ramses666

iTrader: (1)

After pondering the Renesis Intake system & comparing to the S5 VDI setup, There seems to be an added air intake that effectively bypasses the long stock air box on the Renesis Intake.

I'm thinking about cutting the top off the VDI & installing a throttle plate with a filter and fabbing an Air Ram using the Intercooler Scoop on a Turbo Hood for the inlet.

I was considering controlling the opening with an RPM switch & a WOT Relay somewhere in the 4K & up range and running an R-Tek ECU updgrade for Tuning with larger injectors. Stock ports, RB dual exhaust.

I've done the VDI to S4 previously with good success & have an "Un-Molested" '88 GTU to work with that currently runs good. I've already done the exhaust & have the VDI-S4 manifold setup from my old base model S4 that got stripped before going to the junk yard.

The tricky part is getting all the ports to work properly, but I had previously fabbed a custom air system using stock air solenoids & RPM switches. I even made a custom gauge with open & closing LED indicators for monitoring operation of all the individual ports. I still have this setup in my Bone Yard & plan on revamping it somewhat to use the stock air pump instead of the old electric air pump.

My Main Question is "What type of gains should I anticipate from shortening the intake path via a Ram-Air through the top of the VDI?"

RotaryEvolution

iTrader: (30)

you're way overthinking it.

ramses666

iTrader: (1)

Is this an attempt at Trolling? Shirley Knot? I expect better treatment by & of Forum Veterans...

Would you care to Modify your post or else we can resort to proper Moderation of the Forum.

I'm trying to ask for an informed opinion, not a simple denial of the relevance of the topic.

Please try again...

scathcart

i don't find his post offensive, and I tend to agree.

At the speeds an N/A RX-7 can achieve, ram air will develop less intake pressure than is developed by the dyamic wave tuning of the stock intake manifold. Essentially, you would be building an elaborate cold air intake, something of which the stock intake snorkel already provides.

ramses666

iTrader: (1)

ok... I get what your saying. But I don't agree with your reasoning or assumptions.

If we sample the manifold pressure at the VDI, just after the throttle plates, we will get a negative value showing the resistance through the snorkel & stock air box setup. I'm looking to lower that resistance value at the VDI to increase air flow.

The virtue of tapping the VDI top with another throttle plate allows the pulsed resonance waves to be maintained through the manifolds & the air flow will keep up with demand better with less resistance.

It seems rather obvious that the poor NA performance is flow related & the Renesis's use of this type of shortening of the airway points to the possible effectiveness. Having freed up the exhaust end already, I need more flow at WOT through the VDI.

The Ram-Air effectively drops the resistance to large air flow volume better than any of the other half-baked attempts I've encountered here over the years.

It might be a little "Too Sophisticated" for the Turbo Crowd & that's ok. I'm more interested in having a Beefy NA that is Reliable. I don't require emissions, cats or passing inspections & I already plan on removing the existing vacuum rat's nest & replacing it with my own already built & tested custom setup. I already have most all the parts...

Perhaps the only benefit would be the Uniqueness or "Cooler than You" Factor... I would imagine that the Sound would be Incredible & maybe reveals the actual reason why the flow is improved

- The Resonance of the Primary Waves becomes un-coupled from the limiting stock air system at WOT somewhere in the 4000 rpm range. It's more "Musical Instrument" than anything in the simplified Turbo World & that's more of how I think about an NA Rotary & Mazda's Brilliant Manifold Designs.

Perhaps Rotary God will have already tried something like this... I found his port runner length calculations helpful & informative to my limited experience.

lastphaseofthis

iTrader: (8)

you have to have length for velocity. a turbo hood wouldnt provide this well. look to the bumper

misterstyx69

iTrader: (142)

I'm sure that if it is beneficial then some sort of version would have been done.

The Gist of RE's reply is simply "why"?..nothing more.
I also have questions about the reasoning behind it as for me,at the end of the day all that work may or may not not gain a lot of significant horsepower.
I mean knock yourself out of you are determined to build a better mouse trap but personally My mousetrap would be just to go to another power plant if I am looking at spending eternity trying to get 5 extra Hp out of an N/A.
Why settle for a minute amount of HP with all that work?Again personally I'd just skip it and go to something proven.
(you know what engine I would recommend so I won't say it!).

By the way Moderation of the forum is not required for simple blunt replies to Technical questions.
You should know by now that there will be good and bad answers posted..so sift out the ones that you think are useful,not attack the ones you feel you think are not helpful.
Thanks..good luck to you in whatever you decide to do..you got more Gumption than I do.

ramses666

iTrader: (1)

I expect dubious & circumspect responses around here from Noobs. I try to avoid colorful personal comments, but I also understand everyone has their own way of communicating... It's cool...

