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Discussion Starter #1
right, i need help on this project im building, im starting with the head, i want to know how many people,if any, are running around 600bhp with standard springs,valves,collets,pins and cams, im just tring to get a feel of how strong parts are, im am getiing the head,pressure tested skimmed and gas flowed at the moment, also the inlet plenum,sandwich plate are also getiing ported and polished and bored out, we found alot of restrictions and lips which can be removed to give a vast amount of improvement within the standard head, i will be changine cams, but i dont want to go overkill and do springs,valves, stems if its not going to make an improvement around the 600 mark! any advice would be gratefull!
 

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Last year i made 550hp at the hubs on the dyno with rearwheel drive only.
Completely stock head.

Earlier this summer i made 584hp 680nm at all 4hubs with only chaging cams to Tomei 260 / 9.15mm Type B.

Pressure comes on earlier, torque / hp lasts higher up the revs.

Asim
 

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^^^ much the same as me, 260 poncams with every thing else std. the only thing i've changed it the valve guides which were worn. 520hp at the hubs on 4x4

....I will prob do head work when I build the RB30
 

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thank you, this is the info i was loking for! i have done alot of extensive research of how to make the head flow better, the person doing the head work does alot of drag spec heads, by changing valve degrees of how the valve sits in the head can increase flow, we are triying alot of different things to squeeze as much power out of the head and standard intake as possible, i never knew there were so many restrictions that we found! i amveryl curious to see the results!
 

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A Lil story, hopefully wont bore ya...

But about 8 months ago my ceramic turbo shat itself, complete exhaust wheel came off... odd i thought... but engine running sweet, so put a pair of steel turbo's on

anyhow, recently did a big end, so did a complete rebuild. upon rebuild found bores and pistons on rear 3 cylinders, mainly cylinder 6 however damaged by debris. Found my inlet valve guide had half fallen off, and a couple others cracked

Spoke to Ron at RK Tuning round the corner from me, who advised this is a common concern for ppl who like to use the high revving capability (as i do), and to upgrade to bronzed valve guides... which i did, and all lush again

so after the long story... Defo put bronzed valve guides in! ive owned mine for 3 n half years n id never heard of this common fault before and believe its 1 of those known faults, but only known by the ppl its affected.. doh!
 

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Discussion Starter #8
so has anybody else had problems with valve guides then? and does anybody know how much of a difference bigger valves/springs will make to torque?
 

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so has anybody else had problems with valve guides then? and does anybody know how much of a difference bigger valves/springs will make to torque?
Depends on how much hp you are aiming for.
And if you at a later point will try to go higher than your goal for now.

I think it is a waste of money to get bigger valves / springs etc, unless you are aiming for 900++ hp.
 

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yea im aiming for 700hp on my build im doing now and i have type "B" tomei poncams, the knife edge on the inlet is a good idea but isnt the temps from the exhaust ports going to be so high it can burn the divider away?
i wanted to do both but was advised not to do the exhaust side
please advise as i need to know this

very helpfull thread ;)

alex
 

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Discussion Starter #11
i was thiniking that, i dont want to folk out money that doesnt need to be spent! just need to get a feel of how strong stock parts are!
 

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im useing ARP head studs not bolts, the benifit of this is that the origonal head bolt streatches and the torque can be not perfect and if you are running big boost this can cause headgasket failure, also if you intend doing this replace the headgasket with a metal one ;)
 

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Maybe I'm wrong, because I'm not that good in English, but the RB26 has no Rocker Arms. The Valves are driven directly by the buckets, which are driven by the Camshafts.

Marc
 

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Not really a power level, more a rev limit thing, all springs loose there tension , so if you are wanting to raise the rev limit then aftermarket heavier ones, OR just put a new set of factory ones in.
Dont use the old ones at all.
 

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Quck question wots the maxuim bhp the standard head can flow I have recently put tomie stage three 10.9lift cams springs and retainers with out porting it my tuner seems to think that the head is restricting the flow at 600 bhp wots your veiws plz i thought 700 would have been acheiveable with this set up opinions plz
 
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