ok as some of you may know, as per Honda Challenge rules, we are limited to an OEM intake manifold. ITR is the best choice obviously, but thats not so great for us running a GSR head. ive been thinking about what all is needed to do to fit the ITR manifold on the GSR head, and theres a serious lack of information on what all is exactly needed. i know the ports are a slightly different shape, and only the bottom bolt holes line up. also just by looking at pictures the coolant passages are not only a different shape, but the coolant hole on the ITR looks to be about an inch higher. ive seens some people say that you need to weld and reshape the coolant holes on either the manifold, head, or both. and to me this doesnt fit the rules defined in section 16.3.g of the HC rulebook "items that attach to the head (IM) may be redrilled for fitment purposes ONLY. Alteration of air, fuel and/or coolant passages is prohibited." then theres the problem of what gasket to use, you will probably need to make your own.

so ive been kicking around the idea of making an adapter plate to convert from the mani to the head. and use stock gaskets on each side. GSR for the head side, and ITR for the mani side. you will still have to redrill the manifold for the bolt pattern, but under the rules this is still legal. im planning to make a plate 3/8" thick AL plate to adapt the different port shape and different coolant hole locations. obviously extended IM studs will be necessary. i already have them on my head. mine are about 35mm long (from the surface on the head) whereas the stock ones are about 25mm

now my questions... has this been done before? CNC isnt really an option since many cuts will have to go through the plate at an angle. or is it? some of the angles will be weird and i cant see doung this with any kind of machine. a because of different size and shape of things on different sides of the plate. ill probably cut out the basic holes and then clean it up with a dremel/grinder/sandpaper. any tips for fabbing up something like this?

 

pic for views, and to show the challenge i face. adapting the port size shape is easy, they are at least in the same spot. coolant hole is gonna be tricky, different shape and pretty far of from each other

 

are you allowed to modify the itr mani to fit the gsr head? if so, i've done one before, all you need to do is modify the coolant passage location and mounting hole on that end of the mani, as well as add another hole in the middle of the mani. i made up a piece to replace the end i cut off around the #4 intake port and welded in a new one that had the proper location for mounting holes and coolant.

 

you are allowed to drill holes for fitment only. alteration of air, fuel and/or coolant passages is prohibited. only thing thats allowed is portmatching the manifold as long as the port matching doesnt extend past 1" into the manifold.

 

I've got a set of both and as far as I can tell the runners line up exactly. If you're only doing summer driving then you would probably want to block off that coolant port anyways, it only leads to the TB and allows a cold weather start but robs some HP. I think the top bolts are all that need to be modifier, and you could probably just weld on a plate and drill some holes.

 

where does the big coolant port go? it slips my mind right now. and ive thought about blocking it off completely but i do want to keep the IACV which gets its coolant source from the TB.

 

This has actually been done before way back in the day. AEM made some plates a while back. Sorry I can't find the drawings. It was about 3/8" aluminum CNC the coolant ports where cut on both sides to match up as well as the ports. Also for the holes where you could not use the stock GSR studs countersunk bolts were used and studs were installed in the adapter. Actually just found some files we actually had two different flanges bolted together


Modified by Rtype16 at 3:26 PM 2/13/2006

 

hmm thats interesting. might wanna see if i can find some information on this. thanks.

 

just buy this kids manifold, i think its worth it! https://honda-tech.com/zerothread?id=1511115

 

1. no pics
2. its illegal.

"items that attach to the head (IM) may be redrilled for fitment purposes ONLY. Alteration of air, fuel and/or coolant passages is prohibited."

manifold must be a stock unmodified Honda part.

 

youve said that rule like 3 times now, i guess nobody is paying attention...lol

ive been thinking about getting some of the adapters made for me to sell on my site..we'll see if i feel like going through with it...just doesnt seem like theres a huge demand for them.

