Preparing For Honda K24a3/AST5 6spd Conversion

Discussion in 'Workshop Forum' started by lookforjoe, Aug 31, 2018.

  1. darwoodious

    darwoodious Darin Nelson

    Location:
    Seattle, WA
    On the K20A2 the PCV valve is on the
    IMG_20160507_155305.jpg

    Here's a ClubRSX discussion on it.

    Here's from the parts guys.

    What's on the front (right) side of your intake plenum - looks like the same.
     
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  2. lookforjoe

    lookforjoe True Classic

    I'll take a read over there.

    The other control on the right in photo (#12 in diagram) is called "Air assist valve" & is vaccum controlled, determined by coolant temp. Not clear what it (the vacuum draw on the intake channel around the injector ports) really does in operation

    [​IMG]

    EDIT: Found this on the K-Tuned website

    "The K-Tuned Idle Air Assist Delete Kit will help clean up the overall look of any K-series engine by removing the ugly and unnecessary Idle Air Assist valve from the engine. This valve is typically mounted on the rad inlet or intake manifold depending on what engine you have. It has a hose running from the top of the valve to the center of the intake manifold and a second hose from the valve to the intake piping. The air assist valve was designed to raise the idle during a cold start up to increase engine warm up speed. Our testing has proved to us that this sensor can be deleted because a properly functioning IACV (Idle Air Control Valve) already does the same job. RSX, TSX, 8TH Gen Civic and EP3 owners will appreciate this delete kit even more because the Air Assist Valve always seems to get in the way when installing an upgraded fuel rail. Included in the delete kit is a plug for the intake manifold port and a plug for the coolant port on the rad inlet or intake manifold."

    So, I think I can safely remove that aspect. I would like an IACV, but I'd need to add the TPS & IACV from an RSX, etc., since my engine came with electronic throttle it didn't need them. Not sure if the wiring from the E-throttle can be repurposed for those two items. I would think so, but haven't researched that.
     
    Last edited: Sep 11, 2018
  3. kmead

    kmead Old enough to know better

    Location:
    Michigan
  4. lookforjoe

    lookforjoe True Classic

    Thanks for the mock ups, Karl!

    Pretty sure it won't work going up on such a steep angle right off the flange, there needs to be few inches out to allow for the correct angle of the injectors & a fuel rail with standoffs.

    I may well be able to put 90º elbows on the end of the existing runner, or cut it back 2-3" (and loose the crankcase breather setup), then build or use one of the existing plenums pushed back over the runners.

    I've ordered 4 cast aluminum 2.25" elbows to play around with this.

    Since I haven't spent $$$ on the cooling housings I'm going to use a 80mm K-Tuned throttle body :)

    [​IMG]
     
    Last edited: Sep 12, 2018
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  5. lookforjoe

    lookforjoe True Classic

    Finished welding the extension - had to grind all the welds, they really looked nasty.

    [​IMG]

    [​IMG]

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    Room to fit the coolant hose between the extension and the edge of the flange on the ancillary bracket

    [​IMG]

    Still need to finish the porting to match the two flanges. I also damaged the flange on the Honda end clamping it in the vice - I forgot the two ends aren't parallel. I have to reinforce the backside of the flange & then get the mating surface flat again.

    Volvo end

    [​IMG]

    Honda end

    [​IMG]
     
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  6. kmead

    kmead Old enough to know better

    Location:
    Michigan
    Nice casting. :) Looks very good.

    I know I am beating my own dead horse here, so feel free to ignore the following. After this I will keep it to myself as its not pertinent if its not something you want to do.

    This engine, like most modern engines, was designed to be put under the lowest possible hood in a front drive car which can have plenty of room for hanging things in front of the engine. A proper length, downwardly curved manifold to clear that low hood then drives the accessories downward as well. As we all know, on an X there is a finite amount of room to the firewall and the structure of the car. Changing the manifold and going to an electric water pump would allow moving the alternator and AC compressor accessories upward, reducing the need to cut away so much of the structural tub around the lower area of the engine compartment. The alternator could be moved to the rear of the engine to make room for the compressor potentially though likely not needed.

