Rb30det/tt Gtr Conversion Thread

[purpleskyline]

does anyone have the mesuarements for tapping the upper cam tensioner,

or does it go in the middle above the water pump.

[purpleskyline]

does anyone have the mesuarements for tapping the upper cam tensioner,

or does it go in the middle above the water pump.

just read the excellent pdf.

[GT-RZ]

i'm confused. did you just answer your own question.

[purpleskyline]

yes i did, thanks.

[aphid]

Haha, he means READ, not REED.. so to speak

A quick one - The rb26 head bolts are thicker as well as being a different thread to the rb30 head bolts arn't they?

I noticed a post from shanef from quite some time ago detailing how he used rb25 ARP head studs to bolt on an rb26 head to avoid having to getting a block machined... does the extra 1mm difference in stud thickness matter that much in the positioning of the head, or do the two dowels do a good enough job?

[r33_racer]

It should work fine, but isnt ideal engineering practice.

The bolts/studs shouldnt be aligning the head at all. All holes have some clearance, which means movement...even if tiny. The dowels will align it all fine, then you are only relying on the bolts/studs tensile strength to hold it all down.

By all rights, you would have more clamping force and strength, by opting for the 12mm bolts/studs which is always cool....unless your budget doesnt allow for it.

[shanef]

Said rb25 arp headstuds went into a ~900hp engine so if they are not upto the task we'll soon find out.

I asked both jhh and chilton engingeering about whether we needed extra dowels/collars to support the head and both said the factory fitted locating dowels will be fine.

Heres another way to think about it. Any extra meat left in the block is only going to make it stronger.

[purpleskyline]

another question, can i bore a rb 30 out from 86mm to 87.5

as have seen on a thread somewhere that the bores split on to much boost.

[r33_racer]

60 thou oversize....that is alot. maybe if it were a rd28. I havent seen anyone do that yet, on here anyway. Nor know of anyone whose gone that far over. No doubt it would be custom pistons. I dont think many places would stock pistons that big....shit, sometimes we have trouble finding 40 thou oversize.

If your not intending on big power, perhaps you can do it, and let everyone know how it goes?

[brother_david]

Bringing up the sticky

Havent recieved my block yet so i dont know how much it will be bored but do you reckon i should go with the 86.5mm instead of the 87mm pistons if possible? Dont know how good the RB30 handles bore and 2 of my mates cars have had cracks in the cylinders due to to much bore/to thin walls, this was on toyota's though...

[GT-RZ]

It should work fine, but isnt ideal engineering practice.

The bolts/studs shouldnt be aligning the head at all. All holes have some clearance, which means movement...even if tiny. The dowels will align it all fine, then you are only relying on the bolts/studs tensile strength to hold it all down.

By all rights, you would have more clamping force and strength, by opting for the 12mm bolts/studs which is always cool....unless your budget doesnt allow for it.

Actually in the case of the RB30 block it's wiser to maintain the original tensioner size. The block is not quite thick enough around the holes to allow for rb26 bolts imo. Which has been backed up by quite a few engine builders who stay with the 25 standard size (including RIPS).

The clamping force provided with aftermarket studs + nuts is superior to that of nissans bolts.Generally if you look at aftermarket 25 studs and 26 studs they have the same tensile strength anyway because they both have the same minimum thickness. No advantage in using 26 tensioners unless you could only use nissans bolts.

studs and nuts are superior to bolts in an application such as this. With a shaft and a nut the threads under tension stays constant throughout tightening but with a Bolt the further it is screwed in the larger the thread contact area which is more friction and more torque required to get the same clamping force. Hence why it is possible to provide greater clamping force with less torque using a shaft and a nut. The lower the thread friction the more accurately a tightener can be tensioned. That is the reason torque wrenches are not always the bees knees, preparation to the manufactures steps is key.

In a production assembly it is cheaper and more efficient to utilize a bolt however... NISSAN you...

Edited September 15, 2009 by GT-RZ

[Marko R1]

^ i thought u were refering to head bolts until i noticed the word 'tensioner'. its been a long day for me

[Jmaac]

Damn me too..........

