OpTiCaL

What a tease ... back to the cardboard mockups...

Benjamz

Originally Posted by OpTiCaL
So, has everyone stopped researching this or just said **** it, its not worth it?



Above is an ascii diagram of how i understand our engine to be. R1 & 2 being the rotors and the 1a, 1b, 2a, 2b, being the side exhaust ports. .

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My site will be open I hope by this friday, if not next week for sure. I will be adding RX-8 custom products as I make them. Some of the custom RX-7 stuff on my site will give you an idea of what I have comming out for the RX-8.

An ETA on the header back exhaust system, I will start making it next week and I will have It at sevenstock for show with dyno results.

I will also have free T-shirts and pens, so look for me Ben with Rotary Extreme.

swoope

iTrader: (5)

yeay!!!

would love to see some photos of the exhaust. remember who your friends are.

btw, are you going to do the cf wing again?

beers

Benjamz

I took the ms carbon fiber wing off the site for the time being. I will not be doing any body kit sales. The only the body kit related thing I may sell will be a new wing for the rx-8 that is not on the market yet. The wing is a modified wing made by me and the shop I work with and they will be able to paint it according to the car paint code for the customer. The wing bolts up in the stock location. It will be on display on the project car at sevenstock. The header will be pretty cool, I hope that the dyno shows postive results. The mid-pipe and cat back are the easy parts. I should have photos on the site when its all done. But this exhaust is made here in the states so dont expect it to be too cheap. Quality is important for me as much as it is for my customers.

Ben

OpTiCaL

Back after doing some homework... looks to me like headers will do no good on this car. Yeah i know this is a total flip of position, but i was talkin with an oldschool wrench at the mazda dealership (he actually knew some things, which is rare these days) and we got on the topic of headers and siamesed center ports. He mentioned that this wasn't the first street car to use a siamesed center port (i think he said it was an old oldsmobile). Any who what we reached as a general consensus is the HP gains to be made with a header will depend on the VE of the stock engine. Looking around i found a few different articles on the Volumetric Efficiency of the Stock 13B Renesis.

http://www.rotarydevelopment.net/Rot...790_Rotary.pdf
shows on page 7 that the VE is above 100% after 5k RPM.

http://www.myrotarycar.com/portal/fo...sts.asp?tid=17
this one shows real world calcs for VE.

With most piston engines having a VE between 70-85% it makes total sense why we have seen almost 0 gains in HP with intake and exhaust on these cars. Unfortunately i am on board with TeamRX8 on this one and am ceasing work on the RG headers. Please let me know if i am mistaken, thanks all!

Big Money Pit

good work!

i'm still looking forward to mine, though... let's face it, the stock exhaust manifold isn't exactly attractive.

rotarygod

I will admit that headers may have no real benefit. But just remember if neither mine nor anyone elses work, neither do teams! I've got a hunch he'll debate that though. Keep in mind that this conclusion is reached based on the information in the above post. I disagree though.

The engine isn't above 100% VE everywhere. Only at certain points. The goal is to increase VE where it needs it so tuning goals may seem a bit strange when it comes to tuning as you may not be shooting for a peak hp to help but rather a location somewhere else. Average is what we need.

rotarygod

While I have never said my header idea will work, I will say that it has the best chance of working however slim it may be. Here's why. My header idea takes into account the fact that the center ports are siamesed. It is deisnged for a siamesed port. The reason why no other design (and I do mean NO other design!) has proven to work any better than any other is because none of them treat the center port any differently than the outers. Equal length, non equal length, tubular, log, etc. None of those designs is functionally any different when it come to a siamesed port engine. ONLY my design takes it into account.

Now saying that, it might not work. However "might" is worth a shot as NONE of the others are any better than any other one. NONE!

Every header out there that has been tried and used on a rotary engine is findamentally the same as those on piston engines. I know many people like to think that the rotary doesn't rely on the same rules of physics as a piston engine but they do. This applies right down to intake tuning, exhaust tuning, etc. It's all the same. Air doesn't know if it's being ingested, compressed, or exhausted by a piston or a rotor. It doesn't matter.

The reason header designs have worked on a rotary is because those same principles have been proven to work on a piston engine. It doesn't matter. It's the same thing. For the longest time people have believed, and many still do, that you need overlap to make power. This is absolutely false. Timing is just as important as overlap and the Renesis is proof. It doesn't make more power than the 13B because of higher compression. It doesn't make more power than the 13B because of the fance intake manifold. Sure these contribute but at the end of the day there is only one thing that makes the Renesis so good and that is a lack of overlap! It makes more power even though the peripheral exhaust ports can flow more in a static test. So what! This is a different engine so different techniques need to be tried to get results. Fortunately no overlap as well as siamesed ports have been tried in piston engines before too and improved.

Since every rotary concept in the past has taken cues directly from their piston engine counterparts, we again can do the same. We need to look at what has been tried and known to work on a siamesed port engine. Everything else is irrelevant which is why nothing has proven better than the other and never will. My header design isn't really mine. That's OK though as team's design really isn't his and no design tried yet is unique to the people that have been trying them. It's all been done before! The best way to figure out what works is to look and see if something similar has worked before. In this case, it has! This is where my header ideas come from. They come from engines that had siamesed ports. Their designs treated these runners differently as THEY HAD TOO!!! Is anyone listening! If you are not treating the center port completely unique from the other ports, regardless of your manifold/header design, you are not going to get more than 4-5 hp out of it. Period. NO ONE has proven this wrong!

