Preparing For Honda K24a3/AST5 6spd Conversion

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

  1. lookforjoe

    lookforjoe True Classic

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

    Now, where's the fun in that :D?

    I think there are enough pics to gauge the available space, I just have to pay attention. I know I will have to wait for some things, like the exhaust. I'm going to make as much as I can. If I end up having to rework what I have it will still be less work than starting for scratch, IMO. This sort of challenge is engaging.

    I would have no problem with you as a neighbor - I appreciate your ideas and input. Defintitely helps keep me on my toes :)
     
    Last edited: Sep 16, 2018
    stingray250 and kmead like this.
  2. TonyK

    TonyK True Classic

    Location:
    Grimsby Ont Canada

    Not to highjack this thread but similar problems arose when I was installing the Abarth engine in my test body that needed to be resolved. Use of the spare tire compartment is often a solution for more room in the engine bay in engine swaps. The approach though between the K20 and the Abarth swap is basically the same but differs in that the K20 has an extension tube that is welded to the enlarged hole into the passenger compartment and a bolted cover. The Abarth swap rather than using a tube with a cover uses only a formed removable cover. Due to the size of the turbo Exhaust and CAT some space was also required into the gas tank area and that is where casting a hammer form to accomplish the complex shaping of the section around the turbo charger exhaust pipe was required. Some shaping of the gas tank was also required. Rather than get into a long description I think it is better to share some picture with you SAM_5827.JPG IMG_0702.JPG IMG_0703.JPG IMG_0704.JPG IMG_1495.JPG of the solution.

    TonyK

    Grimsby Ontario Canada.
     
  3. lookforjoe

    lookforjoe True Classic

    Many thanks for sharing that Tony. Good to note that need be, It's not the end of the world if the tank has to be modded also. I definitely am not moving it to the front :D Your pics also make me think I should chop the back off my parts car & set it up the garage so I can work on it over the winter. Not sure I have room, actually, but it's a nice idea :D

    What did you use to chop it off?
     
    fiatmonkey, aarpcard and TonyK like this.
  4. kmead

    kmead Old enough to know better

    Location:
    Michigan
    Sawzall, metal blade. Slice and dice.
     
  5. Hasbro

    Hasbro True Classic

    Location:
    Danielsville, Ga
  6. lookforjoe

    lookforjoe True Classic

    Had about an hour to work on the plenum today. Realized it will be much easier to repurpose the stock plenum entry/flange & pie cut pieces to fill the void vs. building a new extension. Welded it along the base after I test fit to check TB clearance.

    [​IMG]

    Depth looks good - not much over 5" off the head

    [​IMG]

    Rad hose neck will be redone after intake
    [​IMG]

    Should fit like this though

    [​IMG]

    Stock TB flange will be ported to match adaptor ID

    [​IMG]
     
  7. Rodger

    Rodger True Classic

    Location:
    Olympia, WA
    That 80 mm TB looks huge compared to the stock 62 mm one. Is there enough beef in your intake tube/flange to hog it out to 80 mm? Sure doesn't look like it.
     
  8. lookforjoe

    lookforjoe True Classic

    Hey Rodger, yes there is plenty of meat in the flange to accommodate the removal of about 5-6mm all around the ID. I’ll take a few pics when I actually get to that part.

    EDIT: To clarify, the bore is tapered from the flange going inward, so it's not 80mm straight back into the plenum neck.
     
    Last edited: Sep 18, 2018
  9. TonyK

    TonyK True Classic

    Location:
    Grimsby Ont Canada
    A Sawsall with a 12" metal blade.

    TonyK.

    Grimsby Ontario Canada.
     
    lookforjoe likes this.
  10. lookforjoe

    lookforjoe True Classic

    Thanks Tony. I can do that :)
     
  11. lookforjoe

    lookforjoe True Classic

    Got the Plenum > TB Flange junction squared away. Not pretty, but functional. Have to do the hogging out of the internal weld overlaps & TB porting next. 2.25" cast 90º elbows should be here in a week or so, then I can play around with the runner layout. They are gonna be a PITA to weld.

    [​IMG]

    [​IMG]

    Cut a wedge of thick wall 4" aluminum tube , tacked it at one end, and beat it into submission as I went around the other side. Not a uniform shape, so it got a tad messy (hence all the bash marks). Top has to indent to allow for passage under runner #4 (above pic)
    [​IMG]

    [​IMG]

    Found I already have a nice 2.5" SS rigid liner flex coupler & 3" SS V-band, so those will be put into service when the time comes. Braided mesh liners are very bad - the liner will swell & choke the passage. Ordered the same magnaflow 11236 muffler as Rodger has, a cat and some 2.5" SS U-Y piping. I’ll use standard pin type hangers with Volvo mounts.

