Mapping recomendations

[A7NTY]

Hi all, The RX arrives from Japan in a couple of weeks!

I am concerned about having it remapped as I have heard of many remapped cars blowing up etc.

This is what it has had done to it.

HKS induction kit and hard piping,
Apexi Exhaust system,
Blitz intercooler and hard piping,
Apexi power FC ECU and commander,
Twin spark amplifier,
17" Enkei Alloys,
Front and rear strut braces,
SARD dump valve,
Twin plate clutch and lightened flywheel.
Mapped by RX7 specialists in Japan to approximately 330-350+bhp.

When it arrives I am going to fit these;

Magnecor leads,
Uprated plugs,
Cat removal pipe,
Apexi S-AVC R electronic boost controller,
Apexi revs/power meter,
Uprated radiator,

Fitting a cat removal pipe - will this mean it has to be remapped,
do you need to richen the mixture if you do this?

I was planning on getting Abbey Motorsport to just test the car out on their Dynopack and make sure it wasnt detonating etc. Maybe retard the timing a little. I use them for my GTR and I get on really well with them, but if I fit the Cat removal pipe what will I need to change, bearing in mind it has an Apexi power FC ECU and AVC-R electronic boost controller.

Cheers, Anthony.

[Fish]

Anthony, I know that Geff at ReWorx has used the DynoPack at Abbey for a couple of cars now.

I would guess that as it already has an Apexi PFC fitted, it should be ok. But putting it on the dynopack would tell you if its running lean, plus I think the map would need some form of tinkering as dont forget the cars from japan are mapped for 100RON fuel, we dont get that over here. So yes either the fuelling or ignition would need changing.

Dan

[A7NTY]

I realise we would have to retard the timing for uk 97ron fuel but its the cat removal pipe I was concerned about, would I just need to richen the mixture for this?

[maximtaylor]

Whether you will need to richen the map will really depend on what the state of the cat was when it was last mapped.

Also, how well was it mapped - who knows! Could have been mapped rich, could have been borderline good power/leanish.


If it was fairly free flowing, then going decat will mean a little richening. If it was fairly blocked though, as they do tend to get, you may need considerable richening.

Any answer would be guesswork without going on a rolling road afterwards and finding a/f ratio\'s for sure.

Regards

Max

[bill shurvinton]

Dunno the apexi intimately, but if it still uses the MAF (hotwire) that will correct for the increased airflow. What  it won\'t do necessarily is deal with the reduced backpressure and increased boost that will result. The boost controller will once set up. You will of course have to tweak things for drivability, but the dyno is no use there.

But I\'d get it checked out before you mod anything. Oddly there is no mention of uprated turbos there in your list, suggesting that you are on the limit anyway, but I\'m a NA man at heart.

[A7NTY]

How do you mean - \'tweak for driveability\'

and why do you recomend checking before modifying?#
Its only done 28,000 miles so I expect compression to be nice and high.

If it has been mapped in Japan then I imagine the mapping will be superb.

It doesnt have uprated turbos, I want the car to be reliable so I am going for good performance on stock twins, I am after about 350bhp so it keeps up with my 400bhp R32 GTR

Anthony.

[maximtaylor]

The Fd uses a map (pressure) sensor rather than airflow, so cannot self compensate for higher flow.

Regards

Max

[A7NTY]

Right so if it doesnt self regulate for higher air flow then it will need the mixture richening to compensate for this - right?
How rich should one of these babies run?

Anthony.

[maximtaylor]

Correct!

Different rotary sources will give different a/f ratio\'s.

Some recommend 11:1 (0.75 lambda), whilst others recommend closer to 12:1 (0.81 lambda) whilst under boost.

Mine are between the two!

The non boost portions can be considerably leaner of course.

Regards

Max

[bill shurvinton]

Ah, didn\'t know when mazda changed to Speed density. FWIW it will still self correct to a degree, but that\'s  topic for \'EFI algorithms 101\' . Need to check my notes as I\'m sure the US spec FDs were MAF. Maybe my brain has just gone to mush :-)

\'How rich\' is a bit like \'how long is a piece of string\' and depends upon a number of factors.  Best power is made at 13.5:1 or thereabouts. Any additional fuel is to keep things cool and prevent detonation. The balance is to get the spark retard and fuelling such that you get the best safe compromise. For example if you have water injection you can run very high boost at 13:1 AFR. You have to approach this carefully, but i would question things if you are richer than 11.5:1 as you will certainly be losing power above this point.

I know that doesn\'t really help, but if you \'just\' set AFRs to a particular value you are not ensuring a good or safe tune which is why i recommend a dyno session first to see what it was tuned to when you got it. This gives you a baseline to work from.

I\'ll but out now and go back to my 1984 vintage 13B