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Megane F4rt - Mk2 vs Mk3

Ronjon46

New Member
Hi there,

I own a LY R26 with all the usual mods possible with standard internals, mapped to 279 bhp courtesy of EFI.

I would like to start pulling parts together for a replacement engine aiming for somewhere between 350 and 450 bhp. Really ahppy with the car as it is but I would love another ewngine project and I am sure I'll get bored/used to 280 at some point.

I am still relatively new to the Renault world having previously tuned old VWs but I believe the F4RT with forged internals, bigger injectors (maybe?) and an appropriately sized turbo should cope with this power ok. My main question is whether to start with a Mk2 or Mk3 engine. I believe the main differences are something to do with fuel pressure from previous searches but have found complete information hard to come by, I also really value the knowledge found in forums like this. Would the fuel pressure of the mk2 engine become a restricting factor in the long term?

Any help with this would be appreciated. I did try searching but did not find much so I apologise if this has been covered already.

Thanks and nice to meet you all.
 
Loads of different ways to approach the higher power builds. My take on it

You will need a better fuel system, fixed rate fuel pressure on mk2 not adequate for 330+ hp. Do it right and fit a surge pot, decent main pump, rising rate regulator and fuel rail with return with injectors to suit 630cc+ depending on hp.

Oem megane 2 ecu is crap at 350hp+, safety and closed loop boost control is poor. Your better off upgrading to a decent standalone ecu. Ecumaster works with the original dash/canbus.

A good 20t Hybrid turbo will do 350-380hp maxed out, reliability is questionable at them power levels for track use, ideally a larger garrett or similar is a much better approach.

Mk2 or mk3 bottom end is ok to forge. The mk3 head flows better and quite an easy fit and has vvt, but you will need a standalone ecu to use it.
 
Same as what brigsy said, I had a 350bhp meglio… was on the limit of the ecu’s capability. Had a TD04-19t hybrid that was great and made power and torque everywhere but you could run a better turbo at that rate of power. Had a return fuel system on it which was fine untill you ran less than half a tank of fuel and you would see fuel surge.
 
Thanks a lot for taking the time to reply guys, I really appreciate it.

Seems like there is a bit of a tipping point in terms of complexity and cost when looking for over 350bhp, so maybe a staged approach is the best way forward.

Not being clued up in the world of ECU mapping, am I correct in assuming that the stock ECU is not capable above 350ish as you are simply not able to tune enough parameters required to achieve this power level?

Maybe stage one is to forge the bottom end, Garrett turbo with some headroom above 330 if/when required, standard ECU, already has 630 injectors. I assume this would safely make 330bhp?

Then stage 2 would be standalone ECU, uprated fuel pumps, regulator and rail and possibly a mk3 head? Could the mk2 head be ported to achieve similar flow to the mk3? Would also have to look at fitment compatibility of throttle body and fuel rail onto chosen cylinder head to see what combination makes the most sense.

I assume EFI would be ok tuning an ECU master standalone ECU?

Thanks again
 
Thanks a lot for taking the time to reply guys, I really appreciate it.

Seems like there is a bit of a tipping point in terms of complexity and cost when looking for over 350bhp, so maybe a staged approach is the best way forward.

Not being clued up in the world of ECU mapping, am I correct in assuming that the stock ECU is not capable above 350ish as you are simply not able to tune enough parameters required to achieve this power level?

Maybe stage one is to forge the bottom end, Garrett turbo with some headroom above 330 if/when required, standard ECU, already has 630 injectors. I assume this would safely make 330bhp?

Then stage 2 would be standalone ECU, uprated fuel pumps, regulator and rail and possibly a mk3 head? Could the mk2 head be ported to achieve similar flow to the mk3? Would also have to look at fitment compatibility of throttle body and fuel rail onto chosen cylinder head to see what combination makes the most sense.

I assume EFI would be ok tuning an ECU master standalone ECU?

Thanks again
Personally I would put the block together with the final goal in mind.
Something like a 784 block with the respective head, cams, springs.
Stick with the smaller turbo if budget it a concern

Save like mad then ECU
Save again then turbo / injectors.

Thats the way I would do it as otherwise you are halfway house / compromised and having to double upgrade every time
 
Lots more modern with new features. The ECU in these must be 15+ years old now?
Indeed oem ecu is old tech and there is loads of issues with it when you start looking at the software. Still see people messing about with boost controllers on oem ecu with large garrett turbos. 10k of engine and crap oem ecu, the mind boggles.

Proper dialled in modern standalone is mega in comparison. Boost by gear, multiple boost settings, egt, wideband 02 for corrections etc.
 
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