DriveFast7

iTrader: (1)

Are they complaining about the smell of wackyracer or the smell of your Rx3?

I've looked into the metallic substrate catalytic converters and the 3rd gen guys are using them and they can handle the heat and premix. And last after years of use. Can't remember the website but they tested them on a honda civic and it only took away ONE HORSEPOWER compared to a straight pipe

For reference: http://store.summitracing.com/partde...5&autoview=sku

And to those who doubt pressure wave tuning, how many racecars have you seen with an uncollected exhaust pipe? As for those quoting mazdaspeed's tech manual, there is a lot of power to be LOST by not collecting or properly collecting at the right length a peripheral port of bridgeport motor. I've seen it firsthand and others have documented it in the Race section. You see by an order of magnitude the number of people using a collected pipe vs. uncollected/true duals. A lot of guessing and supposition on this thread.

Hyper4mance2k

iTrader: (40)

I have the comp manual and it says nothing about running true duals. It says to run a long primary exhaust collected above the axle and out 1 muffler. I think the people quoting the manual don't know the difference between long primary and true duals... Borlas won't last more than 2 years. should've went with magnaflow.

Siraniko

iTrader: (13)

good one bro. of course its the smell of unburnt gas from the RX-3's

Keeble

iTrader: (3)

ok well the one i was looking at just showed a picture from the side and then the mounting points which had 2 pipes, sorry about that.

ok then, say im running a large bridgeport what would the optimum collected length be?

DriveFast7

iTrader: (1)

What does the Mazda Competition Manual that you misquoted say?

MTheoryInc

iTrader: (3)

No one has doubted the value of pressure wave tuning. Seems like you base your knowledge on what you read on the internet and what the popular assumption is and not actually on your own R&D or experience of using both setups.

You really need pay attention to the post its not going on a peripheral port or bridgeport motor. It is going on a stockport 89-91 engine so your point is mute about the power lost by not collecting them. There are established and well respected companies in our industry like RacingBeat who build, tested, sell and claim the true duel makes more power than the collected exhaust and Paul Yaw who I dealt with personally when I purchased a Motec m400 from him had no objection to and recommend I do the true duel for the application at hand.
Just because you can post DriveFast7 doesn't mean you should. Quit regurgitating crap you read and misinforming people with your generalizations about exhaust tuning. Every exhaust has its place. Reserve the regurgitating for your own car. (great stuff is for the house not a car)
Im not concerned with the couple of horses to be lost or gained by the setup I built. If it was about power I would have a turbo on the car. It is pretty obvious that I could replace the mufflers with ease if I can build this setup. Next time Ill put v-bands on the muffler inlets and change them like oil.

StumpDrummer

I dont know what or why everyone is talking crap
I ran a 12-A with rb headers into 2, 2 inch pipes and it kicked major *** to 9k
street ported and an edelbrock 650

so... Nice setup youll be fine and start saving money for the tickets

tuned exhaust on a street machine yeah like im gonna spend a grand to perfectly tune an exhaust system for 4-12 more hp depending on the application

Box_Man

I see alot of SCCA ITS 2nd gens running expansion chambers in the exhaust. ISC header collected into a megaphone which expands to ~3" or 4" if I remember correctly, with about 2 feet of pipe before it goes back down to 2.5" for the rest of the system. The expansion chamber sits right under the passenger seat.

DriveFast7

iTrader: (1)

Go to your local SCCA race weekend and tell us how many people run uncollected exhausts in the unported ITA and ITS classes. There are nothing but benefits to be had by exhaust scavenging. Paul can tell you that. Have you seen the header PAUL made for stock port 12a's in ITA? I've run short primary, long primary, and medium primary length exhausts on stock, street, and J-bridge 12a's and 13b's. What exactly are you trying to gain by using a true dual uncollected exhaust system anyways? Is it just a 'look at me, I'm different' thing?

Are you saying just because a motor is not ported, that it won't benefit from reducing exhast gas dilution? Or the ability to widen the powerband and place it at the rpm range you want it at?

With your in-depth insight, tell us why RB never sold an uncollected exhaust system for the 1st gen.

So instead you spend top dollar on a Motec to maximize the intake side of the engine and lose out on the exhaust side. Are you concerned about a narrow powerband? Or excessive noise? Or drifting? Bouncing on the rev limiter?

Brilliant.

MTheoryInc

iTrader: (3)

I have and MOST are the biggest hacked up messes of rx7s I have ever seen having a strong likeness to your car so I try not to go.
So what?? Do you DriveFast7 have proof of power made or lost as in dyno runs on your many setups you have had? None as you state are a uncollected true duel which is in question here. If not you comments are baseless and of what you read, heard, or seen others do.


That is exactly what Im doing. It seems to be working too and its not even on the car yet. Its got you all wound up.


Well the first thing that comes to mind is cost to build, complexity, and not a lot of room to place two mufflers. Also if you would pay attention you would know its a 2 gen engine we are using and RacingBeat makes one for the 2gen and claim hp gain over the collected system. Are you calling one of the leaders in rotary technology outright liars about there claims? Have you not seen the aluminum end and intermediate engine plates they make. You must not like them because there different.


So I should run a crap setup like your lakecities manifold and carb? Maybe if I chose megasquirts you wouldn't feel so inadequate?
Dont hate because I can out spend you with high quality parts.
How much HP do you really think you are gaining by collecting the exhaust 3 to 5 HP if at all? Thats not going to make or break a street car.
If your going to post back read carefully, post facts, and answer the questions asked dont dance around them with everyone else does it crap.

Keeble

iTrader: (3)

eh who knows, i'm running true duals and its awesome as far as im concerned

Hyper4mance2k

iTrader: (40)

Just please read this, and at least put in an X pipe at one of these legnths.
http://www.racingbeat.com/Tech/Tech.Exhaust.2.htm

Keeble

iTrader: (3)

ya looks like im making a new exhaust for my bp engine, has anybody proven whether short primary or long primary makes more torque?

Hyper4mance2k

iTrader: (40)

Short make peak TQ up higher in the rpm range than long primary. remember tq and hp are relitive. all TQ is a twisting force, and hp is where you make that tq. TQxRPM/5252=HP. ALWAYS! so if you make 125ftlbs at 6000 rpm you're making 142.8 hp at 6000 RPM. Now if you make 125 ft lbs at 8000RPM you're making 190.4 hp. The point with exhaust tuning is to make peak tq at the rpm that your engine is most efficiant at, and where you want to make the most power at. making 125 ftlbs at 10,000 rpm might make a lot of power, (238) but it isn't going to be useable on the street. I've got a small SP13B and I collect at 25" then into an ISC expansion chanmber and it's clear how tuned the exhaust is for 5500-8000 RPM. The car is a pig below 4k, but once I hit 5500 it's like hitting vtec and it pulls all the way to 7500 before it falls on it's face at 8k.