Julian Thompson Posted January 12, 2003 Share Posted January 12, 2003 Chatting with Ammo (Raceco) earlier about alloy front pulleys for the K series. He needs 10 orders to do them for £100 inc VAT. They will be over a kilo lighter than standard and will be resized to run the alternator 15% slower which will reduce losses further as well as lowering rotating mass. Sounds great and I'd like one. Anyone else? Link to comment Share on other sites More sharing options...
WILL FLY Posted January 12, 2003 Share Posted January 12, 2003 They were less than that on the QED stand at Autosport. I thought there was a damper built into the pulley and removing this was a bad thing. V7 SLR discussed this on the Se7ens List. See willfly.net for more info. If you don't spin you ain't trying Edited by - will fly on 12 Jan 2003 20:48:02 Link to comment Share on other sites More sharing options...
STEVE GILBERT Posted January 12, 2003 Share Posted January 12, 2003 I have a Raceco Zetec Pulley and its the bollocks, the hard anodizing is so hard its harder than a very hard thing and the standard of the machining is faultless. Just wish id gotten one of the silencers.... Oh nearly forgot..there is a pulley pic on my website Steve See My Zetec Power 7 Here Edited by - STEVE GILBERT on 12 Jan 2003 20:51:38 Link to comment Share on other sites More sharing options...
Luke Beaumont Posted January 12, 2003 Share Posted January 12, 2003 Count me in for one. I saw the QED one yesterday but that is WAY underdriven. Don't know the diameter, but I think it would be too low for the road. Link to comment Share on other sites More sharing options...
Julian Thompson Posted January 12, 2003 Author Share Posted January 12, 2003 If anyone else wants one please be sure to indicate if you require drysump or wetsump. The wetsump one will apparantly be a tadge cheaper. (Or if just me and Luke want them they'll cost us £300 each !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) Link to comment Share on other sites More sharing options...
oilyhands Posted January 12, 2003 Share Posted January 12, 2003 The pulley/damper arrangement serves a purpose in dampening crank windup especially with longer stroke cranks like the 1.8K. Oily Link to comment Share on other sites More sharing options...
Julian Thompson Posted January 13, 2003 Author Share Posted January 13, 2003 So is this not a good idea Dave? Link to comment Share on other sites More sharing options...
Bob Corb Posted January 13, 2003 Share Posted January 13, 2003 Julian I talked to QED about this on friday, I mentioned that the torsional forces in the crank would no longer be balanced which could lead to all sorts of problems (problem = shattered oil pump rotor or a flywheel parting company with the crank or worse). They said that they would advise fitting their steel oil pump gear to preserve the pump but on the other issues they had no answer other than the alloy pulley was best used in sprints/short races. They didn't advise using it on either a road car or a racer used for endurance work. The whole crank/flywheel combo needs to be run on a dyno and tested by a pulley supplier to set the mass and stiffnes of the damper. I assume DKE cranks are tested in this way, well I hope they are. Miraz is fitting one with a quartermaster clutch and has been told to use a specific pulley to suit... fingers crossed Geoff. BC Link to comment Share on other sites More sharing options...
Julian Thompson Posted January 13, 2003 Author Share Posted January 13, 2003 All very complex and I'm afraid I can contribute not at all! I shall sit back and read with interest - I might learn something! Link to comment Share on other sites More sharing options...
Luke Beaumont Posted January 13, 2003 Share Posted January 13, 2003 I'm afraid my knowledge on this subject is sketchy at best, but The whole crank/flywheel combo needs to be run on a dyno and tested by a pulley supplier to set the mass and stiffnes of the damper. is how I understood it to be - with the result that changing the flywheel for something half the weight when installed in a Caterham has already shot the harmonic balance of the arrangement before you even start on the front pulley. Link to comment Share on other sites More sharing options...
Peter Carmichael Posted January 13, 2003 Share Posted January 13, 2003 The flywheel end of the crankshaft is usually considered to be attached to the large effective mass of your entire car, via the springs in the clutch. The big deal is that the power is supplied in pulses to the crankshaft journals and the reciprocating forces also are distributed along the length of the crank. This makes the free end of the crank do a little Mr Whippy dance all on its own, particularly at a number of resonant frequencies. You need some way of getting vibrational energy out of the crank rather than leaving it to act like a tuning fork. Any damper is better than none. A tuned damper is obviously best. It is important to consider the coupled mass of the entire system, including such items as: water pump, camshafts, alternator and any external pumps. It is posisble for other forms of damping to exist in the system. It would be interesting to know what sort of damping is achieved from the belt drive to the alternator, say. Could the drive belt be specifically made from a higher hysteresis material to any good effect? Received wisdom suggests that cast cranks are more susceptible to the fatigue consequences of running with inadequate damping. A forged or billet crank is probably a prerequisite before considering a solid pulley. R500s run solid pulleys, but have billet steel cranks. Link to comment Share on other sites More sharing options...
