Speedworks

coming out of the piston powered engine world and being dropped with few knowledge of rotaries it's interesting to find out about all the specifics of it.

Formost the problem with running lean, especially when changing intakes, exhaust...

In my opinion this is a problem of the rotary engine in general. On the other and the lack of a air mass meter on the intake side.

This item should be, together with the lambda, the base for the ECU to set the correct air/gas mixture.

Second point to that is the ECU's incapability to read any air mass info, or even use it in it's prgramm.

When using for example a Halltech E6K it is possible to add n air mass meter to the system.

How would this affect the ability to have the rotary engine learn and put together it's own, optimal, mixture, without reprogramming the ECU everytime you add or change something which will affect the intake and/or exhaust part of the engine?

I know, when using a Halltech you can alter the settings to your own wish, but you will have to keep doing it manually and have it doen by professional programmers (not always available)

So what would be the benefit of adding a air mass meter tot the rotary system??

Just a thought from my knwoledge...

Jims5543

iTrader: (2)

Air Mass meter restricts the intake and is not needed.

Most people that a serious about tuning Rotary engines go for a stand alone ACU whether it be a Haltech Wolf3D Motec Microtec etc...

I personally use a Motec. I just dyno'd my 13B-REW and had a AFR of 11.5:1 all the way across the boost band.

My car adds fuel purely based on the Manifold Air Pressure. As long as that is monitored I cannot see how you could run lean. The only way you could run lean is poor tuning. ILets say you tuned for a AFR of 14:11 leaving no consideration for cooler temps.

I tuned in 85° temps with almost 100% humidity. So I know I needed some room for error to make sure she doesn't pop on a cold winter night.

Ths thing that limits the second gen RX-7's is the AFM it restricts the intake.

I am glad not to have one.

maxcooper

I think Speedworks is referring to the fact that you have to retune whenever you change the flow characteristics of the system. That is admittedly a PITA, but it does come with the nice feature that you don't have an air flow meter restricting things on the intake side.

The fact that turbo rotaries are sensitive to running lean is another PITA, but hey you get all that smooth power in a small package. Another trade-off, but it is one that lots of people seem willing to make.

I believe you can go stand-alone and then install an air flow meter (perhaps a low-restriction "hot wire" one). But there are other reasons to dislike air flow meters -- throttle response and having to deal with metered air (rich after BOV blows) are two of them.

You can also setup some kind of wideband-based closed loop system. That can be dangerous, though, since wideband O2 sensors (well, O2 sensors in general) are not known for their robustness. One option is to have a base map that you arrive at through tuning, and then use a wideband closed-loop to adjust it slightly (10% or something).

-Max

RETed

It is also the same contraption that allows "us" FC guys to run more boost or change to mild turbo upgrade and still allow for decent stock ECU control.

It's the MAP based load system on the FD that causes a lot of blown engines.


-Ted

Speedworks

You are right Max, I live in Europe and use the car as well on a cold and dry spring or fall evening (nothing better then cold air and dry roads) as well as on a hot summer afternnon.

Temperature and humidity settings change accordinglyy to that. I just meant I'm not into it to retune the car everytime, or take it for a 300$ retune at the shop twice a year.

I think with today's air mass (those hotwires in the middle of a tube going to the intake/turbo) have a minimum of restriction. I do not know how comparable piston engines work (Supra TT or Skyline TT). If they use air mass meters or not??

Base line for me is, that I want to go to a 350-400 BHP car over 2 or 3 years (no mods done yet), but with a tune that will give me security a all times (or as much as possible). Turbo pressure will not be over 12PSI I hope, so fairly in the neighbourhood of the standard specs (single turbo offcourse)

I just don't want a PFC or labtop hanging or swirling around as the cockpit is already as tiny as it is. (you need some room for the misses you know ;-)

Any input would be welcome, and thanks for the answers.

maxcooper

Most or all stand-alones have compensation adjustments for air temp, but the stock intake air temp sensor is lousy (very slow and located in a hot area). There are some folks on the Datalogit email list that are working in finding a faster-reacting replacement, and others have had some success simply relocating the stock sensor. Lots of people just have their cars tuned a little rich so they are okay even if the air temp sensor is reading poorly.

As long as you get the car tuned for whatever flow parts you have (intake, IC, ports, turbo, exhaust) and have some decent temp compensation values, you should be fine no matter what the weather is. You shouldn't have to retune when the weather changes -- just when you change the engine parts.

-Max

Jims5543

iTrader: (2)

Agreed, it is safer but more restrictive.

The stock FD ECU leaves much to be desired. It was the first thing I ditched when I swapped in the engine.

Maybe I have my head up my ***, I just cannot understand how I am running a risky setup with a Motec and no AFM. Like Maxcooper said my ECU compensates for Air temps and engine temp too.

Bottom line? If your modding your FD and your not taking it straight to a dyno or at the very least hooking up a wideband O2 sensor to make sure it is not running lean, your ASKING for trouble.

There are way too many people modding these cars without checking to make sure that they are indeed still in a safe zone.

Speedworks

If you talk about restriction, about which figures are we talking about then?

Is the AFM figure based on what the stock sensor indicates or do you have to add an aftermarket one ?
What is the best place to put it on?

And in the end what would be the best price/product choice for the FD?

I already was in contact with my countries Halltech importer but I'm a bit worried about hooking it up to the engine without having to figure out a new, home made elektrical system.

I know there is someone making the connection between the stock engine harness and the Halltech, but he's asking a lot of money for it. (500-600$??)

Here, these Halltech/Motec system are known how they work, Apexi's PFC is completely unknoown here and certainly for an FD (only 15 left here)

What is your opinion between, let's say a Halltech E6K and PFC when it comes to setting possibilities, parameters and grade of difficulty when it comes to tuning it?

YellowT2

iTrader: (1)

I don't think his point is that your setup is risky. His point is that any modification you make that changes the volumetric efficiency or your engine requires a return to the dyno for another tuning session.

A properly setup fuel control system that uses a mass-air sensor will adjust for changes in VE without having to be re-tuned.

As you (Jim) said, this is only a good thing if the mass-air sensor is not a restriction.

Marcel Burkett

The 3RD gen was designed as an affordable High performance car , it was to be better than the previous generations . Which factory turbocharged car you know spits out 260 - 280 bhp @ 10psi boost ?, everything was developed for horsepower and performance, sure some things weren't done as we'd like , but the price of the car is another factor to be concidered. An AFM isn't the best for performance and power . My turbo has a 5" suction , where would I find a 5" AFM ?? .
If you want to take your car to next level , you just HAVE to do certain things , one of them is retuning after you make majour VE changes .
You can look into an aftermarket ECU that features AUTOTUNE if you need a shortcut.

cruiser

If you are concerned about overboosting or about cold weather, run lower boost. Use BC.