FFS Tech > Skunk2 manifold for the GSR/P72 head

SKUNK2's Type-R style intake manifold for the GSR/P72 head is a definite bang fo' yo' buck.upgrade. Finally, a company that mimicks a Type-R intake manifold and bolts right up to a B18C/P72 head! Not only does it free up intake breathing, but it's a bolt-on power maker (approx. 7-8 horseys). This manifold unlocks top-end power unlike the restrictive OEM GSR snail-shell manifold. The GSR manifold was mainly designed for a better low-to-mid range, get around town power.

It seems no one on the net has made a how-to-install for this specific manifold, so without further ado ....here it is =D

-- katman


12mm+10mm socket (short & deep), rachet, and extensions
12mm+10mm open/closed end wrenches
Phillips head screw driver
Small pic or tiny flat head screwdriver for injector clip removal
Long bent-tip needle nose pliers for those damn hose clamps
Some shop rags to collect spills
Small Japanese hands


Parts needed...

Integra-R throttle cable bracket / Honda part # 16411-P73-000
Integra-R throttle cable / Honda part # 17190-ST7-R01
Throttlebody pulley from a non-GSR throttlebody
A GS-R intake manifold gasket (if you can't reuse your old one, for some reason)
A GS-R throttlebody gasket (if you can't reuse your old one, for some reason)
Small Japanese hands


  • Begin, by raising the front end of your car up and placing it on jack stands.
  • Disconnect the battery cables for safety.
  • Drain the coolant into some kind of container that you can cover,
    so dirt will not fall in and/or animals will not drink from it.
    If dogs/cats/etc drink coolant they have a pretty good chance of dying from it!. NO JOKE..
  • Loosen up your gas cap to relieve gas pressure from the fuel tank.
  • Start disconnecting all vacuum & radiator hoses/lines from the intake manifold
    using the long needlenose pliers (real handy).
  • Disconnect sensor plugs, injector plugs (use a pick), etc., from the intake manifold and throttlebody.
  • Take the 12mm socket + ratchet and loosen up the fuel filter pressure-release bolt.
    Some fuel will come out, so have a rag handy.
  • Using a 10mm socket, remove the black plastic wire harness cover from the fuel rail.
  • Remove the vaccum hoses from the FPR (fuel pressure regulator).
  • Using the 10mm socket again, carefully remove the nuts that hold the fuel rail down to the intake manifold. These small screws tend to fall behind the engine easily (i hate when that happens), so be careful!
  • Carefully wiggle the fuel rail off. The injectors will probably come off along w/the rail. Try not to damage/rip the rubber o-rings that are on the injectors. Also, try to not lose the round black grommets that hold the injectors in place.
  • Place the fuel rail w/injectors still attached to it, somewhere out of the way, even though the rail is still connected to the fuel filter line. Just get it outta the way, near the battery somewhere.

[Underside Manifold Bracket Removal]

  • Next, are the 12mm intake manifold flange nuts & intake manifold underside-bracket (if applicable).
  • If this is a first-time-removal of your GSR's intake manifold, you're in for a real treat! (see frustration not @ bottom)
  • Get under your car so you can see the underside of the GSR manifold & underside-bracket.
  • Use the ratchet with a lengthly extention to reach the two 12mm bolts seen in pics 1-3 below.
  • Taking this bracket off, will make the swap waaaay easier.
  • While you're under the car, disconnect any sensors that are still connected to the GSR manifold, such as the IAB sensor (black-round canister mounted on the underside of the GSR manifold)...
  • Now, loosen up and remove all of the 12mm flange nuts that are holding the GSR manifold to the head.
pic 1-3 remove underside bracket pic 1-3 remove underside bracket pic 1-3 remove underside bracket


[Swapping of Parts]

  • Once you're finished removing all 12mm flange nuts, double check that all sensors, vaccum lines, and any coolant lines are not connected to the manifold.
  • If everything looks go-to-go, carefully remove the GSR manifold. (PIC 4).
  • Using a 12mm socket, remove the TB from the GSR manifold and carefully peel the TB gasket off using a razor blade to help.
  • Next, you will prep the Skunk2 manifold, by swapping over the GSR's fuel rail + TB mounting posts and required sensors.
  • You can start off by removing the GSR's fuel rail mounting posts using two of the 10mm fuel rail nuts.. (PIC 5)
  • Next are the throttlebody posts.
    Remove & apply these posts using the same technique as used on the fuel rail posts.
  • Next are the sensors...
    Swap over the IAT and IACV sensors. (PIC 6+7)
    Then, apply the ITR throttle cable bracket. (PIC 8)
    Lastly, swap over the rubber fuel injector grommets onto the Skunk2 manifold. (PIC 9)

pic 4 - manifold removal pic 5 - fuel rail post swap pic 6 - IAT sensor swap
pic 7 - IACV swap pic 8 - apply ITR throttle cable bracket pic 9 - apply injector grommets


[Throttle Pulley Swap]

  • Now that you're temporarily done fussing w/ either manifold, it's time for throttlebody (TB) adventures!
  • I'm assuming you've acquired a non-GSR throttle pulley. If you haven't done so, get one! (PIC 10).
    TIP: almost any 88-01 civic/integra (non-94-01 GSR TB) throttle pulley will work on the GSR TB.

