My car is currently SORN'd after my recent valve issue whilst I get an ABF head given the mr hillclimber treatment & then refitted in the Autumn.... My plan is to keep the car for weekend fast road/track use next year. The planned spec will be the stock ACE 2L block with JMR head, baffled sump/windage tray lightened flywheel, 2Y 16v box, K-Jet fuelling, 50mm port matched inlet, port matched 4 branch, Jetex 2 box system, mocal 13 row oil cooler & a raised 7800 rev limit In essence not dissimilar to ianb with CFJ & the fifth gear TSR car The only area I am yet to fully decide on is the cams. I want to retain reasonable drivability low down- but the engine to really come alive at the top end. If I have any criticism of a stereotypical 2L conversion it is that the engine becomes very linear to drive without the "coming on-cam" feeling you get in a KR. I'm sure this is because the low end & mid range are better- but it's a bit boring if I'm honest. Don't mind sacrificing a bit of mid range for some extra top end sparkle I also want a bit of a gruff & lumpy idle too-have missed that from my 8v days! From previous experience with split duration Schricks (268/276) on ITBs I reckon a straight Schrick 268 setup is favourite on plenum- if somewhat pricey! Vernier pulley to swing the timing, no need for an internal vernier (CFJ doesn't run one) & away you go. Has anyone else done similar on a 2L running kjet? I know GVK tried Schricks a few years back in his 16v but hated them- dyno time & a raised rev limit were req'd IMO.. I'd be open to try other cams if recommended- CAT cams, Piper, Kent??? Realistically I'm looking to be getting upwards of 165BHP (real world) as a target. Any input gratefully received. Cheers
Probably not the answer you want, but I'd say spend the money on: 1. A Quaife or other ATB Diff if you want the car to be quicker in the real world. 2. Megasquirt or other Mappable Management - you can tune it to give the high end urge you want. Then maybe think about cams, which will work better on proper management anyway. If you really want the car to run badly at low RPM, just retard your timing. It'll be slower, but you'll get that 'coming on cam' feeling you're after.
F.D & Quaife will be done in good time Megasquirt/mappable ECU is only worth the effort if going EFi (a la ABF) IMO- no point mapping ignition without relevant fuel control really. Isn't ignition fully advanced to ~30degs by 4.5k anyhow? Whilst the k jet is crude- the likes of ianb, GVK & Tub all got great results from it. Tubs car was the quickest 0-60 at Bruntingthorpe I recall
Hi Chris, Hope that the rebuild goes well. A bit late but .... You can guess what my view would be however I would suggest that you consider a 4.25 FD as an option vs cams & ^ rev limit. pp Mike on the Quaife
With the gearing Il probably go to a 3.9fd when I go for a Quaife having ran GVKs old gearbox for a while..any shorter might be a tad busy for road use. Might have a few Oxford to Manchester Airport journeys coming up next year to be thinking about I'm just keen to fit new cams with the head off the car (much simpler & easier to time) so that my physical engine mods will (hopefully) be complete. Seems the most sensible time to do it...I have sold on my ABF cams already too A proper minefield of info out there- & has brought back some good memories reading back through GVKs old 2L 16v threads
I don't think you can go far wrong on the Schrick splits as a pretty proven mod. In fariness to K-jet, it keeps a layer of cost out, but MS / standalone benefits (controls fuel and spark - this is not K-Star!) have been thoroughly demonstrated - one for later mods in the pipeline? The recent 16v RR day provided the best 'on day' comparison in years. http://www.clubgti.com/forum/showthread.php?t=228244&page=14 http://www.clubgti.com/forum/showthread.php?t=228244&page=17 Outputs, just a number and all that, but this recent thread is an extremely insightful guide to validating 'plots of yore' http://www.clubgti.com/forum/showthread.php?t=235714 => expectations can thus be set accordingly. Ref Tubthumped, please see slick tyres & warm up laps! No worthwhile comparisons come out of that
Really? But in comparison to what? And under what condtions? It is quite easy these days to have 'fast' become faster! Many accurate ways besides WOT testing to evaluating 'faster' too. Mike H and Jamesa gave combined solutions and that would be, a shorter diff @ 3.9 FD and a remapped ( requiring any good SEM) and optimised engine as it is. Then the performance can be studied and efforts can be made to extend or amplify torque further by the use of effective components. Have a read at that threads that Chris suggested. It should give a baseline towards an engine that would suit you.
