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RGHTBrainDesign - Rotary Engine Development Projects

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RGHTBrainDesign - Rotary Engine Development Projects

Old 09-16-18, 10:18 PM
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Originally Posted by Skeese View Post
So you mean the the butterfly plates in the fd uim? The very first thing anyone does when they pull a uim off is rip those out and toss them in the trash...

Their entire point is to ensure you dont see substantial throttle when the engine is cold regardless of what you do with the pedal, which can be countered with the use of a modern ecu.

If you are going to do that anyways for the purpose of having independent control of the secondary throttle plates why not use a FD tb in the first place? Under what tuning scenario would you need it to be different than the way the mechanical linkage works as it is?

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I can think of multiple if you're trying to build a fully functional oem-like build. Partial throttle lockout for valet modes, much easier and repeatable staging points unrestricted by the diaphragm used in stock configs, interesting traction control strategies that some OEMs are doing. It's just a nerd toy but I like the idea of DBW now that we have ECUs that are somewhat affordable to control it.
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Old 09-16-18, 10:50 PM
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Originally Posted by dguy View Post
repeatable staging points unrestricted by the diaphragm used in stock configs
In the OEM setup, staging is done mechanically via the throttle body linkages, not by diaphragm (although I'm not disagreeing with you that doing electronically allows you set up staging points wherever you want).

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Old 09-17-18, 12:30 AM
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Originally Posted by Skeese View Post
So you mean the the butterfly plates in the fd uim? The very first thing anyone does when they pull a uim off is rip those out and toss them in the trash...

Their entire point is to ensure you dont see substantial throttle when the engine is cold regardless of what you do with the pedal, which can be countered with the use of a modern ecu.

If you are going to do that anyways for the purpose of having independent control of the secondary throttle plates why not use a FD tb in the first place? Under what tuning scenario would you need it to be different than the way the mechanical linkage works as it is?

Skeese
You and I both love the Haltech Elite. It has Dual Runner Control, in which you can plot the solenoid that triggers this vacuum module in the UIM perfectly. Why you aren't using it on a Semi-PP motor specifically is beyond me, but then again, I'd never consider running an FD throttle body. For HUGE ported engines (Semi-PP and Half-Bridge), you'll gain vacuum by having the motor run only on Primary Runners (streetported or whatever) in which you inherently make more torque at lower RPM and drivability is SUPERIOR. Open the Secondaries up as you wish using ECU control of MAP vs. TPS vs. RPM or whatever you want. Estimated Airflow based on Estimated Fuel Flow x AFR. Possibilities are endless and you should remember to open this up before secondary injector staging starts up.

I think that DBW is the way to go for boost control, transient fueling calculations, efficiency, etc, but to each their own. I'd also rather trust a little set of 22ga wires in an aftermarket application than a custom cable when grafting in a motor into a car that didn't have it originally. That's MY perspective though, as I don't ever intend on owning an FD. Love your input, but I'm crystal clear as to WHY I think this is a smart decision for those with aftermarket configurations. On a factory FD, just run it with factory components... Go big or go home applies here.
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Old 09-17-18, 11:10 AM
  #29  
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Originally Posted by KYPREO View Post
In the OEM setup, staging is done mechanically via the throttle body linkages, not by diaphragm (although I'm not disagreeing with you that doing electronically allows you set up staging points wherever you want).
People seem to be getting this confused. What RBD and I are referring to are the secondary throttle plates in the manifold that are pressure actuated, not the secondary plates in the throttle body that are mechanically actuated. Hence (and he corrected me on this the other month because even though I've been looking at my manifolds and deciding on the DBW setup I'm a 'tard) using a DBW throttle and some sort of stepper/solenoid to open the plates in the manifold.
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Old 09-17-18, 11:32 AM
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Originally Posted by dguy View Post
People seem to be getting this confused. What RBD and I are referring to are the secondary throttle plates in the manifold that are pressure actuated, not the secondary plates in the throttle body that are mechanically actuated. Hence (and he corrected me on this the other month because even though I've been looking at my manifolds and deciding on the DBW setup I'm a 'tard) using a DBW throttle and some sort of stepper/solenoid to open the plates in the manifold.
You would think after three videos and a full explanation that it would sink in. I think it's laziness and lack of comprehension before "debating" this small project.