  • Use a 10mm socket to remove the GSR TB pulley, and swap over the non-GSR TB pulley. You *might* have to fiddle w/remounting the retensioning spring a bit, but its not hard to figure out.
  • Next, remove the GSR throttle cable bracket thats on the TB, as well. (PIC 11).
  • That was easy wasn't it? (yes). If you'd like to, you can now mount the TB onto the Skunk2 manifold, reusing your GSR TB gasket (if you haven't fully damaged it).
  • Now, go install the Type-R throttle cable. It's pretty straight forward, so I'm not including the how-to on this.
pic 10 - swap throttle pulleys pic 11 -  swap tb pulleys cont.


[Prepping the PCV Valve]

  • Go back to your engine bay, and take a look at the area where that bloody intake manifold underside-bracket is.
    You should see the factory oil catch can with 2 lines plugged into the topside.
    This is where the PCV valve lives. (PIC 12)
  • Once you've pulled out the PCV valve, get a lenghtly vaccum or coolant tube and attatch to the PCV valve. Then plug the PCV valve back into its respective location for test fitting. (PIC 13)
  • Now, take the Skunk2 manifold, place it on the head, and fit the PCV tube up in between the manifold's runners till it reaches the vaccum spout in the middle of the plenum. (PIC 14).
pic 12 - PCV valving pic 13 - test fit PCV tubing pic 14 - test fit PCV tubing to Skunk2 manifold


[Finishing moves]

  • Now that the PCV valve is taken care of, check to see if all coolant lines can be put back to their orginal location. If you're like me; I like to bypass the coolant lines which run to the TB's fast idle valve (FIV).. Bypassing the FIV is not a good idea if you live in a cold weather climate zone though. Once you've overlooked your coolant routings, install the Skunk2 manifold.
  • Tighten down all of the 12mm flange nuts to a good snug or to factory tourque spec (that is, if you can reach a torque wrench down into those tiiite spots).
  • Apply the TB to the Skunk2 manifold if you haven't yet.
  • Fit the PCV valve and coolant lines back to their respective location(s).
  • Remember the fuel rail +injectors? Well, it's time to re-install those. Use the 10mm nuts to secure the fuel rail to the fuel rail posts, then connect the fuel pressure regulator vaccuum tubing. NOTE: The brown ceramic spacers that sandwich inbetween the fuel rail + manifold are not used on some installs. To check this, make sure that there are no loose gaps between the fuel injectors and fuel rail. If there is a gap and the injectors sit rather loose, remove the spacers.
  • Connect the throttle cable's hammer-end into the throttle pulley; then mount the cable to the throttle-cable bracket. Make sure you're getting full throttle too. Have someone sit in the car while stepping on the throttle, look into the TB and see if the brass butterfly inside the TB is opening all the way, while you adjust the throttle-cable settings.
  • Connect all of the sensors to the engine harness (MAP, TPS, IAT, IACV, etc).
    Don't forget that! (tighten snug or to torque spec)
  • Re-tighten your gas cap.
  • Refill your radiator either w/ your old coolant fluid or some new stuff.
  • Double-check that everything is A-OK/connected/lookin good/etc.
  • If its all good, get in your car and turn your ignition on (2 clicks of the key), but don't turn the car over (idiot lights should be on). This will build up fuel pressure. Now, go see if there's any fuel leaks or spray coming from the fuel injectors/fuel rail/or fuel filter. There shouldn't be any leaks if everything was back correctly. If there's no leaks, so-far-so-good; go ahead turn the engine on now. It might take a couple turns for it to kick over, so don't trip!
  • Once running, check for coolant leaks etc, if all looks good you're install is a success!
    If you have any funky, high or irradic idle problems, double-check any vacuum lines or any unplugged sensors.
    Lower the car back down to the ground, go for a test drive, and clean up yo' damn mess!

[Additional Info Regarding ECU Tuning]

You should know that a Skunk2 manifold uses a single-butterfly design and the GSR manifold uses a dual-butterfly design. Well, a stock GSR (P72) ecu doesn't know that you changed over to a single butterfly style intake manifold; and seeing that the Skunk2 manifold is essentially a Type-R manifold, you'll need to adjust your ecu for this change, mainly the VTEC crossover point (needs to raised). Here's your options:

  • Option 1)
    You can run your stock GSR ecu as-is, but it probably won't feel right w/ the stock vtec crossover kicking on around 5000rpms so..
  • Option 2)
    Purchase a VTEC controller so you can move the VTEC point up to about 5500-5700rpm or..
  • Option 3)
    If you have an OBD1 P72 ecu have it reprogrammed (by me!) w/ a customized VTEC, redline, & fuel maps.
    Although, if you go this route I suggest you upgrade your camshafts to at least Type-R cams. Actually, you should upgrade your camshafts anyways, to benefit even more from this Skunk2 manifold upgrade.

The end.
any questions/comments/hating/praising, email me at katman@ff-squad.com


GSR intake manifold removal can be a royal pain in the ass. So don't hesitate,
go ahead and shoot yourself in the head...
DISCLAIMER: FFS will not take any direct responsiblity for your actions.
the easy way out...