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Was just curious to see difference in turbo threshold, VD should give that answer pretty clear.
I think you'll get pressure earlier if you floor it in a high gear, compared to 2nd gear, since RPM isnt climbing as fast. For a dragrace that does not matter much, but say that we get pressure 3-500RPM earlier in 5th, it means it will feel even quicker for everyday driving and cruising. This difference is noticeable in my other car, but thats only 1.75l.
Yes ...it's as you say . I do most of my logs in 3rd .... and that was where the 12psi @35-3600 figure came from. In second it's a good 4-500 rpm later . And in the higher gears earlier.
Just came back from a 900 mile road trip (to tune five rx8 race cars on dyno). Wanted to see if the new manifold would hold up ok under extended cruise conditions. No problem at all , car performed great and even managed to break my record for miles on one tank of gas (320) . The better spoolup really does make a difference ...especially in high gear overtaking with just rolling on the throttle and blitzing past without even changing gear.
Just like a smaller A/R twin scroll should. I never could put my finger on why it wasn’t working out that way before in our long ago previous “discussion“ over 1.06 vs smaller especially for a Renesis. Why do you think it was that way then?
You didn’t run yours on the dyno too while you were there?
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I think it was two things .
1/ The original design directed almost half of the pulse energy (siamese port) into a dead end (until the WG opened ) . This meant there was nowhere for exhaust gasses to go except back into the chamber or into the opposing rotor. As the larger turbine used more flow from the outer ports , the effects of this were reduced with a bigger turbine housing. So even though the smaller AR did spool the turbo a little earlier, it wasn't making the same mid range torque, which defeated the purpose of using it. With the Later iteration of that design I gave the siamese gases somewhere to go ,via a balance tube, which helped eliminate this issue.
2/ The pulse energy on the new design is much more effectively utilised via the rear port having a straight shot into the turbine.
So the smaller AR is now much more effective as there is no dead end for siamese anymore and it gets a decent pulse on one side of the twin scroll.
Re the dyno : Not what I went for . There are plenty of dynos up here I can utilise.
I moved on by deleting what I didn’t consider relative or not conveyed clearly
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Thanks for making me look like I'm arguing with no-one .... annoying to go back and read the thread now. So from now on I'll go back to quoting everything you say (haven't been doing it after our discussion on that topic) so you can't go back an do that.
Originally Posted by TeamRX8
Which due to phase timing of the two rotors, there is a period when the exhaust cycle between them overlaps with the siamese port being open on both rotors at the same time; as the exhaust cycle on one side is closing (lower pressure) the exhaust cycle on the other rotor is opening (higher pressure). What occurs in the NA configuration during this overlap period is not the same as when turbine backpressure is introduced.
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I've proved (to myself) that backpressure does not cause any crossflow contamination at all by making a sleeve that sealed off any chance of this. I took the engine with this sleeve in place to over 400whp and there was ZERO difference in performance from a standard sleeve. I will concede there is still a chance that this happens once the engine chokes in the 400plus range as I never tested that engine to breaking point.
Originally Posted by TeamRX8
I disagree with the flow percentages being estimated. It’s important to understand they are only estimated.
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Yes the flow percentages are estimates . It's all very well for you to disagree but you give no basis and provide no backup info to make this assertion. My estimates are based on years of trials and observations of what happens with various combinations. I have many examples that corroborate this. What do you have ?
Originally Posted by TeamRX8
It’s equally important to understand they’re not fixed values either, but will vary by engine rpm, the distribution of pressure as influenced by the manifold flow paths, the turbine A/R, the turbo impeller size configuration and so forth.
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Agreed , and have stated this previously.
Originally Posted by TeamRX8
In particular, my perception of the comments is that the impact of A/R relative to the distribution of pressure and flow between the two turbine scrolls; which will be determined by the configuration of two divided paths of the manifold, and how it will affect those flow percentages is not being fully realized.
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Maybe not fully ...but getting close to understanding it . Certainly more so than you appear to.
