[HELP] Tuning a single turbo FD
 

Hi,

I am from sri lanka. A vehicle importer at my place has brought down a RX7 from japan and it has gone through the single turbo modification already. The car has an Apexi power fc ecu + the commander.
The seller doesnt have any idea of rotary engines. So i dont have any idea whether he or his employees have messed any map settings using the commander if that is possible (I am pretty sure that they couldnt have connected a laptop and made any changes coz they dont have that knowledge). In sri lanka there are only a handful of rotary cars and no rotary specific workshops/tuners.
I am interested in buying that car. So I have 2 questions for which i seek answers from you guys.

1) Can they mess up any map related settings using the commander? if yes is there any way for me to rectify it?
2) Do I need a specific rotary tuner to tune the rotary engine or is it same as tuning any other engine so that i can take it to a normal tuner with a dyno and get it tuned?

Thanks in advance.

Test drive it. If the engine explodes, they messed with the tuning.

Yes, you can mess with the tuning with a commander.

You need a rotary tuner or you need to do it yourself.

So a guy who tunes evos and GTRs wont be able to tune a rotary?
If i am doing it by myself how am I supposed to do.

I am an engineer so i do understand the theory and terms so can you point me the right direction?

HPA or efi101 are good resources. If you still have access to any academic resources and can revise combustion science and look up SAE papers it is worthwhile.

To be honest the best threads with general tuning advice are probably 10 year old threads here in rx7 club, nopistons or Ausrotary before too many idiots overran forums and kept posting the same questions expecting to be spoon fed. The related thread linking on Ausrotary and tech reference is pretty good without being overwhelming in volume to sort through like this forum.

Just be aware that for comvustion stability and temperature management rotaries tend to want less timing advance and richer fuel mixes than similarly specced pistion engine packages.


A good cautious tuner would probably be ok but often they don't realise the above and that rotaries are less tolerant of knock which can lead to problems. Likewise there is a significant investment in effort in genuinely understanding dead time compensation, injector staging and the sequential turbo control system that they either won't be interested in or will mean you have a large labour bill for if they are not likely to be able get value from that effort tuning similar vehicles.

Huge thanks for shedding some light on this matter. I'll keep that in mind. Thanks a lot.

I just realised it is single turbo. That removes a lot of headaches, provided the fuel system is adequate or you are happy to develop it.

An aluminum Air Separator Tank or AST delete kit is a good idea to avoid engine failure due to the standard one failing if it still has the standard intercooler/AST.

The biggest mistake made by non rotary tuners is: not adjusting trailing (IGL) ignition to maintain proper timing split.
Yes you can tune with the commander only but it is very time consuming. For timing you have to deal with two 20X20 maps or 800 cells.
The only way to safely do it is with the DATALOGIT hardware and software.

Even the default Apexi PFC map has bad timing split in it!

So if I don't have a rotary tuner in my country then am I screwed forever? Can I get the power fc tuned online by someone abroad? Or can I download maps somewhere and then tweak it if it doesn't fit 100%?

With a technical background there is no reason you cannot develop a tune carefully yourself.

I have some unclear areas regarding tuning.below are them

1) Do I need a dyno for tuning purposes?
2) Is there a way that i can extract the wide band readings / tuning settings / map which is there in the ecu and post it in the forum so that someone can tell me whether there is something wrong with it?
3) Are there any videos or tutorials on rotary tuning which can help me?

Thanks in advance

If you search there are pdfs members here have made about pfc tuning rx7s.

If you get a datalogit you can take an anslog channel from most widebands to log AFR agsinst running conditions. A lot of guys just street tune with conservative timing, with a decent intercooler/turbo/exhaust and fuel and ignition system to support you power goals you can get a lot more thsn factory power without leaning on ignition timing.

1) Do I need a dyno for tuning purposes? No. Many excellent tunes have been written using data from street driving only.
2) Is there a way that i can extract the wide band readings / tuning settings / map which is there in the ecu and post it in the forum so that someone can tell me whether there is something wrong with it? You will need a DATALOGIT to interface with the power FC and be able to log wideband data.
3) Are there any videos or tutorials on rotary tuning which can help me? See attached document regarding single turbo rotary tuning using a PFC. Everything you need should be in there.

With some patience and the internet you can self teach yourself to tune anything.

-Skeese

If you don't have access to someone who has tuned a PFC on a rotary you're better off converting to something that the tuner is at least more comfortable with. Many people disagree with me but the PFC compared to todays ECUs is a total piece of shit. Getting an Elite 1500 (or 2500) is a snap and will save you in the long run on dicking around with a lot of the 'expertise' required to get a PFC to run completely like a stock ECU. They just have to understand what all elemental differentials affect an engine. A PFC is retarded weird and don't add up at times (please read its manual).

I still tune PFCs, but I still hate them.

Thanks a lot for the answers bro.
I have wargasm's pdf I am going through it. I'll get back when I am stuck.

Are you saying that if I get an ecu like elite 1500 then any tuner who tunes piston engines will be able to tune my single turbo rotary without any issues ?

No.

somebody who does not know how to tune a turbo rotary can blow the car up regardless of what ecu is used. The PFC is just ancient in comparison. Modern ecus allow you to use a number of engine protection features that if setup properly will save the motor should something go wrong in tuning that could blow it. They're also alot more user friendly when it comes to logging data and then using that data to further the tune.

It isn't necessary to upgrade, but it definitely makes it easier. You can probably get where you need to go with the pfc using the notes.

Skeese