Anyway... I'm a retired audio engineer & have designed & used sound enclosures of myriad forms. I was unusually successful with getting far larger outputs with less power by increasing coupling efficiences & proper time alignment.

The NA Rotary is just a Musical Instrument... I prefer a finer approach than most perhaps, but I have the Mouse-Trap & extra parts laying around so why not?

I wish I could just swap in a different power plant & perhaps I might do that, but I haven't really come across any engine swaps that I found acceptable... Mostly cost $$$$ related. Who wouldn't want something Better than Stock?

The only part I don't have is the R-Tek and I should get that Regardless... I have a spare ECU to send off for that & a dual wideband and either a manifold pressure or EGT sensor could be helpful for actually tuning the thing properly.

I'm certainly going lose the AC & power steering systems as I don't need them at all... Weight Reduction is an easy way to increase performance...

I think I can make a throttle plate for my old K&N intake filter adaptor and just bolt it on top the VDI actually... It might turn out to be a Perfectly Red-Neck NA Upgrade?

I'll Pray for a proper budget for the Future... Maybe that will work?

Any Engine Swap Suggestions? I might just be an Idiot!

RotaryEvolution

iTrader: (30)

i wasn't trying to be offensive, i was asking why you would go to such trouble for a simple ram air induction system. the stock airbox is in fact a ram air induction cowling which is hidden under the hood, it however is not sealed very well. the air pressure is taken from the front bumper air inlet, same as the radiator.

you gotta take the good with the bad, it's not like i haven't had negative remarks for some of my ideas on this forum before but i didn't moan about it.

any gains for the amount of work would be almost unnoticable. the turbo hood intake idea is probably best but also going to be the messiest to accomplish.

ramses666

iTrader: (1)

ok then... I supppose I'll have to prove it... BTW... I don't agree with the comments about the stock air box being any sort of ram-air in a conventional sense. It is well designed & tuned with a helmholz resonator to provide quiet operation and good economy with a reasonable diameter & volume.

Mazda improved this system for the Renesis by shortening the length of the intake under WOT conditions... Why someone would think that Mazda would do it for "No Good Reason" seems to be identical to the prevailing "Experts" opinion on my idea to do the same thing.

I'll side with the factory thank you...

misterstyx69

iTrader: (142)

I had toyed with the idea of taking the brake ducts and using them as a intake inlet.
The passenger would be easy as pie as there is a hole below the stock air box,but the driver's would need a little pipe to get to that area.
..and since I am not getting any younger,this "nutbar"" would just toss a TII in there.
(actually started N/A when I got into it and went full on Crazy..500 dollar car went to 11K in parts!)

RotaryEvolution

iTrader: (30)

most of the problem is with the FC non turbo intake manifold being a bottleneck. you can actually get more gains from going to a shorty manifold and carb, however you lose the bottom end response and fuel economy that rounded off the FC better, overall the fuel injection system has a longer powerband and is ultimately quicker with less power.

clokker

iTrader: (2)

How is the MAF going to measure- and the ECU account for- all this extra air you're bringing in?

ramses666

iTrader: (1)

I suppose the answer i'm looking for requires a different question.

What are the Manifold Pressure Values of an NA S4 & S5 & Renesis at WOT?

Why? The data will reveal where the air box runs out of efficiency and drag ensues. It's not that difficult a concept. Put a 5th string on the bass guitar would be a good analogy.

I had been looking at just dropping in a Renesis 6 port & really wanted to understand WTF Mazda actually did to coax out some extra Mojo that hasn't ever seemed to happen around here...

Really... Seriously... What kind of "Experts" do we have in the 200 HP NA Club around here? I've been here off & on for Many Years & always found what I required, but the NA guys just always seemed skoffed at for wasting everyone else's time with digging into esoterica like port length & velocity for intakes & exhausts.

What do the "Experts" have to offer as advice??? Does a Rotary Spin in your Heart or Not?

Give Up the Data if you have it Please! MAP curves for S4/S5 & Renesis

lastphaseofthis

iTrader: (8)

mazda... cast larger diameter runner going into the engine, made the whole thing bigger for more air, and made it rev 1k higher, .. the renisis can't run below 2000 rpm very well, as port velocity falls out with such larger runners then the regular 13b.

ramses666

iTrader: (1)

The MAF is clearly an issue. I could go on at length decrying the R-Tek for not yet having a replacement of the Flapping Nightmare MAF with a Manifold Pressure Sensor.

However, since I'm dealing with a strictly WOT situation for activating the Ram-Air Duct, I should be able to easily compensate for wavering MAF values - which will surely happen - AAAARRRGGGHHH!

It "Should Be" a limited area of the fuel map that will need to be adjusted & larger injectors to start with would seem to be a good idea to not detonate prematurely.

I can manage all the various port openings & still get dual wide band O2 and either an MAP or EGT Sensor or 1 wide band O2, 1 MAP & 1 EGT for tuning in the R-Tek for the '88 NA.