Originally Posted by TeamRX8
The design is simple, but perhaps too simple. It’s my belief that keeping the three ports on separate flow paths is the way to go. One example of this is the RX8Performance turbo system manifold as JCB is using on his RX8. That design is based on an open V-band turbine though. The way to address it with a divided scroll is to accept that we can never fully separate and isolate the exhaust streams due to the shared siamese port. Be that as it may, I still believe keeping the three port flows separate with a dual scroll turbine housing has value. It’s how the middle siamese pipe is configured and joined at the divided turbine flange that will determine how well it works.
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Again , you are merely theorising. We wouldn't have advanced the way we have if we all just parroted information out of books and didn't try things that others thought wouldn't work. I would happily compare my setup to others out there and based on what i've seen (remember ...I've tuned dozens of different turbo setups) It would stand up to that kind of scrutiny exceedingly well.
yeah, that’s where we’re different. I’m not interested in playing the reply-copy gotcha game and holding stuff over someone’s head. What was mostly deleted was useless bickering. I thought you might have enough sense to then go back and clean up your own to match. Which I did then restate my position in more clear terms. Nothing was actually lost from what my intended points were. Just the useless clutter was removed.
I actually gave my basis in another thread, again not trying to keep the bickering going on as you seem to so crave. Which also again, you have nothing to base what I know and am doing on. You think just because it’s not posted on here makes you the expert on that. You basically refuse to believe in God for the same thought process. Well why would he bother to reveal himself to anyone with that attitude? Whether you believe in either situation is irrelevant to the truth. I’m willing to stand on those points regardless of whatever you think your experience and insight is.
I actually had concluded that we were finally getting past all that. I even stated that it wasn’t to get into any debate or challenges, but to clarify what was already said. Rather disappointing to be honest.
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yeah, that’s where we’re different. I’m not interested in playing the reply-copy gotcha game and holding stuff over someone’s head. What was mostly deleted was useless bickering. I thought you might have enough sense to then go back and clean up your own to match. Which I did then restate my position in more clear terms. Nothing was actually lost from what my intended points were. Just the useless clutter was removed.
I actually gave my basis in another thread, again not trying to keep the bickering going on as you seem to so crave. Which also again, you have nothing to base what I know and am doing on. You think just because it’s not posted on here makes you the expert on that. You basically refuse to believe in God for the same thought process. Well why would he bother to reveal himself to anyone with that attitude? Whether you believe in either situation is irrelevant to the truth. I’m willing to stand on those points regardless of whatever you think your experience and insight is.
I actually had concluded that we were finally getting past all that. I even stated that it wasn’t to get into any debate or challenges, but to clarify what was already said. Rather disappointing to be honest.
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Well ... before you went back and made the thread unreadable I was happy to let what was said stand and move on. But then I realised what you did and how it messed up the flow of the thread.
So at the risk of repeating myself - I decided your points needed re-addressing.
As for the religious comment ..... you know not to bring that up on here, are you trying to bait me into an argument on that? Quite happy to have that convo in private ...
No baiting. We both know our positions on that and neither am I trying to have a discussion on it. Because knowing that between us simply reinforced the point I was making. You get so focused on minutia that the bigger picture is being missed. Just like you’re overlooking the obvious right now.
You get so focused on minutia that the bigger picture is being missed. Just like you’re overlooking the obvious right now.
Small leaks sink great ships.
If anything, I'm more of a big picture person though, maybe you haven't noticed that I'm time rich? That didn't come by focusing on minutia.
But if something works or doesn't work, I'm interested to know why. Which is when I like to delve into the minor details to see what's what.
you know Brettus, rather than post a novel-length reply I’m just going to let you believe what you want. What I will say is that you’re just doing the same thing again with this manifold as the previous one. It’s just a different set of circumstances is all. You were convinced for years on that one, and now you’ve convinced yourself on this one. What you call theory are facts you’re either not aware of are refusing to acknowledge. You refused to acknowledge me before and even though it played out that way, you refuse to hear me again. Hopefully it won’t be another 5 years before you find out that it’s still not as optimized as you had convinced yourself it was, again.
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The previous manifold worked well and this one works better ,dunno why you can't see it that way.
Is it perfect ? No
Can there ever be a perfect manifold for the Renesis ? I doubt that
Is it better than others out there? absolutely
Is it the best that ever been built ..... dunno ...............maybe.............. maybe not. Find one that works better ... lets do a comparison. I'm definitely up for that!
