Auto tune idea for blowthrough carb
+ Reply to Thread
Page 1 of 2 1 2 LastLast
Results 1 to 14 of 21

Thread:
Auto tune idea for blowthrough carb

  1. #1
    Senior Member Hass828's Avatar
    Join Date
    Dec 2007
    Location
    okie, lake Texoma
    Posts
    6,275

    Default Auto tune idea for blowthrough carb

    So I have this crazy idea.
    Been thinking about this FiTech setup for tuning carbs.
    FiTech Go Tune AFR Basic and Power Adder Systems | FITech Fuel Injection
    Its cool & everything but I have one more feature that they need to add, and have a call in with one of their engineers to discuss it.

    Since the blowthrough carbs have the powervalves referenced to the hat, why not external reference them instead and control them with this 02 sensor setup so that it chases a target A/F ratio?

    Would be a regular carb while idling, cruising under vacuum , but once any boost pressure is present have this controller take control of the powervalve system and keep it at a plotted a/f ratio all through the boost curve.

    Plot an a/f ratio curve on a map of 1psi-30psi, then make a pass, overlay the two, commanded & observed to make sure it does as commanded.

    I talked with Rodger @ C&S, he said the PV's are variable so should work just fine, although might want to add spring pressure to the PV's so that they are a little less sensitive. He says the stock spring go from closed to open with less than 1 psi differential, so adding a 10psi spring so it actually takes 1-10psi to go full open might make more managable.

    Also talked with Sebastian from AMS , their AMS2000 will do what I am asking. Its just to expensive.

    So what you think? Set Idle - and cruise a/f just like any other carb, but have computer take over the powervalves when under boost. No extra wires, sensors, none of that BS, unhook one boost line and its still just a carb.





    This FiTech setup already data logs everything, controls timing in reference to A/F-ect. and has 02 sensor.
    Just needs one more option.
    SMART CARB
    Last edited by Hass828; 02-08-2016 at 09:18 AM.
    "if we keep doing it the same way we always do..we will always get the same results"
    H8-2-W8
    [email protected] first pass

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member
    Join Date
    May 2014
    Posts
    266

    Default

    Why would you not just put one of holley's new terminator set ups on it at that point?
    It sounds to me like you are just ready for EFI at this point !
    Carbs make great hp and work as good if not better than EFI ...... On a naturally asperated motor, but to run big power and high boost numbers on a blow threw carb set up well that kinda like trying to rope the wind

  4. #3
    Senior Member Hass828's Avatar
    Join Date
    Dec 2007
    Location
    okie, lake Texoma
    Posts
    6,275

    Default

    Quote Originally Posted by tbscustoms View Post
    Why would you not just put one of holley's new terminator set ups on it at that point?
    It sounds to me like you are just ready for EFI at this point !
    Carbs make great hp and work as good if not better than EFI ...... On a naturally asperated motor, but to run big power and high boost numbers on a blow threw carb set up well that kinda like trying to rope the wind
    Incorrect. I have been running 30psi of boost with my blowthrough carb for a long time now with no problems. My deal works very-very well and I couldnt be more pleased with it. I was thinking of this idea more for some of the guys building fresh stuff. Why make a pass and datalog , then try to tune to what it did, when you could command what you want it to do beforehand. And I still like the fact that other than a single boost reference line (that any blowthrough would have anyway) its just a carb. The blowthroughs are making over 22-2300hp today. A set of injectors capable of moving that much fuel are very expensive and dont idle worth a crap, need servicing every season, ect.
    "if we keep doing it the same way we always do..we will always get the same results"
    H8-2-W8
    [email protected] first pass

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    Or Seth, either one Budweiser's Avatar
    Join Date
    Dec 2007
    Location
    Tower Park Resort, Lodi, CA
    Posts
    3,270

    Default

    I always thought the volume of fuel delivered through the power valve circuit was determined by the power valve circuit restrictor and that the power valve acted more like an on/off switch. I see the vision, but think it'll definitely require some specific mods to work properly. Nothing to it but to figure it out. Open the PVCR up and use a custom power valve designed to variably meter fuel precisely over a certain pressure range is where I'd start.
    Last edited by Budweiser; 02-08-2016 at 10:05 PM.

