Head Studs For An Open Deck Engine

[GTRNUR]

Hi Guys,

My open deck RB26 project is coming along nicely, however I am still trying to locate a good option for the head studs or bolts to hold it all together.

The engine has an additional height of about 2mm, so the studs need to be 150mm long approximatly... The closest I have found from another engine is 149mm, which is probably going to do the job fine, but these bolts are $35USD each so Im looking for another option.

Im considering having the block drilled and helicoiled so I can use alternative head studs or bolts with imperial threads, as that opens up the world of chev and ford studs as being a possability.

Does anyone who's done this kind if build in the past have a suggestion?

Cheers,

Ian

[shanef]

id go to a stud, that way you could just use the std arp rb26 headstud kit as i dont think the 2mm is going to make any difference as theres plenty of thread for the nut to screw down onto.

[GTRNUR]

id go to a stud, that way you could just use the std arp rb26 headstud kit as i dont think the 2mm is going to make any difference as theres plenty of thread for the nut to screw down onto.

Are you saying the RB26 ARP studs are 20mm longer than they need to be? I havnt got a set handy to compare to a standard head bolt for thread penetration depth into the block...

Edited June 3, 2009 by GTRNUR

[FineLine]

Are you saying the RB26 ARP studs are 20mm longer than they need to be? I havnt got a set handy to compare to a standard head bolt for thread penetration depth into the block...

Must have been a typo Ian, Your original post said "2ml" longer

[Adriano]

Do you have 2mm or 20mm extra height?

[GTRNUR]

Must have been a typo Ian, Your original post said "2ml" longer

Yep a typo...thanks for spotting that Noel, and CRAP I cant edit the first post....

Spacer plate is 20mm, not 2mm...

[Adriano]

I would use 1/2in studs, im pretty sure they fit the head without modification.

[GTRNUR]

I would use 1/2in studs, im pretty sure they fit the head without modification.

The only problem is with the head locator dowels that are 13.1mm in diameter. If I go to 1/2" studs it means adding dowels elsewhere to positively locate the head. Ive yet to find out what people do when running 1/2" studs in the RB engines.... I did read somewhere that on RB30's the 100ft-lb torque that the 1/2" studs need to get the right bolt stretch causes the top of the deck to distort a little so the head gasket probably wont seal too well witht that...

If that is a problem for a block thats got flanged sleeves in it though is anyone's guess.

[Adriano]

Easy enough to fit bigger dowels in the stock location. I wouldnt imagine there would be issued with a dohc head with the crush, but you could do a comparison on the crush. Maybe the sohc heads cant handle the pressure?

[bigmikespec]

The only problem is with the head locator dowels that are 13.1mm in diameter. If I go to 1/2" studs it means adding dowels elsewhere to positively locate the head. Ive yet to find out what people do when running 1/2" studs in the RB engines.... I did read somewhere that on RB30's the 100ft-lb torque that the 1/2" studs need to get the right bolt stretch causes the top of the deck to distort a little so the head gasket probably wont seal too well witht that...

If that is a problem for a block thats got flanged sleeves in it though is anyone's guess.

I think Dirtgarage uses 1/2" studs on Twoogle?

Hope the build is going well.

[shanef]

20mm makes it a problem with the arp rb26 studs . i just measured it then, with the arp rb26 studs, theres 13mm from the top of the nut to the top of the stud with it torqued to arp specs

what you will have to do is either fill out an order form, or ring arp direct and order a set of studs similar to the rb26 kit but with 20mm more shank. shouldnt be too much more expensive then a normal arp set.

pic is of rb26 headbolt and arp2000 headstud

P.S got pics of said spacer/hi deck setup?

[GTRNUR]

I think Dirtgarage uses 1/2" studs on Twoogle?

Hope the build is going well.

Yes im making good headway with the project.

The crankshaft modifications are finished and its now drilled, screwed and balanced and has an 87mm stroke. The Rb26 block was bored out to 92mm today and I believe some if not all of the sleeves were pressed in today too. Ive had the oil galleries drilled and grub screwed too. I am still waiting on the custom order CP pistons and a nismo twin plate to arrive so I can have the bottom end balance finished, and I also need the pistons so the sleeves can be bored to match etc. Ive gone for 87mm pistons for this prototype engine.

The spacer plate fabriaction has been an excercise and a half. Got it right on the 4th attempt. The waterjet cutters had a tooling problem that caused the trial template I had cut from thing material to be inaccurate. The 3 plates I then had cut from 20mm plate after that were all useless. They then replaced their cutting nossels and the 4th cut came up perfect.

