are you saying that pipe ID has no bearing or relationship to WHP and no direct effect on where power is made?

 

Please go back and reread the very first post because you clearly didn’t fully comprehend what was already stated there by asking this question.

 

Alright, since this has been quiet for while, I'm going to ask what may be a dumb question.

You mention a 12° race collector. Excuse my ignorance, but is 12° optimal for some reason or another? Is it to reduce the turbulence between the merging pipes/exhaust flows?

If so, would there be any benefit to smoothing the transition between the engine exhaust ports and the header ports, like what the racing beat flange seems to do? The transitions appear to be smoothed, albeit fairly sharply. Would there be any benefit to making the transition more gradual? CNC-ing individual ports to fit like your longtube mockup shouldn't be too much of an issue. Space may be a concern, depending on how tall the transition ends up being. Cost may become prohibitive as well, but if you want to get yourself a perfect match for your baller 22ga iconel build, it'd be a way to do it.

Of course if there's no benefit, the whole thing is cost prohibitive from the jump.

 

^ that dumb, or that dead?

 

I think the idea is to reduce turbulence as much as possible. The smaller the collector angle, the less turbulence. Obviously, after a certain point, you get into diminishing returns.

 

https://www.rx8club.com/series-i-tec...10/#post154360


I am sure you have read Rotarygod's thoughts on a custom header back in the days.
Is this something you could try with your "modular" prototype?


"...figuring out the perfect header primary pipe length and then making the 2 outer pipes collect at this distance. The center pipe does not collect here. Take the length of the primary runners and multiply it by 3. This is how far down after the first collector that the 3rd runner will collect at."

 

I think these two quotes summarize what Team has to say about this. The bold-ing is mine. I think understanding the ramifications of that sentence makes all the difference in the world.

Beyond this is all my reasoning, someone more versed please let me know if I've gone wrong somewhere.

The chamber has the highest pressure, when it opens, it equalizes into the atmosphere along the path of the exhaust. Since there isn't any overlap, there's no way to create a low pressure zone behind the front expanding down the tube. The gasses are simply diffusing into a larger container. So you get an ever decreasing pressure gradient as the pulse moves along the exhaust, but never a "wave" of high pressure then atmospheric. Just varying degrees of higher than atmospheric pressure throughout the exhaust system.

God I hope this is at least kinda right...

Anybody have any thoughts on my question about smoothing the transition between the engine and the header (square to circle)?

 

I think we can all agree on this. The point would be calculating the perfect timing of the pulses for a given rpm range and trying to assist that with the header design, as much as possible, right? In my understanding, RGs recommendation would be aiming for the same by collecting the pulses from the siamese ports later. It might produce some great tones in the meantime!

 

Based on the discussions that Team and I had via PM (not specifically about RGs comments, but about this thread) I think that would be the only tangible difference. That and probably cost.

 

Here's a bit that speaks to pulse tuning for interference. If you follow that along, it gives you a better overall picture of the opinions. Team admits that there may be there, but isn't interested in pursuing it.

 

He outright rejected the design without ever having tried it. Never reject something without testing it first. I would have but I've never owned an RX-8 and now I haven't messed with cars in years.

 

Hey RG, both of those points suck... You've got a lot of very helpful info on here.

By "flat out rejected it" do you mean via this thread or via other discussions? I think Team was poo-pooing the idea in the thread that Marton quoted, albeit in a somewhat obtuse way to the uninitiated or less knowledgeable users.

 

All this poo pooing reminded me of this :

 

General question. I went to my local muffler shop today and asked him to order me a midpipe to get rid of my cat. However...he suggested that he could just cut the cat off and weld a pipe to existing midpipe and put what he called a bung in it to screw the o2 sensor in. I already have a borla system from cat back. So my question is will what he suggested work? Or should I buy a aftermarket midpipe without cat? His would only be around $25.

 

or just gut the cat and save yourself a few $ .....

Leave the stock resonator in place if you do this ...unless you like the sound of a chainsaw that is .

 

How hard is it to gut the cat? I will leave the resonator on for sure. It already sounds good. I just wanna delete the cat.

 

wrong thread ...please do a search ...we have derailed this thread enough already.

 

I've always been an RX-7 guy and still have one. I've never owned an RX-8 so I never had a car to try the idea on. It might not have worked but since it was never tried, we'll never know. Team thought the idea was a waste of time and wouldn't work so he just rejected the concept entirely having not even tried it. I'd love to know for sure either way. I've learned a bit about rotary port timing since then but primarily on the 13B so I'm not sure what new info I could suggest for the Renesis.

 

Blackadder is something I feel like I would really enjoy, but I've never watched. Rowan Atkinson, Stephen Fry, Hugh Laurie, Brian Blessed, Robbie Coltrane. All greats of British TV.

 

Well, they're cheap now. I assume you've got the necessary fab skills, go pick one up and report back here at once! If we were neighbors I'd be more than happy to let you play with mine, but alas.

 

Yeah I know. I'm just not motivated to work on cars anymore. My RX-7 has been on jack stands for a few years. It's sad considering I have everything necessary to get it running. I just haven't taken the time. I did start working on it again this week but I typically do that for a few days and then not touch it again for months. If this were 20 years ago, it would be running in a weekend.

 

I rejected it on sound reasoning, not ignorance; as long as there’s a siamese port that can’t be separated along with no timing overlap I’m not going to pursue what I already know to be a dead end alley to nowhere. The timing needed to actually pull something out of a one-opening chamber (exhaust port open only) is so extremely critical to limit rpm from a range to a singular point that would then be so sensitive as to vary due to stmospheric conditions, etc. and then the amount of force needed to pulling anything meaningful out of a non-vented chamber without pressure/momentum to assist is so large compared to anything that can be generated from the exhaust stream itself.

Again, the whole premise of that argument is based off of a theory for an engine with overlap timing where none exists on this completely unique situation of the Renesis, which is an engine with no overlap timing. It’s an apple hypothesis for a watermelon application.

Instead of evaluating the unique situation of not having any timing overlap and trying to understand and work a solution from that fundamental basis people are instead just blindly taking what they already know for a completely different application and throwing that at it instead. Putting into terms you might better relate to; I don’t know any respectable engineer who would consider that to be a rational approach to the situation.


.

 

 

I was able to influence turbo spool significantly by opening the side exhaust ports before the siamese . I wonder .................. if the same thing done on an NA engine with an equal length header would it have any affect ??????????????????

 

It doesn’t seem that well thought through to me, but anybody else is free to pursue it as they see fit