  7. #5
    Senior Member Hass828's Avatar
    Join Date
    Dec 2007
    Location
    okie, lake Texoma
    Posts
    6,275

    Default

    Quote Originally Posted by Budweiser View Post
    I always thought the volume of fuel delivered through the power valve circuit was determined by the power valve circuit restrictor and that the power valve acted more like an on/off switch. I see the vision, but think it'll definitely require some specific mods to work properly. Nothing to it but to figure it out. Open the PVCR up and use a custom power valve designed to variably meter fuel precisely over a certain pressure range is where I'd start.
    Quote Originally Posted by Hass828 View Post
    I talked with Rodger @ C&S, he said the PV's are variable so should work just fine, although might want to add spring pressure to the PV's so that they are a little less sensitive. He says the stock spring go from closed to open with less than 1 psi differential, so adding a 10psi spring so it actually takes 1-10psi to go full open might make more managable.
    The powervalve is variable, not just on or off.
    On my C&S you can control when & how much the PV opens by turning that carb stud so the reference hole is 90* or 180* from inlet to hat. Makes a substantial change in a/f curve.
    Rodger builds these and knows more about them than anyone, he seems to think it would work just fine, just might need a little stiffer spring on the PV.
    Last edited by Hass828; 02-09-2016 at 04:50 AM.
    "if we keep doing it the same way we always do..we will always get the same results"
    H8-2-W8
    [email protected] first pass

  8. #6
    mo balls than $cents$ IMPATIENT 1's Avatar
    Join Date
    Dec 2007
    Location
    hugo,okla
    Posts
    11,727

    Default

    When you mentioned variable pv i was wondering what you meant. My last carb i built using stiffest pv spring i cld find so itd snap shut asap when it wasnt getting signal from the airpump. Light springs jus made it wanna die on shutdown running rich till the pv cavity had less pressure than the spring. I was feeding the carb 35psi of metered airpresssure to make sure it stayed open at 20-22lbs of boost. It would be nice to operate my pumps with the fitech deal, personally id like to use boost level tho but having afr trigger it during a lean condition would be great too. To make it variable you would need a variable airpressure source since youre no longer getting stud signal. I tried turbine pressure, pre and post intercooler pressures and they didnt work very good. You had to hope the pv saw pressure before the bowl or it wouldnt open good.

    Dare to be different, if it turns out great you can claim you planned it that way.

    Jetboatperformance.com

  9. #7
    Or Seth, either one Budweiser's Avatar
    Join Date
    Dec 2007
    Location
    Tower Park Resort, Lodi, CA
    Posts
    3,270

    Default

    Quote Originally Posted by Hass828 View Post
    The powervalve is variable, not just on or off.
    On my C&S you can control when & how much the PV opens by turning that carb stud so the reference hole is 90* or 180* from inlet to hat. Makes a substantial change in a/f curve.
    Rodger builds these and knows more about them than anyone, he seems to think it would work just fine, just might need a little stiffer spring on the PV.
    I'm with ya Hass and I'm always up for a better and more accurate understanding of nearly anything engine related, as well as investigating new ideas and thoughts. Totally my thing. I read what ya wrote and I get that if you test a PV it will open variably. IMO, full open over 1 psi (2" hg) is pretty much an on/off switch. I like your idea of a heavier spring. My point, or thought, is if the PVCR is unchanged and if a power valve is indeed variable, the only benefit I see at the moment is having control over the transition between main jetting AFR and the full rich AFR that's already tuned into the carburetor as it sits. Presently, blow through carbs seem to be able to achieve a very good fuel curve for every driving condition. Would being able to control the ramp of the enrichment fuel add enough benefit to make it a worth while modification?

    Also, while the valve actuation may be variable, how far does it have to be off it's seat until the open flowable area of the valve is equal to the PVCR area? So if the valve is variable over (no idea, let's say) 1/8", if it's flowing enough to equal the PVCR at 1/64" or 1/32" open, then the remainder of the "variable" valve motion would have no effect... Which is why I figure you'd need a "custom power valve designed to variably meter fuel precisely"

    EDIT: And the PVCR would have to be sized to equal or out flow the full open PV, so that the PV completely controlled and metered enrichment fuel. That's the only way I see the plan being able to expand the tune beyond the existing PVCR AFR limit.

