

| Subject: | Re: Timing Chains, Belts, Gears, etc |
| From: | benoit |
| Date: | Fri, 22 Jun 2007 17:01:52 -0400 |
I'm backing up my knowledge because i have been playing in engine since i was 9, yea, even if " Gas powered model airplane & car" have been my first eperience (and believe me, it was a good scool), it followed by moped, motorcycle, cars, airplane, VW Baja and now Vanagon & Bus's, my hands have been dirty since i can remember. I have tried all kind of stuff, some went good and some went bad, i'm a certified aiplane mechanic and have a degree in airplane construction, i'm also qualified in avionic. I have worked 3 years as a Honda mechanic, and i was not changing brake's. As opposed to most engineers, i get the work done and a'm not afraid to get dirty, if it does't work, i try until i succeed (and i sometime also think :-) So let's say that i have been around. In life, there is the one who talk and think and there is the one that act, i'm the second kind. (not talking about you at all), i swap westy wasser engine in 4 hours, and it's bleed! I consider myself as a long trip Westy driver, and i had my share of problem over the years, now, i want to enjoy the snenery instead of thinking of what may happen in the back, but hey! that's me! Regards, Ben Jim Akiba wrote: > Ben you can't be backing up your generalization with one example from > a motorcycle engine? As to why it had a large effect on the bike, the > cam gears for a bike are much smaller than for a car engine. Belt > stretch will then translate into much higher cam gear angle changes > and much greater slop in valvetrain timed events. This is what you're > seeing with the bike. It does not translate as readily to car engines. > > > > Power transmission via belt vs. chain translates even less. > > > > Camping sounds good, and is a refresher... but my true passion lies in > the means and technologies that allow us to do such things, which is > why I'm here, typing my reply, happy as a clam. > > > > Jim Akiba > > > > > > > > From: Ben [mailto:huotb@videotron.ca] > Sent: 2007-06-22 2:42 PM > To: Jim Akiba > Cc: vanagon@GERRY.VANAGON.COM > Subject: Re: Timing Chains, Belts, Gears, etc > > > > Well, thell that to Honda engineers! In 93, when i ask what was the > problem with my bike (low power band) this was the answer from Honda > Canada. They have done excessive testing way before we, or other > company did so about engine configuration (we all agree that Honda > tried almost all possile engine configuration). > > The same CB 1000R when back the next year with a T-Chain, more torque > in low RPM, problem with the chain. So you draw your own opinion about > that my dear Jim. I'm far from being an Engineer, but i know and i > read a lot about the subject.. > > But on another hand, i was liking the fack that i had no chain or > belt, another exemple is my 1983 CX650 Turbo, drive shaft instead of a > chain (engine to wheel), what a pleasure to drive, but again, poor > handling because each time you punch the bike, the rear was raising > (torque/drive shaft). Some like Harley wnet with belt with good success. > > I often state motorcycle company as example, why, because they have to > to the long way against competition, they try hard and they try > everything. Of course, it would be nice to have a gear driven cam to > crank engine, but company are staying away from those for different > reason, i'm sure that one is a power related one. > > I said SOHC for low coast, good power and fuel economy, again, i fully > agree that power wise, DOHC is the way to go, again, the Honda S2000 > with 2000CC as 250hp, no turbo, no nothing! > > As for GM..... oufffffff, sorry here but you guys loose me big time. > Wile every company were working on smaller efficient 4cyl, those > company were still "fiddling" with old V8 :-) > > Jim, your conversion is quite something and i have great respect for > what you do, BUT, i now ( for now) drive a Subi, and i have the right > to say that i'm more than happy and T-belt change should NOT be a > concern at all wile thinking about a conversion. Subi have been in > Westy way before anything was tried there, why, it's a boxer engine! > > Anyway, you guys do what you have to do, me, i'll go camping with that > nice engine in the back of my van.... > > Ben > > Jim Akiba wrote: > >There is nothing about the inherent design differences in driving the > >camshafts that will produce more power/torque in and of itself. I don't > >believe that the flexibility of a timing chain produces more power/torque. > >It will help dampen power pulses from the crank however, which contributes > >to longer wearing on valvetrain parts. The valve timing event placement is > >what will determine the output characteristics of the engine. The primary > >reason for not using timing gears on OHC engines is because of the distance > >between the crank and cams. The number of parts and rotating mass are > >somewhat prohibitive, and belts do have benefits mostly in cost of > >production and maintenance. The trend toward light chains however is > >continuing, and as Toyota demonstrated this year, if you can lower the > >spring rate on the valve springs and not sacrifice sealing or return > >speeds(they did so iva much lighter valves), you can run a much smaller, > >lower mass timing chain, which we will start to see more of in the next 5 > >years. With older pushrods engines, timing gears are much more common. I > >have a set of timing gears on my 302, but they don't make sense for the > >majority of OHCs. > > > >As far as "almost all went back to SOHC 4 valves per cylinder" this is true > >of Honda, but not generally speaking. Also