of doing it in the W pipe would be maximum air flow for uniformity and owners could easily mail in a W pipe for a modification rather than say a whole manifold.
    • If one of the two above could work, there would be no need to find new manifolds, change the stock throttle body or throttle cable or build fuel rails. A pressure regulator would need to go inline, but other than that, the fuel system could remain pretty much intact.
    • Idle air would be an issue. I think the best solution for that would be to machine a small aluminum block into which a standard GM worm gear idle air valve (<$100) would fit. This could be mounted pretty easily in the above mentioned beginning of the W pipe if the injectors were in the elbows. It wouldn't be very big and could be made to screw into the cover plate holes to hold it down.
    • Replace narrow band 02 with wide band. Add in an intake air temperature sensor (could be put into the back side of the stock air filter housing with just a small drill hole), re purpose the water temp sensor in the Y pipe, remove the air deflector plate or block it open, and done. If spark control were desired, the mechanical advance in the dizzy must be locked in place (need to see if that can be done without the little tack weld I used).
    • Megasquirt would then control the system. Wiring into our cars would be comparable to what is in my write up earlier in this thread.

    A user could then remove a lot of the hoses and K-Jet components to clean the engine bay up if they wanted to, but wouldn't have to if they wanted to leave it looking essentially stock.

    The success of a mod like this would appear to depend entirely on the aerodynamics of our stock manifolds and whether throttle body injection rather than port injection would be good enough. If it weren't, I'm sure that we have sufficient brain power in this group to come up with the "master" fuel injectors that could be installed upstream of our existing injectors (sounds like frequency valves or 60 lb/hr fuel injectors minus their spray nozzles) to keep our port injection system.

    Calling all fabricators and tinkers!
    Cool project idea there, Owen.

    Some thoughts I have:

    I think it is easier to do the coolant temperature sensor by removing the thermotime switch, tapping the adapter, and inserting a standard GM CLT sensor. No need to worry about configuring tables in the MS then.

    I don't think idle air would be a problem. Even with my Z7U manifold, I am keeping the stock idle speed motor and vacuum advance solenoid. The way I am making it work (and this is very much credited to Jim Reeve) is that I wire into the wire coming from the idle ECU with the diode in it. I connect that wire to one of the extra output ports on the MS ECU. I then use Tuner Studio to provide ground over that channel when the throttle position sensor shows that the throttle is closed.

    This is a really cool project idea. Let's keep the brain storming coming!

  3. #3
    Back to the Omnipresent! Spittybug's Avatar
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    Ouch. You just reminded me about the throttle position sensor. Making one that would work with the stock throttle body would be a little challenging. Maybe one could be made to sit on top of the throttle spool. Need to think on that.

    I personally don't like the idea of the stock idle air. I think that is one of the areas where people have difficulties. It's like being half pregnant keeping that, isn't it? Just my opinion.
    Owen
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  4. #4
    Not a DeLorean Guru
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    Quote Originally Posted by Spittybug View Post
    Ouch. You just reminded me about the throttle position sensor. Making one that would work with the stock throttle body would be a little challenging. Maybe one could be made to sit on top of the throttle spool. Need to think on that.

    I personally don't like the idea of the stock idle air. I think that is one of the areas where people have difficulties. It's like being half pregnant keeping that, isn't it? Just my opinion.
    Yeah, I agree to an extent with you. I'm a bit conservative in my approach to modernizing my engine management in that I am taking it one single step at a time. First, I'm going to get the fueling right, then maybe a better ISM, then timing.

  5. #5
    Back to the Omnipresent! Spittybug's Avatar
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    I mocked this up just to see if the clearances are there and for everyone to be able to visualize what I'm brainstorming. These are only 19 lb/hr injectors, but I don't think there is any material difference in size (if any) for higher flow ones. Use your imagination on the relay in the center! That's about the right size and shape for an aluminum block to accept the pintle of the idle air valve. Underneath the cover that has been removed are two 1/4" or so holes, one into each side of the W pipe. Perfect for idle air. Obviously the aluminum rod and flashlight were there for staging the pic, but the rod could be a very short length of fuel rail that was mechanically connected to the idle block to hold the injectors in place. Fabrication of something like this would be a bit of work up front, but it would create a standardized setup onto any W pipe. The key is whether a wet manifold setup would work in the first place. Note too the GM throttle position sensor precariously perched on the throttle spool. Need ideas for that. Typically they go on the end of the butterfly shaft, opposite the linkage. Ours is enclosed in the throttle body.

