FWIW ...I wasn't arguing with you over header theory...... Just questioning the benefit of a 63mm ID manifold back system vs a 72mm ID (3"OD) system. If I were building a new system ...I'd def go 3"..... just because there MIGHT be 1-2hp in it.

you were arguing against it all up until a month or two ago and now you have it all figured out, ok then :)

I was never arguing against it ... I just thought there might be ways to reduce backpressure not thought of before. But I accept what you are saying ...just question the minor details like ........thou shalt run 3" or thine engine will suffer !
When my dyno shows highest whp ever recorded for a Renesis maybe then you will shut up about your 3" :fingersx:

Yeah 220whp.. very nice. Many people with full bolt ons dream of 220whp.
Im sure more could be had with a full 3”, but at what cost?
You did mention you were trying to save money.
Hoping the new engine has something special because 220 is amazing in stock form with basically a cat delete.
I hope the new one can produce a bit more!

Cheers
When I say I'm trying to save money ....it's more .....I don't want to waste money on something that does stuff all. If I thought there was 10whp in going 3" I would do it ....but I don't.

Also ...there are details I haven't mentioned that (when revealed) will make it more obvious why I don't think a 3" system will be of benefit.

Cleaned up an intake assy. for the project. Used thinners,rags and wire wheels ..... wont do it that way again , way too much work!
Tried to flow the channels with a wire wheel but don't think I achieved a lot from that.

https://cimg9.ibsrv.net/gimg/www.rx8...ded63cd9ba.jpg
https://cimg6.ibsrv.net/gimg/www.rx8...d31a233ce6.jpg

Looks good. The problem is always that uncoated aluminum is going to oxidize and discolor.

I’m not trying to argue with you, B. You mistook my previous commentary as being directed at you, but I was addressing Jakes comment. People just can’t get past what they think is the end-all of exhaust theory, which for the unique situation of the Renesis, it’s not.

Haven't had a problem with the last one I cleaned up ....but that has always been stored in a gge.

Is there a product I can spray on it to keep it looking good ?

I understand where you are coming from Team. A Rotary doesnt have air pulses like a piston engine. The theory isn’t exactly the same. You would know considering your time spent with these cars whilst i’m not a veteran here.

Just for his application and what he is trying to achieve, maybe that full 3” should be one of the last things considering the cost? Unless of course he has a mig welder, mandrel bender and a day or so.


Looking really good Brettus. It is clean as a whistle, so they say. Good things take time. Hope you wore gloves lol. Nothing like thinner in closed spaces :Freak_ani

Ummmmmm ....most of the time I did ...lol

Well Jake you still don’t have it right. It’s all about the Renesis not having any exhaust scavenging ability due to having zero overlap timing between the intake and exhaust cycle. This makes it different than any other modern day engine; rotary or piston. I’m not trying to beat you up. I’m trying to get people to understand, still ...

Much appreciated for the knowledge.

Just to clarify something ... this project isn't about putting every possible N/A power modification in place to get the highest possible WHP. I've already been down that path and spent way too much on practically useless mods in the past. Hence the reason I'm reluctant to replace what I see as a relatively free flowing exhaust system.

It's primarily about testing a porting idea that should produce more power without compromising the streeability of the Renesis too much. I am pretty confident that there will be some power gain , but how much that will be and whether it will be worth it for others to do the same .... I have no idea at this point.

I apologize if you feel like I’m digging you over it. It’s just after all these years my experience tells me that unless you can improve how it get’s out too to get a net overall improvement in dynamic resonance, then messing with the flow dynamics of the intake is more likely to have more negative consequences than positive. With the exhaust port limitation that means you have very little chance to move the powerband up. Mazda didn’t really leave much on the table for the existing powerband.

Even my own intake mods center around not trying to do anything more fine tune the intake to a higher level than Mazda considers feasible for production cost vs benefit purposes; blend/smooth abrupt transitions, reduce both intake and exhaust restrictions to the minimum possible, and so on. I’m intentionally not hogging out material or anything else that will alter velocity or volume significantly. Which I actually did take the grinder to a LIM and alter it a few years back, but then decided that was a mistake made more out of wishful thinking than careful consideration. So I decided to scrap it instead.

Because on a 6-port if you alter the LIM and it has a negative end result, then swapping it out is a big headache that either requires pulling the engine to do it properly or doing a potentially sloppy job trying to swap it out in the engine bay. So while I wait to see what it is that you intend to do, I remain skeptical on the final impact. Only because I understand how resonance dependent the system is for achieving the original design concept. While something may seem like a good idea conceptually, it’s unlikely you can conceptually understand what the resonance design impact is going to be.

the feedback I got from someone that had the experience, skill, knowledge, and facility to verify the actual results is nothing of notable value was achieved, mostly the opposite. The same was mostly true for porting, though up to 10 bhp (flywheel) was achieved, there’s a durability impact on the rotor sealing. That’s why I always scoff about XYZ porting mods that you rarely ever see any actual end results other than sales claims.

.

Well despite the fact that we disagree on almost everything ...... I think you know me enough to know that whatever happens ...you wont get BS from me. I wont be trying to make any money from this if it's successful.
The high probability of engine failure is perhaps one reason why this hasn't been done before,but I had a spare engine and like tinkering so .......... :)

Ok, because I have no idea what you have planned. :)

Engine is done ...but when I can fit it is a problem.
The engine in there seems too good to pull out ..... Been taking a look at a couple of 8s with blown engines as an alternative ....hmmmm decisions !
Just been getting Blueys' front bumper painted and painting the side skirts (myself ) so she will be looking mint.

Did you ever run it on a different dyno? Those oscillations didn’t seem right.

Nothing wrong with having a known good motor in hand. Introducing another car rather than keeping same introduces variability to the result comparison.

No ..... I'll just use the original dyno with stock manifold as a base I think.

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.

I posted a response in my header thread rather than here.

Certainly wont be doing any from this side of the Pacific. Although it was of fairly simple construction, it still cost me a lot to get it made.

In other news , I'm pretty sure that pulling the cat canister out and replacing it with a resonator has lost me power :( . Three VD pulls on different days all lower than before ..... maybe I was right about the cat providing some degree of 'settling' after the manifold.

It seemed like the previous numbers might be highly suspect. Perhaps you should start over on a different dyno if available. The other option is to replace the resonator, or convert it with flanges to be removable, and put a straight tube section in instead. That isn’t going to hurt power.

Not really sure what you’re thinking is with the “settling” comment. Imo the OE cat housing transitions are too abrupt without the honeycomb cat substrate in place. Or at least the inlet transition for sure. You could even flange an open cat section and try all three. I don’t see that helping flow/power though.

I think you are focusing too much on the red line in that dyno ... which I agree is suspect. The blue line ,however, is fine and I have no reason to believe the result isn't realistic. As I mentioned earlier , I've dynoed several other RX8s on this same dyno and got results consistent with what is expected. Stockish freash redbuild .... 195whp . Race prepped new rebuild ..... 205-210whp.

Re the resonator ... I was tossing up as to whether I just did as you suggested and put a straight 3" pipe in place of the cat or fit the resonator . I did the resonator because I thought it would improve the accoustics. Might rethink that. Suffice it to say ...the original setup with a 3" pipe going into the stock cat was a good one as far as power went.