    These are just my thoughts. I could be wrong. Let's figure it out.
    Last edited by Budweiser; 02-09-2016 at 09:30 AM.

  10. #8
    Senior Member Hass828's Avatar
    Join Date
    Dec 2007
    Location
    okie, lake Texoma
    Posts
    6,275

    Default

    Quote Originally Posted by Budweiser View Post
    I'm with ya Hass and I'm always up for a better and more accurate understanding of nearly anything engine related, as well as investigating new ideas and thoughts. Totally my thing. I read what ya wrote and I get that if you test a PV it will open variably. IMO, full open over 1 psi (2" hg) is pretty much an on/off switch. I like your idea of a heavier spring. My point, or thought, is if the PVCR is unchanged and if a power valve is indeed variable, the only benefit I see at the moment is having control over the transition between main jetting AFR and the full rich AFR that's already tuned into the carburetor as it sits. Presently, blow through carbs seem to be able to achieve a very good fuel curve for every driving condition. Would being able to control the ramp of the enrichment fuel add enough benefit to make it a worth while modification?

    Also, while the valve actuation may be variable, how far does it have to be off it's seat until the open flowable area of the valve is equal to the PVCR area? So if the valve is variable over (no idea, let's say) 1/8", if it's flowing enough to equal the PVCR at 1/64" or 1/32" open, then the remainder of the "variable" valve motion would have no effect... Which is why I figure you'd need a "custom power valve designed to variably meter fuel precisely"

    EDIT: And the PVCR would have to be sized to equal or out flow the full open PV, so that the PV completely controlled and metered enrichment fuel. That's the only way I see the plan being able to expand the tune beyond the existing PVCR AFR limit.

    These are just my thoughts. I could be wrong. Let's figure it out.
    Keep in mind that adding the 10psi spring was Rodgers suggestion so that it would be a 10 psi sweep from closed to full open. Also keep in mind that the opening of the PV isnt the only thing at work there that is richening the a/f ratio when boost comes in, the boost above the carb enters the bowls through the vents and since the boost above the carb is always higher than below , this helps push the fuel through the system and form your curve.
    With that said though, if the full sweep is 0-10psi, and it has the ability to be dead lean- or full on FAT, then no reason a controller shouldnt be able to take command of it and follow a target. jmo.

    The blowthrough carbs are advanced enough to beg the question--- Is this necessary??
    I dont know for sure because getting and keeping mine in tune was pretty simple/easy. Just an idea.
    Last edited by Hass828; 02-09-2016 at 09:40 AM.
    "if we keep doing it the same way we always do..we will always get the same results"
    H8-2-W8
    [email protected] first pass

  11. #9
    Or Seth, either one Budweiser's Avatar
    Join Date
    Dec 2007
    Location
    Tower Park Resort, Lodi, CA
    Posts
    3,270

    Default

    Then... you could tune your main circuit for the highest DA you think you may encounter and let the PV fine tune based on AFR and "fuel map", I'd think. In the mountains, adjust idle mixture and go. Sea level, adjust idle mixture and go.

  12. #10
    Senior Member Hass828's Avatar
    Join Date
    Dec 2007
    Location
    okie, lake Texoma
    Posts
    6,275

    Default

    You could also run dual carbs with the entire PV sytem being controlled and make as much power as any efi system out there, not have to dick with the expensive injectors & stuff.
    "if we keep doing it the same way we always do..we will always get the same results"
    H8-2-W8
    [email protected] first pass

  13. #11
    Senior Member Hass828's Avatar
    Join Date
    Dec 2007
    Location
    okie, lake Texoma
    Posts
    6,275

    Default

    If this would actually work, then why couldnt you design a plate simular to a perimeter NOS plate to ad enrichment fuel, and use any standard dominator carb for blowthrough, and as soon as any boost is present let the fuel enrichment plate come on and keep the engine at a target a/f ratio while under boost? Control the plate instead of PV circuit.
    Bet that they could market a boost fuel enrichment system like that.
    "if we keep doing it the same way we always do..we will always get the same results"
    H8-2-W8
    [email protected] first pass

