Postby Sailor » Mon Mar 21, 2016 6:38 pm
You guys crack me up!!
The Cosworth NOW FM (they are the same after Cosworth bailed and FM took over supply) were NEVER designed to give big horsepower.
The system was developed by CW in conjunction with Mazda with the intention of being fitted to the NC in what would probably have been a Mazdaspeed version with just the blower breathing through the OEM exhaust.
It would have been a performance upgrade with good HP and torque increases while driving like one would expect a showroom car...it achieves this very well as my wife who drives ours daily can attest.
It has a smallish air water intercooler which works fine at the boost levels originally intended but suffers when boost is raised to 11psi or so and the car is tracked.
Mazda and CW bailed on the project when they had engine failures which were thought to be strength related..and were to some extent..but were more tune related.
The tune has been sorted and strength improved with a stronger bottom end in later models (2009 on IIRC but someone will confirm this)
The big HP ones you're seeing in the US are NOT early models with fragile innards and most are 2.5l conversions, many with cams.
Advantage of the centrifugal ones is as someone mentioned, is the air to air intercooler which gives a more dense, cooler charge so you get more power with lower boost.
Turbos for RHD are around and making great power but even the best one that claimed be lag free has recently put a little caveat in stating the no turbo system is completely lag free.
Each has it's advantages...if you want a DD with instant boost as the bypass snaps shut..go for the SC. Mine pulls from 1500rpm in 4th WOT with zero knock and 183kW ATW which is rarely if ever used on the road.
I have 3 tunes onboard and am perfectly happy with a slightly less aggressive one in the interest of longevity. One day I'll pull the engine and do a freshen up with forged rods and crank from a later model.
If you're looking for ultimate power or don't mind keeping the revs up all day long go turbo or CF.
Of course there are exceptions to any rule of thumb. Spend up, build a tough engine and SC and you get the best of both, and of course you could do a 2.5 and SC but remember 2.5 won't be legal in NSW because % capacity increase.
Oh and Ron...you really REALLY DO need to monitor knock till you are absolutely certain it's not present whichever way you drive.
I'm not alone in having problems with mine when using cruise on the highway and the cruise applying just a little throttle to climb a very slight rise at 110kph plus.
I found it almost impossible to duplicate manually what happened in cruise.
The amount of KR required at these times was alarming (literally the alarm went off) but was sorted with careful attention by my tuner.
Also make sure you log to see if you are running out of fuel at the top end...Mine was and needed a better pump.
Check also those pesky coil wires as the miss at high rpm and load has popped a couple of engines.
You might also consider having the rev limiter lifted so you don't hit it under high load/boost.....but of course you'll then need to be extra vigilant and stay under where it used to be. A difficult task in 1st and 2nd.
Rob
05 NCLE, Cosworth SC,PF01,Ohlins,Selby,GWR exh
"We're only given a tiny spark of madness.We mustn't lose it"(Robin Williams)