I have recently switched from A 135BHP 1700 X Flow engine to a Blacktop 2.0L ZETEC from the Focus. With the exception of a lightened flywheel and 4 to 1 exhaust the engine is standard and I have retained my Weber 40's.
I was very pleased with the outcome, lots of toque through the rev range, obviously more power and generally much more drivable. However I was disappointed with the performance at high revs, in short it didn't really want to go above 5,500 and if you did, it seemed to take forever to get to 6,500 and didn't seem worth the effort.
So yesterday I took it to Sigma to see if a rolling road session would improve anything. At this stage I don't want to mess about with the map as it has the OMEX ECU with the well proven (read tame) Raceline map.
The carbs were jetted as per Caterham's spec for the Supersprint i.e.
120 mains
F16 emulsions
165 airs
50F9 idles
The only thing I had done was change the chokes from 32mm to 34's as many searches of Tech Talk seemed to indicate was the right thing to do, as did few people who had been there before me!
On the first run Peter took it up to 4,000, cut the engine, shook his head and muttered "I don't like that, (you have to understand Peter is one of the Old School of engine tuners), put 35 mains in it Bob (Bob is the oily rag but a very nice bloke)".
Second run up to 5,000 and again he shuts it off and says "still not enough, try 45 mains".
On the third run Peter took it up to 7,000, down and up a few times (it's frightening to watch and yes the primaries do glow red hot) shut it down and announced "that's better". The airs were then changed to 175's and after another run he was happy, said the engine performs well, spent a couple of minutes on the slow running jets and told Bob to make out the bill.
I went out this afternoon and the car is totally different, it gets to 7,000 so quickly and the power and torque is there all the way through the rev range, it really feels like a different engine. 😬
I was told by many when I fitted my ZETEC that it will run happily on the Super Sprint carburettor set up, all you have to do is change the chokes to 34mm, well this has proved not to be so in my case and I strongly advise anyone doing the upgrade to put it on a rolling road as soon as it is run in and to anyone thinking of upgrading to the ZETEC - JUST DO IT, you won't be disappointed and the Raceline offer will not last for ever.
Guy SB Lowe o *arrowup*o
The ZETEC is now running here