 

yea i dont think theres a huge demand for it now. cause everyone just says "not worth it, dont try, blah blah blah" but i think if someone actually makes one that works then everyone (especially people in the HC crowd) will be interested. i personally dont plan on mass producing these things. im really just making one for myself. and documenting it since theres no one doing it, and no one supporting it. i mean does everyone in HC just run itr/b16 heads? the gsr head is sperior IMO. do the same thing to each head and the gsr will make more power.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSRCRXsi &raquo;</TD></TR><TR><TD CLASS="quote">where does the big coolant port go? it slips my mind right now. and ive thought about blocking it off completely but i do want to keep the IACV which gets its coolant source from the TB.</TD></TR></TABLE>

I said it only goes to the TB....then it goes back into your coolan system. The Hondata IM gasket blocks the port off and I capped it on my turbo gsr. The ONLY reason it is there is so the car will start in freezing weather.

 

i dnt understand how not having it would prevent the car from starting... i mean its not like anything wams up until its already started anyway. i checked on my car and it just goes from the head to the thermostat. kinda pointless. im still gonna make 2 different plates though, cause capping the huge open port on the thermostat seems like a big pain. keeping it seeled and all. what would you even use to cap it? i would want to do it right/clean. and not some ghetto way like clamping off a hose or something.

 

The water line to the throttle body is actually to warm the throttle body so that in really cold climates the throttle plate will not get stuck.

 

ok, makes sense. still not needed since it doesnt get THAT cold here and its not entirely necessary on a race car, but what about the big one that goes from the head to the thermostat? whats the point of that.

 

just bought enough aluminum for 2 plates from mcmaster. also picked up an ITR intake gasket for the template on that side. the plate was 3/8"x4"x36" 6061 aluminum. should be fairly easy to work with.

 

ok well an update.

i got the plate and used the hondata gasket as a stencil to drill the mounting holes. aparently the hondata gasket sucks ***** as a stensil. i guess it doesnt have to be perfect since it just gets pressed on by the manifold. i had to fudge the holes a little bit but i got them all lined up now and it fits tight on the head which is all that matters.


next i lined up the intake manifold gasket with the hondata gasket to drill the correct holes in the ITR gasket. holes drilled and on the head to check fitment. perfect



now i would like to say something about drilling the holes. in the very little bit of information ive found about doing this (ITR mani on GSR head) it said that the bottom holes were the only ones that lined up. this isnt entirely true. they are the correct spacing yes, but they are a different distance from the ports. meaning that if you mount the ITR mani on the gsr head without reaming the bottom holes lower, the mani will sit too low and most certainly interfere with airflow. so when i lined up the gaskets to drill holes i made sure to base everything off the PORTS. if anyone out there attempts to do this, i cant stress this enough. dont expletive up your airflow for the sake of it being easier. its not even that much more work to do.



now another thing to note is that im going to abandon messing with the coolant ports. mainly cause making a passage through this plate would be too steep and very difficult to cut. to really be able to adapt them you need a thick plate, probably thicker then 1/2" and IMO thats too thick. so screw it. theres really no point in having that bypass anyway, its to help out in cold weather but my racecar never gets run in the winter. besides its less heat soak. now you may ask, why even bother with the plate? well besides the fact that im still adapting port shape, this is why...



the ITR mani doesnt even cover the hole on the gsr head. so the plate (along with a hondata race gasket) will cover the hole and keep any coolant from leaking out. plugging the hole isnt really an option as theres not enough material on that wall to hold threads. and im not welding it up. i really dont want to mod it at all. in case i ever want to sell it.

next thing i did was bolt everythying up to the head. one cause i wanted to see how everything looked. and two i needed to trace the ports for the ITR. seen below



and here it is with the ITR ports traced and the GSR outline traced. ready to cut.



now all i really have to do is cut it out, then screw with the port shape on the GSR side. and it will pretty much be done. i aslo have enough metal left to make another one, so ill probably do that and sell it or something. ill update as things progress . probably wont be for a few weeks since most of my tools are in baltimore. i dont have what i need here to cut the amount of material off that i need to at this point. let me know what you think