gearing

I know this has been touched on before but I need some opinions. Feb version of "Hot VWs" goes into detail of gearing. Has anyone had a box built that has as described by Kevin Richards "a 4:12r&p and 3,78 first gear stock 2nd 1:48 3rd and 1.04 4th"
What I would like is smooth acceleration up to 50 MPH and then a freeway flyer fourth so that I do not need ot turn over 3300 rpm for those long rides to Knotts berry Farm etc.
A local builder warned me that there is a major bog into 4th and then I assume the reverse would be the possiblity of over reving if one is too aggressive downshifting.

Ralph, what engine size do you have? I belive 1.04 on 4th might not be the best choice for a "freeway flyer" setup, unless you have a 5th. Although this subject has been covered extensively, it is always interesting. I still have a tranny swap on schedule on my build. After all the reading I could summarize the following: Highway driving, big engine = 3.88r&p .89 or .82 4th. Stop and go town driving 1776cc or higher engine = 4.12r&p stock gearing (.89 4th). Swapping the .89 to .82 ratio on 4th might make the jump from 3rd too long, compensate with more engine power, but cooling suffers (add little pulley, ext oil cooler etc). Remember that keeping the revs over 3200rpm on 4th is important for proper engine cooling, specially on higher than stock displacement engines... These are my opinions based on what I have learned, Im pretty sure that many would differ, but this is a very controversial subject with many "variables" involved, ranging from driving habits to engine sizes... my $0.02 - greetings - JJ

Ralph,

That combination would spin your engine like a top on the highway. Please do a site search on gear ratios, and/or get a Rancho catalog to look at the available gears. There are many gear ratio/ speed calculators on the web- use the ratios in the catalog to match what you want.

Or you can just talk to Sam at Rancho, and tell him what you are after. If your engine is big enough, you shouldn't need the extra cog, unless you want to drag race. Email me offsite if you'd like, as I've done quite a bit of calculating for my new powertrain combination.

Yeah - Stan shared some of that info with us a while back, and I think the general consensus (which continues the same train of thought started back in the 60's) is to end up with a final gear ratio that gives you about 3250 at 70 mph and around 4K for 80 mph.

That should give you enough fan speed to provide adequate cooling for the oil and heads.

It may seem high (in RPM) to you, but the engine needs the fan speed for cooling and the higher revs are OK, even on long trips (look how many "real" 356's have been doing it for years).

The addition of a smaller diameter fan pulley (the so-called 356 fan pulley) will spin the fan faster at ALL speeds, and will provide 11% more cooling overall, and bring better cooling down into the 50-60 mph range in fourth.

BTW: I'm running a Rancho transmission, too. All beefed up for the higher horsepower, but all stock VW ratios and it seems fine so far (three years).

Gordon

"a final gear ratio that gives you about 3250 at 70 mph and around 4K for 80 mph.
That should give you enough fan speed to provide adequate cooling for the oil and heads."

You can trust Gordon on this one! There's a real delicate balance taking place between low/comfortable highway RPM and enough air to keep the engine cool.

You ought to make sure that your 30+ year old cooling fan is up to handling the revs as well. You should look for a later fan from a fuel injected car, or possibly one from a VW Thing and make sure that the bent tabs holding it together are sound. Maybe even go for a welded fan.

I only mention this because I used my Karmann Ghia for regular weekly trips from Boston to NYC, all highway with tall rear tires (Jeep Wrangler) to alter the relative trans ratio. High revs for three/four hours at a stretch. The fan eventually gave out. You can hear them breaking-up before they go, at least, but still . . .

Luck,

TC

Thanks TC. I have a new balanced fan. I guess I still think big motors and 3400rpm all day in a v8 could be lights out in a short time.

A cousin of mine had a bone-stock, 65 hp "Super Beetle" back in the early 70's. He was stationed in the Navy in Norfolk, VA, and made weekend trips back to Massachusetts where he was building a house.

He regularly made the trip in 9 hours at between 80 and 90 mph, sustained (that's somewhere betwen 4,000 and 4,500 RPM sustained). His engine ran fine for all that punishment, finally giving up the ghost to burnt exhaust valves at somewhere around 160,000 miles.

We pulled the engine and did a weekend rebuild on it and he was back in business, eventually selling it to a Navy buddy who drove it to San Diego and put another 120,000 on it. Never needed to touch the transmission, as far as I know.

Who says these engines can't last??

gn

Ralph,

You're so right

What's unusual about "big v8" engines running 3500 RPM all day long? Had several V8s where that was normal freeway speeds. Last one was a 3/4 ton F-250 that pulled campers and skiboats all over the west coast. Long days of over 100 degrees on highway. With a 4.11 axle yet. Engine had about 150,000 miles on it when I sold it, still running very well. Never even got a valve job. Long, small diameter headers, oil coolers and dual exhaust. What it did have was a full sweep tachomoter that only went to 4000 RPM at full scale (near 90 MPH as I remember it). That engine never saw 4100 RPM in any gear.

Gordon,
Correct me if I'm wrong but you suggested:
"The addition of a smaller diameter fan pulley (the so-called 356 fan pulley) will spin the fan faster at ALL speeds, and will provide 11% more cooling overall, and bring better cooling down into the 50-60 mph range in fourth."
Isn't that backwards?
If you're talking about a smaller crank pulley, that will slow the fan down, not speed it up.

The ones sold for VW application were|are called Power Pulleys.


Greg B

Greg, yes, you're wrong. Given the same size crank pulley, installing a smaller alternator (fan) pulley will increase the speed of the fan at any given RPM.

So called "power pulleys" are smaller diameter crank pulleys that slow down the fan to reduce the BHP it takes to turn it (and nreduce cooling at any given RPM).

Maybe the confusion is in the terminology:

The smaller FAN pulley would be the one on the top (but you knew that already).

The "crank" or "Power" Pulley (explained nicely by George) would be on the bottom.

I don't believe there would be any advantage to using a 356 (smaller) fan pulley AND a (smaller) Power pulley at the same time, and it would probably be a bitch to try and find a proper fan belt size for that combination, too.

I remember a guy in the 60's who ran a "Drag VW" and actually popped the fan belt off before a run to "get lots more power".

It did, but it also siezed on the way back to the pits.... 8>(

Alot of guys would take the fan blades off their engines in SCCA racing in the 60s. I guess they just use an electric fan now but back in the day: taking off the fan blades cost nothing and some sort of electric fan cost money so most people on any sort of budget just removed the blades. Also used to try and make the generator spin as easily as possible. A buddy did mine, I'm not sure what he did but I must have gained at least 1/4 hp
wed

OK,
I agree now.
The crank pulley : smaller = less fan rpm.
The fan pulley : smaller = more fan rpm.

My confusion was I was't aware that there were different sized fan pulleys available.
Where do I get info on type one different sized fan pulleys?

Greg B
PS
We used to run (loose) sewing machine belts on our FV motors (in the 1970's)to slow the fan down and pick up some horse power. Until we finally developed ducting that would allow us to run without a fan altogether. (40 hp motors putting out somewheres around 50 hp at 6000 rpm).
If you want to talk about squeezing every bit of HP out of a formula motor, that was the class to run in SCCA. I learned Lots of things to do and NOT to do developing VW motors back then.

Photo below is a Power Pulley:
aprox 2" smaller than stock:

Greg; basically there's two sizes of fan/gen/alt. pulleys for Type I's that I know of, and that's stock and 356 style which is smaller (the crank pulley on 356's was also smaller - akin if not the same as a VW "power pulley"). I guess the 356 compensated by having both in a smaller size.