    I know that a spare tire is much less needed today, my beef isn’t (specifically) with cutting away that relatively non structural area, it is the lower tub of structure that is removed that I am more concerned with. One can add back the same amount of steel into the lower area but the reality is that the same amount of steel in a narrower cross section is not as strong as that same steel placed across a larger cross section. This is the base principal around the structural difference between a piece of bar stock versus a tube, a tube (with a thick wall) can have nearly the same strength as a bar of steel due to the fact that as the material gets closer to the center of the section the amount it contributes to stiffness is reduced very quickly to the point where it contributes nothing at the center. Additionally, inducing all manner of corners and sharp edges creates areas where stresses can contribute to cracking and folding under load. Load like a side impact or other impacts in addition to rhythmic loading from driving down the road and engine vibrations.

    In looking at the cutaways of the K20 head (and Toyota 2ZZ head) the path to the valves in the head is effectively level or slightly pitched down to start then pitches down further to the valves in a fast arc. Coming from above in an upwardly facing arc isn’t much of a leap versus coming from a downwardly facing arc.

    76418125-395B-4469-8514-270D4A1874C7.jpeg D0B9B8D9-0916-4982-8611-CD065E77ED07.jpeg

    I know, different engine but handling a similar amount of air, the Toyota intakes do start with a flat arc in the intake and then start a fast curve down and around to meet the plenum which has an offset of the log to the extended curved transitions into the plenum log.

    5FF03E66-3310-49FB-91B0-C513B046B934.jpeg 478DB5E0-2882-4219-8CF1-1EC338D05F1A.jpeg

    Following this logic one could start with an upward arc and then turn more quickly upward to place the intake plenum log where it will fit.

    What could be done certainly can’t be resolved before putting the engine into the car. One could imagine cutting the existing castings apart and rewelding them or using a bolt on plenum to attach to fabricated SS or bent aluminum tubular runners going to a machined intake flange.

    F1483CEE-BF48-404B-A4D6-62873E239EF0.jpeg 37761956-D51D-47C6-8EE5-AF30C8F58D24.jpeg 2E30D879-DEE9-4E23-98D9-06314212F5A0.jpeg 06D2EAA4-8CDB-40AB-8E4A-ED630AC23CEE.jpeg
    https://xcessivemanufacturing.com/honda/k-series/honda-h-k-a2-bif.html

    Given your handiwork it seems within the realm of possibility. Anyway, dead horse beating is done. https://goo.gl/images/f7BFg2

    Nice work as always, great to see.

    Thanks

    Karl
     

    Attached Files:

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  7. lookforjoe

    lookforjoe True Classic


    I defintely want to explore an alternative intake, whether it's top mount plenum/TB or tucked under :D The concerns are whether there is space for the radius (correct term here?) required to arc the runners up to situate the plenum so it's not too high, nor set too far forward where it would end up being more of an issue with the upper firewall area/engine cover hinge/rear glass support.

    The actual arc (up/down/sideways) of the runners relative to the head ports has little to no impact on performance, assuming the arc transition is smooth, so that's all packaging concerns as you stated.

    If I do an end mount TB, then a tapered plenum is best. Volume should be around engine displacement or more, most stock plenums are typically smaller. My practical experience with all this was for positive pressure setups, so I didn't pay much attention to NA requirements. I'm going to assume plenum sizing proportion is still comparable.

    The stock RBB runners are approx 1.9" round at the outer flange, flattened to meet the head ports. If I can use the RBB runner, I can use 2.25" (approx 1.9" ID) 90º cast elbows off that flange, then offset the plenum over the existing runner. I don't want to build something that makes servicing the injectors, etc. a PITA, so nothing that extends back over the engine.

    [​IMG]

    I'm still going to make the frame cuts as spec'd by MWB. I'm going to leave the alternator where it sits. I really don't want to get involved in building the belt drive system & component placement, unless it turns out I have no choice. Don't have an AC compressor around, so I haven't played with that or really decided if I'm going to keep AC. The engine performance & service access is more important to me than allowing for an AC install, although I may regret that later.
     
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  8. fiatmonkey

    fiatmonkey Tim Hoover

    Location:
    Redwood City, CA
    FYI - my mani is an aftermarket unit from k-tuned. I bought it specifically for its power making and that it is multi directional. I don't have a spare RBC like the one at your metal guys shop.
     
