dowel pinned 12a
 

ok, i really need some pics or a writeup on dowel pinning, im building up a 12a and im a machinist, and i really want to know whether its worth it on a 12a, for one and also what do people use as "pins", where do they go, what do i machine, pics would be great,

yes ill need the extra support in the motor for my custom turbo 12a, yes all other aspects of the engine will be taken care of aka oil etc, anything to make it last long. thanks,

oh ya, i searched, couldnt find one thing on it, no writeup, nothing, cant even find a pic, is this some sort of high hp people secret, cause i cant find anything, in archives, race forum or here, any help greatly apreciated,

Try the engine building section on NoPistons. Iirc the is a pretty good thread over there on that.

thanks allot "trochiod" ill do that

Not necessary, unless you have high boost with bad or roughly tuned with bad fuel mixture and incorrect timing. I learned the hard way, that too much boost(with close to correct fuel and spark) WILL and DOES indeed crack the rear endplate dowel area, and then leak. It does have lots of power with 15-16psi, but its really straining the engine ablity to stay rigid for long with extremely high cumbustion pressures. A extra dowel would have possibly distrubuted the load better. However, then the new locations tend to bear the grunt then, and crack also. -This is what I have been hearing, but this may be counterdicted by someone? But at least the new dowel location won't leak oil?

do you just pin the endplate, or do you need 2 dowels per tension bolt, in the places that are pinned? i wondered cause everybody talks about cracking an endplate
also i wondered if stiffening the oil pan, would help distribute the stress of the motor, unless im just crazy, anyways, just wanted to know if people run the pins on the front and rear rotor, or just the endplate to intermediat, thanks

another q'n
 

where is the most common place to pin?, i remember a thread we had, a while back about combatting engine twist on 12a's, and stress and the topic of dowel pinning was brought up, there was some great pictures of where are good spots to dowel pinn, and now i cant find that thread anymore,

thanks wackyracer
i really wanna see how hard it is to dowel pin, before i decide whether or not i want to do it,

Dont bother with dowells, do this. 4140 chromoly heat treated studs.

And the price and availibility on these would be?

Oh Snap! Can I get these for a GSL-SE? 13B

Those are some trick bolts.

~T.J.

Those bolt kits are spendy, I looked them up not to long ago and they were over a couple hundred for the set (of course I guess that is cheaper than toasting an engine, but still that is spendy for bolts!).

and all of the sleves have to be inlarged? or just the endplate for the larger bolt size? or just drilled out, and new bolts at the end? and do they come for 12a im actually interested if it means i can run killer boost without fear of destroying my motor of course with proper tuning,

yeah ive heard the stud kit is a better way to go. they're a little over $200 and well worth it.you can get them for the 12a and 13b. i also remember someone saying something about using an older 13b rear plate,something about it has thicker bosses around the bolts and it holds up better

$200 I doubt it try something like $400+ actually $485 total with shipping from Australia, trust me on the pricing that's what I paid to get them for a friend. Company is called Xtreme Rotaries http://www.xtremerotaries.com/ shoot them an email the person you will contact is Judy but you can give Mazdatrix a call talk to Henry they get the stud kits and perform the machining. All bolt holes are drilled, tapped and reamed. Something like $950 for studs and machine work. I got lucky and a good friend of mine added dowel pins on my motor for free.

ive seen people break the motor with this stud kit. there is still alot of motor flex with this kit, enough to break the motor...
pining the motor is the best way to go..

still nobody has answered, about how to go about dowel pinning, or explained what is better, or anything, does nobody know?


i searched the other forum (nopistons) and couldnt find anything iether, if anybody can link me to a faq on it or something thatd be great, as i said i really wanna see how this works, benafits, and what parts are involved

its a very elaborate process, not too easy to explain on the internet.....
the peolple that do pin motors, arnt anxious to explain how they do it....

here is a pic of one of my customers ported ///pinned motors i add 64 stainless pins to the motor to make it bulletproof..

http://www.imagestation.com/picture/...4/f33838d9.jpg

cool so its just a little pin that slides into a machined slot in both sides of the housings, and on the intermediat front and rear plates, and it all just slides together, cool, if im right, it definately seems difficult, and precise, where do you get these little pins, can i use stock dowel pins that are in the motor, and cut them to size and only do a few places, also on the front plate where the threads are, what do you do, only use half the thread and allow the pin to sit in the other half? or is there some sort of custom longer bolt with a nut that sits on the other side of the front plate? sorry for all the quesions, but im really curious about this process,
thanks for all yourhelp so far,

the original pins are sloppy, they vary in size and hardness, not to mention they are large. when you machine the housings to accept the stock dowel size you have to take out so much material it weakens the housings, thats not good..

the pins i use are custom made out of stainless thats been heat treated to a 49 rockwall so there is no give.. also the pins are small so when you machine the housings your not removing too much material keeping the motor strong, actually bullet proof...
the pins go in all the housings thus locking the motor together... the pins go in the front housing too , since they dont go that far into the housing the factory bolts work fine..
each hole has to be machined 3 times,1st, with an end mill (mostly to break through the nitriting) 2nd a rougher and 3rd a finish cut.. thats a total of 384 passes on the machine to make the holes plus setup time.............

can you do the same process but in only a few places around the motor, in the main stress points or is that just absurd, thanks for the info, ps i pmed you about the manifold, dont know if you got it,
thanks again,

some guys add 6 to 10 extra stock dowels, but there motors still break, just not as often...
i cant get pm's ...
you have to e-mail me

robert@rotaryshack.com

tried that too,, you should have an email hah, thanks for the info, ill do some research and decide whether i want to do all the work of pinning thanks for your help once again,

im not trying to shy you away from doing it, but unless you have a shop, its not worth it finacially to make all the tooling to do one motor...

Care to elaborate? How was the motor broken? The stud kit wont save you from bad tuning. It is just a much stronger alternative to extra dowells. I run the full 12.7mm stud kit and I also have a 5mm steel sump plate. No twisting for me.