Yo guys, I havn't posted a build thread of my car on here ye but I have a 1.6 driver of which i'am modifying so far i have done the following; PB head fully ported and polished, recon'd and skimmed to hopfully reach about 10:5:1 to 11:1 cr stainless miltek 4 branch and gti exhaust system custom stainless inlet mani mated to gsxr600 srad carbs gti kjet dizzy i'am going to fit a newman 272 cam Would it be worth it to have the crank balanced and maybe knife edged? and also have the flywheel lightned and balanced? I'd like to make it quite 'revvy' and assuming it being a shorter stroke to 1.8's but same bore it naturally would rev quicker? especally with a 272! What kind of price would I be looking at for either or both jobs to be done if it is worth me doing it? I do hear of alot of people using the G60 flywheel and having that done! any bonus about that? thanks Rhys
Depends how much money time and patience you have. 99% of people would probably think spending any money on a driver engine isn't worth it!! Abf/20vt = bangs per buck
The G60 flywheel won't fit your box as it's an 02a/j cable change box flywheel not an 020 (assuming you have a mk2 or3) If you have an 020 then it's already lighter than a lightened 02a/j flywheel but can be taken down safely to around 3-3.2kg from around 5kg. Doing a crank is alot of work for little gains, as no offence, a 272 cam isn't a 'big' cam with peak power below 7k . Your carbs will help though. I've done several in the past, all aiming past 8k, most of them being diesel cranks that are really heavy and deserve a little diet plan! The 1800 crank isn't really a 'heavy' crank, and they are balanced ok from the factory. You'd be better off changing the box to something like a mk1 2h/fm short ratio box which will improve acceleration. It'll cost less than having a crank done and will be more beneficial to you, especially with a lightened flywheel. It'll spin up quicker and easier and improve the overall feel of the car, where as a crank would be hardly noticable.
If you want a revvy engine then you will notice the extra speed that a lighter flywheel will allow the engine to pick-up revs. I've only ever done crank balancing on anchient British cars, where it made a noticable difference. I've got a 1.6 GTI which is pretty smooth at 6.5k revs so it might not make so much difference on a VW. It isn't expensive though, if you've got it appart so you might as well get it done while the flywheel is being done.
C/C, whats 'not expensive' the balancing or the machining that goes into one having knife-edged? Edit, reading it back I assume you mean balancing, not the actual lightening.
HotGolf, you replied while I was typing so happy to go with your VW experience. Also, having typed "not expensive" I then remembered that I can't remember how much it cost! However, I remember that in the context of a full rebuild to a road / light competition spec on an old MG, balancing the crank didn't seem expensive compared to some of the other jobs. BUt the MG would have broken, literally, if the crank hadnt been balanced so in that context it was cheap! I didn't have it knife edged and couldn't comment on that. I assume it would be a lot more as much more metal would have to be removed. Is knife edging to cut down on drag in the sump? If so a windage tray might have similar effect for less?
Lol nice one, I know where you're coing from. If it's out and it needs it do it and false economy if you would need it done anyway in the future. Yes the knife-edging reduces windage, but also helps reduce the reciprocating mass like having the flywheel done. A windage tray has the same effect (and a damn site cheaper!) Are the old MG cranks prone to failure at high rpm then? I've literally no experience of them. Like you said though, cheap in comparison to a new engine!
I was using a MG Midget 1500 which fitted the class rules perfectly for the sprints / hillclimbs I did but the engine (originally a Triumph design) started as an 800cc and by the time it got to 1500 was just stretched too far for a 3 bearing crank. Some BL reduction in quality of steel didn't help. Long and short was a flexible crank and frequent run big ends, main bearings and thrown rods, all at 5500 rpm! My sister snapped a crank clean in two on the road! I loved that little car and did loads of differnt events with it but just spent too long fixing it. Hence move to VW. If you are really interested http://shoestringmgracer.com/ has the sorry tale.