AMMO Posted January 13, 2003 Share Posted January 13, 2003 I am not an "expert" on anything at all (expert is a term I hate anyway). I really have great difficulty putting something down for profession when filling in forms. One thing I do know is that I'm terribly ignorant about a whole range of things. However, having been involved with engines for over twenty two years with some success I am in the fortunate position to be able to call on the knowledge of others when needed. I have spoken to two successful engine designers this morning. Their attitude was that it would be OK unless the crank has a reputation for breaking. The torsionals are specific to each engine but in a four cylinder happen around 4,000 and again at 8,000 rpm. The damper works mainly at one rpm where the natural vibration of the engine occurs. I have someone who works on K-Series development looking to suck someone's brains regarding the manufacturer of the original pulley to find out what the exact torsionals are on the K. I should have an answer by Thursday. I was told that unless you operate the engine on the node of the torsional you would have no problems. The harmonic damper is there for Mr. and Mrs. Bloggs driving to Tesco so that the engine is smooth and transmits no vibration to the body shell of you average tin top. This is backed up by three different crank balancing companies, one of which I have been using for the last twenty years. I supplied some components to Ricardo last year for a project and have been trying to call in a favour with the head of drive train for his opinion. Answering service on his mobile is on. Hopefully I will have spoken to him by tomorrrow. I have already manufactured hard anodised pulleys for the Zetec. When fitted to my engine I didn't detect and increase in vibration or any harshness. Nor has anyone else I have supplied them to. Don't get me wrong, I'm not saying that there will be no problems. That would be foolish. Only that from speaking to people who know more about it than I do that it is unlikely. Anybody who thinks he can tell you what will happen is quite simply deluding himself. The likely problems that could be encountered are things like single valve springs breaking. This is unlikely with belt driven cams and not an issue with dual springs. Put simply these pulleys have to be made and tested by the people who are interested in removing a kilo of mass from their engines and slowing down their alternators. It's strange that people are willing to take an engine out of a saloon car, put valves, cams, a lighter flywheel and change everything in sight to double the horsepower. When it comes to a simple pulley they put garlic around their necks and hold a big cross up whilst backing their way to a convenient exit. :-) On the subject of price, yes they may be a few pounds more than somebody elses but I only supply components of the highest quality. I could make them cheaper by not hard anodising them but they would probably wear out very quickly. I assure you that the profit from ten pulleys will not allow me to retire to my dream home in the Bahamas. Up to you if you want to experiment with something new rather than treading the beaten path. If I had a K-Series I would definately try one as I'm obsessed with weight saving. Bottom line is that unless we try this nobody will know the outcome. AMMO Link to comment Share on other sites More sharing options...
V7 SLR Posted January 13, 2003 Share Posted January 13, 2003 Somewhere I've got a good document which illustrates what PC is referring to. It has diagrams showing the Mr Whippy end of the crank. Email me direct and I'll find it and post back. With (further) reference to the above, the harmonic damper built into the flywheel is supposed to be "tuned" but probably cannot be considered to be "in tune" with a Caterham engine. It was designed for a Rover engine with all their inherent components. A Caterham has at least a different flywheel/clutch. Mine has forged pistons etc... all which adds up to un-tuning the damper. Perhaps the damper is still within "range" though. Who knows? Whatever, Maybe it is still in range and is still helping to damp out the torsionals. No failures so far is what I mean. Fingers crossed. If you consider that any damping is a good thing, then it is likely that the alternator, dry sump pump and cam belts are doing something, but whether you'd want to be the development engineer for this on a standard crank or not is up to you (no-one in particular). I'd almost certainly put a lightweight alloy pulley on if I had a steel crank. I've convinced myself that a little sliver of rubber in the flywheel (bugger: I meant pulley) could do no more than the combined damping of the drive belts. Couple this with the lack of related failures shown by those with race engines, despite their limited mileage, and it looks safe. No guarantees though, and that's the problem. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Edited by - V7 SLR on 13 Jan 2003 12:24:18 Link to comment Share on other sites More sharing options...
Julian Thompson Posted January 13, 2003 Author Share Posted January 13, 2003 hmmmmn. What sort of improvement can we expect in performance using the lighter pulley? Link to comment Share on other sites More sharing options...
V7 SLR Posted January 13, 2003 Share Posted January 13, 2003 Not nearly as much as a lighter flywheel, but it's an easier to implement "gain". One which I'd be interested in for sure. It ought to gain revs quicker because of the lighter weight. The 15% decrease in alt speed will help overall power by a tad too BUT won't this mean the alt won't charge at idle. More specifically, at what idle speed will a normal alt stop charging? I run mine idle at about 1100rpm, so I believe I would be safe. Some people run theirs at 800rpm which may make it marginal. Also, wouldn't you need a correspondingly larger alt pulley or can you get a slightly smaller belt? I'm interested. Would it be anodized? Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
AMMO Posted January 13, 2003 Share Posted January 13, 2003 V7 SLR My ali crank pulley on the Zetec is 110 mm (down from 131 mm) and I have increased the size of the alternator pulley to 77 mm. My idle is 1,000 rpm and the alternator charges fine. At max engine rpm of 7,500 the alternator is doing 10,700 rpm. Before changing the pulleys it was getting closer to 15,000 rpm. My alternator is Lucas 45 A unit as fitted to my old Crossflow engine and has no problem charging my small 13 A/h Odyssey battery (2.5 kilos lighter). A little chart came with the recon alternator that showed it starts charging at around 1500 rpm and gives maximum power at 6,000 rpm. The car always starts but then I don't have an alarm or anything to sap the power. In the States they quote a 6 - 8 bhp increase in power when fitting an under driven pulley to a road going Zetec. The pulley drives the water pump as well as the alternator but more importantly it also drives the aircon. I like to think that on my car I may have gained 1 or 2 bhp. I have no way of backing this up because the last time I went to the dyno I had also made changes to the exhaust and gained 4 bhp overall. The engine is very smooth but it was balanced as part of the re-build. It does feel like it whizzes uf quicker but that may be just my impression. In theory the engine should accelerate and decelerate faster. Out of curiosity does anybody know the diameter of the K-Series alternator pulley? AMMO Link to comment Share on other sites More sharing options...
