Ok here is what I know: Lighter rotors, different intake, different flywheel, different compression.

What was changed to make the engine safe at 8k rpms that the S4 didn't have?



Santiago

 

Lighter flywheel, lighter rotors, retuned intake.

the flywheel and rotors were the biggest things.

If you note, the auto tranny S5 has the same redline as everything else (7K). Only the manual tranny went to 8K.

But without the VDI, they could never get any useable power past 6500 anyway.

And the S5 Turbo, used the same weight (and compression) rotors as the S4 non-turbo... so that is why it is stuck at 7K.

 

So could I use my S4 N/a rotors if my S5 TII's rotors are damaged?

Are all FC stationary gears the same? what about the e-shaft?


Santiago

 

S4 NA= 9.4:1 compression
S5 T = 9.0:1 compression

Same.

 

i remember hearing that the s5 n/a stationary gears were hardened like the fd ones. or am i off?
were any stock stationary gears hardened?

 

As far as I know, no FC came stock with hardened stationary gears.

 

Mo powa!

 

lower compression rotors alow use to use more boost. They might be heavier but more boost is better for me.
When we built my motor I went with s4 turbo rotors milled out for 3mm apex seals.

 

the s5 gears do have a different part number, and rumor has it that they are hardened, but they dont look any different to me and i had a new set

 

Eitherway, what's a safe redline for the s4 and s5, respectively? (n/a)

 

For the S4 N/A... 7K.
S5 N/A.. 8K.

 

Wasn't quite sure, because i've heard different things, like rotaries don't have a redline, and all that, but that sounde fishy to me. Just curious (btw, i have an 88 SE)

 

Read the tacho.
Again, read the tacho.

 

Ok given the Rotors on all our FC's are made of the same material they are basically the same strength right? So Say I can lighten the S5 TII rotors to the S5 N/a rotors' weight and get a light flywheel for it(I guess I would need s custom counterweight). I could go up to 8 grand right? Given my turbo can maintain decent boost up high. What do you all think?


Santiago

 

well you wouldnt be able to tell if they were hardened just by looking at them. do all the other stationary gears have the same # except for the s5 n/a? or are they different # for each model?

 

dp

 

And just how are you going to lighten them? Racing beat has superlight rotors, but they cost a bundle, and I am pretty sure it is more than just randomly taking material off of the rotor.

I dont think this whole thing is really that hard to understand. The reason that the engines have different readlines is based on the weight off of the rotors. These has been explained many times, including in this post. The lighter the rotors you have the less rotational mass you also have. Therefore, less mass would require less force to do that same amount of work, or you can do more work for the same amount of force.

So, yes if you "could" lighten your rotors you would be able to go up to 8 grand. The real question is why? If you are going though that much work to lighten the rotors for a TII, just use the higher compression rotors and make less boast.

 

I was always told that the S5 stationary gears were harden compared to S4 gears. Apparently I am wrong about that.

 

go look at the mazda trix site. they sell both stock and stock/hardened stat. gears for 13b through 1992 which says to me the s5 na have hardened gears.

 

How does cost affect me? I have already said it isn't about "how much" or "worth it". That is something left to me not to you. And yes I was refering to something along the lines of professionally lightened rotors. I'd also want to have them balanced and I guess RB had the special counterweight for that setup.


Santaigo

 

Then I dont understand what you are asking.

If you know that they will have to be professionally lighten, and will cost a bundle. And you understand that the lighter the rotor the higher you can spin, and that once you have the weight of the rotors you are going to use in your project that you will need a matching counter weight, what is the question here?

 

Its not what is the question but what wasn't the question. You started off talking about how was I going to remove weight and cost. I didn't ask anyone about that. I asked about weight and how it would affect the redline. YOu don't need to tell me it costs a lot of money or that it has to be done proffesionally.

Get it now?

 

well all that lightening the rotors does in terms of redline is take some stress of the stat. gears.

it'll spin up faster but that wont change the redline itself

 

I dont think that the extra 1K rpm due to the ligher rotors spinning faster, but to the less amount of strain they have on everything else. From what I've read on here in the past, the e-shaft and stationary gears are what tend to fail at crazy high rpms. less weight, less centrifical force, less strain. the heavier S4 rotors could spin just as fast as the lighter ones, but would take that much longer to get up to speed such as a lightened aluminum flywheel vs stock. just my 2 cents...

--Paul

 

Well basically I was making the assumption that the S5 N/a stationary gears aren't hardened or harder than the rest of them on FC's. IF and only IF this is true then they are not a weak point and would withstand the extra 1k rpms. But if they are harder/hardened compared to the rest then I may need to change to hardened gears.


Santiago