ok as you all 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? is this legal? i dont see anything against anything like this in the rule book. and what are your overall opinions? unfortunately an item like this will have to be handmade. CNC isnt really an option since many cuts will have to go through the plate at an angle 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.

i know this is well suited for the RR forum, and i have it over there too. but i would just like some input from you guys for a performance standpoint. like how well you think this would work, design suggestions, whatever. thanks

 

up for the late night kids

 

Sorry to say it like this, but your better off spending your money on seat time rather than trying to ring out a few more ponies.

Just eliminate the secondaries and hone out the OEM manifold if you want more flow.

 

cant do that. against the rules. manifold must be stock unmodified. portmatching is only allowed 1" into the ports of the manifold. nothing else.

 

how will they know you actually ported out the intake manifold

 

someone contests. you have to take it off and show them.

 

theyre not gonna make u take it off on the spot are they

 

i wouldnt put it past them. its not exactly hard to take off an IM. besides, im not gonna port out a manifold when its against the rules. i dont like to cheat, just not the kinda person i am. not when it comes to racing anyway

 

Ever consider switching to Type-R head and intake mani, the best factory top end anyway. ?

 

considering i have over 2 grand into my gsr head, it doesnt seem logical to just sell it and start over. IMO the GSR head is superior anyway. it will always create more compression and everything else equal, more power.

 

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 block off that coolant port for your class?

i blocked this off, and it's one less thing to worry about with a phenolic spacer...

I don't need all the coolant running to my throttle body or heating up my IM anyway.....

Also, you may also want to consider that the gsr intake ports are at a slightly different angle than the b16/ itr, so your adaptor plate will need to have an angle at the flange to keep the airflow inline.....

I had toyed with this idea as well a while back, but kinda lost interest since I already had an itr head and decided on the IM I was going to use.

 

yes i know about the different port shape and had planned to angle it up going into the head so i would still have a nice smooth flow. and ive thought about blocking it off. im pretty sure its allowed, but what would i do about the IACV? i still need a coolant source for that and it gets its source from the tb (which gets it from the head). also where does the bigger port go to? i cant remmeber.

 

Which class is this?

 

H1 Honda Challenge

 

plenty of people have put irt mani's on gsr heads thats what people did for years prior to skunk's mani's came out. You will have to redrill the mounting holes to match the head.

 

can you cut and reweld or is that against the rules? easy to cut the runners after they come out an inch and then mate the itr mani to that.

 

im pretty sure you cant cut and reweld. hold on one sec, ill get the exact rules...

 

16.3.f - "throttle bodies and intake manifolds are not considered part of the cylinder head and must be unmodified Honda parts. Port matching is allowed but cannot be machined beyond 1" into the intake."

16.3.g - "items (such as throttle bodies and intake manifolds) that attach to the cylinder head may be re-drilled for fitment purposes ONLY. Alteration of air, fuel and/or coolant passages is not permitted. fitment modifications that alter air, fuel and/or coolant passages as a side affect will be deemed illegal"

redrilling is no problem. coolant holes are way off though. thats why im gonna make this plate, to adapt it from the itr mani to the gsr head.

 

larry at endyn had a writeup on his site about doing this. He just redrilled. And you can mill a grove from the gsr head coolant port laterally across the manifold flange to the itr coolant port in the manifold . Id bet the adaptor would be illegal because it moves everything outward and it also lenthens the runners. http://www.theoldone.com check it out its in the articles section. Larry also will sell these premoded or you might send him yours.

 

Hmm, I had always thought that in H1 they were more liberal on everything above the head gasket.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtecmissle &raquo;</TD></TR><TR><TD CLASS="quote">larry at endyn had a writeup on his site about doing this. He just redrilled. And you can mill a grove from the gsr head coolant port laterally across the manifold flange to the itr coolant port in the manifold . Id bet the adaptor would be illegal because it moves everything outward and it also lenthens the runners. http://www.theoldone.com check it out its in the articles section. Larry also will sell these premoded or you might send him yours.</TD></TR></TABLE>
hmm i checked out the site and couldnt really find anything. there was a section bout him putting a itr supercharger on a ls/b20. but i didnt see anything about the itr mani on the gsr head. mind getting a direct link? and sure it brings it out but its seperate from the manifold. it would be no difference then using a stupid thick IM gasket, which i have seen people do.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rochesterricer &raquo;</TD></TR><TR><TD CLASS="quote">Hmm, I had always thought that in H1 they were more liberal on everything above the head gasket.</TD></TR></TABLE>
they are, in the head. they dont consider the manifold to be part of the head so it has to be a stock piece

 

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.

 

Take into consideration the angle the head accepts air from the stock manifold.(I'm sure you already planned this but I believe that was the hold up many Im designers had when doing gsr manifolds.)

 

im not quite sure i know what you are talking about.... what about the angle?