Actually, bolts are stronger than studs+nuts in terms of clamping force as the nut is sacraficial to the stud thread. There is no such failsafe in a bolt. The reason for studs being superior in this type of application is because when a stud is torqued there is a state of compression left in the blocks thread region. Next when you clamp the head on with nuts, it exerts an opposite state of tension to the area. This tension cancels out this compression and eleminates the majority of residual stresses in your block.

Yes bolt torques will differ from nut torques because of the increased contact area but that is how it was originally calculated/measured from factory. Needless to say, applying that same torque to a nut could be dangerous (even with a different type of factory lubricant). Also there are two types of friction working, static and dynamic. Static friction is much higher than dynamic hence you should never torque a bolt from stop i.e. should be torqued from a 'running' continous movement. Using torque wrenches correctly is quite complicated because of the different types but I wont get started here.

With regards to the different head stud sizes (M10x1.5p and M12x1.75p) then theres deffinately a difference in tensile stress areas (58.0 and 84.3mm^2 respectively) and hence overall strength (M12x1.75p 45% stronger than M10x1.5p). Although a/market bolts are genuinely treated to higher grades, I would say a/market 25 nuts (or bolts) would definately be superior to the original 26 bolts. As above the dowels do the locating. That said, you have to machine at the top of M12 tolerances to get the correct clearances from an M10 thread (M10 on top and M12 on bottom tolerance = problems).

hmm so a/m 25 studs for 26 head application most likely ok in my opinion and studs are good in general when doing block modifications

Edited September 25, 2009 by Jmaac

[Adriano]

rb25 head bolts are m11

[monty_r33]

can anyone help, my freind is building a rb30/26, but wants to keep the standard pistons, will the valves clear.

Yeh man they will. But what we do at work with standard pistons Is put the head gasket on the head and scribe around the ring of the gasket on the head and then grind the head out. much safer for standard pistons. If you want pics or more info let me know

[GT-RZ]

Damn me too..........

Actually, bolts are stronger than studs+nuts in terms of clamping force as the nut is sacraficial to the stud thread. There is no such failsafe in a bolt. The reason for studs being superior in this type of application is because when a stud is torqued there is a state of compression left in the blocks thread region. Next when you clamp the head on with nuts, it exerts an opposite state of tension to the area. This tension cancels out this compression and eleminates the majority of residual stresses in your block.

Yes bolt torques will differ from nut torques because of the increased contact area but that is how it was originally calculated/measured from factory. Needless to say, applying that same torque to a nut could be dangerous (even with a different type of factory lubricant). Also there are two types of friction working, static and dynamic. Static friction is much higher than dynamic hence you should never torque a bolt from stop i.e. should be torqued from a 'running' continous movement. Using torque wrenches correctly is quite complicated because of the different types but I wont get started here.

With regards to the different head stud sizes (M10x1.5p and M12x1.75p) then theres deffinately a difference in tensile stress areas (58.0 and 84.3mm^2 respectively) and hence overall strength (M12x1.75p 45% stronger than M10x1.5p). Although a/market bolts are genuinely treated to higher grades, I would say a/market 25 nuts (or bolts) would definately be superior to the original 26 bolts. As above the dowels do the locating. That said, you have to machine at the top of M12 tolerances to get the correct clearances from an M10 thread (M10 on top and M12 on bottom tolerance = problems).

hmm so a/m 25 studs for 26 head application most likely ok in my opinion and studs are good in general when doing block modifications

I'm quite confused by reading your post, no! amused... Unsure if you grasped what i was saying or if you were too busy looking up google for random jibberish. Without going in to much detail i'll leave so,e brief points.

First of all your opening statement is absolute rubbush. You are forgetting allot of key factors here (or maybe you never new them in the first place?) First of all a NUT is NEVER manufactured with a lower thread shear tolerance than the shaft it will be attached too. The stud/shaft always defines the UTS. (especially when we are talking about quality fastners here not some chinese plastic metal) Furthermore a bolt is always going to be inferior to a stud and nut simply due to the way it must be tightened, As i'm sure your aware off the UTS of torsional shear stress is far lower than that of the UTS in axial tension, by tighning a bolt (especialy a long head bolt) you are multiplying the torsional stress on the bolts shaft in to a far greater stress than a stud will ever get to see, the nut takes care off all that torsional force and translates it in to clamping force.

