RXBeetle

The E&J is $750... I don't like spraying injectors at the runner wall either.
I guess it depends on what your goals are. I'd like drivablity and economy in the widely varying Michigan weather. WOT power is secondary to having a car that doesn't suck to drive.
I'm debating staged or simultaneous, I have a 6 port with the sleeves pulled. The aux port makes the port timing comparable to a modified atkinsion cycle (late closing intkae) which could help bump up the mpg at the expense of some torque. hmmm

BLUE TII

iTrader: (9)

RXBeetle The E&J is $750... I don't like spraying injectors at the runner wall either.
I guess it depends on what your goals are. I'd like drivablity and economy in the widely varying Michigan weather. WOT power is secondary to having a car that doesn't suck to drive.
I'm debating staged or simultaneous, I have a 6 port with the sleeves pulled. The aux port makes the port timing comparable to a modified atkinsion cycle (late closing intkae) which could help bump up the mpg at the expense of some torque. hmmm

I believe Mazda's goals were also driveability and economy yet they also spray the injector directly at the runner wall for the primary injectors and at an angle of incidence for the 2ndaries. Hmmn, perhaps spraying the injector at a right angle to flow helps with fuel suspension at low intake velocities.

If you start with a fuel injected rotary you can keep your primary injectors with whatever TB you use so it is not really an issue with driveability/fuel economy anyways.

RXBeetle

Mazda went to quite a bit of trouble to stop the primary injector wall wetting on the Renesis for better fuel economy and lower emissions.
http://www.rx8club.com/attachments/s...-09s-fig18.jpg
http://www.rx8club.com/attachments/s...-09s-fig20.jpg

They also used an "injector diffuser" to keep the spray up in the air stream in the earlier engines.
http://atkinsrotary.com/store/images/P/N3A2-13-C61.jpg
https://www.rx7club.com/attachments/...y-airbleed.jpg

I'm getting a little off topic here I guess though. I'm not going to go to all the trouble of relocating the primary injectors to the other side of the intake (right above the exhaust) to get --possibly-- better injector placement. Secondary injectors, on the other hand, I'm going to do the best I can.

BLUE TII

iTrader: (9)

Sounds like your engine was a factory carbed rotary?

BLUE TII

iTrader: (9)

Mazda went to quite a bit of trouble to stop the primary injector wall wetting on the Renesis for better fuel economy and lower emissions.
RX8Club.com
RX8Club.com

They also used an "injector diffuser" to keep the spray up in the air stream in the earlier engines.
http://atkinsrotary.com/store/images/P/N3A2-13-C61.jpg
https://www.rx7club.com/attachments/2...y-airbleed.jpg

You are right, Mazda went to a lot of work to increase driveability/fuel economy with the primary injector placement.

If it was as easy as changing the angle of the injector instead I am sure they would have done that. Do you follow?

peejay

So don't spray at the wall... use the inserts and connect the air bleeds to filtered air. Mazda did the work for you, all you have to do is not throw the parts away.

Simultaneous all the way. Theories about intake velocity mean dick when you're talking about low flows where the engine is making maybe 10-30hp. Issues like exhaust gas reversion play a much larger role, and to combat that you need to ensure no port sees high vacuum.

Here, my latest "driving around because there's no racing happening" video. 4 barrel Holley with non-staged operation. 2x1000cc injectors, with inserts and air bleeds thankyouverymuch (drilled a couple holes in the RB manifold, one from the face and one from the top, pressed a piece of brake line in the top, then ground a channel in the manifold face to mate up the the bleed ports in the center housing) Bridge ported engine opened to the limits of the coolant seals and the port heights. Port runners opened to as far as I dared before hitting water. Driving with a very gentle foot because I'm trying to limp home with a broken axle and it is raining and driving a RWD car that torque steers hard, with old all-season tires, in the rain, while towing a trailer, requires gentle throttle.


Only the first minute is important. But it still illustrates the drivability just fine. (Oh and I have a 9lb flywheel too )

RXBeetle

Nice Peejay! I think that's about a good a setup as you can get on the primaries. any pics of the air bleeds?

My engine is a street ported 6p S4. Its been sitting on the stand for way to long. Life happens.