Please enlighten me then.... I am sticking with kjet for now in the interests of originality. With k star obsolete nowadays I understand the fuelling adjustment is crudely done via the WUR & metering head flap to find a suitable AFR compromise...(setting of system & control fuel pressures etc) With that in mind (& having researched it) I can't see a huge amount of point in splashing out for mappable ignition only if fuelling adjustment is so crude? The k jet cars mentioned were all known to be strong 2L 16v examples
Originality does not always mean performance and in an engine we are looking at ways of improving burn with respect to torque production not only at WOT. If programmable fuel (and spark) mapping is "crude" why has it been demonstrated to have significant benefits on otherwise std engines mostly without the engine modifications you listed? I am not saying K-Jet cannot be fettled to be stronger than std settings, is but with SEM you can adjust selectively rather than globally. This will help when eventually making a cam change or justifing the pumping loss improvement when a head is ported. This is the type of option Tom (smudge) would have on his 160+lbft engine when overall cam timing and overlap are experimented with. A calibration will have to be done for every hardware change to understand the effects the changes will have on torque.
VW_Singh went from Kjet to Megasquirt and got 20+bhp and LbFt. You'll never see that with a pair of Schrick Cams alone. I'd bet with a JMR head and megasquirt you'd get around 180 bhp and 150+lbft. You won't be able to map as aggressively as Gurds on a heavier and higher geared car, but you'll get more power and a wider power band. I've got more power low down, and an extended top end on mine. (2.0 8v, 285 cam, Pack D head). I get mid 30s MPG on the road too. A Megasquirt install would bin all the Kjet hardware. You could use ABF stuff if you want an OEM look, and a GTD type airbox. Nice and understated, subtle, and lighter than the Kjet metering head, etc. As I said, if you want max bang for bucks real world performance, Quaife (and 3.9 CWP) first, MegaSquirt 2nd. If you want more engine power and pub numbers, MegaSquirt First, Cams 2nd. You won't like Megasquirt though, as it'll idle smoothly. I guess you could mess up the mapping to get a lumpy idle though.
I think I have been misunderstood here. Programmable modern stuff ISN'T crude!! What I said is adjusting kjet fuelling IS crude. I am in agreement that optimised fuelling/ignition reaps rewards but if kjet fuelling isn't mappable (as standard) unlike mk3 digi efi (with Megasquirt or other) then I am loathed to go to the effort of mapped ignition only as it's half a job!! I fully accept modern ECU tuning is the way ahead as is shorter gearing blah blah- I have got experience of this having owned & tweaked mattd's old ITBd and DTA ECU'd 2L 16v so I'm not a total virgin to the subject.... I respect the modern way with programmable ECUs and the like but these weren't around to a large extent in the heydays of TSR/ GTi Engineering etc etc yet they still managed to build quick cars & that is the path I really want to follow... I hope we are all on the same wavelength now
Not denying those vehicles were indeed relatively quick in those days. However technology and knowlege has moved on lots and some of this is in the hands of private enthusiasts rather than firms and a lot is shared on this forum. Gearbox and FD aside, with OE engines also improving over time it would not surprise me that such old school modified vehicles as your references are would not be very different to drive vs a properly tweaked OE engine that had a bit of thought put into it. This is where the bang for buck discussion comes in... I understand what you are after. Putting gearbox and grip into the equation you are after the same "Forward G" force that you can remember, subjectively, those old KJet but well fettled cars were delivering. Thing is do you really need to follow the same method to achieve the same or and improved thing? Can you get the same expertise at minimum cost to integrate it like those old cars? Are you chasing a datum that is really no better than a more recent and modern reference. In a friendly way consider these things before chucking parts at an engine for a real world "165bhp" with a 7800rpm cut out. Torque wins races and Gs cannot be fettled with
Different ways to skin a cat indeed- I want my car to retain its period originality though. Much the same as the 16v GTi's of Mark_B, Newey/Loach, ianb etc etc. Making the most of the kjet 16v setup albeit with increased cc My original question was really aimed at cam choice assuming an old school tuning approach was adopted. Megasquirt really doesn't appeal knowing how well some properly fettled k jet machines go... Newey with ~180 BHP at TSR, Mark_B with ~175.
I'd liked to see how those figures would have translated on the 16v day. Don't think any KR gave figures remotely near that.
+1 These are merely numbers ^^ and a total distraction. As we know, rolling roads vary hugely. However, this is the best piece of 16v comparative information we have ever seen on Club GTI: Mass data power Mass data torque. Ultimately if it is about originality, it is not about optimising output. Period. There is no sense in discussing numbers.
As above post. Your banding names and numbers around that mean nothing unless measured all on the same day and rolling road. If you want a gaurentee of decent numbers then you need meagsquirt or the like. Its not like it cost a lot more to do either. Im sure you already know what cams you want, maybe the same ones that ..... or ..... had in theirs!
