...things that make you say damn!

 

why not flash tune?

if the std fuel system has enough juice for 300hp FI then a little bridge is nothing.

 

Any updates?

 

Keeping an eye on this thread

 

nobody worth their weight in salt gives a r@ts @ss whether it sounds cool or not, they want to know if it makes more power and at what detriment to the rest of the powerband

 

The sad thing is there are plenty of people who spend big money for "sound" modiciations.

 

What an awesome thread.. I'm subscribing to keep up!

 

I've actually been thinking of this for a while... The stock bevel is only on the closing edge...and according to mazda that constitutes for a 15Deg later closing of the ports... (it looked small to me but that is what they said...) If you were to replicate this on the leading edge of the rotor it would open the ports earlier by 15deg, at least in theory....and 15>6 so youwould introduce 9deg of overlap....without having to do a bridge....that sounds good to me....the draw back is that it would force the exhaust ports to open earlier also which might be detrimental for N/A but for Boosted applications that is gravy helping you boost sooner.

what do you think?

Chris

 

Yeah like the thousands that replaced a brand new perfectly tuned Mazda Factory Cat Back Rotary Exhaust, for a 'pretty' stainless steel job that added no performance gains whatsoever, only a little more or different noise.

And I have nothing against HYMEE...

 

Without getting too far off the topic of this thread, I'm a huge fan of expectations when it comes to products, services and the like. My belief is as long as my customers are armed with a proper set of expectations that they are responsible for their own decision. I cannot expect my customers to make good part decisions if they expect something they won't get.

In the case of cat back exhausts, no one should expect power gains from something like that. In that case, it's a modification for sound and sometimes weight reduction. If/when BHR moves that route it will be marketed as such.

Intakes, for example, are not marketed as sound generators but power adders yet we've seen very limited proof of that. Yet, about the only two things they do is lighten your wallet and make lots of noise.

As Charles pointed out, if you want the engine sound of overlap I'm sure it could be produced for less than it would cost for a bridge port. Porting is about performance, not sound.

 

Agree,
However as we know so many of these so called reputable Cat Back sellers and manufacturers were talking HP gains, and it was wrong of them to do so, I said it years back and got the usual response.

Mazda just spend a small fortune on getting it right for the past 40 years but 'others' know better.....it's called marketing...and bullshit.

As far a Philip and this thread, I have got to know Phillip over a few years and I believe him when he says there are some gains, even though I did say to him you have a new engine you should see a difference from the old.

In time I think he will put it on the Dyno.
He has a young family with expenses that take priority, the guy was not even sure he would see his car back because it took 2 Months to do a re-build..the business kept stalling him....engine in pieces, what does one do.

Thankfully the rebuild had no serious issues first up...so give the guy some time and space I am sure he will let us know..

Ash

 

Forgot to add, I don't think I have seen Any performance gains from ANYTHING that is sold here or anywhere else for the RX-8, apart from Turbo's or Superchargers.

Everything else is just FLUFF, crap that is said to be better than the original.

It just shows what a good job Mazda does..to the RX-8 and other RX-'s.

Maybe the Water Pump is the exception.

 

Orly?

 

Just to try and keep things on track...

Anyone have an opinion on my previous post regarding beveling of the leading edge of the rotors to advance/increase duration of both intake and exhaust ports?

Best regards,

Chris

 

I hadn't really given it much thought. The balancing could be an issue but as a band aid you could weight the rotors before and after the first cut with a precision scale and then make dimensional templates so you remove material from the same area and ensure that you remove the same amount of mass with each bevel by weighting the rotor in every time ensuring the same mass was removed. I don't know if it will require different counterweights....hmmmm...stock rotors come in A through D which all have different weights and there is only one type of counterweight available...if you want to be safe only do this on rotors from C to D which already have more weight than A's and the worst case scenario is that you end up with two A weight rotors.... If I am not mistaken, the important thing is that both rotors match up in weight (according to mazda ideally you want to match up rotor letters....).

The bevel, if at least .125"into the rotor face....would be similar to porting .125" on the leading edge of a port...and that is not huge but it is certainly noticeable by porting standards....the bridgeport in the engine from SA is probably about .125" wide itself if that...

I have lots to think about...I might do something crazy soon....

Chris

 

I see, that is completely true....I guess its like advancing the cam opening point(increasing overall duration) without increasing lift. The ports are already pretty big though....maybe a little more port advance/duration is all we need for good results...

I'd like to add that I am thinking of this with FI in mind where the air is sitting there under pressure waiting for the rotor to move out of the way.

Chris

 

What, What??

 

I'd agree with that. To understand why we need to think in piston engine terms. A scalloped rotor would have the same effect as changing cam duration. Enlargening the port would have the same effect as a cam duration change AND a lift increase as there would also be more open area. That's about the closest comparison I can think of.

 

Is there enough room to bevel the rotor edge enough to see noticeable gains? Our rotors are pretty light from the factory and probably beveling\rebalancing them would be too much.
Who wants to try?

 

I might be misinterpreting your post so forgive me if I am.

The beveling of the rotors is not to make them lighter but to cause them to "move out of the way" of the port sooner effectively increasing the length of time the port remains open.

I know our rotors are light but we are removing material from a section which has plenty support and in an area which already comes beveled on the closing edge.

Best regards,

Chris

 

Chris, you got me right on the support thing. So the rotor faces are thick enough to support some beveling!
I thought they were too thin to scrape material off of them!

 

You don't want to scrape anything off from the "chamber" face because the casting is thin there but on the corners there is enough "meat" to support side seals etc...and the beveling is not going past where the side seals are. If there is enough material to allow the grooves for the side seals there should be plenty for a bevel on the edge.

Chris

 

Great! Now if there only was some shop capable of rebalancing rotors in italy i would do some experiments!

 

Hi All,

it took a while, but here are another clip when driving,

i took it from second gear, low revs, and then just feed it through, changed to 3rd up to about 8000rpm,

i will do another one from 1st gear.

the cel is on, i know, but my battery went bang today and i had to go buy other one, so all reset, including fuel trims, thus i need another week or so for it to learn from start,

we live in high altitude bery high and far from coast, thus we do loose a lot of power due to less oxygen, when at the coast it should be faster, and when trims are learnt again, also better.

still no other problems,

will keep all up to date,

new clip soon


Philip


[EMBED]http://www.youtube.com/watch?v=JgFUgThyV9s[/EMBED]

 

If it didnt work


http://www.youtube.com/watch?v=JgFUgThyV9s