head is off - what to change while its off?

[Black BNR32]

hey guys, unfortunately i have my head off (short block still installed) for some repairs. what do you suggest i take care of while its off? i'm thinking:

-finally get an oil cooler and delete the stocker
-replace all hoses, maybe?
-delete hicas
-refinish valve and cam covers, intake plenum
-rear oil drain/breather


what else you got?

[bellis_GTR]

I highly recommend you do all of what you said. Especially replace the hoses underneath the collector, if you haven't done so already. Oil cooler would be a good idea too since it helps keep oil temps down a whole lot more than that water to water cooler. And if you don't have a filter relocation kit this would be a good time to do it as well to save the bad words when doing a oil change. While your AAC valve is out, replace the gasket and give it a good cleaning. Do not adjust the screw on the side. It controls idle.

Since you have your head off, you can check your valve clearance to make sure your within spec. You can measure cams to make there their also in spec. You didn't mention getting new head bolts. You should replace them every time you take the head off over long periods of time or hard driving. If they are OEM head bolts they will stretch from heat cycle and always taking a beating. If you go ARP they say you can reuse them, but I never heard that from anyone else. Change up the bolts so your head doesn't lift.

You can always freshen the engine bay up now since you got a lot more space. Clean it up, get all the 20+ year old gunk in there. I would look for any leaks from power steering lines as well.

I think you got a lot of the main ones. Others would be port and polish, new cams, cam gears, valves. But that's not necessary if you like your power now.

[Black BNR32]

head is being rebuilt

iirc arp studs have a length spec they need to stay in. that's how you know if they need replacing.

[evilgtr]

Who is building your head in Saskatchewan >
my suggestions
-new valves - they are cheap
-mild machine work to clean things up and increase flow,the RB26 head responds well to a mild port and polish
-a nice set of poncams with medium lift
-adjustable cam gears
-stronger timing belt and replace tensioner
-aftermarket dumps and turbos
-YES new hoses they are a prick to change

[Black BNR32]

i'm researching options still, but there is a place called precise automotive in saskatoon that has some experience assembling our heads.

[DJ]

Make sure you get some bronze vakve guides cause the stock ones tend to crack then bye bye engine

[Bruizer]

Who is building your head in Saskatchewan >
my suggestions
-new valves - they are cheap
-mild machine work to clean things up and increase flow,the RB26 head responds well to a mild port and polish
-a nice set of poncams with medium lift
-adjustable cam gears
-stronger timing belt and replace tensioner
-aftermarket dumps and turbos
-YES new hoses they are a prick to change

Dont forget to oversize the new valves, springs, cam cap studs, exhaust manifold, Freddy intake plenum, autoselect larger ITBs. Get a serious port job though, forget the chump minor one. I'm sure there's more while the head is off. Should be a reliable for any power under 800 you throw at it

As for new hoses under the plenum, they're about $350 new, the proper ones, not the cheapcrap autobarhf 88

[GTR-Dad]

Bruizer,
Couldn't tell if you were on a sarcastic rant or serious! (I'm thinking bitterly serious... and can understand the difficulty of desciding where to draw the line.)

OP,
I'd pick a power goal and a budget and then hold them up against each other and check for compatibility. It's easy to spend a lot of money on stuff that 'makes sense' but it not really going to be worthwhile. What's worthwhile? Therein lies the rub!

People have suggested a bunch of good things. It'd be nice to know exactly what the bottleneck is and assign the highest priority there. No use doing everything else and leaving stock cams, for example, unless you're a cam salesman wanting to show a big power gain. Here's my guess at the value of head mods.
1 - Cams - Probably biggest bang for the buck. Adjustable gears are a must, particularly when block and head have been decked and pully centre distances change. Make sure whoever assembles the engine degrees the cams. Mfr recommendation is a good starting point.

2 - Exhaust manifold and turbo dumps - I think port matching to reduce turbulence is worth doing. OEM manifold can support a bunch of power, but turbo dumps are restrictive. Do them first if you can only afford one.
3 - Intake tract. No opinion on filters, hard piping with nice convergence on the Y (twin turbo Y), good intercooler are pretty worthwhile when you add them all together. OEM intake can support bags of power. Main criticism I've heard is that airflow to 6 is on the high side and can lean it out. A decent ECU can add fuel to it. A really decent ECU can do that in real time if EGT gets too warm.
4 - Porting - Not sure if porting or valves are more restrictive.
4 - Valves (requires appropriate springs) This is a combination of greater flow area and lower mass to enable higher rpm.

5 - RPM (requires better springs, lower reciprocating mass) Spinning faster only makes more power if all your bottlenecks are gone. The dyno will tell truth here. Maybe bigger ITB's or a big single will make a difference at really high airflows. Remember that no matter how good the parts are, they will wear out faster at higher rpm. Remember that inertial stress on reciprocating parts increases with rpmē.

Good things to think about...
Make sure the oil can get back to the sump.
Make sure the head stays bolted down.
o-ring head only for crazy boost, and do it right if you do it.
deburr and polish any sharp edges in the combustion chamber. This will reduce the peak temperature of the thin sections and help control autoignition.
Consider compression ratio. Higher compression ratio = better off boost torque, better spooling, but lower peak boost for a given fuel. 9:1 is a practical max on the RB26. Some smart guys in Australia have played around and report only mariginal improvements above 9:1 fwiw. Lower compression ratio will let you run more boost for a given fuel at the expense of the good things mentioned above. Drag racers will like lower CR at lot more than circuit racers and street drivers.
Metal gaskets everywhere help manage leaks.
New throttle butterfly seals will reduce risk of intake leaks.

That's all I can think of right now, but I'll update as I can.

Cheers,
Dan

[Black BNR32]

cant find the freddy intake or autoselect throttles anywhere

cant wait to see your +1 valve results!

[jrhdohc]

you could machine the head for high lift cams.



max for stock head (w/stock base circle) is about 9.1-9.2mm lift.
shouldn't cost much. even if you only run low lift now, it will allow high lift later.
I'm running ~10mm and love them.

i would also stick with stock valves and use that money to clean up & balance combustion chamber (& unshroud valves). it might drop your compression 0.1 -> 8.4 but thats ok.

gasket matching: turbo compressor side, piping, plentum, ITB, runners, head, exhaust manifold and turbo exhaust side. don't need to go deep only 5mm or so. it's a effeciency thing and will lower lag, increase responce, increase tq & hp.

easiest way to fix 6th from going lean and/or getting hot. cleaned and flow tested your injectors. highest flow should go to #6. while tuning check plugs don't put 100% faith in the wideband.

[Black BNR32]

i'll check the gasket matching on the intake side, thanks

all else is done

[gtrjon]

hey bud i dunno if you need any but i have a set of supertech valve seals i ordered them months ago and just got them but i already put my oem ones in. just hit me up if you need them they are like 20 bucks