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Questions about the capabilities of a WRX9+ G4+


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Hello everybody,

I'm currently planning the build of a new engine for my Scooby (2.1 strocker fully forged  3/4 closed-deck, blueprinted and balanced EJ20), and so I'm  looking for a new ECU for my 2004 WRX, but only to get certains specifics functions (for the engine management alone, my actual Denso AJ840 ECU with Eculabs is perfectly fine).

So why change ? Because I want to be able to switch between maps in real-time and without delay, and I need something that can handle 3 or 4 maps (for exemple :
- street (300hp)
- track soft (400hp)
- track hard (500hp)
- straight line boost/overtaking (550 or 600hp)

The engine and turbo (GTX3576R Gen2) can stand up to 600hp+ easily, but I want it to be "reliable" (this is a Nürburgring car, used on the street only to go to the ring and go back home.).

So my question is : can the G4+ handle this ? How many fuel/ignition/VE/boost maps are possible, and can you swtich between them without delay and on the fly ? (for example, the "straight line boost/overtaking" will be activated by a button on the steering wheel).

I don't want to have 400hp boost with 500hp ignition map for example


Thanks for your answers !

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Basically what you're describing is purely only 4 boost levels. With MAP vs RPM, which is the typical load table arrangement with most ecu's ( without MAF obviously ) it is up to you to ensure running for each level is correct for that level. But in no way at all does it require 4 fuel or spark tables.

So..even a simple boost controller with your current ecu could do that


Via a replacement ecu, you could achieve multiple boost levels via a multiposition switch...with I guess an override type feature from a further momentary push switch on the wheel as you describe for that "overboost"...seems a bit messy and pointless though to need that additional switch for that though.

Although if you want a reliable 600hp engine, just build one.

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500hp 2.1l = almost 240hp per liter. Porsche's 919 2.0 V4 is outputing 500hp (so 250hp per liter) with factory money. Why ? Because it was required to last more than 24h and 5000km... At a point physic is the problem, and of course my engine will be able to hold even 800hp, but I'm looking for an endurance-style engine (with the associated reliability), not a drag-race engine ;)

My mechanic/mapper was in Subaru WRC team for 7 years, I don't think we can pretend to learn him things, especially about EJ engines ;)

So I just want an answer to my question, can the G4+ do this ? I know the AEM Infinity 506 can, but the G4+ is plug'n'play, so a little bit cheaper (no expensive harness needed).


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Ducie54 : Or maybe somebody is trying to keep the reliability of his very expensive engine while still be able to fully use it when needed. But you know me and what I'm doing so of course you can judge. Internet/keyboard pride I guess.

Stevie of course he has, and that's not the question. Don't take yoursevles too seriously guys, chill, we're talking about ECU, not cancer.
And do you think every former top level (F1/WRC/WTEC/Nascar etc...) mechanic lives hidden in a cave after leaving the competition world ? Guess what, some of the are still working, and some even got their own business.


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using a single tuned map you can easily have it range between 300-600hp, simply by leveraging Link's boost control.  You don't need to be switching fuel and ignition maps for different power levels.  What ECU does your tuner recommend?

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Ducie54 I don't know if you're a d-bag or just a troll, but you must be seriously embittered in your life to act like this (plus you don't know what you're talking about, you can ask the best mapper in the world to tune a 800hp 2.0 mass produced - cast aluminium block it will never be reliable for more than drag-race use. Open a book of physic and learn about a lot of things, including mechanical stress. Knock, auto-ignition and AFR aren't everything).

JMP my mapper is used to Motec, but is ok to map on Link, Sybele and AEM. And I want a stand-alone ECU because I plan to add a race dash later.


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As others have already said, can't you achieve your aim primarily through boost control? If you have DBW throttle then again you can control/ limit power with that. 

So far as I understand it, and I am far from an authority, reducing power by altering fuel and ignition maps isn't the way to go as for one reason, retarding ignition will generally increase EGT. 

To answer your question on hardware, the PNP ECU is the same as the Extreme. It may have some additional I/O and probably an on-board MAP sensor over the loose Extreme ECU. 

Hope that helps?!

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Your first post talked about 500hp track and 600hp for straight line/over boost. How did you now come to 800hp. Maybe I missed read help me out where I went wrong. Or has your goals now change from the first post....

You can run all the best gear in the world but a Shit tune will still kill it. 

BTW if I was going to troll which I can't see the point of I would of been alot harsher. 

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Guys relax a bit. 

I've mapped and I'm supporting several 600-800hp 2.0 to 2.3l time attack engines/cars with a Link ECU and multimap strategy.  Such an engine runs usually for 5000 race track kilometers until a rebuilt is needed. That's a similar distance to a 24h race.  I like to answer your question.: 

All LINK ECU use the same PC-Software and the same Firmware. The main difference between all LINK G4+ ECU's is only the hardware.

your tuner should tune the main Fuel and ign Maps from the lowest to the highest boost levels. There are 3 main Boost Maps in the LINK ECU. You can additionally span one of the axis of the Boost Wastegate or Target table to a driver Rotary Switch. So it's possible to have up to 33 different boost maps, which all can be switched on the fly. 

On top of that, you can activate 4D fuel and ignition tables on one or several of the boost maps. This allows trimming Ignition and Fuel on some maps if you or your tuner like to do that. 

The Link Ecu is really flexible. Usually, the only limit what you can do is the creativity of the tuner. 

As an example, we installed 3 rotary switches in a Time Attack/ Hillclimb car.  One 12-Position Rotary Switch is used to choose between 12 different torque maps (mainly altered by boost strategy). The Launch RPM can be chosen over another 12-Position Switch, depending on whether and Track conditions. And lastly, we have a 3-Position Rotary Switch to choose one of 3 Drive by wire Throttle Maps.  

For engine Safety, we set up Limits for too low and to high Coolant temp, Oil temp, Oil press and Fuel press. We are also using full time closed loop lambda and sending a lot of Data over a custom CAN. 

As you see, the LINK is a very capable system.  But as every ECU, it needs a capable tuner to use it properly. 


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Adturb no DBW on my car, those are the firsts blobeye models, DBW came later. Cable 4 life !

Ducie54 of course the tune is an important part of the reliability, but you can have the best tune, if your parts aren't strong enough it will break. EJ20 (even "3/4 closed-deck") (I'm not talking about EJ25 wich is just a bored EJ20) reach their structural limit at 600hp, after that they need to be sleeved or converted to fully closed-deck.

At 600hp, I'm losing a lot of reliability versus using my engine at "only" 500hp (wich is less reliable than 400hp, etc...). Mechanical stress... More power (in fact more torque) = more pressure in the combustion chambers, no matter how good the tune is.

mapper thanks a lot for your answer. I'm not mapping (I understand how it works, I've read books like Engine management advanced tuning by Greg Banish), I'm just gathering informations to choose parts wisely ;)

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