  9. lookforjoe

    lookforjoe True Classic

    Yes - it's more so I can gauge depth. I can see where yours sits relative to the firewall. It's the distance to the flange that the plenum bolts to I'm most interested in.
     
  10. kmead

    kmead Old enough to know better

    Location:
    Michigan
    It is interesting that the K24 uses a manifold to a manifold connection. The initial one carrying the injectors and much of the plumbing and the runner manifold. VW did this on the old twin cams with most of the runner and the plenum being one part and the last turn and offset being the carrier for the injectors. Many changed from CIS Motronic to VWs own injection system which used a fuel rail etc.

    7451B4BC-0771-4D13-A2C7-51F48C9E309A.gif C2CB52C6-4CD7-420C-90BB-5A51E1A8C08F.jpeg DB7E3463-70F5-43D4-9187-85A9E2F6575B.jpeg

    Given the two part nature, assuming the fasteners would be accessible, having the runner portion curve up and around the injectors would seem to be reasonable for servicing the injectors (which hardly ever has to happen).

    Anyway looks to be an interesting packaging problem, much like the water pump/thermostat housing arranging down below.

    I found the description of this engine builder’s K24 instructive: https://www.staffordengines.com/honda-k24-25-16v.html
     
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  11. fiatmonkey

    fiatmonkey Tim Hoover

    Location:
    Redwood City, CA
    @lookforjoe Hussein - Did you/are you replacing the underside coolant hard lines? I made a set to replace mine and I added 16AN ends on the engine side and shortened the lines to make it easier to connect. The stock length lines exit rather close to the point where the custom engine cradle sat (on my first k20 swap car).

    IMG_0599.JPG IMG_0598.JPG
     
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  12. lookforjoe

    lookforjoe True Classic

    Nothing wrong with my pipes, so I wasn't planning on removing them :D At the very least I should look at shortening them, it seems.
     
  13. lookforjoe

    lookforjoe True Classic

    Problems with using the K24, harness & ECU.

    Since the '05 TSX is DBW, I need to replace the ECU (37820-RBB-E05, manual) with one from an '05 Accord EX (37820-RAD-A04, manual), which was DBC in order to get a K-Tuner User Board installed. This means I may need to re pin the ECU, and/or remove the DBW connector & repin for TPS and IACV.

    Looking on DennisH's K20a.org conversion, he also mentioned replacing the knock sensor and crank sensor when going from K20 to K24, but I'm not sure if that was because his motor was missing them, or the K20 ECU input is different for them, I dunno..

    Anyway, I have now a 37820-RAD-A04 on the way.

    Bosch 15482 O2 sensor is ordered.
    Civic slave cylinder LuK LSC452 with end fitting (instead of top) for hydraulic hose is ordered. Looking at various installs, that top mount fitting is really up against the bulkhead.
    Misc intake gaskets ordered, incase I want to use the RBB runners.
     
  14. lookforjoe

    lookforjoe True Classic

    Having trouble locating electrical connectors for the Honda harness. Looks like they may be Sumitomo. No one seems to be able to answer the question on K20a or K-Tuner. Doesn't make sense to me that no one has figured that out

    Edit: Honda manifold tests
    http://www.superstreetonline.com/how-to/engine/sstp-1002-k-series-intake-manifold-shootout/

    Anyway, I started modifying the RBB runners. cut off & ground away the coolant heating channel

    [​IMG]

    Looking at engine pics like this

    [​IMG]

    and DennisH's engine/ bay clearance measurements

    [​IMG]

    [​IMG]

    There is no room to put the plenum over the runners. The arc of the runners will run into the structural metal under the window, and the height of the plenum will be an issue. Unless I chop at least 2" off the runners, there's no room to allow for the arc upwards.

    [​IMG]

    I'm going to put the plenum under the runners. That way the TB has a straight path, it will work as long as the plenum can be removed from the runners, or there would be no way to reach the headflange bolts & nuts. Should be plenty of room under it for the rad feed hose.

