Air Cooled vs Liquid Cooled

lipcrkr · Post by **lipcrkr** » Fri Sep 03, 2010 9:21 am

New to scooters but apparently a bike being liquid cooled performs better than an air cooled one. I haven't heard anyone say they prefer air over liquid, although many people have said it's not a deal breaker. Just wondering why the new Blur would keep an air cooled engine on a FI sport scooter that can do some miles on the freeway. Having never ridden a scooter as of yet (still waiting for the Blur in CA), i do know a liquid engine is primarily maintained by obviously keeping an eye on the fluid level, like a car. But, if i'm riding the new Blur, how do i know the engine is OK? How do i maintain an air cooled engine? I heard Genuine may have kept the "air" to keep the weight down, but why keep the weight down if this scooter is fine on the freeway? Wouldn't a little more weight add to the stability without sacrificing mobility?

killbilly · Post by **killbilly** » Fri Sep 03, 2010 12:13 pm

It's air and oil-cooled, much like the old four-cylinder VW motor, for example.

Liquid-cooling systems add weight, complexity and cost to the design. If the air-and-oil systems work, there is no reason to go liquid-cooling.

gt1000 · Post by **gt1000** » Fri Sep 03, 2010 3:13 pm

Weight has nothing to do with stability. Stability is about good overall design and especially good suspension design. Weight is the enemy and shedding weight is one of the single most expensive tasks in vehicle design.

That said, weight is not an automatic byproduct of liquid cooling. For example, Ducati's liquid cooled Streetfighter weighs a few pounds less than my air-cooled Hypermotard. Liquid cooling does add complexity and a whole lot of "plumbing" so a lot of old school bike riders don't like the look of a liquid cooled motor. That, of course, is irrelevant in a scooter.

I'm perfectly fine with either system. However, one thing that is lacking on many air-cooled bikes is a temperature gauge and I do like to know if my engine is running hot. If I were in the market for a scooter whose main purpose was lengthy rides at high speeds (or constant stop and go traffic) I'd probably lean more towards a liquid cooled bike. Also, some scooter designs don't allow for sufficient airflow to the engine compartment (like my old Mojito) and you definitely don't want air-cooled if no air is reaching the motor or oil cooler. There's no right answer to your question, it's really a matter of bike design, personal taste and riding style.

illnoise · Post by **illnoise** » Fri Sep 03, 2010 4:53 pm

Complexity is the main thing. Sure, a liquid cooled engine can run at higher RPMs and higher compression, but the tradeoff is more maintenance, and more parts to break, and more stuff in the way when you're doing engine work. It also adds to the purchase cost and maintenance cost of the bike.

Just like all the sensors and wiring in a new car. Modern conveniences (especially safety-related) are nice, but the sensors are failure-prone and it makes it impossible to work on your car without a computer and specialized tools.

Bb.

jasondavis48108 · Post by **jasondavis48108** » Fri Sep 03, 2010 11:17 pm

illnoise wrote:Complexity is the main thing. Sure, a liquid cooled engine can run at higher RPMs and higher compression, but the tradeoff is more maintenance, and more parts to break, and more stuff in the way when you're doing engine work. It also adds to the purchase cost and maintenance cost of the bike.

Just like all the sensors and wiring in a new car. Modern conveniences (especially safety-related) are nice, but the sensors are failure-prone and it makes it impossible to work on your car without a computer and specialized tools.

Bb.

this is what I was most worried about when I bought my sh150, so I also bought the 4 year warranty. Figure that gives me 4 years to learn how to service the bike. The little Buddy 50 is so easy to work on, the sh150 is way more intimidating in the maintnance dept.

davelhunter · Post by **davelhunter** » Fri Sep 03, 2010 11:46 pm

I really would not worry about the Blur too much for 2 reasons. Frist, people have ridden these bikes on cross country trips with no problem overheating. Second, our bikes have an "oil cooler" which, I guess I could say, is almost like a radiator for oil. In addition, the older bikes (ex.750cc's) were air cooled. I think our 150cc & 220cc bikes should be fine.

Lostmycage · Post by **Lostmycage** » Sat Sep 04, 2010 5:31 am

There's one thing not commonly thought of in the air vs oil cooled as applied to scooters. That's the air flow. The classic air cooled bikes (usually bigger twins) have their cylinder jugs out in the open to catch all the cooling air between their fins. Scooters (many single cylinder high revvers) have their engines neatly tucked away behind a bunch of plastic, which blocks a lot of the cooling air.

The Blur further proves it's impressive design in that it was one of the first small displacement scoots to sport an oil cooler that's got a good exposure to incoming air streams (which is in the same place that many water cooled bikes mount their radiator - where it'll catch plenty of cooling wind) and that was carried on to the second revision (on Us shores). Actually... I'm working on an assumption that it would be completely idiotic to place the oil filter elsewhere; is it still behind the large plastic grill behind the front wheel?

Yes, a water-cooled version of this engine would be better on many levels, but the oil cooled engine has less parts to break and translates to simpler maintenance. It's a well designed air-cooled bike, so I wouldn't let that detail keep me off of a Blur. Think of it this way, you can spend some of the money you saved not buying a water-cooled bike to get a rear rack, windshield or getting a custom seat that you can sit on long enough worry about long periods of high rev travel.

lipcrkr · Post by **lipcrkr** » Sat Sep 04, 2010 9:14 am

Lostmycage wrote:There's one thing not commonly thought of in the air vs oil cooled as applied to scooters. That's the air flow. The classic air cooled bikes (usually bigger twins) have their cylinder jugs out in the open to catch all the cooling air between their fins. Scooters (many single cylinder high revvers) have their engines neatly tucked away behind a bunch of plastic, which blocks a lot of the cooling air.

