I think the best thing I can do here to help out is to dyno the car with a standard manfold on if I can get hold of one and it'll fit, then put ours on, then try it with the centre pipe taken around the back of the engine as a completely seperate pipe with it's own silencer.

That should help with an idea of where to head with the systems

 

That's always the best way. You never know, you may discover that really long pipe work good on the Renesis which is why we've never seen anything do much.

 

We seem to have hijacked Lasse's thread a bit. Does everyone remember Hymee's pics?

 

kev,

nice to see you around.. king of the quote pic posts..

that is a damn sexy cat and resonator..


beers

 

The power gain he reported with that header wasn't spectacular but also included removing the cat which alone adds about 7 hp or so. I think he made somewhere around 12-13 hp with that exhaust which adds proof that headers can only give around 5 or so more peak.

A video he posted of that engine on the dyno also clearly showed the difference in energy in the center port vs the outers. The center pipe glowed MUCH faster than the outers did. This is proof that it needs to be treated differently.

 

Rotarygod, the only header I've seen that used the 4 pipe design was Knight sports's header.



http://www.knightsports.co.jp/blog/R...dependent.html

What do you think of that header in comparison to the others?

 

all are absolutely pointless ....

 

Which begs the question why hasn't anyone else designed a "log" type of header similar to yours? It seems to be the simplest design and since there is no overlap complicated tube style headers may be convoluted and unnecessary.

 

Because tubular manifolds can still provide a benefit to an engine with no overlap....

 

you can build a better manifold than the OE design, but a tubular design only complicates the fabrication and cost without any payoff over a log manifold

 

but they look so pretty.

 

as long as you don't mind a heavy car and a light wallet

 

You can't provide the correct harmonic pressure pulses with a log manifold, which still help, even with no overlap.

 

I appreciate your design and the theory that Rotarygod has presented as viable. I just think you will have a hell of a time putting that manifold you have created - or similar variant - into an RX8 chassis. It doesn't have nearly the room to work with that you do. It could probably be done but you will also probably be fabricating a complete exhaust system at that point, too. Thats not going to be cheap for your average joe that doesn't have access to a lift and welding equipment/skills. I think all that is being said by Team is that for the effort and money required to make the project work in a stock RX8 chassis you might as well go with a lightweight OE-like design and call it a day as only modest HP gains will come from an all out N/A setup anyway.

 

It would be a lot of time and money I agree.
But then so is any modification compared t just buying a faster car, so....

 

$5,000 USD into a, well designed F/I setup can make you faster than $5000 towards a faster factory car, IMO.

And there are not many other cars in the price range of the RX that have as well an engineered chassis, suspension or brakes to begin with so you will stop and turn faster as well. but now i'm just playing the fan boy roll.

 

Keep in mind that my header design is not proven. No one has built one. I truly can't say it does work. It is just my approach to dealing with the setup we have. The lack of overlap does pose a problem. For all I know my design is viable. However is it viable on an engine with no port overlap. That design is nothing more than a hypothesis I have based on what I know. I do admit that it will be very hard to fit it in an RX-8. I am going to install a Renesis in an old RX-7 so I have plenty of room. I just have no idea when I'm going to get around to this though as I have a wedding and a new house to worry about first.

Team is a smart guy. The exhaust issue is the one thing that we have disagreed about. Not because I don't think his design is bad but because he blatantly feels my design which he also hasn't tried won't work. I prefer to keep an open mind but do admit that it might not work as I hope it will. The only way to find out is to build one and that's not something that get's priority from me. If I actually owned an RX-8 you can be rest assured that I'd have tried it by now.

I do think Team is correct based on what we know to this point that there isn't necessarily any point in building a full tubular header. I know for a fact that Racing Beat has tried very many different combinations and lengths and has never really shown an advantage of one over the other. It doesn't matter if it's been long or short. They all give 4-5 more horsepower over the stock log style manifold. This seems to suggest that the only thing that matters is flow and once you hit what you need there is no more to be had. Up to this point tuning hasn't been beneficial to the Renesis. Flow has. Team has come up with a simple design that gives the gains of any other header system out there and for simplicity sake it's hard to justify doing it any other way.

I actually have 4 different designs that I still want to see tried. Keep in mind NONE of them would be emissions legal. I have no way of knowing up front whether any of them will work better than anything else that has been done. From the sheer number of designs that have been tried so far it would seem the odds are against me. That's OK though. This only means they haven't been proven not to work. My optimism for these designs comes from the fact that although many different setups have been tried, they have all fundamentally been just 2 separate designs. They have been log and equal length header. The other couple of designs I have contemplated are not either of these. Since none of these have been proven not to work, I have to hold out some optimism that there's a chance that they will. These other designs are the only things that take into account the crazy center port characteristics.

I do know that a true 4 runner header has been made and it too showed no significant gains over the 3 runner which would suggest that this isn't an issue. However I feel that the design that was tried was a bit too short and not quite what I want to try.

Here are a couple of simple things I want to try. The first is to build a true 4 tube header but then collect the rear rotor and front rotor pipes so that now we have 2 pipes. The front rotor and the rear rotor. Now we try a couple of things. The first is to have 2 totally independent pipes going all the way out through 2 mufflers. True dual exhaust. This works fantastic on stock port 13B's but it's effectiveness actually falls off as port overlap increases. That's an interesting trait. Does this mean that it would be beneficial with no overlap?

The other thing to try is to collect these 2 pipes at the back of the car right before the muffler to have what the RX-7 world refers to as a "long primary". This is my personal favorite setup on a 13B but then again that's not a side exhaust port engine. I've talked about the other setups before.

I'm not saying any of them would work any better. They are different though and no one has tried them. Until someone proves them not to work, I have to believe that they might. If someone does try this and shows no significant gains, go ahead and just build tubular manifolds all day. When it's all said and done, after everything has been tried, the best product will be the one that is the simplest that still does what it's supposed to. From what we have seen so far, Team just might have this part figured out.

 

So after reading all that...how much do you need for material costs and when would you like my time/car to mess around with this stuff?

I'm going to be moving to FI soon...but due to technical difficulties not for a while...so in the interim I don't mind messing with it in N/A trim...and I'll have it probably ripped apart with extra parts and stuff...

I mean...if your just wanting to mess around with it...

 

I'm willing to bet it took you longer to write all of that than it did just to read and comprehend it!

 

Heh...yeah...however it does indicate that I at least DID read it...

You might be seriously long winded...but its always good stuff...ramble on...ramble on...

 

zero overlap = closed chamber

closed chamber = no flow momentum potential past evacuation

I wish anyone the best to try and pulse additional flow out of a closed chamber.

 

The good ol...suck on the end of a sealed straw argument...

Heh...I think everyone agrees...but its all in the name of "screwin around"...

 

The real question is what is the pressure inside the closed chamber? If it isn't at absolute vacuum (and it isn't) then there's still some potential left. Extracting it is an entirely different thing though.

 

The trick is the evacute the exhaust side of the chamber more effiecently, as the chamber does not empty completely - more vacuum = more inlet charge when the inlet port opens.

=You can suck on a closed straw.

 

Even without overlap there could be a benefit from scavaging, a vaccum created before the port opens may help(but by how much?)