    [​IMG]
     
    Last edited: Sep 18, 2018
    aarpcard likes this.
  12. lookforjoe

    lookforjoe True Classic

    So, I did the TB flange work today. In fact, only about 6mm additional material is removed,

    PRB TB flange approx 64mm

    [​IMG]


    as the flange adaptor is just over 70mm ID

    [​IMG]

    flaring out to 80mm on the TB side

    [​IMG]

    Mine, after enlarging. Need to remove approx another 1mm around

    [​IMG]

    Rough work with a barrel grinder, working into marker line (RBB flange)

    [​IMG]

    then finer carbide grinder, coarse file, fine file & a little sandpaper



    [​IMG]

    flange fit

    [​IMG]

    TB

    [​IMG]
     
    Last edited: Sep 20, 2018
    Hasbro likes this.
  13. fiatmonkey

    fiatmonkey Tim Hoover

    Location:
    Redwood City, CA
    I did the same thing - I can't find my post, maybe its on FB, but I used a plasma cutter to saw X in 1/2. Saved the engine bay for fitting engine. REALLY helped me when I decided to reverse mount the intake manifold. It saved me from having to modify the fuel tank side of the engine bay (for the most part).
     
    lookforjoe likes this.
  14. Rodger

    Rodger True Classic

    Location:
    Olympia, WA
    Ok, I am going to ask a dumb question here. Why start with an 80 mm TB if you are confined to the original inner diameter of the stock intake? I realize that you tapered the flange to transition from 80 mm down the the 64 of the original intake, but isn't airflow volume dictated by the cross section of the narrowest place in the intake?
    This is a quote from Hybrid Racing. This is from the description of their 70 mm throttle body that I had purchased, but have passed on to Tim for one of his projects. "A note about boring your intake manifold: It should be noted that a big bore throttle body should never be used on an intake manifold that has not had the inlet bored out to match the bore of the throttle body. A setup using a big bore throttle body mated to an OEM sized inlet port will yield lower performance than the OEM throttle body. That said, when boring the inlet on an intake manifold, it’s best to overbore slightly (about .25-.5mm is sufficient), to prevent the chance of a lip that could create turbulence."
     
  15. lookforjoe

    lookforjoe True Classic

    Hey Rodger the intake is “bored”. What they are referring to is the TB flange/neck area. That has to match the ID of the backside of the TB housing. The inside of any manifold is much larger than the reduced neck/flange area, varying by design of course.

    What I meant was using the adaptor flanges that KTuned provides, the increase in ID is only about 6mm (64 up to 70ish).

    I admit I was surprised that they taper the flange ID down from 80 to 72, that would seem counter productive. What I may do is weld their 1st flange to the intake, as that is a straight 80 ID.

    I’m going to leave it as is until I’ve put it all together & driven it. If the Butterfly is too large for the build, you end up with a very twitchy throttle. The plan here was to allow for further mods DTR, so the reduction to 72mm may be fine with the current overall setup.
     
  16. Rodger

    Rodger True Classic

    Location:
    Olympia, WA
    I understand that the plenum is larger than 80 mm. What is the inner diameter of the pipe that you made to go from the flange to the plenum?
     
  17. lookforjoe

    lookforjoe True Classic

    That section is the original RBB plenum neck, rotated & expanded/tapered to meet the plenum orifice - it is 4" or greater once you go past the flange area, it expands off to the right (in terms of the pics I took)

    Neck/Throat opens to this:

    [​IMG]

    You can pretty much see the increase off the flange here:

    [​IMG]
     
    Last edited: Sep 20, 2018
  18. lookforjoe

    lookforjoe True Classic

    After Rodger's observations, I went back in & removed a fair amount more out of the entire throat. Got the bore as straight-walled as I can. I realized that although the RBB adapter is only 72mm ID there is that lower 1.25” area to be factored into the ID. I don’t have math skills to figure out what that does to the overall ID.

    EDIT: Looking at these, I still need to take little more out on the right (in pic)

    [​IMG]

    [​IMG]
     
    Last edited: Sep 21, 2018
    Rodger likes this.
  19. stingray250

    stingray250 True Classic

    Location:
    Oz
  20. lookforjoe

    lookforjoe True Classic

    That says it an RBC, but the RBC is not a two part manifold. Different ones identified & tested here:

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

    That looks like the RBB intake I have. Could also be RAA which is also two-part. The TB flange position is identical. It is quite possible the stock RBB manifold would fit in the available space better than the K20 manifolds, simply because the flange is offset differently.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice