ramses666

iTrader: (1)

Thank you for the responses & interest. I apologize for my Passive-Aggressive Taunting. Technical discussions can be a little boring & I tend to try to whip up some feelings one way or the other. If your get Smoke or Blood coming from your eyes or ears I'm sorry.

I mention Renesis improvements & many other factors contribute to it's higher output as mentioned by others - higher compression, side exhaust ports & scalloped rotors are the more obvious - but the intake improvements are where I've been focusing for this discussion.

It's just long & drawn out to explain How I can actually control the whole system & make it function properly when that's not really the issue for me here. The issue is "Will lowering the intake manifold pressure at WOT give any improvement in flow?" & "Will un-coupling the VDI from the air-box circuit accomplish this with a Ram-air inductor" & "What kind of improvement might we anticipate?"

I would answer Yes, Yes & Maybe 10% more flow?

RotaryEvolution

iTrader: (30)

comparing a 2nd gen engine to the renesis is apples to oranges though. the rx8 irons are thicker and so the secondary/auxiliary ports can be larger than you'd ever get with the FC irons.

also keep in mind that the rx8 is claimed to have more power than it does have in reality, in the real world the 6 port engines only put out about 195 horsepower at the wheels. that is with full emissions though, so not too shabby, comparably to what some people manage to urk out of a 6port FC engine stripped and tuned.

Evil Aviator

I can't speculate on any possible gains from tuning, but if you design a proper divergent duct then the estimated ram air pressure gain is as follows: PSI = (mph)^2 * 0.0000176. Therefore, at 50mph you are looking at a 0.044 psi gain which is about 1/2 hp on an NA street engine.

Also, you can use the below app.
Ram Air Calculator

^ This

ramses666

iTrader: (1)

Hmmm... Thanks for the Ram-Air calculator... I still need some Manifold Pressure Values for the stock setups to calculate the Difference in Pressure. The Ram-Air MPH value is not usable without the baseline vacuum at WOT.

The Divergent Ducting is a great term & it should be understood that there will be some resonant flow through the stock air system when the Divergent Duct is opened... Something like making a beer bottle whistle by blowing across the top at the correct angle & pressure.

If I measure the Ram-Air inlet area as the opening on the turbo hood & the outlet area to the VDI I can determine the pressure change at 50 MPH as:

Inlet area = 20 divided by:
Outlet area = 5.84 gives
Ram Multiplier Factor = 3.42 multiplied by
Pressure at 50 MPH = .044 PSI Yields
VDI inlet pressure at positive .15 PSI

If I had the Stock vacuum values at WOT I could get the difference. It's not quite that simple because the stock air system is left out of the VDI inlet calculation. The stock inlet size to the VDI is about 8 square inches. I could modify the Ram Air Outlet Size, but the Multiplier factor would drop & the gains would diminish.

Figuring out what the Average flow rate is going to end up being seems to require some Helmholz Resonator Calculations to figure out the pulse width, but I could try & hazard a guess of a Net 1 PSI of Boost instead of a Negative Vacuum State?

Maybe we can change the calculations and use the combined VDI Inlet Area that becomes 8 (stock) + 5.84 (Ram) & now have to divide the total air flow by 13.84 ?

scathcart

So essentially, you are wanting to add a second throttle plate immediately after the existing throttle, and connect that to ram air, in an attempt to reduce the manifold vacuum at WOT?

This assumes the intake snorkel and stock throttle plates are a restriction, which they are not. Your efforts would be more worthwhile being spent building a new manifold set.

KompressorLOgic

iTrader: (6)

r u talking about the VFAD variable fresh air duct on the rx8?, ive heard its main purpose was the lower the intake noise of the rotary at low rpms



the longer part of the intake is a meshy hose which takes sound away

the intake tubing off the throttle body is massive, why not make a better ram air into the AFM by making larger ducting to the front, or from the brake duct? I would think you would have too many bends to use the t2 hood scoop.

utilizing the AFM in that would be tricky as well, as you cannot just have bypassed air entering with the stock ecu, or rtek.

a full standalone would be required.

ramses666

iTrader: (1)

Why would anyone assume that the stock air system has zero resistance? That is obviously a False Assumption. There must be a negative value for it. That's why I'm looking for some Manifold Vacuum Charts.

Obviously, a Turbo creates a Positive Manifold Pressure. I'm looking for something like Unity or Zero Manifold Pressure for perfect tuning. The Ram-Air extra port is one way to balance the equation. Any positive pressure really is translated into more air volume as the intake tries to balance the flow. Finding the choke point of the air flow/air velocity equation is where I'm looking ATM.

I could just strap a leaf-blower to the hood...

KompressorLOgic

iTrader: (6)

the biggest restriction probably lies within the runner size and port size going into the engine

ramses666

iTrader: (1)

Thanks for the pic of the VFAD. Your description of the function is partially correct. The longer air tube is used as you say... To keep the intake quieter & more efficient at partial throttle conditions where the engine will normally operate.

The short tube is for WOT conditions where the longer intake isn't beneficial & limits the air flow.

The AFM is the sticky wicket... but I'm a pretty crafty guy... I'll cheat if I have to...

What's the stand-alone ECU of choice for NA's with an AFM-delete capability? I didn't think anything decent was really available without re-wiring everything & spending large dollars.

I read the R-Tek manual & might be able to coax the thing to do what I want - since I'm keeping a basically stock setup except WOT conditions over an arbitrary 4000 RPM's.

So what kinda HP output would I care to estimate? 20% over stock (146HP) for an S4 with S5 VDI, freed up exhaust, ECU & Air Ram Mod = 175 HP Tuned?

The real difference will be how the torque curve ends up... I might smoke a stock turbo car because of a broader torque curve in the most useable zone.

scathcart

The choke point is the intake runners. What you are equating to doing is changing the throttle body and piping leading up to it; just making it far more complicated.

KompressorLOgic

iTrader: (6)

a stock t2 will have more torque than an NA at any rpm above 2500ish

the rx8 has less torque than a stock t2 with its highly tuned intake system

DC5Daniel

iTrader: (10)

Not to mention that a stock TII is nothing to brag about

In regards to your question about standalone, I think you're stuck with a catch 22. There's nothing, that I'm aware of, that's going to give you the flexibility you want while remaining relatively simple and cheap. The RTEK is the closest thing to your basic needs, with the exception of its reliance on the AFM. With that being said, RTEK was great 10+ years ago, its reign has come and gone due to its inability to adapt and grow with modern expectations and technologies. Your next choice would most likely be an Adaptronic, but that's not cheap and far overkill for what you seem to have planned.

KompressorLOgic

iTrader: (6)

a stock t2 with just a k&n filter


an rx8 dyno


the rx8 torque never comes anywhere near what the t2 produces even stock

KompressorLOgic

iTrader: (6)

I'm not even sure a stock t2 exists anymore lol

ramses666

iTrader: (1)

Perhaps it seems more complicated at face value. I tend to just look up her skirt to find out about the business end of the deal.

As far as limitations of the intake runners, I'd say a turbo manifold is several orders of efficiency- inferior. 6-port Turbo's would be a good example of Length/Volume/# of Ports.

I think I'm seeing "Simple Guesses" about the limiting Port Runner Velocity vs. Vacuum-Unity or Boost conditions.

We could look at Carbs on a Turbo LIM for a ball-park comparison & come up with about 175 hp @7k RPM, but the low-end torque would be awful & the Sound would be obnoxiously annoying. I'm try to get the "Happy Medium".

KompressorLOgic

iTrader: (6)

id agree running turbo manifolds on an na would probably lose power in most of the powerband except up towards the top.


ive used port matched t2 manifolds on a 6 port turbosetup before,but your tring to avoid going turbo....

ramses666

iTrader: (1)

I'm looking for some different comparisons.. I think other setups are very informative about what works well & where gains can be made. They also highlight the trade-offs and reveal the weaknesses.

I think a 20% increase in HP with a broad torque band would suit my needs without breaking the rest of the vehicle components. How to get there without breaking the engine or my wallet is quite a challenge.

Am I asking for Too Much? Is it Reasonably Possible?!? I've never heard of anyone actually "Improving" an S5 NA intake in any significant way except Mazda & this VFAD (Variable Fresh Air Duct) thing.

TonyD89

iTrader: (10)

I think class racers have picked up HP by knocking whatever bumps they could in the runners and extrude hone. The S5 lower manifold is not really that bad. I've done a lot of thought on the manifold, modifying it, retaining the 5th and 6th port actuators, and ditching everything else.

ramses666

iTrader: (1)

I've got both s4 & s5 NA manifolds in my bone yard - The lower s4 manifold is rather interesting. I cut out the middle part years ago & cut semi-peripheral ports in it. I had contemplated a rotating valve similar to the aux port sleeves & a pair of extra throttle bodies & injectors.