The thing this thread needs is MORE projects of value. I already have one figured out for us, so let's move on and continue progressing with engine control systems.
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Old 09-17-18, 06:47 PM
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Originally Posted by dguy View Post
People seem to be getting this confused. What RBD and I are referring to are the secondary throttle plates in the manifold that are pressure actuated, not the secondary plates in the throttle body that are mechanically actuated. Hence (and he corrected me on this the other month because even though I've been looking at my manifolds and deciding on the DBW setup I'm a 'tard) using a DBW throttle and some sort of stepper/solenoid to open the plates in the manifold.
I'm not getting confused about anything. I'm clearing up confusion. If the merits of this modification are to be evaluated, it is important to determine the parameters of what is being compared. You referred to a benefit of RBD's approach being "much easier and repeatable staging points unrestricted by the diaphragm used in stock configs". The stock config, while involving a vacuum driven actuator, does not do any sort of staging via pressure. The secondary throttle plates in the UIM are purely on/off dependent on coolant temperature - that's all they do - so it does not present any kind of limitation or restriction on the staging of primary vs secondary intake port timing as your post suggested. The actual staging is done via the throttle body, mechanically. The secondary plates will transition from closed to open by reference to a fixed throttle opening angle, but even this could be easily modified/tuned by playing with the linkages (eg you have a ported engine and want to maximise low load torque). This is actually a simple, repeatable, 100% error-free method of staging and has nothing to do vacuum. Arguably it is also more reliable as the secondaries will never get stuck closed through faulty solenoid, vacuum leak, cracked hose etc (although I'm sure RBD will have those bases covered).

Now, in RBD's approach, because he has a single plate DBW throttle body, he loses the mechanical staging but could potentially reintroduce some form of primary/secondary staging by controlling the UIM double throttle plates. Therefore, the comparison being done is between primary/secondary staging by throttle position alone (the OE setup) vs primary/secondary staging based on (potentially) multiple parameters.
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Old 09-17-18, 07:04 PM
  #32  
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Originally Posted by KYPREO View Post
Therefore, the comparison being done is between primary/secondary staging by throttle position alone (the OE setup) vs primary/secondary staging based on (potentially) multiple parameters.
I suppose so.

I wasn't going to bring this up on here since I don't think anyone else is doing it, but the whole Throttle Mass Flow with the Emtron KV8 can utilize those Pre-TB and Post-TB MAP sensors as a high-flow Mass Air Flow, so my hidden agenda was to actually control this using throttle mass flow generated by those. The one that pertains to everyone though is MAP vs. RPM.

After hundreds of hours behind a laptop with the Honda doing secondary butterflies in the intake manifold and blending with VTEC, it became apparent to me that there should be more than just a TPS relation (mechanical linkage) to controlling primary/secondary transition. Going WOT on a factory FD throttle body will just dump open the secondary butterflies which as you can guess, will LAG the system.

I truly believe a 90mm DBW TB is superior to a factory FD or more specifically FC (in my case since I had a 13BT grafted into my 1st Gen Rx7), and therefore am building systems around it to give me power out of the hole on corner exit in tight mountain roads. That's what this ONE experiment is about. Just getting that low RPM torque out of a small displacement motor. Sure as **** works for the Honda, so believe me when I say we can do it better for the Rx7.

So this is good and done. Let's move on and continue development on another project. Any ideas?

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Old 09-17-18, 07:41 PM
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you might think about looking at how Mazda did this with the Rx8, they call it an SSV
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Old 09-17-18, 11:10 PM
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If you don't mind a huge project, I think it would be interesting to try an intake setup similar to the E46 BMW M3. Those engines use DBW-actuated individual throttles near the intake ports plus a very large IAC solenoid. The IAC solenoid is so large they use it to supply all the airflow when cruising, the DBW throttles are completely shut. This seems to solve the problem of synchronizing lots of individual throttles at low throttle angles. If I had lots of time and money to burn I would try to build something like this for a peripheral-ported engine, possibly retain the OEM side ports but ideally I'd like to block them off completely.

On the more realistic side of things, I'm very interested to try an ECU-controlled exhaust cutout before the cat converter. If you haven't seen the Monsterbox build thread in the 3rd Gen section, it's one of the many cool things he's doing plus cheap enough that I could justify spending money on it. The car might have some hope of smelling OK at idle, and you could still have all the benefits of less exhaust backpressure at full throttle.
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Old 09-17-18, 11:43 PM
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Originally Posted by scotty305 View Post
On the more realistic side of things, I'm very interested to try an ECU-controlled exhaust cutout before the cat converter. If you haven't seen the Monsterbox build thread in the 3rd Gen section, it's one of the many cool things he's doing plus cheap enough that I could justify spending money on it. The car might have some hope of smelling OK at idle, and you could still have all the benefits of less exhaust backpressure at full throttle.
There is a seller in Australia who has been developing high performance rotary-specific mufflers and exhaust components for many years called AES. He also has a range of butterfly cut-out valves specifically for this purpose. They are engineered to tolerate turbo rotary exhaust temps. Some have been used to control EWG dump pipes, while others for reducing noise or tuning exhaust backpressure. There's some info here: Active Exhausts and Active Exhausts Information plus some of his more recent product developments are showcased on his Facebook page.

