Xtreme Rotaries Stud Kit: Reviews and Cost?
 

Anyone have any experience with the Xtreme Rotaries stud kit for the 20B?

http://xtremerotaries.com/

The kit costs about $500 and supposed eliminates engine flex. However, you have to drill ream and tap each stud hole to use.

So, what is your experience with these? Do they work? What is the cost to have the machine work done?

Hey David

I have been running the 10 mm stud kit for the 13b for 3 years now and im realy happy with it. I have a freind here in norway that is running a 20b with the 12.7mm stud kit now. And his engine is realy tight.

When using this kit u need to have the new holes drilled by proffessionals to make the clearance perfect. I would recomend using it for your 20b.

If ur looking into the Xtreme Rotaries ones they are pretty cheap.

I will be using the 12.7mm ones for my new PP engine im building next year.

Regards
JT

Xtreme rotaries sell their product under the "GURU" name so other rotary shops dont feel weak pushing a competitors product.

They manufacture their own stationary gears, 2-3-4 rotor shafts, centre bearing plates, Aluminium centre bearing plates for a 3-rotor, bearings, stud kits & more.

The quality of work is exceptional as they learn techniques from the F1 world.

So think about this. They have hundreds of stud kits out there all dealing with flexing issues & I am yet to read anything bad about them. However, you can read bad stories here & there about dowelling

Go for it I say

REgards

^What is the approximate cost for the machine work? Anyone?

David,
I have their stud kit and E-shaft. Their stud kit you can do without. All you have to do is pin your motor a few extra spots. The e-shaft, however, is a fantastic piece. This is also a known weak point of the 20B and not only eliminates breakage, but eliminates flexing of the motor all togeather. I have this for my 13B, but will be ordering the e-shaft for my 20B this winter.
Ernie

Thanks Ernie. Curiously, this is the opposite of what I've heard from others. I've heard the Xtreme Rotories eshaft is very good, but uneccessary if you keep RPMs under 9,000 which is where I'll be. If you race and plan on running high RPMs, it's the way to go. I've generally heard the stud kit is grea for the 20B because it solves the engine flex issue for normal street applications.

Can I ask what it cost you to machine your engine for the stud kit or did you use the OEM size kit?

David,
I don't have any experience with the 20B, only the 13b at high boost which does the same thing at that point as the 20B. The engine will flex. After the e-shaft (only) was installed I made almost 30more rwhp at 32psi on a street port with nothing else changed. The simple fact that your albe to clearance the motor tighter and it wont flex allows more power. The stud kit helps, but you have to find a good machine shop. I paid $500 and they screwed up. Ray had to try and fix it. After that he just pinned the motor which accomplished the same thing. Like I said, I know its not a 20B, but its the same principles.

Ernie.
The 20B is a little different to the 13B it the principles.
The casting in the 20B does not support pinning as easily as the 13B do. It's not that extra dowelling can't be done but the bigger stud technique have been found to be more reliable for the 3-rotor. One of the major problems with the 20b is the that the thick housing is very prone to cracking due to the limited casting around the bolt areas. Plus due to the layout of the bolts from factory meaning that some of the bolts go all the way through from the rear to the front. Some go to the thick housing only from the rear and the rest go from the front housing to the thick housing also. When using the Guru studs all the ones on the compression side and the knock zone area that are proned to cracking go all the way through the motor and two nuts are then used on each side of the studs. That's one of the major advantage of the studs vs say pinning with extra dowels. Plus with the studs a lot less material is removed so the housings are much stronger and less prone to cracking.
I've seen the studs in action on a street ported 20b that's been abused for a couple of years now on pump gas at 20 psi. Let's say the motor was opened up once due to a spun bearing from the abuse but all the housings showed no signs of moving. The motor is still runing at presently.

^Hey Chris, do you know the cost for the machining of the 20B for the studs?

Talk to A-spec. I originally was going to get my machining done from them, but ended up doing it myself with some help from a neighbor who is a machininst. It turned out well and the motor is holding out great.

Mazdatrix sells the Guru studkit for $486 if i remember correctly.

^Thanks. Has anyone paid for the machining and if so, how much was it?

David, a few quick points...

1) You're right, the e-shaft is unnecessary if you'll be staying under 8,500 rpm. For a 20B that isn't purpose-built (for high rev racing), 8,000 rpm would be even better. Keep in mind that with the added torque of the 20B, you won't NEED to shift so high up in the powerband to make power. So don't overdwell on how high you CAN shift, rather than how high you NEED to shift ;)

2) I disagree w/ Ernie. The 13B and 20B are apples and oranges. Essentially the only thing similar between the two motors is that they use rotors. One of the GREATEST mistakes ppl make is thinking a 20B is simply a 13B with an extra rotor. I'll *guarantee* you that that isn't the case. It's a lot more complex, and clearancing a 20B alone is something that can only be done correctly with LOTS of practice. Ask some of the guys who race 20Bs (professional circuits) and you'll find that they've build and blown their motors DOZENS upon DOZENS of times before getting it right.

