A challenge for cat-back exhaust makers...
 

Between recent conversations with rotarygod and a couple products in the rotary mags I picked up have convinced me that we will begin to see decent gains when people go beyond the easy conventionally designed mods. Simply... resonance tuning is needed... for the intake as well as the exhaust. Now I can imagine that a few of you will say that you have done this already to produce the unique sound your system gives off. What I am talking about is a little more complex than that...

I ran across two systems recently that have caught my eye... both JDM. The first by Leg Motorsports is called the "Sequential Muffler System" and was tested by the magazine that I am getting this info from (March issue RX-7 Magazine). It's a muffler that offers an exhaust note as quiet as stock when around idling level, but an aggressive note with increased volume as the rpms rise. This is good for those who worry about distrubing neighbors early in the morning and/or late at night. Leg Motorsports' system consists of a 4 outlets (not just tips) where the inner two are controlled by an actuator valve At low rpms only the outer two outlets are running, but as you accelerate and backpressure from the engine rises the two extra outlets open up to become 4. Under WOT conditions it switches over at around 4000 rpm You can feel some increased torque in the 3000- 4000 rpm range. The exhaust system sounds like you're driving through a tunnel. Actuator valve is operated by a house from the engine. The current configuration has a 60 theta main pipe and 40 theta muffler ends. Handmade and estimate price (as sale has not begun yet) is 300,000 JPY - 400,000 JPY...

http://f1.pg.photos.yahoo.com/ph/jou...f4.jpg&.src=ph

http://f1.pg.photos.yahoo.com/ph/jou...5f.jpg&.src=ph


The other system by Odula is the "V-spec Muffler." The test system has repeeatdly produced a combination of an increase in torque from 2000-7000rpm and sound quality. main 70 theta -> split into 2 50 theta -> 90 theta exit. Exhaust sound fall into 91db WOT and 76db at idle. It uses a small setup with a 13kg rear piece and a 3kg main pipe. Cost is 95,000 JPY...


http://f1.pg.photos.yahoo.com/ph/jou...5f.jpg&.src=ph


While I imagine that the 4 outlet system looks different, I think most people would prefer a traditional dual system on their 8. Additionally if you live in the ice and snow, the actuator may freeze outside. Thus my idea is to incorporate the actuator and piping differences into the inside of a single "big" can. The piping inside there could work as a combination of these two systems... to offer extra hp at the N/A hp peak... 8k-8.5k and additionally offer a needed low-end torque boost down at 2k-7k. For weight concerns a limited amount of titanium could be used to keep the weight down. This will of course cost more than a typical system available now, but on the other hand what it offers... but needs to be reasonable, not 300,000 JPY! The ideal target would be $800-$1,000. Especially for someone coming in late to the market, something different that can really produce is a good way to get the market's attention.... thoughts? Any takers?

how do you get pics to show up??

...you can't get those pics to show up (at least, i don't know a way to), they're embedded in your yahoo page. just provide links to them, so people can click through cleaner looking links.

I have the original pics... if you tell me how to embedded them in this page I can. If I have to have them on my own server on the net or something to do that then Yahoo it is...

Why not just get 1 valve & actutator put in the intermediate, or mid pipe, and let it go straight to a dump pipe?

Lots of folk have setups like that before. I'd reckon all the "tuning" etc has already happened in a stock car, and is really dependant on the length of the primary runners in the header. The longer the higher the RPM for max torque. Pitty they are so short on the '8 :)

Cheers,
Hymee.

True... which is why I hadn't put any thought to the exhaust system until now. However, according to the mag's test ride with one and the info on the other... there is some torque to be gained through the exhaust system. What I really wonder is how much... I wanna see dynos. They'd say no since this is just a development mule.

RG and I were going over a tuned intake system ways back... particularly Greddy's intake system they're just releasing in Japan. Blitz has made an intake that is supposed to be CAI and variable length... does it work? I dunno... someone buy one when it's released and dyno it.... or get the kit from Super Autobacs in Chiba. They've got pics of this intake on the Blitz supercharger system...

