Date: Thu, 1 Apr 1999 11:42:18 -0600 From: "Philip Hult" <hultnopsamdu> Subject: Re: 9-3 v 328i (subthread:4 v 6+ cyl)
Tim Baker wrote in message <370369d9.231326710nopsam.sgi.net>... >On Thu, 01 Apr 1999 08:17:57 GMT, Riff <turbospgnopsamsouth.net> wrote: > >>"Who care if its the fastest 4 cylinder?" >> >> >>I do! a 4 cyl is better than an 8cyl because it has >>1 less internal friction > >Are you suggesting that the cyliners in a 4 cylinder engine glide >easier than those in a V8? Granted a V8 has more moving parts which >would translate to more overall friction. But, with this rationale, >we should all have Briggs & Stratton air cooled engines in our cars. >If this is truely the case, than why do all Formula 1 cars use V10 and >V12 engines? Especially given the fact that they turn 15-18000rpms as >a matter of normal use. I would think the fabricators of these spare >no expense machines would want to take full advantage of that low >internal friction of a 4 cylinder engine. Recall if you will that F1 cars aren't notorious for real great 0-30 times. Low internal friction helps with those quick starts, as the engine needs to accelerate as well. Put your car in nuetral slam on the gas, it take .5-.75 seconds for the engine to redline, low internal friction reduces this, and aids in low gear acceleration. An F1 car by contrast doesn't have much need to accelerate from 0-30 very quickly, so it is less of an issue. It is true that all else being the same lower engine friction = more output, I don' think that this is, however, the commercial ratrionale for making low friction engines. Friction = heat, heat = death to all things automotive. By reducing friction in an engine, one reduces wear on all the moving parts of an engine. Less wear = longer life. In summary, I don't think that the formula 1 car engines are going to give me 200k+ miles with out a rebuild. In contrast Briggs & Stratton engines, especially 2 stroke (even fewer moving parts!), are commonly used in applications where long, relatively maintenance free life is expected; lawn movers, snowblowers, pumps, generators...etc. > >>2 higher power to weight ratio > >That depends entirely on the size, materials used and the type of >construction. The Mercedes V8 powerplant in a CART Champ car is >smaller and lighter than a Saab 4 cylinder and produces in excess of >1000 hp. Have you ever seen the V8 engine in a Lotus Esprit? Its >slightly larger, slightly lighter and much more powerful than the >turbo 4 it replaced a few years back. Once again I suspect there aren't alot of those merc v8's with 200k+ miles on them. >>3 can be put in smaller compartment to have a better handling car. > >What was I thinking? Gee, I guess thats why Ferrari, Lotus, >Lamborghini, Porsche 911, Corvette, Viper, NSX, Bugatti, Camaro, >Firebird, Mustang, BMW 540i, Mercedes Benz C430, Lexus, Infinity, F1, >CART, IRL, INDY Lites, and just about every other high performance, >good handling car out there uses a 4 cylinder powerplant. Oh wait, >none of these use a 4 cylinder powerplant. Duh. > >Good handling cars are not the result of smaller engine compartments >and 4 cylinder engines. Good handling comes from proper engineering >and good design. The Chevy Corvette comes to mind. Huge engine and >engine compartment and incredible handling. And, lets not forget the >Dodge Viper with its mammoth V10. > >>4 is easier to work on > >Oh really? In what way? Less moving parts, less cramped. Wanna change all the spark plugs on your 8cyl? I bet I could change all of the ones in my 4 banger in roughly half the time! Generally more available room and larger spacing between parts too. > >>I have seen 500 hp 4cyl 8v 944 turbo's > >And, I have seen 900 HP cast iron push rod V8s in Chevrolet Corvettes. >So what? >>if SAAB could have a 3.0L 4, that would be cool > >Personally, I'd rather see an all aluminum narrow angle 3.0 liter DOHC >32 valve V8 easily and comfortably producing, lets say 270 HP, in a >Saab. This would be much more efficient and reliable than an >overbored and strung out stroked 4 cylinder engine any day. Yeah, but it wouldn't have that racy highRPM-highHP feel to it, it would be more like an... um Cadilac. Lot's of power, no doubt, but a substatially diffenent feel. >>Mark >> >Tim, agreeing to disagree > >> >>Tim Baker wrote: >>> >>> >The Saab Turbo is one of it's kind, you don't find a 4 cylinder in that >>> >region with that performance. >>> >>> This is the same thing they said about the Lotus Esprit. But, what >>> kind of engine does that speedy little devil now sport? Can you say >>> small displacement V8? I dont think your arguement for the for the 4 >>> cyliner has much merit. Who care if its the fastest 4 cylinder? >>> >>> > My additional thoughts, I think that one of the more substantial differences in 4 vs 6+ cyl engines, is that in general higher cylinder engines are designed with shorter strokes. The shorter and higher firing rate (each cylinder fires once per revolution, right?) produces a substantially smoother power in the low rpm range, and in general lowers the redline, and flattens out the top of the HP curve. (I know there are exceptions in $100k racing cars, but were talking comercial right?). I would suspect, (I haven't designed a lot of IC engines myself, yet <smirk>) that a larger displacement per cylinder and larger stroke length is more responsive to turbo charging. Turbocharging incidently is what gives SAAB 4cyl engines that racy feel we loyalist love. I for one have heard complaints from the non-turbo charged 6cyl SAAB crowd that they have a lot of power, but they don't feel the same. (I would be very interested in trying SAABs new asymTurbo V6, but until they mate it with stick (currently only available with an auto tranny), I will let it be. telling what I know, and making up the rest, -Phil 84 900 Turbo Sedan 200k mi and still purring 89 900 Turbo Conv 80k 90 9000 CD Turbo, 100k
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