Add this one to the list:
1000 Cfm 4 Barrel 4150 Billet Throttle Body
Doesn't look like it has an IAC port.

peejay

I looked for pics, could have sworn I took some, but all I could find in my Photobucket account was one image:



You can just barely see the piece of brake line sticking up in the middle of the manifold.

Way easy to overthink. Look at an OE manifold to see what they did: drill here, drill intersecting hole there, press a tube in the one hole for hose attachment, and cut a channel in the manifold face for the passage to intersect with the two little holes in the center manifold.

Note that I do not have primaries. All four ports do equal duty, there is no primary/secondary. Secondary action makes for bad drivability on a large ported engine, i can NOT stress that enough.

No IAC either. It isn't really necessary in my experience. If the idle speed is too high I flip the fans on and it kills the idle speed nicely

j9fd3s

iTrader: (3)

+1, i found the same thing. intake manifold vacuum = more exhaust gesses sucked up = brap brap.

RXBeetle

Update: This is no longer sold they tell me. I managed to get a back shelf one after a lot of back and fourth through Jegs.
http://store.speedmaster79.com/image...ge/4144_1_.jpg

This one is available and Jegs tells me the linkage can be set up to open simultaneously.
http://store.speedmaster79.com/image...ge/2911_1_.jpg
It has provisions for an IAC valve. I've had my hands on it and I'd give it a B in quality. Fasteners and bearings were cheap but the machining is real nice.

KNONFS

iTrader: (14)

Pretty much how I am running my 13bt setup, may I ask what MPG are you getting?

I urge you to reconsider your TB options. I know the projay or E&J are more expensive, but they have provisions for injectors, they are made in the US, and they are proven up to over 1000rwhp (that's a lot of boost). I know you wont be running boost on your setup (perphaps later down the road?)

A forum member is selling an e&j tb:

https://www.rx7club.com/race-parts-o...-body-1085946/

I purchased a CDI from Freddy, and he's a stand up guy

Only mentioning the TB thing, cause I went the same route as you are planning to go, and it was painful, and on the long run, much more expensive

RXBeetle

If I was limited to bolt on configurations and needed more injectors I'd consider the E&J style TB but I've got a mill, lathe, and a tig welder at my disposal so I can stick injectors where ever I want. I also don't like the injector position on the E&J style (admittedly might be unfounded). Having made a few throttle bodies myself, $700 is not an unreasonable price, but I'd also just as soon make one over paying that much. I can stomach paying a bit extra for something made here, but not $500 with features I don't like. I think that's pretty well understood by the fact that we are all driving Mazdas. If I get what I paid for (cheap parts) and have to eat my words I won't hesitate to concede here.

I do plan on going turbo after I get things well sorted N/A. N/A I'm going with 2x 1000cc primaries in the stock center plate location. When I go turbo those will move to bosses in a carb hat as shower injectors and I'll run RX8 injectors in the primary location.

What were some of the issues you ran into if you don't mind me asking?

diabolical1

iTrader: (3)

if you don't mind, which ones are you planning to use? S1 manual secondaries, S1 automatics or S2s? i'm just curious.

KNONFS

iTrader: (14)

Leak between surfaces (TB to intake manifold and TB to hat), leaks between butterfly shafts and TB bearings, sticking butterfly/shafts, and bent butterfly plates (mostly due to backfires while tuning due to a an issue with the ECU)

A lot of time was spent working around the TB, and trying to fix it. Truth be told, I spent about half of what an E&J/Pro Jay TB costs, trying to band aid the freaking thing. Add the cost of the TB itself, the hassle, headaches, heartaches...

Hopefully, you don't have to go through all of that

RXBeetle

S1 manual secondaries, still need to send them out for cleaning/flow testing.

