chip46

Just bought a Dark Horse Racing GSR head and I want to fit it to my '98 JDM ITR,
anything I need to know before I get on and fit it - or is it just a straight swap ??

Thanks from the UK noob

JOHN WAYNE

iTrader: (1)

for future reference, the tech forum is probably best for this type of question.

but in the interest of not being a dick and telling you to go search (n00b), here is some quick info.

the GSR head will be a straight swap onto your ITR block, HOWEVER there are a few things you need to consider:
- you will need a new headgasket...new intake manifold gasket, new throttle body gasket, new valve cover gasket set
- you will need new head bolts (most people prefer to use ARP head-studs instead)
- you should probably get a new timing belt also...hell, might as well do the water pump and tensioner while youre at it.
- and here's the kicker... your ITR intake manifold will NOT fit on the GSR head (most people will suggest something aftermarket like a skunk2/blox/etc instead of a GSR manifold)

if you have never done this type of swap then please dont attempt it on your own. it is a simple enough job, but there are lots of little things that can be overlooked or forgotten, which will ultimately lead to a BIG problem for you.

chip46

Thanks John, sorry for being a dense noob.

I got a head gasket set, Spoon head bolts and Toda cam belt (to go with my spec B cams and pullies) Also have a Skunk 2 inlet manifold but reference the head gasket - I've been told the GSR head if different to the ITR and fitting it would lower the compression ratio, would you advise fitment of a thinner head gasket to raise the compression ?? i checked out DHRacing site and used their cr calculator and using a standard head gasket compression ratio would be 11.36:1 whereas using a Spoon/Mugen (0.01773 in) gasket would up the ratio to 11.72:1 is it worth the extra money ???

By the way - I wont be doing the work myself, I have a very good friend doing it - I'm just holding the tools (no, not them tools)


Thanks for your time

JOHN WAYNE

iTrader: (1)

the GSR head should RAISE your CR because the volume of the chamber is slightly less than your ITR head. what octane do you guys run in the UK? the max here is 93 and running upwards of 11.5:1 gets dangerous with regards to detonation.

chip46

We get from 95 to 102 octane here (but 102 costs big time) normally run 98. but octane ratings are different in the US arent they??

then do I assume it would be a better idea to use an OEM gasket to lower the ratio a little to prevent detonation occuring ?

JOHN WAYNE

iTrader: (1)

you will want to use an OEM gasket and you will want to have this TUNED immediately. hondata, uberdata, crome, powerFC, EMS...whatever, just have it street tuned so that you know you arent running too lean.

also, i dont know if the head has been milled or not...IF it has then you should probably clay the engine and degree the cams.

chip46

Sorry John, this is gonna make me look like a real dumbass but please explain what 'claying the engine' and 'degreeing the cams' means,

I've got some Toda spec B cams to go in too, any more good advice ??

JOHN WAYNE

iTrader: (1)

there are probably a bunch of much more informative posts on this in the all motor or tech forums...

basically you need to make sure that your piston-valve and valve-valve clearances are ok. once you mill a head, the geometry changes and your TDC is slightly off and clearances are different. claying and degreeing the cams will let you know if your clearances are ok and it will also let you know how much room you have to advance or retard your cam timing.

if the head hasnt been milled then you might not need to clay the engine since you are also running stock pistons. if the head has been milled then you should probably have it clayed, its always good to be on the safe side.

migs

Straight swap. Suggested: skunk2 manifold