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Discussion Starter #1
I know is off the Tracker subject but I am wondering if anybody can share some light or knows some about this... :)

One of my co-workers has an 82 RX7 and we are exploring the possibility of a TBI. I am wondering, it was made a TBI without ignition control? The problem that I am facing is, the Wankel Engine ignition sequence is very different from any piston engine. So I am looking for a simple TBI that does not regulate the Ignition Timing.

There is such animal...? :)
 

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ah there are PNP RX7 Custom ECU kits.

why re invent the wheel. curious.?

and did you know detonation on a wankel blows the apex seal ,so fast , in the blink of an eye.

you have now idea how hard that is to stop !!!!
 

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Discussion Starter #3
The thing is...

It has a factory Mazda 4BBL Carb and is much harder to keep up. Too many vacuum lines and other junk that creates a lot of headaches. So we are wondering, why not using a TBI? We are all aware, the Mazda Wankel it has an oil jet in the carb to keep the Apex Seals happy. So that part is easy to do, like the mods for Holley carbs. Also, these engines uses Petroleum Based oils and Synthetics should be avoid at all cost (will eat the Apex Seals).

In reality, is not a step back, is just few steps forward, perhaps from 82 to 87? ;)

We have not done anything yet. Just exploring the possibility.
 

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Why not use the EFI set up from a later RX7? The RX7 ECU was hacked years ago if you need to retune it.
 

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rx7
i think this is one of the motors on every single ECU maker.

82 motor , very very old, long in tooth, how much you going to spend on that.
and on motor to make it worth the effort?
and stock RX7 EFI is like , unobtainium here. where can you find that....?
join the RX forum and find out, last place is here.. this is a suzuki site.


google is your friend. ( but you did not mention the purse and that dictates all)

Mazda RX7 AEM ECU

How To Megasquirt Your 2nd Gen RX-7: Remove Stock Wiring and ECU


Haltech Sport 1000 plug&play EMS ECU 4 86-88 Mazda RX7 : eBay Motors (item 110443568027 end time Apr-06-10 11:45:58 PDT)

pretty much std price.
$1000 + 500 tune or PNP for $1500

pretty hard to beat and like i said, it just hates detonation.
and how to do that TUNING is the TRICK.

oops , boom, got another motor.?

get PNP and be happy
or
get (find ) up scale Stock future RX7 EFI.

and congrats one of the only RX7 posts ever.
 

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TBI is not some magic path to a solution
you need a tuned ECU for your motor, TBI or what ever .

for its desplacement and volumetric efficiencies.

so that boils down to , who's ECU can you afford.

How much is in this EFI RX7 purse?
 

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Discussion Starter #8
The car is 1st Gen RX7 so is all mechanical, the type of systems that I hate, early 80s tech :mad:

We were just talking about it, what if, instead of rebuilding the stock 4 BBL carb, install a simple TBI that is more reliable, drives better, more efficient and less polluting. We do not want to modify it for performance, just keep it pretty much stock. We have the rebuild kit for the carb if we can not find a suitable TBI.

Also, I went through the RX7Forums and I found some interesting things, like a TBI side draft style systems.

I found a pretty neat mod....

Is for the Oil jet by the intake. Instead of using Engine Oil as it was design it, uses 2 Stroke oil and you can use Synthetic for the engine. According to the site, Synthetic oils are not design to be burnt, so they eat the seals on the Wankel, but using dirty crankcase oil is not good either. So using 2 separate oil systems you get the best of both worlds. The ratio is 1:100 so a Gallon of 2 Stroke Oil it will last like aprox 25 Fill Ups, so that is what they claimed.
 

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TBI IS EFI

MPI is EFI

A throttle body is just a block of aluminum with an air valve.
EFI TBI is a complex ECU System.
look at our TBI and MPI note only 3 missing injectors., and all else the same.!
And all tuning is quite unique in the 2. ( 8v and 16v ) .


OIL ,OMG dont say oil or the witch hunt starts..... LOL !!!

actually all crank case oils are ment to be burnt.
the only issues is ,how fast. ( 2 stoke oil a classic case)

all motors let oil slide up past the ring (oil control ring ) then into the top 2 rings.
where it then burns.
must be something about the designed of the apex seal. not liking syn oil. (i dont know)
the other problem there is , that there are oils that are syn oil and not labled as such.

syn oil can be mfg 2 ways.

long chain reduction (dino to syn) ( hydrocracking)
or
short chain to long (add hyrdogen)
the results can be and are the same. ( huge law suit for that; proved that)

The details about these facts are at Chevron.com, all the details.

many oils , the only difference it he additives in the oil , can be big differences.

