My 2.4 JTD mods, Just for the record...
i thought it might be useful to list my few mods to help anyone searching for ideas who wants some improvements options all in one place.
i haven't gone far, but what i have done has been tremendously effective, and so far has probably been the best value mods in terms of power for pounds i have ever achieved, with any car!
1st'ly, and probably in the wrong order, i began with a remap from Nigel at Angel Tune.
What a transformation!
This convinced me that high tec turbo diesels are simply superb, and possibly the way forward. A stock 2.4 is no greedy slouch, in factbthey're great, but the extra acceleration, and torque from the remap, along with actually gaining a couple of mpg on a cruise run, means that in could not be happier with my first choice of mods.
Me being me, i had opted quite an agressive map from Nigel, who essentially could have given me whatever i wanted, any level of power at all, and i was warned that the stock Alfa clutch will only stand around 330ftlb of torque max, and sure enough, i began to start getting minor slip if loaded up in 4th and 5th.
I realised that although its an oil cooker, you can now drive it like you stole, and use the avaialable ponies further up then rev range to great effect, so if the peak torque at around 2k was avoided with a hefty boot in high gears, it was still very usable.
This said, i planned to go further, so a performance clutch was purchased to cope properly. I bought it from CG Motorsport, and at under £200 it was a bargain too. This is a brand new Valeo clutch, which is what Alfa fit as oem, but with a better friction surface and reworked pressure plate which gives around a 30% better bite, making it ideal for remapped cars. If you go too far for this clutch to cope, then they also do a paddle version for about anouther £100/£150 which will cope with loads more, BUT, by that time you must be approaching the 360/370 ftlb of torque that is going to start pushing your gearbox very very hard!
This went in, (eventually! not a pleasant job) and instantly felt great, job done.
My previous experience with modding turbo petrol cars had given me an insight into turbo chracteristics and the possible gains from more effecticve gas evacualtion and free flow exhausts, along with improved and cooler air intakes. So, rather blindly, i applied the same to the JTD, and promptly bought a De-Cat section. This was from Cybox, and cost about £70 plus a bit of P+P, and when you get it, see the quality of assembly and stainless steel components, you'll wonder how the hell they do it for the money! This is a straight through performance baffled silencer box, shaped very similarly to the original CAT, although on my age diesel a CAT is not actually law so i wasn't worried about junking this hugely restrictive piece of ironware anyway. ( I HATE CAT'S!, pieces of Ill Concieved Greeny EuroTrash!)
At the same time as this going on, i experimented with noise levels, and typically found that i could put an empty dustbin on as an exhaust system and not get a substantial increase in noise, SO, off came the back box altogether, and now i have a fully De-Catted straight through tube system, in 2.5" stainless steel, piped directly to a twin 3" tip, a little like the GTA style tip. The note just has a deep and mellow hum just underneath the engine note itself, hardly noticeable, but the effect on turbo spool up and free'er revving was very distinctive.
The tiny amount of lag i had previously has almost all but been eliminated, this thing gets lively so early and at such little revs, it is amazing, but revs so cleanly and quickly, you really don't know youre in a diesel at all. Ive yet to do any trials and calculations, but it wouldn't surprise me if i've picked up another mpg here and there too, as it is so easy to drive at low revs, but requires such little throttle input to pick up a little more speed. Although, this is more likely traded off immediately by the fact that its so much fun to drive you end up using more of those free rev's now anyway!
I want to improve the air intake too, and this will help make the most of de-catting the thing anyway, but not sure which route to take yet.
The BMC cda is likely the best option available i feel, but in all honesty i feel the price for what you get is all wrong, and i'm playing with some ideas of coming up with something of my own. Anything to junk that thing called an airbox will be a start, but the air plumbing on the JTD is so simple, i don't think it will be hard to get some increase in airflow whilst preventing any heat saturation from the motor to mess things up at the same time.
Plus, i'm always aware that if i pick up yet more torque, i'm into those gearbox threatening figures again soon, so my plan is to only do the airbox mods when i can get Nigel back to play with the map a tad further to give me a little safety cushion in the rev range whilst (almost) maximising the better air and exhaust flow.
On the bling side of things, ive gone up to 18" wheels too.
Some say this is a no no, and that 17's are a s big as you should go, but i have fund no detrement whatsoever thus far in the bigger rims.
They are tough to source in Alfa 5 x 98 stud pattern, but Volkswagen Audi group pattern wheels with their 5 x 100 stud pattern, and similar offset and centre bore size, can be found with consumate ease.
Just put Alfa Alloys into fleabay, then try Golf, A3 alloys... see what i mean??
I stuck to larger but reasonable rubber, 225 40 18, and this has given me nothing but improvments, with no jarring ride, a much bigger grip footprint, better, flatter handling, and no rubbing issues. A very good compromise in my opinion.
Thats it for now, but as things go on i'll come back and edit the post.
Hopefully this may be useful to someone thinking of improving their oil cooker, or maybe like me, i couldn't initially make my mind up between the diesel and the V6 (although we now run both!)
Its all good, thanks for reading
Last edited by PETR0LHEAD; 22-05-09 at 20:56.