Lets look at expo1's over 100K renesis motor
02-29-2008, 02:55 PM
#251
Got Another Rotary
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.
02-29-2008, 02:55 PM
#252
Purveyor of fine bass
02-29-2008, 03:01 PM
#253
Purveyor of fine bass
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.
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.
02-29-2008, 03:02 PM
#254
road warrior
Join Date: Feb 2006
Location: Oakland and Los Angeles, CA
Posts: 1,861
Likes: 0
Received 3 Likes
on
3 Posts
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...
... If you insist on upping the RPMs, I suggest a ballistic blanket
02-29-2008, 03:43 PM
#256
Dongbag extrordinare
Join Date: Nov 2004
Location: Away from the fruits of my labor
Posts: 1,090
Likes: 0
Received 0 Likes
on
0 Posts
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.
02-29-2008, 07:02 PM
#259
Got Another Rotary
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.
Last edited by Jax_RX8; 02-29-2008 at 07:05 PM.
02-29-2008, 09:12 PM
#260
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.
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
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.
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.
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.
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.
02-29-2008, 10:17 PM
#261
Registered
Join Date: Jun 2007
Location: Jessup, MD
Posts: 123
Likes: 0
Received 0 Likes
on
0 Posts
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
http://www.xs-engineering.com/xsstor...idproduct=8447
03-01-2008, 09:18 AM
#264
Registered User
Join Date: May 2003
Location: atlanta ga
Posts: 608
Likes: 0
Received 0 Likes
on
0 Posts
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.
Things that make you go hmm.
Seal.
03-01-2008, 10:13 AM
#265
Got Another Rotary
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.
Last edited by Jax_RX8; 03-01-2008 at 10:17 AM.
03-01-2008, 10:37 AM
#266
Lubricious
Join Date: Oct 2003
Location: SF Bay Area, California
Posts: 3,425
Likes: 0
Received 4 Likes
on
4 Posts
03-01-2008, 12:43 PM
#267
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.
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.
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 ....
03-01-2008, 04:05 PM
#270
Got Another Rotary
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.
Last edited by Jax_RX8; 03-01-2008 at 04:08 PM.
03-03-2008, 12:08 PM
#272
Paul.
03-03-2008, 01:49 PM
#274
Registered
iTrader: (1)
Join Date: May 2003
Location: PA
Posts: 3,754
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