  14. #12
    Senior Member Hass828's Avatar
    Join Date
    Dec 2007
    Location
    okie, lake Texoma
    Posts
    6,275

    Default

    Quote Originally Posted by Budweiser View Post
    Then... you could tune your main circuit for the highest DA you think you may encounter and let the PV fine tune based on AFR and "fuel map", I'd think. In the mountains, adjust idle mixture and go. Sea level, adjust idle mixture and go.
    Yes this would only be in action while under boost. The rest of the carbs system would still be normal carb stuff. You should be able to tune it anywhere, any D/A and it still chase the commanded a/f ratio curve. Self tune for higher/lower d/a.
    In other words , if you command a curve that has you @ 11.8-1 a/f ratio @ 25psi, it should be at that 11.8-1 no matter what the d/a changes to.
    Last edited by Hass828; 02-09-2016 at 09:56 AM.
    "if we keep doing it the same way we always do..we will always get the same results"
    H8-2-W8
    [email protected] first pass

  15. #13
    Or Seth, either one Budweiser's Avatar
    Join Date
    Dec 2007
    Location
    Tower Park Resort, Lodi, CA
    Posts
    3,270

    Default

    Last post was meant to be a continuation to my previous.

    Quote Originally Posted by Hass828 View Post
    Keep in mind that adding the 10psi spring was Rodgers suggestion so that it would be a 10 psi sweep from closed to full open. Also keep in mind that the opening of the PV isnt the only thing at work there that is richening the a/f ratio when boost comes in, the boost above the carb enters the bowls through the vents and since the boost above the carb is always higher than below , this helps push the fuel through the system and form your curve.
    With that said though, if the full sweep is 0-10psi, and it has the ability to be dead lean- or full on FAT, then no reason a controller shouldnt be able to take command of it and follow a target. jmo.

    The blowthrough carbs are advanced enough to beg the question--- Is this necessary??
    I dont know for sure because getting and keeping mine in tune was pretty simple/easy. Just an idea.
    Even with 0-10 psi sweep, if the valve flows more than the PVCR, only the portion of valve movement up to the point that the PVCR is limiting flow would be variable. Don't know what that number might be out of 0-10 psi. Wanna guess less than the first half of that, but I could be way out in left field on that. Would have to drill out the PVCR's way big to let the PV do it's thing, but then you may be left with a portion of valve movement that's never used which brings us back to square one again.

    I'd think it needs to have a precision PV capable of precisely metering fuel over a predetermined range with a limit, given a range of pressure applied.

    "Then...you could tune your main circuit for the highest DA you think you may encounter and let the PV fine tune based on AFR and "fuel map", I'd think. In the mountains, adjust idle mixture and go. Sea level, adjust idle mixture and go."


    Possible simple solution... Without drilling out the PVCR, put a 10lb spring in the PV, slowly increase pressure until no added pressure makes additional change. If it's 3 out of 10, put a 30 lb spring in and modulate 0-10 psi. Maybe? Just thinking out loud

    But then, you're still left with the same max AFR and needing to jet for conditions. PVCR's would have to be enlarged to cover the desired additional range
    Last edited by Budweiser; 02-09-2016 at 10:18 AM.

  16. #14
    Or Seth, either one Budweiser's Avatar
    Join Date
    Dec 2007
    Location
    Tower Park Resort, Lodi, CA
    Posts
    3,270

    Default

    Quote Originally Posted by Hass828 View Post
    Yes this would only be in action while under boost. The rest of the carbs system would still be normal carb stuff. You should be able to tune it anywhere, any D/A and it still chase the commanded a/f ratio curve. Self tune for higher/lower d/a.
    In other words , if you command a curve that has you @ 11.8-1 a/f ratio @ 25psi, it should be at that 11.8-1 no matter what the d/a changes to.
    In theory, it could also augment cruise AFR, couldn't it?

+ Reply to Thread
Page 1 of 2 1 2 LastLast

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95