Team,
I'm trying to follow and understand precisely what point(s) you are making.
Originally Posted by TeamRX8
I moved on by deleting what I didn’t consider relative or not conveyed clearly....
As responded to you in my thread ...
Originally Posted by jcbrx8
... I quote the salient portion to what I'm replying ...to make clear to what I'm replying and to avoid the person deleting it, and rendering my response vague, confusing or meaningless. . ...space isn't really an issue...w/ the digital thing you know. So, IMV it's simpler...cleaner.
Do you not stand by what you "yourself" think & write?
Originally Posted by TeamRX8
...but will say the following and let it stand on it’s own... When backpressure is introduced, the impact on flow is not necessarily as perceived.
Which due to phase timing of the two rotors, there is a period when the exhaust cycle between them overlaps with the siamese port being open on both rotors at the same time; as the exhaust cycle on one side is closing (lower pressure) the exhaust cycle on the other rotor is opening (higher pressure). What occurs in the NA configuration during this overlap period is not the same as when turbine backpressure is introduced..
Valid point to articulate the dynamics of the working. B, has tested and stated what his experience and testing revealed. In your experience, and testing what have you found actually occurs in this situation between rotors via the Siamese port in a FI application?
Originally Posted by TeamRX8
I disagree with the flow percentages being estimated. It’s important to understand they are only estimated. .
What does this collection of "words" mean? And what do you make of the strong performance of B's manifold design? How can that be argued against...unless one produces better?
Originally Posted by TeamRX8
In particular, my perception of the comments is that the impact of A/R relative to the distribution of pressure and flow between the two turbine scrolls; which will be determined by the configuration of two divided paths of the manifold, and how it will affect those flow percentages is not being fully realized. Even though a net manifold pressure value may be detected and recorded, we can’t forget that the pressure of the combustion gasses from each rotor is essentially a pulse with it’s own variation of high to low pressure relative to the exhaust port open-close cycle..
Valid observation here regarding the dynamic pulsing nature of the exhaust. Though I find it difficult, no... impossible, to believe that B didn't take that into consideration.
Originally Posted by TeamRX8
The design is simple, but perhaps too simple. It’s my belief that keeping the three ports on separate flow paths is the way to go. One example of this is the RX8Performance turbo system manifold as JCB is using on his RX8. That design is based on an open V-band turbine though. The way to address it with a divided scroll is to accept that we can never fully separate and isolate the exhaust streams due to the shared siamese port. Be that as it may, I still believe keeping the three port flows separate with a dual scroll turbine housing has value. It’s how the middle siamese pipe is configured and joined at the divided turbine flange that will determine how well it works.
Your opinion here is clear. Is this simply "theory"?If not..., on what experience / testing is it based? And how do you interpret B's finding that testing w/ a sleeve which prohibited cross flow found zero affect on performance... indicating that either a) there is no cross-flow typically, or b) that cross flow is of such minimal level as to be insignificant?
Originally Posted by TeamRX8
...What I will say is that you’re just doing the same thing again ...
Originally Posted by Brettus
The previous manifold worked well and this one works better... Find one that works better ... lets do a comparison....
Originally Posted by TeamRX8
I don’t know why you didn’t get it a long time ago otherwise we’ll see.
??? Which is it: Is he doing the same thing again...or has he now gotten it right?
Edit:Since this post... I see you've deleted this last statement. So........, when necessary you simply "unsay" (delete) your conflicting or inconvenient comments? Nice.
And how do you interpret B's finding that testing w/ a sleeve which prohibited cross flow found zero affect on performance... indicating that either a) there is no cross-flow typically, or b) that cross flow is of such minimal level as to be insignificant?
Just in case anyone doesn't think I actually did do this :
I actually lost an engine AND a turbo on that f'n sleeve when the divider disintegrated!
A few of the other iterations I've experimented with
Unfortunately the divider failing is an issue even on NA competition engines; new center plate on my latest build out of an abundance of caution by the builder sho has seen it all.
I never doubted that you didn't do what you claimed to have done. The conditions under which an experiment occurs greatly affects the outcome. Just like trying to duplicate the Mazda patent without fully understanding why it wasn’t being applied properly. Which that one patent is Mazda’s technologically complicated attempt to address that overall issue, but again under a very specific set of circumstances. If the siamese port isn’t the issue, then why go to all the effort and expense?
