Megane 225/230 and 250/265 engines.

Andy all I know is that the rods and pistons are different mate, don't know how though, sorry

 

Megane 225/230 have a turbo with a T14 turbine wheel ....Megane 250/265 is larger T15 .
Internals are more stong in the new Megane.
Head cylinder a bit diferent and also the cams....apart from the VVT.

 

I think the 250 has different exhaust valves as well.

 

250 engine has vvt, different cam profile, lower compression pistons, different conrods, bigger turbo, etc.
225 use the same conrods as a 1*2...

 

I think the comp ratio is 8.5:1.
Rods are definitely the same as a 1*2 in the mk2's.

 

Supposedly rods only fail due to high rpm, but as far as I'm concerned thats complete rubbish!
My engine failed at 3000rpm which is around the max torque area produced from td04, so 325lbft in 2nd gear, no wheel spin, etc so something had to give...
250 has stronger internals, low compression, a larger turbo and vvt, so all this will have an affect on the torque/power curve and help safeguard the engine.

250 has different injectors and a rising rate fuel pressure regulator, but still not return line.

 

Here you have the compression ratios

http://www.engine-dynamics.com/_templates/departments/pdf/compratioguide.pdf

 

I'm sure josh cook used to use the 250 bottom end on an R26 engine, ran it with 280/280 and said it was pretty much bullet proof Andy

 

Sorry along with 250 pistons

 

I was sure the later R26's had vvt? Even Paul @ RSTuning was talking to me about it..

 

r26's dont have vvt mate, i wish they did as i would have went for it when RST built my engine.

im sure iv seen the french lads are fitting 250 engines to mk2's and having a reliable 320bhp.

 

320bhp is probably stretching the limits of the standard internals and also a hybrid turbo.

250 conversion does seem expensive, if the std gearbox isnt compatable, also not sure if the euro 4 r26 ecu will do vvt...

 

Megane 250 or hybrid mate. The 250 has a td04 15T, my R26 has a td04 20T and only makes 315bhp, so i guess the vvt helps make more power.

wasn't sure if the R26 used a sagem3000 ecu or not.

 

What really impresses me is the fact they all make 300plus just off a map and loads of torque.

plus anymore i personally think is too much for fwd, would ruin its handling and torque steer all over the place

 

Fair play then, in the wet though (that we have 90% of the year) its too much, my 265 struggles in second in the wet have to modulate!

 

My car cant put the power down in 3rd gear if its damp, but pauls old .R had no issues with grip at 371bhp in similar conditions. I guess power delivery and mapping makes a difference.

 

My stage one R26 will give me the TC light in first and second in the wet, sometimes third. That's on Michelin PS3s.
by contrast my old 328i would give me no such hassle, on PS2s. Correct axle receiving the power? There was slightly less power and it didn't have TC either.
On the skinny budgets I originally aquired the car on it would spin the wheels in the change up to third, which was at nearly 70mph. That was a little scary.

 

yes. Is possible fit the 250 engine and work with the oem ecu(sagem 3000)here we have one 230 run with this.
but i think head ported + hybrid turbo is a better mod.

 

You need to forge the engine then fella, but then you will want more than 320bhp. Im already bored of mine and want more, but dont think its worth spending another £5000 on the car to gain another 130bhp and have to rebuild the gearbox every other week.

you might be better fitting a hybrid turbo for 300/300 and putting the car on a severe diet?

 

Steven878 it is not the power that brakes the box it is the torque.And torque for 400-420 (on gtx3071) bhp is in the same region as in your hybrid.

 

The 197 head does fit on the megane block & it is a direct fit. The only real gain I can see is if you want to be above 500bhp & the standard head will flow that.
Lee