I have some questions on the 20B's RPM limit. I am planning an N/A build with S5 rotors. What do I need to ensure the engine will no be out of balance. Just 3 matched rotors (letters?). How about the counter weights?

Without extra balancing, what is a relatively "stock" 20b with porting good to wind up to?

What would be needed to if anything to have a 9000RPM limit other than said balancing?

 

what's the aversion to balancing?

 

I don't have one, just want to know all the different ways I can go with the build before settling on a certain direction.

I'm also trying to keep costs down. I don't need an engine that's built to handle 500whp when I don't think I'll ever see 400.

 

Generally it is about 8500 w/o being dynamicly balanced.
https://www.rx7club.com/showpost.php...24&postcount=4

If you are not going to have it balanced put the 2 rotors closest in weight on #2 & #3. If all are pretty close, put the heaviest in #1.

 

OK, thanks for the info.

 

i am all for a 20B swap but i dont see the point if your not going to break 400RWHP, IMO i think porting out a 13B and having a small single turbo would be the best route, but what ever works best for you best of luck.

 

I've been down that road. And currently have a brand new rebuilt engine from DJSeven, a turbo kit and all other things I need to get the car running but I wan't to try something different.

350whp N/A is more fun than 400whp FI.

I've owned a few high HP cars in the past and I really like driving a built N/A.

No turbos for me anymore. I want reliability without having to worry about crap like WI, and getting one bad tank of gas.

 

That's a good comparison since I used to sell Ducati, Suzuki, Honda and Kawasaki... and now I work at a Yamaha/BMW dealership in sales .

I understand your analogy completely.

For instance I rode the new BMW S1000RR last week, and a few weeks ago I rode a BMW HP2 Sport. The HP2 Sport, while only having 125whp (and the S1000RR... 185ish) the HP2 has MUCH lower and stronger torque and I had way more fun on it.

 

Power isn't everything you know!

 

mazda letters the rotors PER BATCH, so an C rotor from may of 1989 may not be equal to an C rotor in 2010.

counterweights come with the 20b, and actually are pretty cheap new.

 

So I can't match rotors then... they have to get balanced.

 

ideally yes it gets balanced. it is possible you could weigh the old rotors and match up the new rotors, within some kind of margin.

IMO it mainly depends on how high you wanna rev the thing. stock redline is 7k

 

I agree... if you want to take it up to 9k redline its probably best to get it done.

 

As somebody who experienced his first Ducati the other day (was next to me for ~1/2 mile then hauled *** away), and subsequently seriously weighed the financial options of buying a $16,000 motorcycle that requires frequent and expensive maintenance, I see your assessment as being valid.

The sound is absolutely incredible.

I'm not entirely a fan of the 20B sound, but throat-closing midrange torque is a wonderful thing to have.

- Pete (and then there are the Audi fives that I've been playing with as of late...)

 

Meh... Ducati`s have gotten a lot better with maintence in the last few years. But yes, you`re right! lol...