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Always love a NA Focused build, irregardless of if it makes big power over stock or not....
So, when is someone going to start cranking out these log headers to sell? I definitely want one, I have the tools and ability to whip up my own, but it would not turn out near as nice as yours or Teams.
Well I don’t really see much difference with a tubular type with the shortest possible pipes into a proper merge. The thing is you have to do the entire rest of the exhaust system for min backpressure to see the full advantage. What I did is more fab labor oriented to get the lightest racing package that met an emission legal race class requirement (by design, not by EPA law).
The shorty tubular I just described would be easier to build for someone with limitations, but a proper merge is usually a bit pricy unless you have the skill and tools to fab & weld it yourself. Otherwise a RB flange is capable of working with 2” OD tubing, it just has flush OD fit up that butt welds to the extension rather than fits down into the overlap with the intended 1.75” OD tube. You can grind the flange port ID out flush to match with a burr grinder first. I have an RB flange and almost went that direction, but don’t need emission capability now.
So I almost cut it apart into individual flanges, but dealing with the cast-in air injection manifold by having to machine/grind off the excess weight and then also deal with the holes that interface with the iron-plate flange opening didn’t fit in with some other stuff I had planned.
Well I don’t really see much difference with a tubular type with the shortest possible pipes into a proper merge. The thing is you have to do the entire rest of the exhaust system for min backpressure to see the full advantage. What I did is more fab labor oriented to get the lightest racing package that met an emission legal race class requirement (by design, not by EPA law).
The shorty tubular I just described would be easier to build for someone with limitations, but a proper merge is usually a bit pricy unless you have the skill and tools to fab & weld it yourself. Otherwise a RB flange is capable of working with 2” OD tubing, it just has flush OD fit up that butt welds to the extension rather than fits down into the overlap with the intended 1.75” OD tube. You can grind the flange port ID out flush to match with a burr grinder first. I have an RB flange and almost went that direction, but don’t need emission capability now.
So I almost cut it apart into individual flanges, but dealing with the cast-in air injection manifold by having to machine/grind off the excess weight and then also deal with the holes that interface with the iron-plate flange opening didn’t fit in with some other stuff I had planned.
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Team I am new to the RX8 world but not to building my own high performance cars. What I am about to ask might be needy but would be much appreciated. I agree with your assessment of the RX8 exhaust and am going to build my own header (and exhaust) because I am not pleased with the aftermarket options (related to flow efficiency and flanges). I want to mimic your first design but with an aftermarket header flange for weight savings. I was going to try to find a cheap aftermarket header (for the flange) and use 2" primaries flowed into 3" as fast as possible as you recommend in your first design (I think the design of your first one is best). Or should I just use the exhaust manifold flange. Did you step the collector of the primaries from 2" to 2.5" to 3"? Or did you use reducer cones? Should I use reducer cones (2"to 2.5") to start from the flange into the collector or just 2" piping? Where I live I have access to aluminized steel 16G, T409 16G stainless steel, and T304 18G stainless steel readily available and would prefer to use one of these. Which metal do you recommend (I am not familiar with the heat the rotary can create and what metals can durably withstand it)? I need the header to last about 3 years and am most worried about durability (I'll be doing a motor swap then or before if the rotary quits, just sold my LS Miata for an Rx-8 so we could fit the kid in it and enjoy the car as a family again). I am not expecting huge gains, and I know it is a waste of time but I have nothing else to do or spend my money on. I want to do the exhaust because after doing extensive research on the RX8s before buying one, I believe the exhaust and tuning is the only realistic (yet still minute gains) to be had from this car. Any recommendations on a catalytic converter that won't break the bank? In my county in Texas no sniffer test but must have cat so I don't care if it can pass sniffer. I still want a cat because I won't be able to take on and off easily because of the customization. I want to at least stop a little emission and smell, but not clog. Quiet single exhaust muffler yall have used that doesn't effect performance much? I plan on doing single exhaust instead of into dual towards the rear of the car. Any other input from anybody else would be appreciated as well.
I have read a lot, especially on your cat (HJS) recommendations. Had trouble with what model number to choose with what I was looking for and where to purchase. It would be very helpful if you could at least talk on that (or somebody else). I’ll experience with the muffler I have a couple brands I have been looking at. I feel confident with how I have the header envisioned in my head and from your first example. It would be helpful if you (or any one else) could have an opinion on the metals I said I had readily available. So in review I was just looking for some reinforcement and extra tips, but I did need a recommendation on model number hjs cat for my application and recommendation for metals I have available I listed for my application.
I read this topic and 've been thinking over it for while, firstly I don't get it why people doesn't understand the timing and lack of over lap ?
Over lap elimination and side ports were main changes in this Renesis design
and as far I can say they did it for emission regulation and better control over timing in addition to
thermodynamic improvement which always been snd is grave issue of rotary engines.
In my humble opinion Renesis engines means to be tame for fuel economy/ emission and production cost.
Great power out and worse fuel consumption of peripheral ports aint deniable, however things comes to a price.
The chief advantage of this side-exhaust / side-intake port layout is that it permits elimination of intake/exhaust port timing overlap, elimination the retention and carry-over of exhaust gas and encouraging more stable combustion. In addition, where the previous engine had one peripheral exhaust port per rotor chamber, RENESIS has two side ports, approximately doubling the port area. The new exhaust arrangement reduces exhaust gas flow-resistance, and while assuring ample exhaust port area, allows delay of the exhaust port opening for a longer expansion cycle, to raise thermal efficiency, power output and fuel economy.
Another major advantage of the side exhaust port is that it allows engineers more freedom to optimize port profiles.
With RENESIS, both the 6-port engine and the 4-port engine have intake port cross-sectional area almost 30% greater than the previous engine.
Back to a main subject about header, basically every engine is a positive displacement pump, however, output is govern by thermodynamic cycles.
We might have increase in g/s or cfm or every other unites we use for flow but can not measure noticeable power out. If we keep playing with parameters
might have other improvements though.
What I want to say is, not every goal is tied to hp/ n.m gain. I had use 4 to1 headers headers perviously just to ease engine and have bring engine temp lower.
currently I am running cheap jaspeed short headers which was pita to resurface flag, emptied oem cat and toyosport cat back.
Again my main aim was to keeping engine happy weather to gain any numbers and I have to admit I might also lost some torque around 1500 rpm.
I kept cat chamber asI believe it also act expansion chamber, my main concern is about expansion index of this cheap headers which may cause premature
cracks and leaks.
I didn't manage to look to rotor ports timing yet as I want to. It must be a way to create a over lap for in/ex port, however question is does it worth it ?
I see few full bridge ported in UK, each of them hardly make ~200 whp and had few mpg lost. 200 whp is sorta a good street port job :D
Other thing to mention if 6 degree timing is on E-shaft it would be equal to 2 on rotor and rotory engine full cycle is on 720 and...
It about why there is no over lap and at end I am referring to math of 6 degree over rotor revolution.
Too many question, what I am doing is reading and looking from outside of box. e.g. if you remove cut-off seal, you have overlap. or only use rx7 rotors.
edit: If something is nuclear kindly ask me/direct quote me.
. e.g. if you remove cut-off seal, you have overlap.
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Other than make your engine fail quickly ...that's going to do 5/8ths of f**k all
Originally Posted by Heisen Delgosha
. e.g. or only use rx7 rotors.
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If you are talking scalloped rotors ?? ...might do a little bit but you would lose more from lower compression ratio than you would ever gain from that.
12-15-2019, 04:32 PM
ok professor