I could go on but really i'v ranted this stuff on here before somewhere. As for the complicated torque wrenches, have you ever used one? Not too complicated really? What is important is how you use them, tighten then loosen untill you get minimum friction and if your a smart as you can measure the stretch on the bolts each time and tighten your bolts up the perfect way. Less torque required with greater clamping force the better, bolts are crap. period.

PS: i believe ARP head studs are around the 1400mpa mark so i rekon that' splenty of strength hey?!! forget 26 head studs.

They are rated almost identicallly to the 25 ones.

[r33_racer]

Ive seen plenty of builds with m12 studs, arp and other used in rb30's with no dramas....i think the difference is probabaly negligible in real world terms.

Ive never heard of any problems with head stud holes cracking out or areas around them cracking due to the extra 1mm increase in diameter or extra clamping force.

I think you will find most of the time if people are using only m11 studs or bolts its simply because their horsepower goals dont require the upgrade. And going by what some people have achieved, it seems unless your really going for major power, like 1500+ you can prob stick to 11mm studs.

[Jmaac]

No need to get your knickers in a knot, just trying to help. Yeah I’m laughing too, some brief answers for your brief ‘points’.

Firstly it depends on the manufacturer and to what extent. Nuts are commonly manufactured to different tolerances than the stud/bolt/shaft ‘it will be attached to’ it’s called class of fit. In general a nut with strip before destroying the stud, this is not coincidence but a design feature. In fact, a nut is usually softer than a bolt to allow slight yielding of the top threads and thus distribute the load more uniformly among the threads in contact. I believe what you are trying to say here is that the length of nut engagement is balanced between bolt tensile and thread stripping strengths, and yes I agree they are made like that in special instances. That would allow you to say the stud/shaft defines the UTS (which is actually a property of the material). When designing around fasteners the 0.2 offset yield is used over the UTS anyway. Without working for ARP I wouldn’t know what their design requirements specify, but you seem to know.

Yes I understand torsional strength is lower than axial strength (in most isotropic materials by a factor of 1/SQRT(3)) and yes in most instances a nut will convert torque into thrust (or clamping force) more efficiently because of the reduction in thread contact area (less energy absorbed by friction i.e. heat, sound etc.) …not simply “by the way it must be tightened”. You have completely forgotten about the nut failing in traverse shear. This is what stud/nut or bolt/nut interactions are based on (as above). I suggest you read some proper literature yourself. Your increased clamping force at the same torque has just brought your nut closer to failing in traverse shear than the much higher axial stress you anticipated it failing at earlier. Don’t worry about torsional shear or axial stress, your going to strip the thread from the nut! (or destroy both equally in your opinion, two birds one stone? economical).

Yes I have used many… both really small and really fkn BIG. Most people don’t know wrench accuracies change with graduations in scale (eg. two parallel scales with a shift each graduation) and unless you can fully distribute your hand across the whole handle or use one finger directly in the middle at perfect right angles your result will be off. The variance is quite surprising.

Remember 1400MPa is strength per unit area. What are the original ones rated at?

I’m just trying to help people by providing an understanding in plain engrish of the benefits of using studs in an engine block. That is, after a stud is installed the block is effectively in a state of stress i.e. there are invisible forces pulling or holding these studs into the engine block. When the head is torqued back into place, these studs are effectively pulled back up out of the block, basically back to its ‘original position’. Even though the head is torqued nice and evenly on, the sum of all force at the block/thread face is next to ZERO.

[GT-RZ]

No need to get your knickers in a knot, just trying to help. Yeah I'm laughing too, some brief answers for your brief 'points'.

