This is true for a stock engine because of intake air resistance and mostly reaching the flow limits of the stock exhaust.

If you have an aftermarket intake/filter and a high-flow exhaust, this would not be true and more rpms will buy you more power above 8500 - with my mods intalled mine pulls very hard well past 9000 as I have hit 9500 a few times by accident from it pulling so well and fast.

My 2 cents.

 

That's because the stock AFR goes pigrich above 8500RPM.

 

How are you revving to 9500? Stock RPM revlimit is 9000. The tach lies at high RPMs. When you hit fuel cut on a stock car, the needle shows about 9300 and when the needle shows 9000 you're still somewhere around 8700.

 

Considering how fragile the transmission is, that would worry me more than whatever the engine is doing if I wanted to rev to 10,000. There is something magical about reaching the 5 digit rev range though...

 

Let's not get back into that thread about 20k rpms ... If you insist on upping the RPMs, I suggest a ballistic blanket

 

Its easy to shoot holes in any theory if you are determined. My original question regarding 10k rpms was related to engine reliabilityand power with ceramic seals. If you look at the dyno plot for the Pettit kit, it continues to build power all the way to redline; There is no power drop at 8.2rpms. Once that has been discussed, then the obviously the discussion will eventually lead to other topics like safety.

 

Awesome thread. Definitely taught me a lot about how to extend the life of the Renesis.

 

Keep in mind that with a positive displacement supercharger, you also need to worry about overspinning it.

 

I am going by the tach, reading about 9500, which is probably erring on the high side like you said.

If I remember right, redline is 9000, but the the fuel cutoff is around 9300, and that is what I was hitting - but it was pulling at the same rpm increase rate till I hit it!! None of this slowing down on the rpm increase on the last 1000 rpm or so.

 

I have RB Flash, which is suppose to *lean out* the upper RPM range AFR.

but still, if u look at RB's dyno graph, u will see that the power still falls after 8500 RPM. They up the rev limit to 9300 simply because as ppl up shift they can go up faster

I already have K&N Intake, I want to go for HKS Hi power intake with hi flow cats. but I heard that is crazy loud, and cops are dick in NYC and they pick on cars like RX8 all the time when at the same time all those crazy Civics running like nuts.

The stock Tach is about 300 rpm off the actual rpm, so when u see 9000 is actually about 8800, then at 9300 is about 9000, my fuel cuts off at around 9500-9600. so its about 9300 like RB saids.

 

I was trying to find the ceramic seals to see how much they cost. Are these them? If so seems like a great price if it is true:

http://www.xs-engineering.com/xsstor...idproduct=8447

 

^ cool

 

Those are probably for the RX7 not the RX8.

 

Those are for RX7. Deeper groove to the rotor apex (Taller seal). I wonder how they got a hold of those to sell at such a discount with Mazda Comp part numbers on them?

Things that make you go hmm.

Seal.

 

Yea, we all know that an exhaust adds only a little power, but the ones gained are all in the 7500+ rpm range where the current exhaust starts to run into it's maximum flow capacity. So, aftermarket exhaust do help power there, especially if you have the RB flash as well - it will really let that better upper rpm range mixture leaning show itself. A high flow cat will make this even better, but it will be very loud unless you go with a quieter exhaust, like maybe the Racing Beat.

Mazda does keep the upper rpm mixture rich to keep exhaust temps down, but also this is required even more when you run out of exhaust flow at the upper rpm range as this creates a lot more back pressure, increasing cat temps even more.

When you add an aftermarket exhaust and reduce the total system back pressure at the upper rpm range (and increasing total system flow as the cat flows maxes out and becomes the choke point on flow instead of the muffler), you will reduce the catalyst temp at as well (better total flow through the catalyst will reduce the catalyst temp as it keeps the heat from "backing up" from the limited muffler flow), helping to protect your cat from the leaner RB flash mixture as well.

This is not to say that you still can't fry your cat, of course you can, but an aftermarket exhaust's increased flow should help keep the overall cat temps down, helping extend the cats life. This would apply to a high-flow cat as well with the only difference being the high-flow cat should stay even cooler from it's higher flow capacity.

 

The OMP is extremely low-flow. It takes hours to deliver a quart. At that rate I doubt if it's viscocity-limited. You could probably run cold gear lube through it.

 

I know what you mean, but like I said, I have to be really careful in choosing an exhaust cuz NYC cops are #@$@)#*$ dicks.

I've been looking at HKS for a long time, but its really loud so ...

and I also look at RB's race Exhaust, but I dont know, it looks kinda weird if you dont see any tail pipes u know ....

Thinking thinking ....

 

I heard the RB race exhaust is pretty loud. It's at the limit. 90 decibels.

 

If thats true ..... 90db will attract a lot of cops ... god damn it.

Dunno about HKS ... I heard ppl said its loud, and I saw the video of it .... it is pretty loud

 

I have heard the same thing on the HKS for it being loud - sounds good, but loud - very similar to the Hymee in construction and tone but I think the Hymee is a little quieter.

Before your decide on your exhaust, you really need to decide if you are ever going to do a high flow cat. If you want a high flow cat one day, you definitely need to err on the quieter side for your exhaust - even without the sound ordinance issues - unless feeling like your in a race car all the time sound appealing to you.

My Hymee exhaust, which I love, it is about medium loud (at least to me) and I am sure it would be too loud for me if I added a high-flow cat - so I imagine the HKS would be really loud with a high flow cat.

 

hks hi-power is very loud. Even with a turbo it was obnoxiously loud.

hks legamax on the other hand is quieter than the borla exhaust.

 

Yeah, that doesn't make sense at all. Those seals are in the $1900 neighbourhood from Mazda Motorsports to their racers. Mighty peculiar!

Paul.

 

anybody ever used that site before? is it legit? could they be used seals??

 

unless you have an aftermarket ecu flash, the rev limit is a hard 9000 rpms no matter what your tach says... i've logged bouncing off the rev limiter while tuning

 

Great thread, i came out of this one much more informed