My mechanic says its not needed. Is this true?

My motor will be running up to 25 or more psi and I would like a shift point around 7500-8000. Most of the time it will be running 18psi.

This is on a haltech E8, 1988 with NRS seals new housing and some spare counterweights that I have kicking around. Also trying to figure out if I should use Rx8 stationary gears or racing beats hardened gears type 1 or 2?

Below is a cut out from racing beat.
If you intend your race engine to run above 8,500 RPM or if the engine is a non-standard assembly, we recommend balancing the rotating assembly. The rotating assembly includes both rotors, main pulley, front and rear counterweights. and the eccentric shaft. We also recommend balancing the pressure plate and the flywheel on the rotating assembly.

In our experience it is not necessary to re-balance a stock or mildly modified engine operating below 8,500 RPM if the rotating parts were originally intended by Mazda to be used together.

Thanks,
Ian

 

Well you just answered your own question...

Of you dont mix and match parts... you dont need to balance.
If all the rotaring assembly is from the same engine... Thats means it is balanced...

IF you use a rotor from a seperate engine... you will need to balance..

Or in your case.. your using "spare" counter weights from another rotating assembly.. SO you DO need to balance.


Got it?

Dont mix and match rotating assemblies

 

+1 for Junito1's post.

B

 

Also, IMO, why not have it done even with "balanced" assemblies. The OE balance job has a pretty wide tolerance and the process is not that expensive.

 

+2 for Junito's post.

 

Not sure if there is anyone in ontario canada that does engine balancing.

 

The cost is 300-400 and that's to do it RIGHT. Really not that expensive at all. You'll likely spend half of that on shipping both ways! If you're running your car hard it would be smart to balance it. Most people think in the sense of staying under 8500rpm as "not hard" but rapid acceleration of the engine internals can elevate the static imbalance.

I will stand next to the statement of anything revving above 8500rpms needs to be balanced. Still if you're running your motor hard, balancing and engine studding should be on your shopping list...

 

So what exactly gets done when balancing a rotory? I would assume the goal is to match the weight of the parts to reduce vibrations (same idea as a piston engine), but which parts get balanced to what?

 

Each rotor gets balanced by itself, both rotors get weight matched. Then bob weights are made and spun on a e-shaft. the counter weights are adjusted to produce the least amount of vibrations. Its almost an art.

As long as you stay within the same series of rotors and counterweight plus using rotors that are only 1 letter code away from each other you can get away without balancing. After that, you must balance.

 

FWIW I had Carlos Lopez do a set for me. Mazda spec for balance is to have each rotor and counter weight within 50 grams of the other. Carlos got mine to .080 grams rear and .050 grams front. The cost is $400. All he needs is the rotors and counter weights. Doesn't need the e-shaft. Shipping really isn't too awful.

 

You missed the fact that it takes Carles months upon months to do your work too.

 

Turn around was about 2 months. He told me up front it would take a while. If the work is good I can wait.

 

Hmm so flywheels have nothing to do with balancing? I mean they have wholes drilled in them like they were balanced or something.

 

A flywheel will have something to do with balancing when it's a factory one. They're cast with the counter balancer on 'em. When balancing an assembly with a factory flywheel in use, it's necessary. An aftermarket flywheel, however, almost always bolts to a rear, automatic model counterweight. That kind of flywheel is just a disc so in that case it's not needed.

I can do the balancing for much cheaper and with a much quicker turn-around time.

B

 

He has had my rotors for just about 9 months now. Its been so long I already built my motor with different rotors.

When I called he said, 'I don't care about non-race business because they don't have schedules so I get to it when I get to it'.

 

Sorry you are having that experience. I've heard other with similar complaints. Maybe I just got lucky? I sent my rotors to him around July last year and got them back in September. He was very willing to talk on the phone and actually offered up a bunch of free advice and time. I really didn't drop Carlos' name meaning to say he is THE place to go. Simply to say that the process is not as expensive and cumbersome as some may think.

Brian, do you compensate for the weight of the oil in the rotor in your balancing process? What's your pricing?

 

Brian, I heard you just handle rotor weight matching... Are you now doing dynamic balancing???

 

Yep, all done on a dynamic balancer. Pretty cool. Need both rotors, front counterweight, and rear counterweight (or stock flywheel). I can supply both indexing keys, flywheel nut, and e-shaft.

B

 

?

 

Hi Chris, nope. Never heard of that before.

 

I don't know what the naysayers do/say/talk smack about but since I actually have experience in this particular thing heres my two cents:

1. Stock FC3s Side and Rotor Housings Street Ported
2. Very tightly built motor by hand obviously, 3mm
3. Balanced BY Racing Beat
4. 489.7 RWHP at 14 - 14.5 psi

As far as I know my last car was one of the highest horsepower FC's built period on the street, still to this day (if I am wrong someone show me dyno sheets and pics pls would be interested)

I can attest to Racing Beats balancing because the car ran one way before on the exact same rotating assembly and much differently after, balancing was done pre-haltech and so forth.

The main thing you are going to get from balancing is the lack of vibration and smoothness of the rotation / ease of the motor spinning. Its actually harder to explain in a rotary vs pistons, ( RB does the front pulley ALLLLLLL the way through, the entire rotating assembly and I think it does matter by the way, they do the e+r+r then they do the e+r+r+FP+FW etc until it all comes clean) but sitting in the car after the balancing I distinctly remember touching the gas probably 500 times over the course of the life of the car ONLY to show people the lack of spin down, I **** you not it was 10 seconds 8k to idle something very close maybe 9, it would just spin and spin.

Have you ever been in a car with a sticky throttle ? Balancing a rotary is like that it just freely spins much more so than normal, my current car is balanced again front to back, turbo motor, 100k on it no idea of RWHP on this car though.

I personally will never NOT balance a rotary if the engine is torn apart and is a Turbo of any kind or i desire it to be quick in any fashion.

Again the naysayers etc can say whatever but 400.00......................cheap for what you get, if I had to pick balancing or an FMIC or turbo I would pick the balancing every time, especially since theoretically you can't go back and do it without pissing away a bunch of money and most other things are outside.


DO IT! lol

 

Brian, what's your pricing for the whole balancing process?

 

Good point...

 

The weight of the oil is supposed to be accounted for when balancing.