Firstly it depends on the manufacturer and to what extent. Nuts are commonly manufactured to different tolerances than the stud/bolt/shaft 'it will be attached to' it's called class of fit. In general a nut with strip before destroying the stud, this is not coincidence but a design feature. In fact, a nut is usually softer than a bolt to allow slight yielding of the top threads and thus distribute the load more uniformly among the threads in contact. I believe what you are trying to say here is that the length of nut engagement is balanced between bolt tensile and thread stripping strengths, and yes I agree they are made like that in special instances. That would allow you to say the stud/shaft defines the UTS (which is actually a property of the material). When designing around fasteners the 0.2 offset yield is used over the UTS anyway. Without working for ARP I wouldn't know what their design requirements specify, but you seem to know.

Yes I understand torsional strength is lower than axial strength (in most isotropic materials by a factor of 1/SQRT(3)) and yes in most instances a nut will convert torque into thrust (or clamping force) more efficiently because of the reduction in thread contact area (less energy absorbed by friction i.e. heat, sound etc.) …not simply "by the way it must be tightened". You have completely forgotten about the nut failing in traverse shear. This is what stud/nut or bolt/nut interactions are based on (as above). I suggest you read some proper literature yourself. Your increased clamping force at the same torque has just brought your nut closer to failing in traverse shear than the much higher axial stress you anticipated it failing at earlier. Don't worry about torsional shear or axial stress, your going to strip the thread from the nut! (or destroy both equally in your opinion, two birds one stone? economical).

Yes I have used many… both really small and really fkn BIG. Most people don't know wrench accuracies change with graduations in scale (eg. two parallel scales with a shift each graduation) and unless you can fully distribute your hand across the whole handle or use one finger directly in the middle at perfect right angles your result will be off. The variance is quite surprising.

Remember 1400MPa is strength per unit area. What are the original ones rated at?

I'm just trying to help people by providing an understanding in plain engrish of the benefits of using studs in an engine block. That is, after a stud is installed the block is effectively in a state of stress i.e. there are invisible forces pulling or holding these studs into the engine block. When the head is torqued back into place, these studs are effectively pulled back up out of the block, basically back to its 'original position'. Even though the head is torqued nice and evenly on, the sum of all force at the block/thread face is next to ZERO.

Without starting another page i would like to let you know if you are shearing threads from the bolt then you are only doing so when you are turning the nut on the shaft, over tensioning.

I can guarantee if you were to place a nut on the thread of the head stud and somehow attach this piece in to a tension breaker the shaft will 'neck' and separate before the threads on the nut give away. Again you have missed the point (this is not for idiots with keep on tigtning something untill the threads let go)

As for the class of fit that depends on the thread and material. Anything rated over 800mpa generally will be provided with a lower rated nut and yes you are correct in saying this is due to the yield strength in the nut providing the grip.

Obviously Generally the higher the UTS of steel the higher the start of plastic deformation in regards to the UTS, which is why there is such a rigorus tightning procedure with fastners like head studs (very high MPA). Obviously tightning a tensioner up correctly is simply a method of reaching a level around the maximum level of the materials elastic limit nibbling the plastic limit (providing the maximum amount of spring in the steel) which can be a hard task when dealing with hard materials as the boundary between elastic and plastic deformation are extremely close, too much tension and you permanently elongate the fastner too much rendering it useless and too little and you run the risk of the working load providing more force than it was tensioned with, creating working stress and potenial premature failure.

As for 1400Mpa then that is what it is... 1400mpa or 1400 newtons per mm in laymans terms. That is all you need to know along with the area under tension to calculate the maximum load. The factory tensioners will not be rated at such a level, bolts in general due to the way they are used have much smaller loading maximums like i explained before. Again a nut does not determine the UTS, the shaft does.

I found this on ARP's website:

Engaged Thread

An additional factor must be taken into account in defining the bolt configuration: the length of engaged thread. If too few threads are engaged, the threads will shear at loads that are lower than the strength of the bolt. As a practical matter, the thread length is always selected so that the thread shear strength is -significantly greater than the bolt tension strength.

This problem is especially important in bolts used in aluminum rods because of the fact that the shear strength of aluminum is much lower than the shear strength of steel.

[purpleskyline]

right guys nearing the end of my build,, question is has anyone used hks2530 on there rb3026 build, plus what power can rb30 rods take,

not for my engine as i have forged, but a freind is doing a cheap build with totaly standard bottom end.