Thanks for the heads up KNONFS. I've already noticed the TB to manifold surfaces aren't flat, I'm pretty sure it's my doing though (preheat intake to weld on it). I hate gaskets... I've o-ringed everything I've made but o-rings aren't going to squeeze runner to runner on a square bore pattern. One big one around them all? hmmm. Were the shaft leaks through the bearing or shaft fit to inner race? Mine are double sealed bearings, the "1200CFM" Speedmaster TB looked like they were just double shielded.
Intake backfires.... I once blew an intake off (rubber booted runners on a bike engine) on the dyno while a friend was standing next to it in a very enclosed dyno cell (yeah-yeah don't do that). Many lols were had from the control room, not so much from the guy inside.

freddyrx3

iTrader: (14)

Tried and True. E&J is one of the best throttle bodies in the market. And now he offers the "Progressive Link" to tune your primaries for street. Mine is for sale and in amazing condition. Thank you KNONfs for the suggestions. I agree, save yourself the frustration.

peejay

WHY would you want progressive linkage? It is detrimental. That is carburetor on a plenum on a piston engine thinking. This is EFI on an ITB style manifold for a rotary. Open all four holes at the same rate. Port velocity means absolutely nothing at the loads and engine speeds where it might theoretically make a difference, in the real world, in the face of the bad things that happen when you pull a hard vacuum on the two non-opening ports.

I'll keep repeating it until you guys understand... all four at the same time makes for *better* drivability. Period.

Jeff20B

iTrader: (13)

peejay, could this be the reason Mazda decided to add channels to their carb intake manifolds at some point around the mid 70s? All early manifolds had separate runners.

Would it be a good idea to go ahead and use a channeled manifold on a half BP 12A, for example? I know the older thinking would have been to keep them separated so the bridged ports don't talk to the regular side ports or whatever. But in reality it didn't seem to matter much and now I'm thinking channels would allow it to run better. Even at low RPM. Your thoughts?

BLUE TII

iTrader: (9)

peejay WHY would you want progressive linkage? It is detrimental. That is carburetor on a plenum on a piston engine thinking. This is EFI on an ITB style manifold for a rotary. Open all four holes at the same rate. Port velocity means absolutely nothing at the loads and engine speeds where it might theoretically make a difference, in the real world, in the face of the bad things that happen when you pull a hard vacuum on the two non-opening ports.

I'll keep repeating it until you guys understand... all four at the same time makes for *better* drivability. Period.

I changed my stock TB away from progressive and I can tell you I had to add a lot more fuel on throttle tip in to keep it accelerating smoothly when I opened the throttle quickly.

Intake velocity drops more with all plates opening at once and fuel does not stay suspended in the intake stream as well.

I believe this is why OEM rotary application had double throttle and progressive linkage- fuel economy and emissions.

Another instance where progressive throttle opening may be good would be on a 6 port engine with primary/secondary ports closing at 40ABDC and auxy ports closing at 80ABDC.

Unlike overlap on a rotary, a closed throttle plate DOES negate the effects of high duration side ports and intake reversion as the side seals form a grid around the rotor blocking intake reversion.
---------------------

I do understand what you are saying though. In almost all the cases we use a 4150 style 4 plate throttle body opening all the plates at once is the best solution for performance.

In particular, on a rotary with overlap (non Renesis) opening all throttle plates at once is also the best solution for drive-ability and power since a closed throttle plate WILL NOT negate the overlap effect of exhaust being drawn in by the rotor vacuum, but rather accentuate the effect by maintaining a higher intake vacuum level.

j9fd3s

iTrader: (3)

in an attempt to use the idle hole on the carb in my P port, i started drilling holes in the throttle plates, as the idle was in the ~600rpm area, and i wanted 900ish. drilling holes in the throttle plates did almost nothing for idle speed, but the bigger i made the holes the better it drove up to the point where there isn't enough vacuum for the carb to actually work.

conclusion, which PJ has peer reviewed, less intake vacuum = less exhaust gasses sucked up into the intake stroke = less brap brap = more drive ability.

i can actually get my PP to idle normally like a stock engine, although having the P port with out the brap brap is just lame....

idle speed is around 900rpm, its idling on the 1st transition hole, so my experiment didn't work...

so moral of the story, lowering intake vacuum on a bridge/PP is a good idea.

Jeff20B

iTrader: (13)

Ok thanks. I'm setting up a hogged out Nikki for one of these engines but I don't have access to the engine so it's only my best guess. But so far my best guess suggests that channels could actually work, based on what you and peejay said, and my own experience having done it with separate runners a few years ago. It doesn't hurt to try. So I'll set the carb up with that in mind.

peejay

The stock throttle body setup is very close to being non-progressive. The progressive Holley style carbs don't even start opening the secondaries until half throttle.