You still haven’t connected all the dots on the things I’ve stated; not just here, but in other threads too. Again, what you keep referring to as theory are facts you either don’t fully comprehend or refuse to accept as such. You also keep accounting them as belonging to me, but they aren’t mine; they exist as truth for those with the eye to see and the ear to hear.
Further, I’m not going to engage other people trying to start their own drawn out peeing match here. The same when I’m having a discussion with them in their thread. I’ve both dug and fallen into that pit too many times.
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Just like trying to duplicate the Mazda patent without fully understanding why it wasn’t being applied properly. Which that one patent is Mazda’s technologically complicated attempt to address that overall issue, but again under a very specific set of circumstances. If the siamese port isn’t the issue, then why go to all the effort and expense?
I hope you aren't referring to my N/A build with the mini pp exhaust ? There was no attempt on my part to try replicate what they are trying to achieve.
Originally Posted by TeamRX8
If the siamese port isn’t the issue, then why go to all the effort and expense?
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I find it quite funny to think that this is what you are basing your argument on ....what you are actually saying in my eyes is that you have no clue but .........gee whiz .....look what Mazda did!
As someone who has spent several years fighting against the siamese ports' pulse dampening effect to try and get the best possible turbo spool from a Renesis, it's plainly obvious to me why Mazda dropped it in the side port turbo patent.
...Further, I’m not going to engage other people trying to start their own drawn out peeing match here...
Seriously? I'm fairly astounded that all it takes to make YOU .... "take your ball and go home".... is a few legit questions requiring you to defend / clarify your thoughts regarding relevant thread discussion.
That new manifold design of yours makes me wonder how much improvement might be seen from putting a wastegate in the same spot on a Greddy manifold/T25 setup.
How was the manifold fabricated? Hard to tell with the black coating, but looks like sheet steel cut and joined to make a rectangular cross section?
Maybe you could price up getting your manifold forged and doing a run of 5 of them. I imagine they'd get snapped up pretty quickly.
That new manifold design of yours makes me wonder how much improvement might be seen from putting a wastegate in the same spot on a Greddy manifold/T25 setup.
How was the manifold fabricated? Hard to tell with the black coating, but looks like sheet steel cut and joined to make a rectangular cross section?
Maybe you could price up getting your manifold forged and doing a run of 5 of them. I imagine they'd get snapped up pretty quickly.
I don't think it would work on the Greddy. You need the log to act as a balance tube as it swaps over from no WG to full WG and one outer port doesn't flow enough to do full WG duties by itself. I think it might boost creep into the mid teens but too hard to tell really because there are so many other factors that come into play.
Manifold is a just piece of mild steel thickwall RHS.
I had thought about making a few the same then once they are out there and running without issues .....Get some investment cast SS ones made.
Got hold of some ethanol and upped the boost to 14psi with E40.
Doesn't look like the new manifold is a restriction so far. EMAP looking fine at 23psi peak.
Torque at 4000 highest I've seen for a renesis.
To add to the above:
The pressure ratio Emap/Imap with the 0.83AR hsg. has dropped from 1.9 at 10psi to 1.6 at 14psi which reinforces my earlier theory about how the manifold is working , and disproves Teams' keyboard warrior notion that the manifold is restrictive.
I was just reading Jimmy's journey on measuring back pressure. It seems as per his results and yours, the biggest contributor to back pressure is the turbine size and not the manifold. Cheers for the great results and specially the data!
I was just reading Jimmy's journey on measuring back pressure. It seems as per his results and yours, the biggest contributor to back pressure is the turbine size and not the manifold. Cheers for the great results and specially the data!
yeah , turbine and AR are biggies but the rest of the system as a whole makes up a big % of it as well. Probably the worst offender for most setups will be the exhaust system.
09-08-2020, 02:45 PM
And what do you make of the strong performance of B's manifold design? How can that be argued against...unless one produces better?
So........, when necessary you simply "unsay" (delete) your conflicting or inconvenient comments? Nice. 
So, IMV it's simpler...cleaner. 