My goal is to broaden the powerband and increase the average power. Another way to look at it is to increase the average VE of the engine over a range. You can actually increase the average while decreasing the peaks. My goal wouldn't necessarily be to make more peak power. It's to make more average power. This is another reason why we aren't seeing any epiphanies when it comes to exhausts. Everyone is going for the same thing and that is to brag on a dyno chart about peak power. As far as I'm concerned peak power isn't that important as long as average power is good.

Maybe mine won't work. I've left the door open for failure for a long time as I've never made any claims. However mine has the best CHANCE of working and no other design out there has proven to work any better than any others. This is because no one else has ever treated the center port differently and if you don't, you are wasting your time.

Daemos

then why do mid-pipes gain more whp? there must be some sort of restriction in the exhaust system (unless if the cat is really the only restriction). This isn't ment to bash you or anything, just a question out of curiosity, as the proof is that intakes and exhausts don't do much for the car but a catless midpipe does =/

Benjamz

Rotarygod, I am curious as to what you think about what I am doing. It will be done and dyno'd to see if it makes usable power or not. What do you think about my header? 2 weeks to completion.

https://www.rx8club.com/showpost.php...&postcount=252

rotarygod

It's a different idea. I have my hunches but I encourage you to try it to prove the concept whether benefical or otherwise. I always encourage experimentation. It's not trying based on opinion that bothers me. This is why I don't like people saying my ideas can't work. Maybe they won't but don't reach that conclusion without trying. That's the problem I have.

OpTiCaL

7-8 WHP isnt much of a gain. Basically just freeing up the flow some. Almost all intake/exhaust systems for our cars free up some flow, and is why we are seeing 5-12 WHP gains with them. All i am sayin is because our engines have a high VE we will not likely see a 20-30 WHP gain with headers.

thanks for the reply RG. From what i have read the reason the Renesis makes more power than the REW is due to its increased effeciency with 100% larger intake and 30% larger exhaust ports. but these details don't really matter or help this debate. (sorry)

Ok, so you say we want to increase overall performance and not just peak... sounds like we need to increase the low end VE from about 2-5k RPM. This begs the question, how do we tune headers for low end power/performance? If i recall correctly this would be better accomplished by a SRI lenght specifically tuned for 3-3.5k RPM?

Benjamz

This is how you help low end!

http://www.frsport.com/Sard-Exhaust-...ve_p_1360.html

I already had plans for a great single exhaust with a sard racing cat, but the cost of the system was close to 2k.

That was midpipe with racing cat and cat back with torque converter, but I chose to go true dual instead.

Rotarygod, if my header craps out I'll try your idea, but like you I like to see proven results more then hear say.

And if my header works, I will still try your idea.. because it will support my dual midpipe to dual cat back system.


Ben

alnielsen

iTrader: (4)

No, Mazda already has valves that open and close, in the intake, to maximize performance.

OpTiCaL

Seems like there should be a lower tech approach to this problem.

yes, but they make the intake length longer which helps high RPMs that can be seen from page 7 of the PDF i posted earlier.

OpTiCaL

i may have found some answers... check out http://www.mez.co.uk/mezporting/exhaust_length.html

Benjamz

The exhaust valve was for race application, it is better suited for minimal upgraded turbo cars from what I have heard. It gives more power under the curve.

OpTiCaL

yeah, but i think you missed my point

TeamRX8

iTrader: (25)

you won't get anywhere until you throw all that old way of thinking crap out the window ... Mazda went to so much trouble on the intake side but not the exhaust, they're just dumb I suppose

TeamRX8

iTrader: (25)

no, that's called guessing without really knowing the application at hand ...

Benjamz

Team, I am not the only one who is involved on my end on making exhaust, I am working with some expierenced people who enjoy a challange.

The header I was working on cost to much for the average joe to buy. The custom trick stainless steel flange alone was near 250. With the collectors, pipes and v-bands the parts alone were around 800. The total cost of the header would be around 1300 to 1500 with labor. This will still be worked with in the future but for now I'm going to use something simular to Rotarygods idea because it's way cheaper to make so with that I will be able to offer it at an affordable price. Maybe around the 800 neigberhood. But it will be a racing header for offroad use only and it deletes the cat and goes straight to the catback.

Estimated time to completion is 2 to 3 weeks and I will have pics and dynos on the site and I will post the link here. The catback system is useing Bassani oval stainless steel mufflers if anyone was wondering. Also the header will use v-bands where it mates the to dual cat back.

Ben

P.S. And yes I know Mazda knew the key to the N/A renesis power was intake design. I also know that Mazda had to meet certain laws with emissions and that they did a damn good job of designing a nice factory exhaust thats tuff to beat.

rotarygod

We know the 16X is going to be more powerful and more efficient. Jsut wait until they figure out variable exhaust timing!

olddragger

iTrader: (3)

there is something to be learned from the exhaust of 2 strokes--not the same--but SOMETHING
olddragger

TeamRX8

iTrader: (25)

well I threw all conventions out and thought outside the box, if you want to try and stay inside it then have at it

my NA low end was fat despite the large diameters, maybe it was the pixie dust ...

Lasse wankel

Me and Mikael was tonight also thinking outside the box! Please see Racing Beat header thread were i have written a few words about our project.

/Lasse