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Interesting... i went and bought 3 RX8's last week for their engines. I really want to do some flow tests on the exhaust ports to see if they all flow the same.
I don't believe it is even possible to do that as it's highly unlikely you will be able to replicate the dynamics of the siamese port accurately.
However ,from all my experimentation and observation, my estimate for the siamese is that it flows somewhere between 35 and 40% of the total flow from the engine.My turbo setup uses the siamese for wastegate duties, so It's not hard to work it back when I know how much the wastegate needs to flow to achieve a certain minimum boost level.
So looking at that in terms of the middle rotor of a 3 rotor engine having two siamese ports..... at lets say 38%, you would get an overall reduction in exhaust flow from that rotor of around 100 -38 -38 = 24%
What that means in terms of power loss is anyone's guess ...... but it would certainly affect it.
a flow test is meaningless once you understand how a Renesis rotary engine works, but then you still don't have a full grasp on that so not unexpected
Its not meaningless. Once i do the tests i will post up my results. I will also show tests on a pp exhaust housing. Happy to teach you about exhaust flow etc. I do have alot of other work on at the moment so results wont be available for a little while yet.
Its not meaningless. Once i do the tests i will post up my results. I will also show tests on a pp exhaust housing. Happy to teach you about exhaust flow etc. I do have alot of other work on at the moment so results wont be available for a little while yet.
One question : Have you actually ever had a Renesis Siamese port sleeve in your hands?
Its not meaningless. Once i do the tests i will post up my results. I will also show tests on a pp exhaust housing. Happy to teach you about exhaust flow etc. I do have alot of other work on at the moment so results wont be available for a little while yet.
ok Mr Bluster, well I’m looking forward to how you can flow test a rotary port the same way they test a head with a valve, especially the siamese exhaust port. Sure, you can push some air through a fully open port, but there’s a lot more to it than that. It might not be as clear to others as me, but you still don’t have a grasp on the dynamics involved.
ok Mr Bluster, well I’m looking forward to how you can flow test a rotary port the same way they test a head with a valve, especially the siamese exhaust port. Sure, you can push some air through a fully open port, but there’s a lot more to it than that. It might not be as clear to others as me, but you still don’t have a grasp on the dynamics involved.
maybe they’re related.
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I think you will find the dynamics on flow testing a rotary port will be different to that of a piston engine.
Im not sure exactly how i will perform the tests as yet but have a few ideas.
Also open to other people's opinions on how they would measure airflow.
let me just throw this in here; there’s a reason the OE exhaust manifold gasket openings are so big compared to the port opening size in the inserts that almost nobody seems to understand why that is ...
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let me just throw this in here; there’s a reason the OE exhaust manifold gasket openings are so big compared to the port opening size in the inserts that almost nobody seems to understand why that is ...
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let me just throw this in here; there’s a reason the OE exhaust manifold gasket openings are so big compared to the port opening size in the inserts that almost nobody seems to understand why that is ...
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It sure looks like an anti-reversion step to me. Is that what you think as well?
that may gave increased flow B, but it had a lot of negative consequences, where was it flowing to?
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It was flowing to where it should ...into the manifold. If it were going anywhere else I would have noticed a drop in power ...I didn't.
As far as why I took it out ... that was more to do with my unconventional manifold design than anything else. In hindsight , I probably should have tried pushing the engine to breaking point with that still in there ...it may have given me a few extra hp.
Take a look at the marks on the side of the insert. With engine still in the car, I got a dremel tool and cut through the tension pins so I could pull the insert out. I then fitted shims such that the manifold flange held the new insert in place.
Which I’m busy working on more *interesting* things at the moment than engaging in an online bickering-fest, so please don’t try to read anything into my silence. Back when that post was made my life was in a bit of a crisis. I wasn’t on the forum much and never saw it then.
So being entirely honest about it, I missed that post by B. Clearly he was aware of this back several years ago and I was mistaken on that point, thinking that he wasn’t. Which, I haven‘t had a chance to dive in an review everything fully yet, but some of the things he’s posting now seem counter to that post. IMO he had it figured out even before I fully recognized it, yet I’m not sure why his head seems to be someplace else on it now. Whether he changed his position or not, I’ll leave that for him to say.
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Yes , at one stage I was convinced that was the issue, same as you are now. I'd actually forgotten about that sketch I made a few years back so thanks for reminding me.
In an attempt to resolve the issue, I had a sleeve made up that totally sealed off all of those potential flow paths (I did mention this earlier but you must have missed it.) Result of this was ...no difference whatsoever.
It was after that failed attempt that I came up with the port timing theory, which as of today, I still believe is the actual issue.
07-13-2020, 02:07 PM
