army_rx8

^tell me abou tit.. i would love to see what kinda numbers it adds:D

StealthFox

Nemesis8, i agree the FEED equal length runners header looks to be the best on the market, but even at that, there is little to be gained from an aftermarket header for the RX-8, costing from 800-1200 bucks, these only give between 1-4 hp on average. greddying/sfr turboing and engine management will be the most cost effective ways to gain good HP gains, and with all of the bolt ons you'll get about 25.

rxadrian

Anyone here speak Japanese so that I can order these things. I am in Tokyo right now and I have their number and called but I cannot communitcate anything with them!!! I am here for a couple of more days if anyone knows Japanese...

I think that the Feed would be the best one then...

therm8

I think the reason no one sees any gains from headers, is that all the units available at this time are equal length. Equal length is fine for the outer 2 runners, but the middle runner has completely different pulse characteristics. The middle runner needs to be significantly longer, and collect with the other 2 further down, in order to jive acoustically with the outer 2 runners.

rotarygod

"Excuse me, stewardess. I speak jive." -Airplane

Nemesis8

iTrader: (3)

Here is a collection of the ones I could find. Are these all equal length??

https://www.rx8club.com/showpost.php...3&postcount=40

rotarygod

No they all aren't equal length but none of them addresses the special needs of the center runner.

devious12

Weren't you saying a while back that the Knight Sports header looked as though they were headed in the right direction with the design and making all lengths differently would increase the power gain?

Do the exhaust ports need to be opened up more, I know they are pretty big to begin with for factory but is there really anyway to make one of the headers that are already availably work by porting the engine?

Thanks

Nemesis8

iTrader: (3)

I forgot that they split the center runner.... Hmmmm four pipes off the engine exhaust ports.

rotarygod

Racing Beat played with a split center runner and found that it didn't do any better than the conventional 3 runner header. That is really strange to me. They did say that the header designs that they tested did about 4-5 hp more but only at the peak point. I still need to build my header design to see if it has any merit. It might not work but I won't know until I try it. The 2 outer runners get collected at the same length. The center runner is 50% longer and connects downstream of them. Off of this center runner is a dead leg pipe to nowhere that is the same length as the outer pipes but blocked off. This is purely for resonance. I have no idea if it would work on the Renesis but on older 4 cylinder piston engines that had siamesed center runners, they did this on the race cars. The original mini was one such vehicle. It worked there. One way to find out I guess.

I do have another thought as to why headers aren't doing much on this engine. Part of it could do with the fact that we have no overlap and therefore no scavenging that can help pull in more intake charge. The other thought is that the exhaust ports right now just don't flow any better than even the stock exhaust manifold and that any increase in flow in the exhaust system really won't do much. I really wonder how a set of headers would do on a ported engine?

devious12

Obviously you will, but please post any info when you get it. I'd rather have a N/A engine with every type of upgrade possible before throwing a turbo on it. I like the turbo but I'd rather see the engine last much longer.

Thanks for the info.

Nemesis8

iTrader: (3)

That's my plan also, do everything possible and stay NA for as long as I can. Maybe one day a SC will go on, but not until Richard says it is ready. :p

I will one day own a header :D

Japan8

i speak Japanese and live in TOkyo, BUT... it is as I said earlier... you can't just arrive here, order and expect to get the part in 2 days and leave. Almost ALL of the parts will be made-to-order and thus not ready for 1-3 weeks.

therm8

In a very old post, when this was being discussed. You stated a 33% length increase for the center runner with a dead leg equal to the outer runner lengths. I was wondering if it's 33% or 50%. Either way space will probably be an issue. But i've been thinking on this recently (and i don't really have the background to figure it out atm).

On a related note:
4 port exhaust timing is:
open: 40 degrees BBDC
shut: 3 degrees BTDC

6 port:
open: 50 degrees BBDC
shut: 3 degrees BTDC

Does this mean the 4 port's exhaust ports are open for 43 degrees and the 6's 53 degrees? I'm having a hard time wrapping my head around the rotary's combustion cycle (even with looking at illustrations). And what is the ideal runner diameter for the Renesis? With 2 strokes, i've read 10-15% greater than the port exit window and a lot of people seem to compare the exhaust pulse of a rotary to a 2 stroke engine's. TIA

Would an expansion chamber (again a 2 stroke concept) in the runners help with scavenging, or is it just not going to happen without overlap?

rotarygod

A pipe that is 50% longer than the original length added onto the original length (100%) is 150%. However divide the added distance (50%) by the new total distance (150%) and you get 1/3 or 33%. That's the source of the confusion.