    Even if the other idea (upstream injectors of our injectors) is a better one, the idle air billet will be necessary, but obviously simpler.
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    Owen
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  6. #6
    Back to the Omnipresent! Spittybug's Avatar
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    In looking around, there are lots of OEM style idle valves that could fit quite easily I believe. This one for example; http://cgi.ebay.com/ebaymotors/STAND...ec5e#vi-ilComp

    A simple adapter plate under it would have a side port nipple to bring air in from the air cleaner box (or through a small filter of its own), up into one of the two ports of this valve, and the output goes straight down through the adapter into the two holes in the W pipe. Really any self contained IAC with two chambers and a worm-gear-moving-pintle between them (opening or blocking off the air) would work. No modification to W pipe.

    I'm spending more time thinking about the idea that uses our existing fuel injectors and simply re-plumbing them. For the throttle position sensor, what would be really neat would be to be able to replace the micro switch that the throttle assembly pushes on (idle speed micro switch) with some kind of linear potentiometer. Dave M. suggested this, but I haven't yet been able to fully visualize how to install something like that.
    Owen
    Tour the country and visit breweries through the eyes of our two puppy dogs. http://www.twobrewdogs.com
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  7. #7
    Senior Member AdmiralSenn's Avatar
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    My conversion uses fuel rails almost identical to yours, but with injectors in the stock fuel injector ports and a bracket that holds the rails down via existing bolt holes in the manifold. Daryl's is very similar. So this is a definite possibility. The only real downside is that it blocks access to the spark plugs, but it's really not that much work to remove the manifold and rails (total of six bolts, I can get to the plugs in about three minutes).

    Idle air is (although still in progress) accomplished through the plate above the W pipe as you mentioned, and CLT is through the TTS adapter as Mike said. The only thing I haven't fully figured out is the TPS - I made a bracket and rain shield for mine but I've gone through several TPS units now so I'm exploring other options.

    I would love if that idle motor could be made to just fit on the W pipe plate. That'd solve a LOT of problems... Especially if it can be pulse width modulated or stepped instead of just being on or off. Our original ISMs could open or close less based on engine needs (at least this is how I've always understood them to work, my car came without one), it would REALLY suck to go "backwards" and have only a standard on-off in its place.
    Last edited by AdmiralSenn; 09-24-2011 at 05:57 PM.

  8. #8
    Back to the Omnipresent! Spittybug's Avatar
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    Quote Originally Posted by AdmiralSenn View Post
    My conversion uses fuel rails almost identical to yours, but with injectors in the stock fuel injector ports and a bracket that holds the rails down via existing bolt holes in the manifold. Daryl's is very similar. So this is a definite possibility.
    I thought that a modern injector was too wide for our ports

    I think it was Josh B. that talked about reaming out the holes to make them wider.....

    IF indeed modern injectors can replace ours, this becomes a no brainer!
    Owen
    Tour the country and visit breweries through the eyes of our two puppy dogs. http://www.twobrewdogs.com
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  9. #9
    Senior Member AdmiralSenn's Avatar
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    Quote Originally Posted by Spittybug View Post
    I thought that a modern injector was too wide for our ports

    I think it was Josh B. that talked about reaming out the holes to make them wider.....

    IF indeed modern injectors can replace ours, this becomes a no brainer!
    Nope. They fit remarkably well. Depending on o-ring tolerances you may have to gently tap them in with a piece of wood but mine pop in exactly as tightly as the old K-jet units did.

    The proper EFI manifold is a FAR better solution, I think, but for absolute cheapness, this is a great way to do it. And an intake is easy - you can remove the mixture box and build a new intake with Autozone style "tuner" stuff - air filter, flexible hose, and a 3"-2.5" adapter, trimmed down, makes a decent intake. Substitute hard tubing or fancy airboxes if you want to make it nicer.

  10. #10
    Senior Member Bitsyncmaster's Avatar
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    I was thinking about the throttle position sensor. You don't really need to put it on the the engine. Just put it on the accelerator pedal. That way you don't have to worry about heat and water.
    Dave M vin 03572
    http://dm-eng.weebly.com/

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