This was to turn a 6 port into an 8 port NA. Could work for a turbo as well. I also contemplated a Franken-Motor with Renesis side exhaust ports with the 8 port setup. If the difficulty for NA power was the available port volume, then this would help with that problem while keeping the "Driveability" intact for normal operation.

Evil Aviator

No, the formula assumes proper duct dimensions for the airflow required to feed the engine. A less-efficient duct will yield less results. It is not a formula for designing the duct, but rather a SWAG at the performance gain from the duct.

Since you do not seem to have a strong physics background, I would recommend that you simply use the online app. When you see the "% power increase" number on the app output, add 100% and then multiply that number times the horsepower of the engine. This will be your theoretical max power gain, although the actual gain will probably be less due to design inefficiencies, pressure loss due to the air filter, ram air temperature rise, etc.

Example using 50mph, ISA conditions, and 160hp engine:
50 mph, 29.92 in Hg, 59 F = 0.3 % power increase
100% + 0.3% = 100.3% = 1.003
1.003 x 160hp engine = 160.48 hp

RotaryEvolution

iTrader: (30)

the actual largest choke point on the n/a engine is the exhaust sleeves, followed by the intake manifold.

getting rid of those exhaust wings requires tearing the whole engine apart.

ramses666

iTrader: (1)

Well... Perhaps I'll have to break the news to you about Physics... Your thinking is limited by the Simplification of Pulse-Flow Dynamics & Boundary Layer Interfaces into "Something Calculatable".

The Truth is that it's much more complex than that. Hence the Voo-Doo of a Rotary Engine. I ran into this Flawed Thinking in the Concert Audio World of High Output Transducers. When you actually dig into the Fundamentals & the Technical Papers regarding Exploitation of Resonant Wave Dynamics for Doubling a Lower Harmonic, you find out how things Actually Work, instead of the Simple Way with Absurd Assumptions that gives a Non-Sensical Result.

The normal calculation for flow can't account for the non-stoichastic boundaries of the entire airway, nor for any pulse-wave energy flow (or lack of it) & we still have no idea what the vacuum level is at the engine port or how that relates to Enlarging the Plenum Opening from 8 sq. inches to 13.5, Positive Ram-Air effect & the De-Coupling of the Airway from the now Resonant Stock Air System.

Not trying to be Obtuse... I just believe in relating my views on Traditional Physics & the limitations of Common Methods & why they fail in a Rotary.

An Example of this Technology would be a Bose Wave Radio - I know the engineer there & got a tour of the factory. It's an incredibly wonderful convoluting shared resonant port type of thing.

scathcart

Sounds like you're ignoring what everyone has already found out.

Try it, then post your results.
Experience tells me we won't ever hear from you again: it's not often people say, "I ignored everyone else, put a pile of effort into a project and it failed as miserably as everyone said it would".

Honestly, if you are going to ignore everyone, why post in the first place?

You want a beefy N/A? Ditch the 6-port engine and start with a 4 port.

ramses666

iTrader: (1)

I wouldn't characterize the offered opinions as actually having tried something like this & knowing from experience that it "won't work".

I would characterize the responses presented as "Worth considering & responding to" in order to present the reasoning behind My absurd proposal & Why it might-could-should seem to defy conventional norms.

Advising me to just Throw My Engine Away seems just as un-reasonable as making a Bose Wave Radio out of an RX-7... Both are Possible... You be the Judge. Even in-valids have Opinions that might be correct.

j9fd3s

iTrader: (3)

if you apply the VFAD system to the FC, it would just bypass the part of the intake tube that goes over the radiator.

notice the picture of the VFAD that got posted, it is in FRONT of the airbox/AFM.

Mazda has published a couple of SAE papers and a book about the Rx8, so we know exactly what they did for power (and emissions),

the power part is actually quite simple. the exhaust port get split from one large one into two smaller ones. port area gets bigger, but net/net the performance isn't as good, as there is a big bend in each port, etc. these exhaust ports then allow a large increase in intake port area, something like 30%. in fact the renesis port areas, and ratio between them is closer to the peripheral port racing engines, than the previous engines.

the intake system is, conceptually the same as the S5, it is just more refined, each pair of runners (primary, secondary and tertiary) get their own runner diameters and lengths. the 6-PI and VDI are the same, again in concept, the actual hardware is sized for more power.

the airbox, and its plumbing get bigger, and shorter, the ecu is more accurate and much much much more powerful, the exhaust is basically straight and diameter increases, spark plugs are better, electric fan, electric power steering, etc etc