kashracing

yea i was just wondering what lightening rotors does. Does it increase the power or does it just make it so you can rev higher.

ErnieT

iTrader: (2)

It lesses the likelyhood of flexing. When your running high boost (higher than 35psi) your E-shaft can flex. This is why some people pin their motors or have lightened rotors. They have other benifits too.

kashracing

say im running stock with just an exhaust and intake what benefits does it have

Gamezilla

It'll rev pretty quick. Thats about it. Its really a waste of money unless you have really high power goals.

kashracing

so it does rev really quick but it doesnt like rev higher so on a stock car theres really no point. But what if im making like 450 hp then should i lighten the rotors or still pointless

Gamezilla

Honostly, I dont know if it revs "really" quick or just a little quicker. Its kinda like the same concept as lightening your flywheel. Less mass that has to be moved, quicker the engine is to get to redline. It can rev high, but there's a point at which you float the apex seals. The stock rotors can get to that point with little modification. Before you can up your redline you need a few things. A turbo/s that arent out of their efficiency range at those rpms (your stock twins would be), fuel and ignition upgrades to handle the new redline, and a decent port job helps wonders.

Basically, when you're making 450hp then ask this question again.

TT_Rex_7

Is the search feature not working?

https://www.rx7club.com/showthread.p...tweight+rotors

-Alex

kashracing

so light wieght rotors do not change hp or tourque but the do make it so u rev up quiker and rev down quicker, but they still allow u to run higher rpms. Finally i understand. All that math in that thread made me a little dizzy.

thnx for the info

t-von

iTrader: (8)

Lightweight rotors are more useful in NA high revving situations. Boost will make even the heaviest rotors rev quicky. Don't waist your money.

Rocking Rotary

iTrader: (14)

I thought the light rotors made less tourqe too.

13b4me

FDNewbie

iTrader: (10)

I was under the same impression...

t-von

iTrader: (8)

Nope. Check out Jimlabs first post in the above link 2nd page. It will explain everything.







You too FdNewbie.

weetbix13

i am using lightened rotors in an otherwise stock engine... revs up faster and with less throttle input (to my feel)... once i start running some boost we'll see what it actually does.

theory/science or not, at my right foot the lightened rotors feel good.

DaleClark

iTrader: (55)

IMHO, lightened rotors are one of those "I'm gonna build a dream engine" mods. The process to lighten them is tricky, then getting the whole assembly re-balanced is tricky, not to mention it would all be quite pricey.

Dale

DaleClark

iTrader: (55)

I think you must have just hit the updates on Racing Beat's page

http://www.racingbeat.com/resultset....rtnumber=10004

$2200 - DEAR GOD!

Dale

kashracing

yea so i think if i just had more boost ill be fine with it revving up fast. The only reason i was thinking about it is because lightend rotors would rev down fast also but i c there is really no need for it

t-von

iTrader: (8)

Light flywheel is the cheapest alternative.

FDNewbie

iTrader: (10)

The NOOB has been served Thanks for the link. I'm guessing then that material is removed from various places in the rotor, but NOT the rotor face, so the displacement will remain the same, huh?

Also, this may actually be ideal for a 20B, seeing that lighter rotors may allow a higher redline, and more hp. Not sure what effect it'll have on e-shaft flex, but hopefully it'll decrease it.

~Ramy

TT_Rex_7

I also thought that removing material from each of the faces would change the displacement, but if you look through my thread, you'll see that JimLab corrected me on that. Removing material from each of the faces would only change the compression ratio. Same thing with taking material off the face of a piston.

-Alex

FDNewbie

iTrader: (10)

Yea you're right Alex. I read that after I posted. I went ahead and read through the ENTIRE thread. I miss stuff like that man. We haven't had any reall useful educational threads in a WHILE... the last one was what...the buttplug debate?

~Ramy

t-von

iTrader: (8)

As long as the material is removed from the sides, the compression ratio will never change.

t-von

iTrader: (8)

The lighter rotors is one of the main reasons the RX8 has a higher rev limit than our older engines and their shorter apex seals. It should decrease the flexing some. Ultimately, you would want an e-shaft with a center bearing. Just imagine if Mazda built our engines with a bearing in between each rotor like what a piston engines crank shaft has. The sky would be the limit with the rpm's because there would be no flexing at all.

FDNewbie

iTrader: (10)

Yea adding a center bearing is one option....OR you can you w/ a multi-piece shaft

Railgun

Beg your pardon?

This is probably a moot point, but how is this even an issue? If the seals are pressing against the housing anyway, and the centrifical force keeps them against the housing, how can you float them?