The Blur further proves it's impressive design in that it was one of the first small displacement scoots to sport an oil cooler that's got a good exposure to incoming air streams (which is in the same place that many water cooled bikes mount their radiator - where it'll catch plenty of cooling wind) and that was carried on to the second revision (on Us shores). Actually... I'm working on an assumption that it would be completely idiotic to place the oil filter elsewhere; is it still behind the large plastic grill behind the front wheel?

Yes, a water-cooled version of this engine would be better on many levels, but the oil cooled engine has less parts to break and translates to simpler maintenance. It's a well designed air-cooled bike, so I wouldn't let that detail keep me off of a Blur. Think of it this way, you can spend some of the money you saved not buying a water-cooled bike to get a rear rack, windshield or getting a custom seat that you can sit on long enough worry about long periods of high rev travel.

Thanks for the info, lots of good stuff there.

illnoise · Post by **illnoise** » Sat Sep 04, 2010 1:08 pm

Lostmycage wrote: Scooters (many single cylinder high revvers) have their engines neatly tucked away behind a bunch of plastic, which blocks a lot of the cooling air.

That's one of my favorite things about the original Vespa design, the flywheel is a fan that sucks in air through the vents on the right cowl, then blows the air through a shroud onto the engine.

killbilly · Post by **killbilly** » Sat Sep 04, 2010 1:32 pm

illnoise wrote:
Lostmycage wrote: Scooters (many single cylinder high revvers) have their engines neatly tucked away behind a bunch of plastic, which blocks a lot of the cooling air.
That's one of my favorite things about the original Vespa design, the flywheel is a fan that sucks in air through the vents on the right cowl, then blows the air through a shroud onto the engine.

I'm not 100% sure, but I think the Blur's design is such that not only is the oil cooler up front and near the wind, but it's a couple feet away from the engine instead of being right on it. That's got to help quite a bit.

babblefish · Post by **babblefish** » Mon Sep 13, 2010 1:31 pm

illnoise wrote:
Lostmycage wrote: Scooters (many single cylinder high revvers) have their engines neatly tucked away behind a bunch of plastic, which blocks a lot of the cooling air.
That's one of my favorite things about the original Vespa design, the flywheel is a fan that sucks in air through the vents on the right cowl, then blows the air through a shroud onto the engine.

The Blur (and Buddy) uses the same cooling design as the Vespa. If what you are saying is that the Blur uses the original Vespa design, then I'll shut my mouth.

Keys · Post by **Keys** » Mon Sep 13, 2010 5:08 pm

The Blur has the same fan/forced air cooling as a Buddy or a Vespa...it, like the Buddy 150's, is also assisted by an oil cooler.

As for liquid cooling, the major reason so many motorcycles went to liquid cooling was not so much for performance or cooling benefits, but as a way to reduce noise. You put a jacket of water around all the moving bits, it does a LOT to quiet things down. The other things were important, but noise abatement was their primary concern at the time.

--Keys

BlueMark · Post by **BlueMark** » Tue Sep 14, 2010 1:22 am

I've never really understood why an engine that is cooled by oil running through a radiator is "air cooled" while one where water is run through the radiator is "water cooled".

They are both cooled by air flowing through a liquid filled radiator.

gt1000 · Post by **gt1000** » Tue Sep 14, 2010 3:04 pm

BlueMark wrote:I've never really understood why an engine that is cooled by oil running through a radiator is "air cooled" while one where water is run through the radiator is "water cooled".

They are both cooled by air flowing through a liquid filled radiator.

Look at it this way: All engines contain oil. Only liquid cooled engines use coolant to help regulate engine temperature.

Rippinyarn · Post by **Rippinyarn** » Tue Sep 14, 2010 6:27 pm

Great stuff on this topic from Al Kolvites (the scooter swami) on the Argo/Bajaj site: http://argousa.com/air%20cooled%20-%20w ... cooled.htm

Mikie M. · Post by **Mikie M.** » Sun Sep 19, 2010 2:30 am

The Pratt and Whitney R-4360 was a 28 cylinder (four rows of 7 cylinders each) that produced 3,000 horsepower. Nicknamed "The Corncob", this radial engine was used on the B-36 bomber, and was briefly used on Howard Hughes's "Spruce Goose".
It was air-cooled.

charlie55 · Post by **charlie55** » Sun Sep 19, 2010 2:47 am

Mikie M. wrote:The Pratt and Whitney R-4360 was a 28 cylinder (four rows of 7 cylinders each) that produced 3,000 horsepower. Nicknamed "The Corncob", this radial engine was used on the B-36 bomber, and was briefly used on Howard Hughes's "Spruce Goose".
It was air-cooled.

What Mikie failed to note is that it sounds exactly like a Blur:

http://www.alexisparkinn.com/photogalle ... arting.wav

I think that they've got a cutaway demo model of one of these at the Franklin Institute in Philly. Massive S.O.B. Must've been a two week job just to gap the plugs and set the valves.

By way of comparison, here's what the liquid-cooled 250 on a Helix sounds like:

http://www.alexisparkinn.com/photogalle ... 50turb.wav

Modern Buddy

Air Cooled vs Liquid Cooled

Air Cooled vs Liquid Cooled

I would not worry

Oil = Air?

Re: Oil = Air?