most DOHC 4 valves are simpler > >than SOHC 4 valve which usually require rockers or oddly shaped lobes to > >achieve, and the SOHC lacks any ability to alter the power making > >characteristics without a cam change. Through phasing changes and tuning > >alone, power adders can be made much more effective on DOHC engines. > > > >" So, now you may have to spend 600$-1000$ for a > >heas gasket job, a new T-belt, guide and maybe a tensionor after 100k miles > >of driving your Westy!" Ok, but you also already spent the money to convert > >it... and you still have an engine with 100k more miles on it. If you had > >gone with a conversion based off a world engine, you would spend the $600 on > >another engine with 10k miles on it, swap it in(just install work) and never > >get into the engine at all, and then everything is low miles all over again, > >for the same cost as maintaining your older Subaru.. and with far less risk, > >skill, knowledge, tools, time required. This is one of the additional > >benefits to owners that vanaru is going to achieve with their new > >conversion. Maybe you should have waited Benny ha. As far as who drives > >that much? Our Colorado customer Jason has put just under 30K miles on his > >westy inside of his first year of owning our conversion. So it can happen > >very quickly if people are really out there driving. > > > >Jim Akiba > > > > > > > > > >-----Original Message----- > >From: Benny boy [mailto:huotb@VIDEOTRON.CA] > >Sent: 2007-06-22 12:13 PM > >To: vanagon@GERRY.VANAGON.COM <mailto:vanagon@GERRY.VANAGON.COM> > >Subject: Re: Timing Chains, Belts, Gears, etc > > > >Hi (longish and boring stuff for those who don't like engine stuff) > > > >Gear Driven (cam to crank) gas engine have NO good torque/HP and poor torque > >curve, i know, i have owned a Honda CB 1000 with that system. That bike had > >NOTHING before 6000-7000 rpm, i said nothing. It felt like something was > >wrong, to tight. The funny thing is a broke one gear teath on the crank... > > > >The relation between the cam and crank have big variation in engine power > >curve and torque. With a belt, that very slight flexibility produce torque. > >We all know the story about DOHC VS single VS 4 valves per cylinder, many > >went DOHC with as much as 5 valves per cylinder (Yamaha Genesis), in cars, > >almost all went back to single (SOHC) 4 valves per cylinder. It was the > >best simplicity VW power VS fuel consumption. Chain, he he he, anyone here > >who have owned a Honda CX bike will stay away from timing chain, binder > >problem. > >My ZR 600 broke a chain because of a faulty bender, now, get that chain out > >of there... no easy way, that engine need to go on the surgery table. > > > >Now, let me do my corruptor thing about T-Belt change, that kind of pis**** > >me off (he he he), i had a few p-mail about that subject, and i find that a > >bit... sorry to say, stupid. Most modern engine have T-Belt, they all need > >preventive change at 60k miles. In the case of a Subi, it's a joke, no more > >dificult than on Honda or Toyota, what the big deal on those???? On your > >wasser, you may go on 4 head gasket change in that 60k miles, you may even > >need new heads or a total rebuilt, so tell me, WHAT is the big deal on > >timming belt? Sorry guys but a timming belt does't break, that's urban > >legend. > > > >Now, another thing, about Subi head gasket problems... i have did my > >research way before i choose that path. The early 2.5L DOHC big scary flat > >four had """some""" problem (even, now we nead to undersand what "some" > >mean), even "Some" late 2.5L had heads gasket problem, Honda 1.6L and 1.7 > >also have their share of ealy head gasket problem, now let see how bad this > >is! Fist of all, most problem found were in general between 60k mile and > >100k miles, on top, it is easy to see the problem as occasional overheating > >occur, so that said, ok, let say you need head gasket job, first there is NO > >need for new heads, it can be easily done with the engine in the "Van", no > >rusty bolt, no damage water jacket, no bent push-rod, bottom end O-ring > >replacement, pushrod seal. > > > >Now, how many of you will reach 60k-110K miles with your westy in the next > >few years? Also, in general, people have done more than 150k miles before a > >head gasket job was needed on most Japanese engine, and that is TOTALY > >normal on most 4cyl engine. So, now you may have to spend 600$-1000$ for a > >heas gasket job, a new T-belt, guide and maybe a tensionor after 100k miles > >of driving your Westy! Very far from a total Wasser engine rebuilt or > >re-seal each 30k-50k miles. > > > >I "would" take a Honda/Subaru belt or head gasket job anytime over a Wasser > >head job. 1/5 of the price on the Japanese engine and my hands stay way > >cleaner. > > > >NO one here will ever convince me otherwise. But don't get me wrong, a well > >maintain Wasser still as in place in the back of our Vanagon, i will give a > >honorable mention to that engine who worked so hard over the years to get us > >there, where we wanted to go. > > > >Ben > >http://www.benplace.com/vw2.htm > > > >On Fri, 22 Jun 2007 06:52:56 -0500, John Rodgers <inua@CHARTER.NET> <mailto:inua@CHARTER.NET> wrote: > > > > > >Just reading the post about "New Engine Conversion" - and I wonder - > >besides cost, is there any reason why engines have not had meshed gears > >to drive the cams. Piston type aircraft engines all have gear driven > >cams. No body wants to try to pull over and park on a cloud when a > >timing chain fails. > > > >Just curious. > > > >John Rodgers > >88 GL Driver > > > > > > > > >
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