I'll be posting up the build when ive got everything back in my workshop. Hope to have it in a car and running and tuned in 2-3 months max.

[GTRNUR]

Thanks for the pics of the bolts too Shane. Interesting the little ridge at the edge of the 12x1.5 thread on the block end of the stud, and looks like 12x1.25 at the other end right?

[shanef]

Thanks for the pics of the bolts too Shane. Interesting the little ridge at the edge of the 12x1.5 thread on the block end of the stud, and looks like 12x1.25 at the other end right?

my verniers are saying its an M11 thread both ends. The block end is definately metric, but im unsure on what thread arp use on their nuts, as u said its obviously finer.

Not sure whats doing with the ridge, cant say ive taken notice whilst installing them so cant say if it stops them bototming out or what. Also the shank is smaller than the threaded ends.

[Adriano]

M11, they must be rb25 studs?

[STATUS]

speak to willall (sa) or racepace (vic) as both have extensive experience with open deck rb26's.

I may be interested in some spacer plates as we have the sleeving process fully sorted now. if your looking to sell some feel free to pm me.

Edited June 3, 2009 by URAS

[GTRNUR]

speak to willall (sa) or racepace (vic) as both have extensive experience with open deck rb26's.

Yeah but its a fine line to cross asking these guys to share the knowledge freely that they use to build their top level engines... If they were willing to volunteer the informaiton freely I'd really appreciate it, but I understand completely why they'd hold most of their cards for an open deck engine close to their chests. After all its their livelyhood.

Also i'd wager they are just using ARP anyway. I was hoping for an alternative and dont need the strength nor the expensive of ARP. Im not building some 700+hp monster. The engine will probably end up with a pair of GTRS's on it and not reving past 7500. 500awhp would be plenty. Its built for torque and low to mid range response.

[STATUS]

Yeah but its a fine line to cross asking these guys to share the knowledge freely that they use to build their top level engines... If they were willing to volunteer the informaiton freely I'd really appreciate it, but I understand completely why they'd hold most of their cards for an open deck engine close to their chests. After all its their livelyhood.

Also i'd wager they are just using ARP anyway. I was hoping for an alternative and dont need the strength nor the expensive of ARP. Im not building some 700+hp monster. The engine will probably end up with a pair of GTRS's on it and not reving past 7500. 500awhp would be plenty. Its built for torque and low to mid range response.

ah sorry yeah i thought you were after ARP's.... i will look at some TB45 and TB48 head studs for you as i remmebr them being longer... i have a few laying about from turbo dirt dweller builds.

Do you have a solution for sealing the deck and plate? dont need to post as i also understand...just interested.

[GTRNUR]

ah sorry yeah i thought you were after ARP's.... i will look at some TB45 and TB48 head studs for you as i remmebr them being longer... i have a few laying about from turbo dirt dweller builds.

Do you have a solution for sealing the deck and plate? dont need to post as i also understand...just interested.

I kept that really simple. A standard RB26 or RB30E head gasket with the center cut out of it to clear the sleeves will do the job, sprayed with some hylomar. I considered making up a copper gasket cut but frakly the price of copper is crazy and using a propper gasket is a cheaper and probably a better option.

The spacer plate can be bolted to the block with a set of 50mm allen head bolts and torqued to spec with a gasket installed when the block is decked. The other option was to mathmatically work it out and set the sleeve height to be about 3 thou higher than the spacer plate and spacer plate gasket to get a better cylinder-head seal. This is one of dartron's tricks with how they recommend setting up sleeved block top ends.

Im keen to see how long the TB45/48 bolts are. Shame there arent many of those engine around dead to pull apart and check out. I figured they'd be built like a diesal though being that the blocks are milspec rated.

[GTRNUR]

Well it looks like i'll be using porsche 928 head studs in this first build. They are certainly up to the task.

Also, for those that were interested I have attached a few pics of the machined engine block. The sleeves still need to be bored out to match the pistons that should be arriving in 3-4 weeks, which isnt a bad thing.. because Ive decided to change the bottom end of the engine a little. Im changing the crank modifications a little and getting a set of pauter x beam rods for it.

Considering this prototype is going in the R34 I want it strong as hell. The x beams should make the bottom end capable of supporting 700hp easy. Im not running an ARP main stud kit in this engine, which is really the only limitation as to why it wouldnt reliably handle more power. Power isnt what this is about anyway, its about response, mid range torque and reliablity.