Northern Nick

iTrader: (1)

I know this is a bit premature but thats me

I'm planning to do a 2.5 conversion in the later part of next year to my MY02 STi.

I've done a few search's until my eye hurt last night and gave up as there no real figures as to who got what with what from a 2.5L.

Currently the car is pretty standard still running the VF35 and top mount, currently 335/320. The idea behind the 2.5L conversion is the boost the torque at low revs as I'm not a ***** out driver, horse power is just a by-product of torque in my opinion (and in reality really). I just like a quick car but love huge torque low down. Ideally I'd love to see 400lbs/ft at around 4000 holding on until 6000rpm, but what I'm really after is 250lbs/ft or there abouts at between 2000-2500rpm, building upto 380-400lbs

So the point of the thread is will my TMIC/VF35 do what I want on a 2.5 STi bottom end. What turbo would be best with the 2.5 to get what I'm looking for. Will I need forged pistons for high boost low down and I suppose the real question is can you get 250 or even 300lbs/ft at 2500rpm? Twin scroll set up considered if thats what it takes

Anybody with boost/torque graphs and spec lists for the 2.5L, it would be very appreciated if you could post them up

Any advice is welcome or a point to a relative thread even but I cant find one

Thanks.

500

Go for an MD321, keep the top mount.

I'd advise at least a set of drop in pistons from Lateral

Possibly also buy a set of rods and a set of ACL race series bearings if you can stretch to it.

Slowboy Racing

No need for rods or bearings at that level unless the block is being built from scratch which i doubt. Pistons are a must imo if you want to retain any reliability.

Drop in or hone to suit starting at around £540.

The 20G spins very well on the 2.5 and will see those 400/400 figures.

Northern Nick

iTrader: (1)

I'll be getting one of the very many new STi bottom ends available from various places so hopefully theres no need for bearings and rods but I've read that the pistons can be a weak link hence why I mentioned them.

What are general feelings on 2L heads on a 2.5L bottom end, I read one guy didn't rate the idea?

frayz

iTrader: (7)

In the real world the 20g wont see 400bhp without meth etc, maybe 400ftlbs on a 2.5 but not the bhp.

Id go with an MD321H or similar for fast response and a genuine 400 of each

Slowboy Racing

I though the real world was where it didn’t matter.

alanbell

iTrader: (6)

The MD is very good on mine.