Grizzly

Is there any advantage using studs over the OE Bolts?

GMON

Not the studs in that picture. The ones in the pic are not a machine fit. So other than being able to add more torqe than the stock bolts, which I personally think is stupid on a RE, they do nothing.



Have a look at these, see the difference?



http://www.xtremerotaries.com/main2/engine_services.htm

j9fd3s

http://ausrotary.dntinternet.com/forums/vi...er=asc&start=60



"As for the debate over whether dowelling is necessary. As Rohan himself told me, rotaries do not twist, they stretch. Dowelling would work if the engines twist, but they don't really do that. This the idea behind stud kits. He has measured 1mm horizontal stretch over the whole engine in a 700hp application. That's a fair bit of movement. And that's what's happening when there is no catastrophic failure. At over 350hp, there is some measureable stretching. The sump plate should go some way to inhibit stretching, but a stud kit is the best idea."

1Revvin7

Same reason you use studs on a piston engine, especially ones with higher cylinder pressures; ie high comp/boosted applications; to keep the head from moving around. The problem with factory bolts is they yield, stretch, like bubble gum. Not to mention bolts twist and create friction at the threads, not only wearing the threads, but providing an inaccurate torque measurement. The studs pictured are the ones I sell, I had them made by the same company that ARP used to use for their" double throw down you can't get any better studs" which also cost 4x the normal price. The materials, manufactoring, and testing process used to create those studs make them about half as susceptable to stretching as the factory bolts. Not to mention vibration and breaking issues are almost eliminated.



P.S. The site is real fresh and I've got a ton of updates for it, I will have more detailed information etc for most products...

banzaitoyota

But did you ever determine what the CORRECT torque value is when the stud kit is used? And what method did you use to determine that value?

GMON

Dowelling is not meant to prevent twisting.



Its to add more support to the combustion chamber which just happens to be the rotor housing. The whole side of the housing can deflect during a bad burn. This pushes the cumbustion chamber away from the rotor. Since the tension bolts are not machine fit there is enough room for the housing to deflect about 10mm which is enough to cause serious problems. After this happens the housing is back in the shape it had and the only evidence is a crack at the stock dowels and/or some scoring on the plates and housings by the water seals.





Studs that act as dowels both add support to the combustion chamber while adding resistance to twisting.

GMON

I see no benifit in the tension bolts not streatching.

A)The engine expands when it warms up and the bolts should streatch a little.

They are designed to do this, as the engine warms up its held toguther tighter.

B)Bolts that dont streatch would not allow for this expansion and would hold the

engine toguther much tighter than stock. I am sure you can think of a few clearences

that this would be detremental to?



As for breaking. Well, we all know how much of a problem those are.

I mean damm, I can get those stupid stock bolts to stop breaking.



As for vibration, Such a major casue of rotary breakdown. Anyone that has ever played a string

istrument knows how to fix this one. Mute it with a bit of silicone. Also, when you make them a macine

fit, dowel or bolt they are not going to vibrate.

ArmyOfOne

It seems that no matter how many times we ask this question we never get an answer. I am wondering if we are on the permanent ignore list.



And the saga continues.

RONIN FC

https://www.nopistons.com/forums/index.php



Mazdatrix recommends 35lbs op to 500 hp. But thats for the studs they sell.

1Revvin7

32 ft #s w/ a removal strength locktite