Peter Carmichael Posted January 13, 2003 Share Posted January 13, 2003 130mm The dry sump drive is ~80mm (3 row) Link to comment Share on other sites More sharing options...
V7 SLR Posted January 13, 2003 Share Posted January 13, 2003 AMMO, I'm with you... that is, totally convinced that most alternators could be geared down a tad, particularly on SLR or equivalent engines where the idle is set high anyway. If they start charging at 1500rpm (I take it that refers to the rpm of the alt and not the engine) then they're way overgeared anyway and even if the power gain from revving the alt is only small, the resultant extra life of the alt may be worth the money. I'm pretty sure that alt wear increases disproportionally with revs. Were you proposing to supply a new alt pulley with the engine pulley or can you suggest the size of alt pulley which would be needed to replace the standard one? Also, would the crank pulley be "keyed" as per the original? 100 quid eh? Blast. I've already spent this year's budget... but I do have a spare 50 quid. Wonder if I can gamble to double it. Suggestions please. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
AMMO Posted January 13, 2003 Share Posted January 13, 2003 Thanks Peter I have a stock crank pulley to use as a pattern. I plan to leave the 80 mm 3 row poly-vee as it is and just reduce the 130 mm alternator drive (5 row?) to 110mm like I did on the Zetec item. Anybody have any idea what diameter the stock pulley on the alternator is? I want to work out the ratio and speed of the alternator? Because the pulley only drives the alternator and not the water pump as well there is some room to manoeuvre in terms of diameter. Don't want to go too small as I want to keep some mass on the nose of the crank. The idea is not to go as small as possible, otherwise you could make it 80 mm front to back. Just want to get a useful weight reduction. AMMO Link to comment Share on other sites More sharing options...
AMMO Posted January 13, 2003 Share Posted January 13, 2003 V7 SLR Yes the pulley would be keyed as per the original. As I said I'm using a 110mm pulley on my crank and a 77 mm on the alternator and it seems fine. My water pump is running 1:1. Before it was overgeared at 1.2:1. Not applicable to K-Series. The price of the pulley is £80.00 (I'm taking a risk on this as I haven't discussed it with the manufacturers yet, I'm just guessing. The Zetec ones are £79.00 and aren't as deep) £5.10 for carriage with insurance and the rest is the Vodka And Tonic for Gordon Brown. AMMO Link to comment Share on other sites More sharing options...
Peter Carmichael Posted January 13, 2003 Share Posted January 13, 2003 Just done some searching and the K-series crank is forged according to the Powertrain website, but is elsewhere described as cast. I have checked with my contacts in Power Train and it is indeed cast, with a coining process before final machining. Edited by - Peter Carmichael on 23 Jan 2003 12:28:53 Link to comment Share on other sites More sharing options...
Peter Carmichael Posted January 13, 2003 Share Posted January 13, 2003 The alternator pulley is tiny. 50mm or thereabouts. I am currently suffering problems from running a nonstandard alternator which has a larger than standard pulley. This brings the belt line rather too close to a bolt head on the cambelt cover. Link to comment Share on other sites More sharing options...
Julian Thompson Posted January 13, 2003 Author Share Posted January 13, 2003 Ahem. And we all know what happens then, eh? ☹️ Link to comment Share on other sites More sharing options...
AMMO Posted January 13, 2003 Share Posted January 13, 2003 Yikes! 50mm alternator pulley. 2.62:1 ratio. At 7500 rpm the alternator is spinning up at 19,650 rpm! This is wrong. 15,000 has got to be considered a maximum and even that is too high. When my alternator ratio was around 2:1 I'm sure I could hear the alternator bearings over the induction noise. Bit more sedate now at only 1.42:1. I seem to remember that Peter had a problem with the alternator belt getting sucked into the cam belt cover. Was this due to speed or the bolt problem mentioned? AMMO Link to comment Share on other sites More sharing options...
Julian Thompson Posted January 13, 2003 Author Share Posted January 13, 2003 Interesting. I suppose the original design didn't call for 8000rpm plus redlines and is another + point in favour of the alloy pulley idea. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now