Date: Thu, 2 Jan 1997 04:56:12 -0800 From: Frank Klein <ascaris@LINKLINE.COM> Subject: Re: mm..Baja revisited.. > > ah ha! just what i was trying to get out of someone!! info!!:) > > the reason i wanted to use the 3.88 was to still have a killer top > speed...take a while to get it there, but on those 2000 mile trips, on > smooth highway.......:) > > of course, maybe instead of the smaller 1,2,3, just use a taller final, > and a smaller 4th....or what ever direction those things go in, but you > know what i mean..:) On longer trips, a gear too tall can mean higher engine temps, which is not what you want 1500 miles from home at 80 mph. The engine has to work harder to turn the gears. With a 3.88 R&P and 225 tires, you'd only be turning 3200 RPM at 75 mph. At 55 mph in 4th, you'd only get up to 2200 RPM. That's too low. You'd also have a heck of a time getting it moving from a stop, especially on an uphill grade. It would be almost like starting in second all of the time with regular tires and ratios. With my 4.125 R&P and stock .89 4th, I cruised from California to Illinois at ~85 mph the whole way. With this same ratio, I could add 225 tires, and I'd have to go 103 mph just to hit the 4500 RPM redline... assuming you have an engine that will do it, and a big bank account for tickets. I've hit 105 in my Bug (yes, I was over-revving the engine), but I would not cruise at that speed, even if my engine could do it for any time. Just how fast do you want to go? :) At speeds above 75 MPH, the wind resistance is quite strong, and your engine could use some help in ramming the non-aerodynamic Bug through. Unless you plan on exceeding 90 MPH as a cruising speed, the stock ratios or equivalent (this means 4.60:1 for 225 tires, btw, to be equivalent to 4.125 with stock tires) will net you MORE speed. It's generally NOT the redline that limits a Bug's speed... it is wind resistance. If you gear it taller, the engine will be LESS able to push the car through the air. Lower gear ratios multiply the engine's torque more, and you need this torque to push the inertia-filled air out of the way. As far as top speed goes: The Bug's cooling system and gear ratios are already quite good up to 85 MPH. Gear it higher (and this means adding big tires without reducing the R&P ratio) and there will be a price. There will be more engine heat, and you will have trouble with hills, etc., as well as a possible LOSS in top end speed. Make no mistake-- the Bug's worst enemy (in general as well as on road trips) is HEAT. I have made several cross-country trips in my Bug, all of them in the summer, and there is not a moment that engine heat slips my mind. Heat is, bar nothing, the top concern I have on any highway trip. Gene Berg wrote to this same effect in his catalog. He also went on to say that the stock gear ratios are optimal for fuel efficiency as well as low engine temps. He says he tried various ratios, and the stock ones netted the highest economy, for the reasons outlined above. For the record, I got 35 mpg @ 75 mph on one of those trips in Indiana, where it was flat. (Obviously, hills or mountains will reduce this.) This was with my '72 Super, 1600 D/P, with a Holley Bug Spray carb, 009, and Bugpack extractor. That is not bad at all. (On that trip, I only calculated MPG 2 times, and that was the higher of the two.) In short, the only time you would need a taller ratio in a Bug is if you intend to cruise at over 90 mph. I don't recommend cruising this fast in a Bug. At 90, the wind resistance is incredible, and the last thing I would want is less torque. You could build a more powerful engine to supply more torque, but then you have more heat (more fuel being burned) and less economy again (since you are pushing the engine harder). FWIW, Frank -- VW web page: http://www.linkline.com/personal/ascaris Re: mm..Baja revisited..