Maxt

Yes I am thinking more about the FD motors, and you are right every engine is a step forward in terms power capabilty and also abuse survival. The s4 could be done up to 700 hp, but its not the best foundation in its original form, mix in the right FD parts and the s4 "block" is still up to 700 hp, I could see the e-shaft and oiling system being the biggest impediment. There are several parts of the s4 motors that are also benenficial in making a 700 hp fd motor as well. But from my own observations and experiences, the best parts engine parts are always mazda, and the right combination of mazda parts is important.

l8t apex

cracked one today....OMG!They intentionally built it with scared rotors, REEEAAALLLY bad, one with an apex missing a portion of the trailing edge, oil passageways on rear and front stationary gears they tried to tear drop port. They were not straight, and went past the seating so as the passageway was open to oil leak. The housing was fine, all irons fine , but other than that Catagory 5 had to obtain an internal setup from me.

Nothing I would call close to porting...seriously.So the customer who paid for this got fucked.

banzaitoyota

Lemme guess? Someone whose name rymes with BOB didnt actually assemble it, it was an employees not performing up to "BOB's" Standard of "excellance"?

kuhnke

will if you stick with the stock bolts is thier any thing you can do to dampan the vibrations of the bolts like cover them in shrink wrap?

zoomazda

I've had a pretty good experience with that stud kit as well. Still, it wouln't hurt if you expand your options. Look through online catalogs. They're of great help!



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j9fd3s

the factory race bolts had little rubber damper sections on em.



racing beat says you can slobber the bolt with silicon



the bolts hit a resonance, and the object of coating the bolt with rubber/silicon is to move the resonant frequency up to an rpm that the engine doesnt see. if the stock bolts vibrate around 8500rpms, and you rev the motor to 9k, this is bad. so if putting rubber or silicon move it up to 9750, this is fine, cause you're not going to see 9700 except by accident.

rfreeman27

I have seen stock tension bolts work (and work well) in engines slightly over 700 HP. However, these engines were used for drag racing, and were replaced frequently wether they were broken or not, so long term could be another story.



However, engine flex did become a big problem at levels higher then this. In my case, both a center bearing (and custom eshaft) were utilized as well as a full engine stud kit. After this, there was really no sign of flex. No more pinched seals, no more compression loss. Rotor housings looked pristine after each tear down. The motors could have stayed in the car...



This is running 900+ on a tworotor and a very very high amount of boost.



I plan on pushing my engine pretty hard, and it is pretty much stock internally. My next will be studded at the very least. At the point of a FULL stud job, there is no real need for extra dowel pins. I'm guessing that this could actually do some harm, removing so much material from the plates...

mazdaspeed7

I put some silicone on the tension bolts where the pass through the center in every engine I build. It takes almost no extra time while putting the tension bolts in, and it makes the bolts less likely to resonate and back out at normal, or even higher than stock rpm's. I put 10k miles revving to 9600 rpm with no problems whatsoever. All of the bolts were still tight when I tore it down(coolant seal failure).

89t295k

I know this is old but, has anyone cracked the e-shaft as well as the rear iron?



Has anyone cracked a S6 or is is this all s4 and s5?





I just cracked S5 and e-shaft by the rear oil hole to rear rotor ...looking at stud kits and where to buy.



I also think missfire and unsprung cluch added to the problem.

Maxt

From Rotary power mobilit.