mazda rx2 rotary

I have broke my engine two times the past 3 months!original motor bone stock FD except rotary aviation super seals,200 plus passes 4-5000 street miles wore the front main bearing out and let the front rotor face touch the rotor housing.I can understand that.rebuilt it with a little port work stock tension bolts,three passes on the street and broke it.rotor touched the housing but only on one side next to the combustion chamber.rebuilt it with the guru 1/2 stud kit with the seven studs going all the way through the engine.I torqued the engine to 60 foot pounds.first pass at Irwindale broke it low compression in the front rotor 50 pounds!I said F it I'm going to make another pass best pass ever with the car it went a 5.91 with a 1.24 sixty foot.tore the motor down and it smoked the front rotor area around the corner seals and also touched the rotor housing!I put the block together with the rotors installed and no E-shaft and found .002 of an inch (rotor gear side)clearance at the thrust lands of the rotor.(didn't check the front rotor before some side clearancing had taken place but I'm sure it was tighter)I would like to know how some of you have managed to cure this problem.what I have done so far is clearanced the thrust land of the front rotor to .010 (I know spec is .004-.008)when I put the engine together with no E-shaft and torqued it to 60 pounds I have .007-.008 side clearance.if any of you have checked how much the rotor rocks on the thrust land (from the combustion side to the corner seal is .030 with the spec of .005 from the thrust land to the side/corner seal area)dam that is a lot!dam this engine flexes to allow contact in these areas!!!what do you guys do to eleminate the contact in these aras?what I am in the process of doing is thrust land of .010 with the block torqued to 60 foot lbs (witch will give me .007-.008 thrust clearance)I have removed .006 from the rotor face.and will clearance the side of the rotor .010 to the thrust area(from the thrust land to the corner/side seals)has any body done this? Thanx for any input

1BADSP

iTrader: (4)

What did you do for break in with the new engines ?

mazda rx2 rotary

Let it warm up

SlimJim

Just wanted to know a few things if I could... what weight of oil,pressure at idle,and at load.And what kind of fuel you are using...mabe I can help.

mazda rx2 rotary

Just wanted to know a few things if I could... what weight of oil,pressure at idle,and at load.And what kind of fuel you are using...mabe I can help.

15-40 oil,40 psi at idle stock oil jets with check ball and spring(street driven car)70-80 psi oil pressure at 25-28 pounds of boost.E85 for fuel,maybe not enough oil pressure at full load?

GoodfellaFD3S

iTrader: (213)

Uh, you're doing it wrong.

torquing tension bolts to 60 foot-pounds? That's over double the factory rating.

Are you measuring the e-shaft endplay? Pressing the bearings correctly?

mazda rx2 rotary

yes e-shaft end play at spec;guru 12.7mm stud kit.the spec for ant half inch bolt (grade 8 or better)is 75+- 15 foot pounds.yes bearings pressed in straight.correctly?

13B-RX3

iTrader: (2)

What e-shaft? Is the shaft straight? I agree, 80ft lb is way too much. 35ft lb is all you need. You shouldnt have to clearance the face of the rotors till you get WAY up in the power!

mazda rx2 rotary

do you use the guru 12.7mm stud kit?i torqued it to 60 foot pounds.i need to V-block that old shaft to verify the trueness of it.how much power until you need to clearance the rotors?the E-shaft is probly bent.

13B-RX3

iTrader: (2)

I have used studs in the past (13mm). I would guess close to 700 before clearancing the sides and i don't believe in clearancing the faces. IMO if the face of the rotor is hitting the housing something is bent or you are detonating! What series shaft are you running? Also measure the rotor housing thickness, you may have crushed them by torquing it so high i have never heard of torquing tension bolts or studs that high.

mazda rx2 rotary

the E-shaft is an FD;the rotor housings miked out to spec,3.148;i tried to find info on the stud kit;so that is why i guessed that 60 foot pounds was good;i am running E85 i have not heard any detonation

13B-RX3

iTrader: (2)

The FD shaft is strong but they will also bend. Check runout at the snout and i bet it's tweaked. I have lost a few motors to detonation and i have never actually heard it, maybe i'm just deaf Are you running a crazy amount of timing or a very narrow split?

mazda rx2 rotary

thank you all for the questions and answers so far guys

mazda rx2 rotary

[QUOTE=13B-RX3;10287200]The FD shaft is strong but they will also bend. Check runout at the snout and i bet it's tweaked. I have lost a few motors to detonation and i have never actually heard it, maybe i'm just deaf Are you running a crazy amount of timing or a very narrow split?[/QUOTE

timming wise i am at 26 degrees at 8000rpm at 29 pounds of boost.the split is at 12 degrees if i remember right,not sure if that is to much timing;this is the thing i have heard people running there timing right were i am at and 10 degrees at that boost level and rpm

mazda rx2 rotary

i have not broke an apex seal just contacting the rotor to side housings and rotor housings

13B-RX3

iTrader: (2)

I'm no expert but if it were me i would run less timing and less split. A lot depends on the port too. I would start around 12 degrees timing and 10 degrees split. keep bumping the timing up until the MPH no longer improves and then back it down a couple degrees for a safety margin. There is power to be had by tweaking the split but it is much more dangerous to play with.


There are only three things that will cause the rotors to contact the housings.

1 a bent shaft
2 shaft flex (detonation, abnormal cylinder pressure)
3 insane amounts of HP

I have seen 750+ hp motors with no problems and i have seen 450 hp motors contact.

mazda rx2 rotary

its a racing beat street intake port with the racing beat exhaust port "race port";i left the exhaust port a little smaller the the templet;timing wise that is what i will try next time out;

13B-RX3

iTrader: (2)

With a street port start at about 15 degrees and go from there.

mazda rx2 rotary

1 a bent shaft
2 shaft flex (detonation, abnormal cylinder pressure)
3 insane amounts of HP

I have seen 750+ hp motors with no problems and i have seen 450 hp motors contact.

i have been running the 9.7to 1 rotors these last two builds.i am going to take the E-shaft to work tomarrow and V-block it to see what the run-out is;spec is 002 max run out

AnthonyNYC

iTrader: (3)

[quote=mazda rx2 rotary;10287207]Wow, what are your EGTs? That's is a LOT of timing. I'm no expert but that is the most amount of timing I have ever heard of at that boost. I have run 20deg advance in the past to test EGTs but in the end you really only need as 13brx3 mentioned 15 deg at 30psi. I stick with a 10-12 split.

Again as was already stated, check the eshaft runout. Mazda allows .002 if I remember correctly but it's better just to start with a perfect shaft. The Vblocks are pretty cheap to pick up a set of those from pineapple racing.

Also check those superseals and make sure they are not warped. They usually warp at high EGTs. Butt 2 of them together and see if there is any light or bowing in the middle of the seal.

mazda rx2 rotary

[QUOTE=AnthonyNYC;10287229]my egt is at 1550 on the big end at full load on E85;the more timing i take away from the tune up the egt's go through the roof

13B-RX3

iTrader: (2)

Are you sure your timing marks are correct? How does the car run with less timing. With 9.7 rotors you should be able to get away with even less timing.

mazda rx2 rotary

not 100% sure about the timing marks;the way i found tdc is center the apex seal in the spark plug holes an split the differance of the marks;i guess i need to take smaller steps with the tune up next time out to the track

13B-RX3

iTrader: (2)

Oh yeah, never trust that method. I just bought a one piece racing beat pulley and lined everything up off that, it's cheap insurance!

mazda rx2 rotary

i have a double shive pulley (racing beat) i will compare the two when i get this back together