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Old 09-18-18, 02:13 AM
  #36  
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Originally Posted by scotty305 View Post
If you don't mind a huge project, I think it would be interesting to try an intake setup similar to the E46 BMW M3. Those engines use DBW-actuated individual throttles near the intake ports plus a very large IAC solenoid. The IAC solenoid is so large they use it to supply all the airflow when cruising, the DBW throttles are completely shut. This seems to solve the problem of synchronizing lots of individual throttles at low throttle angles. If I had lots of time and money to burn I would try to build something like this for a peripheral-ported engine, possibly retain the OEM side ports but ideally I'd like to block them off completely.

On the more realistic side of things, I'm very interested to try an ECU-controlled exhaust cutout before the cat converter. If you haven't seen the Monsterbox build thread in the 3rd Gen section, it's one of the many cool things he's doing plus cheap enough that I could justify spending money on it. The car might have some hope of smelling OK at idle, and you could still have all the benefits of less exhaust backpressure at full throttle.
I feel like that's super easy. Just implement the exact same control strategy as the UIM Secondary Throttle solenoid and have it control a vacuum solenoid cutout or electronic motor. I was going to do this with my factory choke **** on the FB as an override.
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Old 09-18-18, 02:36 AM
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Nice use of choke ****. I have been thinking of what to use mine for. I'm going to try to install a rotary potentiometer behind it and use it as a boost trim.
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Old 09-29-18, 03:22 PM
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The next real thing in my to-do list is an overdesigned intake manifold heatshield.
  • Tri-layer Design
  • Covers Top of Turbine Housing to Protect Hood, Full Exhaust Manifold, Wastegate Pipes (Wastegates need fresh air), and part of the downpipe.
  • Mica Outer (closest to exhaust)
  • Ceramic/Fiberglass Inner (Air Insulator)
  • Mica Inner (closest to intake)
  • Standoffs from Intake Manifold UIM/LIM Studs and Shock Tower (either side)
  • Full Heat Transfer Equations on here... I'll compare materials and placement with real figures. Might as well throw real engineering behind the efforts.
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Old 09-29-18, 08:32 PM
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Heat shields are cool, but the intake manifolds are going to tend to get hot because they're strapped to the engine block. Nobody had had much luck with phenolic spacers on the lower manifold, but it might work with the upper. Even then, there's negligible heat transfer from hotter-than-ambient charge air and hot-as-the-block intake manifold, due to a relative lack of surface area and the sheer speed of the charge air.

Cool project though. Be interested to see what you come up with.
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Old 09-30-18, 06:17 PM
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Originally Posted by Narfle View Post
Heat shields are cool, but the intake manifolds are going to tend to get hot because they're strapped to the engine block. Nobody had had much luck with phenolic spacers on the lower manifold, but it might work with the upper. Even then, there's negligible heat transfer from hotter-than-ambient charge air and hot-as-the-block intake manifold, due to a relative lack of surface area and the sheer speed of the charge air.

Cool project though. Be interested to see what you come up with.
The phenolic spacers are just like polyurethane for suspension. Good for about a week before failure. Great point.

What I was referring to here was an exhaust manifold cover that's located between the shock tower, over the turbo, manifold, and downpipe, and connecting to the intake manifold.

Besides going with the HeaderShield cover for my entire setup, this will be a serviceable/removeable heatshield that is more for protecting paint and cleaning up the engine bay. I think the way Eric Xue (Corner Balanced) did his header heatshield is a perfect example. I'll link it here, just imagine it with two outer shells and a fiberglass/ceramic inner insulation.


I know he did a later video showcasing the work from my buddy (FFR Fabrication), but this is the one I could find.
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Old 10-04-18, 02:33 AM
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Just as first hand feedback from a relatively repeatable exercise, i used to regulary notice a drop in torque while at "heavy cruise" up a steep hill near where I was living which corresponded with the engine reaching 70C. I had attributed it to charcoal cannister vent becoming active or a crude step in fuel/ignition trims in the apexi but the throttle staging makes sense, i would have to apply more throttle to then maintain speed. If I switch to a better ecu I will definitely map it. Even if the resolution on the combustion pressure sensors isn't great at those low loads being able to log 30 mins or more of data for averaging at lower engine speeds on the plex should give pretty decent results for genuine on road conditions.
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Old 02-14-19, 01:23 AM
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I have been planning out my next build and was also thinking about how to use and control the secondary throttle to retain the progressive nature of the throttle. I was thinking more along the lines of an electric motor control them with the ECU but your much further into it. Wish I saw this sooner. With all the modern ECU's being used these days, I'm surprised this has not been tried yet that we know of.

In your video I see you can open and close the secondaries without interference with the FFE adapter and GM TB. Have you check for interference when the DBW throttle butterfly moving thru its range? I know you mentioned turning the TB upside down, which would change the way the b'fly travels. I would think you want it so that the b'fly opens inward from bottom so the air would be better directed to the primary runners.
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