Chaotic_FC

ok
i am almost complete with rebuilding my engine, just waiting for some high compression rotors.

refer this thread for build-up:

https://www.rx7club.com/showthread.p...turbo+rebuild\

what i want to know, is what is the very largest possible porting job that i can manage with having the stock ECU? right now i have given myself a nice sized streetport on my primarys, and left my 6 port end irons stock.

please dont just send me replies saying why i should get standalone.. it is not an option, my funds are insufficient for the time being. I am already aware that i have to run low boost to keep my engine from popping

all help and critique is welcome. and please post porting PICTURES

thanks in advance

RX7 allnight

what turbo will you be running? anything other than a big street port will need a stand alone

Chaotic_FC

i am running the same turbo as i have in the engine rebuild thread
it is out of a diesel truck i belive

and by big streetport, is it literally as big as i can get it, or are there limits (besides the water jacket)

RX7 allnight

changing the size and shape of the ports changes the tourqe curve either lower or higher or if done wrong just ruins it. i forget what company but they make a big street port template. h-bridge or full will reguire a stand alone

Turblown

iTrader: (12)

Stock ecu and a turbo other than factory doesn't work. Different turbos flow differently, stock ecu has no way to adjust.

Chaotic_FC

does anybody have any pics of what shaped ports create certain torque/hp curves?
i am not an idiot, i know what is completely wrong.. (i.e. mishapen, to far in or out)
but if i see a nice pic, i can base my job off of it.

b18crx

iTrader: (3)

this statement is incorrect, my friend is running a large To4 built by turbonectics and hes running 1 bar all on the stock ecu, by stock ecu i mean nothing done to it not even a chip. -mike

b18crx

iTrader: (3)

oh and he also has a streetport on his motor.

Chaotic_FC

really?

so does that mean that with a turbo smaller than his i could run as high as a bar of boost???

fastrotaries

NO piggy back either? stock injectors? Not being able to add more fuel will certainly cause a lean condition. In my experience you can make it work, but really it's a ticking time bomb. higher boost levels will also require timing adjustment.


If you can't afford a standalone, keep the boost low, until you find a way to control things better.

Aaron Cake

iTrader: (1)

The stock EFI system has an AFM, so it can compensate for more airflow to a degree. At some point you will max out the AFM and thus the ECU won't be able to read the increased airflow as it will be wide open.

Still, what you don't have with the stock ECU is good control over fuel, or any control over timing. Even if you keep the boost low on that turbo it's still going to flow way more then the stocker. If you want to do this crudely, then big secondary injectors and a piggyback will certainly give you enough fuel but you will need to really hose it in there since you can't pull back timing. And that makes the 4000 RPM area very dangerous as the injector switchover takes place. This has been done plenty of times in the past and certainly works, but only to a point. There's a reason why big turbo RX-7s are all running standalones.

Keep in mind that the 6 port end plates have way more port area then the TII engine, so you are already well past the port of even a ported 4 port engine as far as port size goes. I suggest simply leaving the port alone. No matter what you do to them, you will have a loss of low end when using a larger turbo and the low compression rotors. You can mitigate this loss of low end by building a new intake manifold, or using high compression rotors.

Chaotic_FC

the 9.7 rotors are already on my to-buy list

b18crx

iTrader: (3)

Yes he has larger injectors and he's running an safc for piggyback but please explain to me how those mods are equal to a full standalone setup. No hard feelings but a piggyback and a standalone are not even comparable.-mike

wafflesincars

Piggy back & standalone are totally and completely comparable, but far from equal.

They do the same thing to different degrees. You are adding more air with the turbocharger, with this you need more fuel to maintain a ratio that will combust at the proper time.

Therein lies the science of tuning an engine, a standalone gives you full control of when and how much fuel is added, as well as control over when it begins to combust.

Stop saying mods.