Why in God's Name can I not just go with an MAP & lose the MAF into the Recycle Bin I Cannot Fathom ATM...

clokker

iTrader: (2)

Any number of aftermarket ECUs would allow just that but you haven't mentioned that yet, so I assumed this included the stock ECU.

I am confused though about the physical layout of this concept...
I had envisioned a more or less stock intake except you've pulled the VDI mechanism, installed a throttle plate in the opening and are porting air in from a turbo hood scoop.
If this is generally what you had in mind, that whole secondary air load is a complete mystery to the ECU, no?

fc323

Your gonna do all of this with a system that wasn't designed for ram air?
I would think that it would mess with the original intake resonances.

ramses666

iTrader: (1)

The VDI mechanism is intact. The Mod is cutting a hole the exact size of the AFM on the top of the VDI with a throttle plate with connecting duct work & filter to the turbo hood air-cooler intake.

The idea is to open this duct in the 4k rpm neighborhood at WOT to lower the manifold vacuum pressure & increase flow.

The ECU issue is critical to seeing anything other than random chaos. The Magic will Reside in the Tuning & having the means to deal with it for Absolutely Sure...

ramses666

iTrader: (1)

It's more than obvious that the stock air system runs out of volumetric efficiency. The ? is where, when & how does that happen & how can I easily adapt & alter the initial circumstances of the volumetric flow equation.

To me it's rather simple. The problem is that "Someone" has been doing it wrong. Same as it ever was in the Rotary World. How many NA 20B's have just been kinda sad no matter how pretty they were? The Lamentations of NA owners about how to have something "Better"?

To be Clear - It Sux because the Fun-D-Mental Harmonics & Resonances have been Ignored.

I Believe that We are Better than just a "Bunch of Quiters" if we can Embrace some of the Finer Aspects of NA Performance.

Don't get me started on Ethanol in my Gasoline... I'll run REC 90 because I can... It seems like adding ethanol to gasoline is less effective than adding recycled/human processed beer to the gasoline for "Anti-Knock/octane enhancement".

The Timing Map & EGT Data will help get the mixture reasonaby lean with-out detonating... LOL! in my dreams... of course... Rumor has it that a Ping-Monster Lurks in the 2-3k Range?!?

TonyD89

iTrader: (10)

I have this idea that started with a guy on the forum that uses motorcycle throttle bodies. Sounds like a good idea but he doesn't stage the primary and secondary's and opens all four at the same time. He says he loves it. I would really like to stage them AND make an intake that was long runner and short with butterflies to change between the two. I would make it tubular but I am thinking along the lines of like a 5th gen Honda Prelude intake manifold. Look it up before you think I'm crazy.

ramses666

iTrader: (1)

I'm right there with you Tony... I met the Crazy Old Man here in Florida & swapped Secret Intake & Crazed Cooling Jacket Mods for FD Turbos...

I'm all about some Rotary Passion... I would think some suspension of normal thinking would be appreciated, but perhaps not... Some Turbo Guy just Blows Hard & says My Reality of Rotary Existence is just Silly or Stupid or perhaps simply Irrelevent to Advancing the Art of Rotary Performance.

I prefer an Open Forum & I'll Fight for "IT" & still ask for non-existent MAP charts for NA S4/S5 & Renesis for a Real Examination of the Situation.

fc323

Hey, stay on your topic.

You already know how the 8 acheives higher power with its intake. But even the rx8 doesn't use ram air, just a shorter intake track (vfad). You're trying to achieve positive pressure with the ram effect. It really sounds like you should redesign the whole intake tract to use the effect instead of trying to rig it together.
Im with you on the n/a performance tuning, but you dont have to be a ***** about an internet response

RotaryEvolution

iTrader: (30)

no one is scoffing, it's been said many times, the intake is the restriction as well as the dated engine management system.

run a peripheral port, standalone and tuned exhaust and you can wind up with 300+whp.

streetable though? maybe if you like having everyone's ears bleed.

the renesis uses scalloped rotors, more refined porting, another set of variable length intake runners, more modern ECU and fuel injection and additional exhaust scavenging from the multi side port engine effects. however you see the drawbacks, the engines only last ~90k miles, and it isn't only because they make a little more power, because a turbo II can easily last twice that many miles.

honestly, you keep talking about trolling but this post resembles more of a troll than any of the responses. as if you keep egging people to respond to your negativity from the constructive criticisms received.

Dak

I would ditch the sock ecu completely and use a standalone. Then you don't have the MAF in the way complicating your plumbing. I might not use a TII hood though. That way you can put your ram air duct in the best place for it and not be restricted to the TII scoop location.

Also I thought the Renesis varied the intake runner length not the intake tract from airbox to throttle body. Someone correct me if I'm wrong.