Anyway... I've really been wondering if there isn't more power to be found in the intake manifold... not the arm infront of the MAF. Do something like an increased area air intake.... keep the variable runner length SDAIS, but increase the overal flow area and make the part in front of the MAF tuned... Or something like that... those who know the 302cid V8 Mustang, I'm thinking of the differnces between the different upper/lower intakes available... Holly, Ford Motorsports, SVT, etc. Equal length runners, short runners, long runners... they all played with this to squeeze out more power and to shift the powerband where the owner wanted it... The Renesis is smelling a lot like we're going to see nice gains by working with this model... not thinking purely of ram air intake, CAI and open filters...

The variable exhaust is nothing new at all. Nissan made it stock on its I35 back in 2000 to give it 5 more hp than the Maxima.

I have seen picture of the Leg's exhaust. It looks weird. But then, the aero kit looks weird too. Too much like a jet plane than a GT car.

No one is saying that it's new, but as usual people forget about things that aren't very "mainstream."

Ultimately... we all need more torque and horsepower from the 8. The upcoming turbo and supercharger kits aren't dropping power beyond what you can get from a Canzoomer Stage1/2 mod... at less than a quarter the price of FI. But we still want more torque at the low end... so just offering another approach that hasn't been used on the 8 yet (well in the US anyway).

Give me access to one for a decent price range and I'll be happy to be the first 8 owner with a sequential muffler system. I think it's a neat design, def something no one else has, w/o looking gawdy.

The exhaust with the actuators that open up at a later rpm is actually something very common with Ferrari. The 575M has this same setup. Ferrari does some very original things with some of their cars exhausts. It is surprising that others don't try to adapt their principles more often in other aspects of the industry..

I know what you mean RG... I am surprised that noone els ein the industry doesn't try to adapt more of Ferrari's ideas. IN the aftermarket, I was hoping that Racing Beat might take a look at something like this since they hadn't released their cat-back when I posted... although they did have a nearly completed development unit.


Frankly... Leg is crazy to think they'll sell any of those mufflers. Cool idea and it looks different, BUT... at that price you can pick up one of the upcoming turbo or supercharger kits. Not enough bang for the buck...

Exactly, this idea has been overused time and time again with ferrari exhausts and aftermarket ferrari exhausts as well.. now only starting to show up in domestic JP cars.

The 360 Aftermarket exhausts use variable valves as well.

no takers?

Especially with how everyone wants more low-mid power, it'd be nice if someone jumped on a variable exhaust and a variable intake... I suppose it's just easier (read cheaper) to stick with the old tried and true crap that isn't doing much for the 8...

I've tried to email Leg like I said, but no reply. If someone can find me a way to order one, hell I'd be willing to give it a try.

Actually... the guys who tried it out in the magazine said that regardless of how much the throttle is open they largely felt an increase in torque at 3,000 - 4,000 rpm. BUT... that isn't really what LEG said they designed it for. They said that it was in order to make a system that would be quiet when driving through your neighborhood (if you think American neighbors complain... try Japanese ones!), but open up to give you some power when you "hit" it. I think the power increase was a side-effect due to the increase in backpressure at low rpm... as it is the increase in pressure that opens the acutator at 4,000 rpm. LEG also does not have anything about this muffler up on their site yet.

Odula, on the other hand, they specifically claim that their muffler increases low-mid horsepower... 2,000 -7,500 rpm torque increase and sharper response their site says. The cost is 95,000 JPY including tax. http://www.odula.com/page/rx8_muffler.htm I don't like the tips though... they just stuck big tips on it instead of having the pipe diameter gradually increase at the end. Looking at their design, I can only figure that this torque increase comes through the use of smaller diameter pipes and more bends in the cat-back. I have to wonder if you don't take a hit on top-end power though.

I have to ask... you're really willing to spend 300,000 - 400,000 JPY on a cat-back muffler? The LEG system is hand-made and it is necessary to order it. They are planning to release it this spring, the article says. my thoughts... save your money. Add a tad more to that amount for install, and you can get either the Trust/GReddy turbo kit, or the Blitz supercharger kit (I don't know if Knight Sports' will be a kit that you can order in the US). You'll get much more bang for your buck here... but also be voiding your engine warranty.

If you still want the LEG system, here's their number 082-823-5888 (country code 81 and drop the first 0 from the number).

How's 300k-400k JPY in USD?

Approx. $2,800- $3,700 USD