The TBI has 1 or 2 injectors.
the reason for 2 is if the main injector cant handle idle ( main becomes non linear at low end)
forget idle. lets talk off idle where all the fun happens....
the main injector needs the same fuel controls as a mpi 4 injection system.
with all the other sensors. ( i just made one with a MS V2 megasquirt TBI)
the whole process is the same for TBI and MPI but one step. ( done automatically
in the equations,) Most cheap ECU MPI systems just do gang injection
so are no better than TBI save he close proxemity to the valves. (intake)
non sequential.

Biggest difference is the smaller injectors. on MPI and coding that in.

TBI an MPI
all have fuel table
Spark Advance tables
VE tables.
and seperate ,cold ,warm and hot tables.
all must be programmed and tuned a dyno.

or buy a PNP kit that has it already done for you.

A TBI is not a carb, nor is it more near a carb, not at all, not even close.
but sure TBI is physical work less work than 4 injector pockets. and sure totally the way to go on a rotary.

You have 3 choices (systems) TBI,MPI or N-Alpha ( aside from carbs)

Dont get me wrong there are -ALPHA systems that have only 2 parts.
a TPS and a TBI , a black box , to control the injector.
it is real crude and will blow a motor fast.
and really dirty at low RPM, black exhaust clouds dirty.

there are race cars that use this system, that never ever go under WOT.
in this case they work ( one AFR , WOT and RPM?TPS based) no map, no maf, no nuttn
Drag cars?
or other fast track cars can have this. and a closely guarded secret by the users.
there are huge sections over at MS forum for this usage.





read about this crude injection form here.

Electronic Fuel Injection Mass Flow vs. Speed Density- Car Craft Magazine
 

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I found a pretty neat mod....

Is for the Oil jet by the intake. Instead of using Engine Oil as it was design it, uses 2 Stroke oil and you can use Synthetic for the engine. According to the site, Synthetic oils are not design to be burnt, so they eat the seals on the Wankel, but using dirty crankcase oil is not good either. So using 2 separate oil systems you get the best of both worlds. The ratio is 1:100 so a Gallon of 2 Stroke Oil it will last like aprox 25 Fill Ups, so that is what they claimed.
The Norton rotary used two stroke oil.
 

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Discussion Starter #11
Why not use the EFI set up from a later RX7? The RX7 ECU was hacked years ago if you need to retune it.
Trying to transplant a whole induction system from those RX7s is too much trouble. Is not impossible, just that too much stuff like harnesses and sensors. We were looking to some much simpler to incorporate.

There are some TBIs that runs for about $1000. Even we found one already made for RX7s but is like $1300 or so.
 

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Discussion Starter #13

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no problme.
$700 for TB (all in AZ bucks)
and
$600 for the loom
$1000 to $25oo for the ECU.
did you ask the tuning charge?

$1k here one k there, and soon we are spniding big money ( i sound like Dick Army)
 

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Discussion Starter #15
I have not received an answer yet, perhaps tomorrow.

Plan A is see if we can get a simple TBI setup on a kit.
Plan B is rebuild the carb that we already have.

So is all depends on how deep are his pockets and what route he wants to go. Seems to like the idea of EFI on the Ol' RX7.

Just a small story behind the car....

It used to be his dad's, he bought brand new back in 1982, is been most of its time on storage in Arizona (Aircraft Hangar to be more precise). Since he did not drove it much, it has like 64,000 miles in the Odometer. The interiors are immaculate, no a single dent and the paint is not even oxidized. No a single speckle of rust either. The problem is that since it was seating for such a long time, the carb needs a rebuild badly. Also the tank, has rust in it since it is all metal. What can we say, is on the end of old technology.

So that is why we are considering the TBI instead the Carb. Either way, it just going to be a stock car and will be sort of a weekend / nice weather driver.
 

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what is a simple TBI kit. ?

i imagine a .
TBI and (pulse box) that connects to the TPS. , as you advance the TPS
the pulses get longer. 2 ms to 10 ms.

but it wont start cold and will flood for just about any reason.
i can make you a box like that but you will hate it.
i will be like the bad carb , one where the float valve is stuck open.

what makes you think TBI is cheaper .? ( injectors are cheap used) so where is the savings. just curious. I too would love a deal on custom ECU with PNP maps.
after all the eCU is $1500 and up. on all.


happy trails and thanks for sharing that history ,cool car.
my neighbor one for sail in like condition. saw it at garage sale.
 

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Discussion Starter #17 (Edited)
What I meant for simple TBI is a kit that has it all already done for these engines.

Kind of a Plug-N-Play kit with all included, that is what I meant.

After digging a bit more last night, seems to be that is going to be more expensive than I thought. Another good option was the Weber carb and Racing Beat kits. Perhaps that is a better choice on for smaller budget.

I was wondering if they had a TBI like I have seen around for V8 that has all included for about $1,500. That is what I was looking for.

It could be a nice project to convert a Wankel that way, just that I do not have the $$$$ to throw away :D
 

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Discussion Starter #18
Not a fan of Lexsucks :lol: They can pursuit all the perfection they want and still not impressed by their products ;)
 
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