As for dowel pinning vs. using a stud kit, Crispeed's on the money (big surprise ;)). Stud kit is the way to go. Housing flex is a MUCH bigger and serious problem on a 20B than it is on a 13B. Any well build 20B should run a stud kit. (Any well build 20B should run a dry sump as well, but I'll take it easy on you guys haha)

3) Mazdatrix does indeed sell a 20B stud kit. Cheaper than Guru's. Save some money for once hehe :p:

4) For machining (as well as clearancing, if you do ever tear down the motor), THIS IS WHERE YOU WANT TO SPEND YOUR MONEY. The best ppl to do this are professional race shops, many of which are contracted by Mazda and do such work. Turnaround might be slower, pricing might be higher, but you'll be getting everything done w/ absolute precision, and it's always done right the FIRST time around. And if you will be tearing down the motor, I'd suggest balancing the rotating assembly while you're at it too.

~Ramy

^Thanks Ramy. You're on point also as usual:) I sitll don't know how much though the machining will be for the 20B stud kit. Anyone know? $500? $1,000? And a slight clarification to the above - the Mazdatrix stud kit is the Guru stud kit. At least this is what the Guru/Xtreme Rotaries guys told me.

David, I honestly never asked for a quote on machining the housings. But given that it's pretty straighforward (when compared to say, machining the rotors for 3mm seals, which is a LOT more intricate), I can't see it being very expensive. I think you're right in the price range though.

David
The average cost here is between $500-700 for a 20B.
The Mazdatrix stud kit is the same as Guru/Xtreme Rotary.

^Thanks Chris.

not to hijack, but do you guys know how people seal the stud kits that go all the way through? Do they actually machine the back side for an oring type seal or just use a copper washer?

I know this is the 20b forum but... I'm looking for a stud kit for my FD. Is Mazdatrix's 20b materials the same as the 13b? I need a stud kit for my peripheral port motor. Guru's site is down (and has been for months) so Mazdatrix is the new alternative.

Mazdatrix stud kits are the Guru studs. Same materials as they get them from Guru - at least it was this way one year ago when I bought my kit. Not sure how it works for the 13B but for the 20B you can get one of two kits, the first requires no machining as it is the same size as OEM bolts (better materials and tensioning though) and the second kit requires drilling as it is beefier.

I went the beefier route for my 20B and it was a pain getting someone to correctly machine the holes.

I read somewhere that someone makes studs that are slightly larger than stock and fit very tight (no machining required). I thought it was in this thread but I can't see it here now. Is this true? I'm going to send Mazdatrix an email once I get a little more information on the various stud kits out there. Keep in mind this is for a 13b not a 20b. Thanks again!

Oversized studs that do not require machine work for a 13B
 

What you are asking for does not exist...

Current choices on the market:
Stock
Stud kit (stock diameter) no machine work required to install
Guru 12.7mm oversized " Tight fit" Requires the complete block to be machined/Bored and re-tapped


Seems like you want the benefits of the oversized studs, (you said "tight fit") without any machince work and that does not exist..atleast not yet.. and I doubt someone will even bother engineering something like that as I doubt its even possible..

That's not entirely true. The Guru stock based studs are a little less than 1mm larger than stock (which does not require machining). It's not a huge difference, but it does account to about 15% increase in strength (according to Xtreme Rotaries when I talked to them a few years back).

I'm about ready to post a thread in the rotary performance section but it's probably going to be one of those bias personal opinion threads. I've read that increasing the clamping force is all you need. People have stated that after increasing the torque that "the plates and housings showed no signs of movement" after being torn down.

It's pretty interesting to hear this but I can surely see the benefits of the 12.7mm studs clearanced tight for HIGH horsepower rotaries. Perhaps the biggest battle is for us people looking for 600-800whp and that the increased torque load from the studs is "enough" for us. I agree you should always do things right and complete but in this case maybe the Guru/Mazdatrix oem sized studs will do the trick. I know everyone has their opinion but "pictures speak a thousand words." If anyone has used the oem sized studs and has proof of the housings and irons shifting I would like to hear your full story.

My next motor is going to be a peripheral ported 13b (possibly direct injected). I'll be using a S374 for quicker spool up (via peripheral ports) and targeting 700-750 whp. Thank you for the experienced people in advance...

If this is true, than I stand corrected.. Is that a 15% increase in clamping strength? I ask because its hard to believe that the undersized studs, considering they would have the same effect the oversized studs do.. How can the 1mm larger than stock studs act as dowels as the oversized do when they have all the space/slop between the plates and housings?

15% more clamping strength I can understand..1mm larger diameter.. and made of better material....but they can not do what the oversized kits does...

Never said they did, and wouldn't expect them to... Still, even if it's a small percentage better than the stock studs, it's not a bad deal since there is no machining.

I don't want put words into Xtreme Rotaries' mouths, but I'm just relaying the info they provided to me. I don't still have the email chain from them (as it was back in late 2004), but I'm under the impression they were referring to the force resisting any twisting (if you want to call that clamping). I do remember they were really working hard on selling me the oversized kit. They also put me in contact with Daryl Drummond who I spoke with about a few things as well.

Here's a shot of them when I bought them:

http://mahjik.homestead.com/files/FD...0/DSCF0059.jpg

Shot of them after the install:

http://mahjik.homestead.com/files/FD...7/DSCF0448.jpg