    [​IMG]

    Removed the coolant housing, and found there is an EGR port off the #4 exhaust that feeds into the housing. Don't want that, so I tapped it with a 3/8" NPT & plugged it.

    [​IMG]

    Heater connection will be along these lines. Other port will go away, black tube will be cut before rad hose connection, and used to connect to expansion tank feed. tank vent will connect to upper nipple.

    [​IMG]
     
    Last edited: Sep 14, 2018
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  15. kmead

    kmead Old enough to know better

    Location:
    Michigan
    It’s clear you have been doing some puzzling and cogitating Jethro. :) (Beverly Hillbillies reference)

    Well there it is sports fans, dimensions don’t lie.

    Your manifold and plenum approach is very much like the Toyota 2ZZ runner and plenum system. There are two factory versions of the early 2ZZ assembly, the Celica which is one piece in a complex casting and the other which is a two piece runner and then plenum used on the Pontiac Vibe and Toyota Matrix XRS.

    As you have mentioned your past intent, this uses a wedge shaped plenum which tapers back to the #1 cylinder.

    Like this manifold, you might consider rotating your runners so the plenum will be moved towards the driver’s side of the compartment a few inches. You will want the room and the air doesn’t care if its going up and around or up, back and around.
    E9A1B293-1456-4429-851D-D68D0ABAFCE0.jpeg
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    Last edited: Sep 14, 2018
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  16. kmead

    kmead Old enough to know better

    Location:
    Michigan
    Though when I look at this image

    D9CD83EC-C95A-45AE-88A1-230604706406.jpeg

    And think about well if it was cut at the kink before it goes level that one could then continue upward and then back around towards the engine.

    But I know you want to keep the construction Honda put on top of the runners before the secondary manifold and want better servicability of the injectors, wiring etc. Which also makes sense.

    In any case clearly a lot of thinking and now action is taking place. Way to go Idaho. (Toy Story reference)
     
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  17. lookforjoe

    lookforjoe True Classic

    4” TB OD to 3.25 for filter. Volvo V6 TB flex hose - I don’t have any silicone step couplers (left overs from various iterations of piping on my old Volvo wagon) in just the right size, but the flex hose probably makes more sense anyway as the TB has to point uphill somewhat to fit

    [​IMG]

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    Not much room

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    Last edited: Sep 17, 2018
  18. kmead

    kmead Old enough to know better

    Location:
    Michigan
    Could you move the plenum towards the drivers side one runner and then offset the runners appropriately?

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    Last edited: Sep 15, 2018
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  19. lookforjoe

    lookforjoe True Classic

    This is about as far as I could offset the plenum

    [​IMG]

    However..... that is not possible as that would put at least #4 runner into the gas tank. If you look at the stock (K20, PRB) intakes (Rodger's etc.,), the TB flange is up against the bulkhead relief for the tank. That’s about 7” off the flange to the firewall

    [​IMG]

    Rodger's - looks like about 6" clearnace from the head to the gas tank bulkhead, based on where the flange opening sits
    [​IMG]

    Although that area can be worked to provide relief (pics in Rodger's thread) for the TB flange, this would be much more than that.
    [​IMG]

    So it pretty much has to be where I had it, with an extended plenum neck to move the TB inboard/rearward & left. It has to stay onboard of where the slave cyl is, as that is up against the firewall on every install I see. Also wondering whether the TB hose and filter I have will actually fit in the space there is available.

    [​IMG]

    Australian K20 swap
    [​IMG]

    I have to chop the rad hose neck off again and point it more or less straight down, and use a rad hose with a 90 degree offset . Can’t make it work as it is

    [​IMG]
     
    Last edited: Sep 16, 2018
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  20. kmead

    kmead Old enough to know better

    Location:
    Michigan
    A tight package indeed.

    Getting the plenum under and back seems like the best way towards keeping the TB out of the space for the fuel tank and not having it removed to the side as others have had to do.

    Not a lot of choices, Midwest certainly did a good job with getting that monster in there in the first place.

    Personally I wouldn’t want to get too many things made and resolved until actually start to fit the beast into the engine bay.

    Sorry for all my dumbass distractions. Thanks for suffering them.

    Wish I lived closer, you on the other hand are likely thankful that I do not.
     
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