Your timing math is a little off. The opening and closing points are a little mixed up as well. The 6 port engine does have 10 degrees more of exhaust timing but it isn't a mere 43 or 53 degrees total. It would take me far too long to explain how the timing of a rotary works as those numbers are based entirely on 2 different top dead centers as references which is weird. Here's a link to Paul Yaw's article on port timing and how to figure it out. He can explain it so much better and he has picutures.

http://www.yawpower.com/dectech.html

You can not compare a rotary to a 2 stroke engine in theory. It doesn't work the same. 2 stroke exhaust design also doesn't work on the rotary. The reason why the 2 stroke engine has such a unique exhaust design is because this is where all of it's power comes from. The intake and exhaust ports are open at the same time and close very near the same time as each other. You don't have a suction stroke from the piston moving downward to help draw air into the engine. You also don't have any point where the piston is moving up to help push out exhaust gasses. You rely on the fact that the exhaust will start to move out of the engine since this is where the least pressure will be and it's momentum will create a suction effect to help pull in the fresh air charge. The big problem is that if scavenging vecomes too good, all that will happen is that a fresh air/fuel mixture will be pulled straight through the engine and out the other side leaving only a small amount left to burn. this is a waste. On a 2 stroke exhaust design, the expansion cone serves to help the scavenging effect which will help pull the exhaust gasses out of the engine and consequently the intake into it. The convergent cone is there to provide a pressure wave that travels back to the engine. Some of the fresh intake charge that passed all the way through the engine will now be stopped and pushed back into the engine in a sense supercharging it. This is how 2 strokes make so much power and why their exhaust design is so critical. Without an exhaust of this system, the engine can never reach 100% volumetric efficency. With this exhaust, it can get over 120% volumetric efficient. Good stuff!

The comparison of the rotary to a 2 stroke is invalid because unlike a 2 stroke, the rotary does have a suction phase and an exhaust phase where the movement of the combustion chamber physically aids in the effect. A 2 stroke uses only the momentum of the air. A 2 stroke exhaust on a 4 stroke type of engine or rotary will scavenge well at the beginning of the exhaust stroke but then towards the end, right before the exhaust port closes, the return wave from the convergent cone will push some of the exhaust gasses back into the engine. That's a terrible idea. On the rotary/conventional 4 stroke, we want the scavenging aiding side which is the divergent (expansion) cone but that's it. Go look at race exhausts and see how they are done! We don't want any pressure waves traveling back towards our engines. On a 2 stroke engine the outlet of the expansion chamber should only be about 50-60% area of the inlet side. Remember that there is air/fuel traveling into it through the larger inlet side but some of it is getting pushed back into the engine leaving a smaller amount, which needs a smaller pipe, to exit the engine. 2 stroke theroy is very fascinating. There is some very good info out there on the internet about it. Once you read it, you'll see that the argument that the rotary is comparable to a 2 stroke is invalid.

RodsterinFL

Hello Japan 8

I read your post in the "going to Japan what should I buy" and I mentioned that I was going in June. Thanks for your comments. I am coming on Delta to Narita and staying in Tokyo asakusa area. I've never been so it will be interesting. My cousin is coming with me and we are actually destined for Australia and New Zealand but decided to take a few in Tokyo. We want to see some of the sites and get a few souvenirs aand I just thought about car stuff but is sounds like it is not really a savings. We will also visit Akihabara and electronic stuff. If you have any thoughts on what are good items for stateside buyers (neat but not available to US but stiil useable with 110V) let me know. Thanks.

PS your personal box is full according to the server.

Japan8

PM is fixed. Sorry about that... had a bit of old PM's taking up space.

For places to stay... here are a couple good places to look for reasonably priced hotels (with English)...
http://www.toyoko-inn.com/eng/
http://www.jref.com/practical/apartments_japan.shtml

Good electronic items to pickup? Well the JDM ones are best, but no warranty in the US (have to ship it to Japan) and all the manuals and menus, etc. will be in Japanese. Voltage is no issue... just get a step-down transformer for it. So anyway, your best bet will be hitting a *Duty Free/For Export" shop. Bic Camera (Ikebukuro), LAOX (Akihabara), and several other large chain electronics stores have such a floor (usually the top floor). The stuff there... well JDM is say 3 gen ahead of the US, but the stuff is only 1-2 gen ahead. OTOH... valid warranty abroad and english manuals, etc.

So... what to get? Digital Cameras here make the ones in the US look like a joke. Digital Video Cameras are tiny and awesome. You may get lucky and find a DVD/HDD Recorder than can be used in the US. The ones here.... screw TiVO.

If you are into paintball/BB guns and such... then hit any major hobby shop in Akihabara... the BB guns here are amazing.

StealthFox

i assume you are talking about airsoft guns as the american pellet type guns arent popular at all in japan, and their native airsoft is what they do.

if thats so and you are intrested talk to me i know ALL the best places in japan to look at the coolest airsoft(tactical weapons replicas that shoot small plastic ***** that people run around and shoot eachother with) guns, its also VERY popular in america and people import the guns from hong kong retailers(that get the guns accesories and upgrades from the japanese manufacturers). if you go to a forum site and locate a group in your area and go to one of the games and borrow some equipment i guarantee you will have a blast if you're into running around with machine guns like in the movies or like tactical combat simulation. www.airsoftretreat.com, airsoftplayers.com, and arniesairsoft.co.uk. are three of the better forums for it. i know pretty much everything about it and have a collection of hundreds of guns from the 80's, just had to share that bit as its one of my hobbies

Need For Speed

knigtsports have a good headers too. its a 4 to 1, the abitual are 3 to 1.
feed its a very good choice to.

i have the REamemiya the was the first on the market and they work good.