TheSamba.com :: View topic - Vanagon 30-50 challenge

Wed Jul 16, 2008 2:40 pm

As soon as my DJ-code WBX is in my Westy I'll do another run and post results here.

We might have more excitement, though... on the Vanagon list we MIGHT share some hardware to reliably test performance with GPS etc. So... stay tuned, pun intended.

In the meantime, it would be great to have some folks with stock 2.1 and 1.9 WBX share their results.

Wed Jul 16, 2008 6:52 pm

First time to 50MPH in 3rd gear!

Year: 1989
Type: Westfalia full camper
Time: 8 seconds
Engine: 2.1 L
Miles on engine: 169,000
Engine mods: K&N air filter, stainless steel exhaust system
Trans: 4 speed manual
Trans mods: stock
Fuel tank: 1/2 full
Tires: Michelin Hydroedge 215/60 16"

Thu Jul 17, 2008 5:04 pm

Ihave a stock 1.9 freshly rebuilt & it will do 0 - 60 today. ;-)

Fri Jul 18, 2008 1:33 pm

woo hooooo! racin' in the vanagon with the 'no-hurry' engine! \:D/
------------------

Year: 1985
Type: Hi-top Adventurewagen (230k chassis)
Time: 13.3 s
Engine: 1.9L WBX
Miles on engine: 70K
Engine mods: None
Trans: 4-sp manual
Trans mods: none
Fuel tank: almost empty (again)
Tires: 185R14 (55-60 psi.)

Sat Jul 19, 2008 7:35 am

Results so far...

http://www.knology.net/~vw/30-50challenge.htm

Thanks and keep them coming!

If you perform a test, please post the results even if they're the same as others. This will help to establish a good baseline.

Sat Jul 19, 2008 4:46 pm

Not having a stop watch, I used my digital camera to record, and then time the video.
It occurred to me that there's two ways of making the run though.
Full powering through 3rd, and timing the segment 30 through 50.
Or option B, holding 30, then gas it. I got better with the first, but seems you would probably want option B? So that's what I'm posting.
1985 Adventurewagen high-top. LOADED with crap, very heavy.
time: 7.1
Engine 1995 2.2 suby
Miles: Unknown
Engine mods: None
Tranny mods: None
Fuel tank: 1/4 full
Tires: 185r14
Altitude: sealevel

Mon Jul 21, 2008 5:01 am

levi wrote: Not having a stop watch, I used my digital camera to record, and then time the video.
It occurred to me that there's two ways of making the run though.
Full powering through 3rd, and timing the segment 30 through 50.
Or option B, holding 30, then gas it. I got better with the first, but seems you would probably want option B? So that's what I'm posting.
1985 Adventurewagen high-top. LOADED with crap, very heavy.
time: 7.1
Engine 1995 2.2 suby
Miles: Unknown
Engine mods: None
Tranny mods: None
Fuel tank: 1/4 full
Tires: 185r14
Altitude: sealevel

Thanks for posting! Yes, option B is the one.

By the way, most car magazines use two tests, 30-50 and 50-70 top gear acceleration, as an indicator of engine flexibility. I thought 3rd gear would be a bit easier to test for us since our flying bricks would need more deserted, flat road than some of us can't easily find.

Mon Jul 21, 2008 4:16 pm

Let us know when you're ready for us to do the 80-100 roll on.

:shock: :shock: :shock: ( 8) )

Mon Jul 21, 2008 4:37 pm

OK, I'll edit the time when I can do over with a stopwatch:
Year: 1984
Type: 2WD Westy
Time: 6 (and some fraction) seconds
Engine: 2.2L Subaru
Miles on engine: 50K
Engine mods: Cone style intake
Trans: 4-sp manual
Trans mods: none
Fuel tank: 5/8 full
Tires: 195/75R14XL (recommended pressure)
No air conditioning or power steering
5000' altitude.
Upgraded speedometer, checked with GPS. (1.9L speedos are typically WAY off)

Mon Jul 21, 2008 7:26 pm

RichBenn wrote: OK, I'll edit the time when I can do over with a stopwatch:
Year: 1984
Type: 2WD Westy
Time: 6 (and some fraction) seconds
Engine: 2.2L Subaru
Miles on engine: 50K
Engine mods: Cone style intake
Trans: 4-sp manual
Trans mods: none
Fuel tank: 5/8 full
Tires: 195/75R14XL (recommended pressure)
No air conditioning or power steering
5000' altitude.
Upgraded speedometer, checked with GPS. (1.9L speedos are typically WAY off)

Excellent time!

Thanks for posting! I'll update the stats tomorrow.

Mon Jul 21, 2008 7:39 pm

Hey tencent, which way does it go?
Less O2 for combustion - or less wind resistance in thin air?
Tony

Tue Jul 22, 2008 4:43 am

Tue Jul 22, 2008 6:58 am

tosu wrote: Hey tencent, which way does it go?
Less O2 for combustion - or less wind resistance in thin air?
Tony

Both.

The common perception is that there is somehow less oxygen available the higher you go, but the percentage of o2 is exactly the same in air as high as you want to go, about 19%; what there is is less atmospheric pressure to fill the cylinders. It really has nothing to do with o2, it's all about charge density. Whatever charge ends up being compressed and burned has the same chemical composition as it would at sea level or any other altitude. We use engine vacuum as a convenient way to describe the depression in the intaking cylinder, but there's actually no such thing as engine vacuum. It's atmospheric pressure that fills the cylinders on intake, and it rushes in less quickly the higher you go, so you end up with less mass of air to compress, and consequently lower compression and lower heat of combustion and less piston force as a result.

As an example of how dramatic the effect is, at my home altitude of 6500' the pressure is only about 11.5 psi vs. 14.7 at sea level. Already there's 22% less pressure even at this moderate altitude.

Here's a chart of the pressure changes:
http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html

Since pressure is less, air mass per unit volume is also less, and that is what matters in wind resistance, although that's also probably an incorrect framing as an engineer would probably begin with static pressures at surfaces in analyzing drag. But to simplify, there's less air to push out of the way, so aerodynamic drag is also reduced. I'm not up on how to analyse that, but the power losses due to lower cylinder pressure plainly outweight the reduced vehicle drag.

A turbocharger has the effect of transporting the engine instantly to below sea level. I've always looked at it that way.

Tue Jul 22, 2008 8:13 am

Holy crap tencent, remind me never to get into a debate with you.
btw, I think somewhere in one of the everest climbing books it talks about the % of o2 declining with altitude, will try to look it up later.
AAAAANNNNNNDDDDD less air pressure = less charge air = less o2!

Tue Jul 22, 2008 10:46 am

tencentlife wrote: tosu wrote: Hey tencent, which way does it go?
Less O2 for combustion - or less wind resistance in thin air?
Tony

Both.

The common perception is that there is somehow less oxygen available the higher you go, but the percentage of o2 is exactly the same in air as high as you want to go, about 19%; what there is is less atmospheric pressure to fill the cylinders. It really has nothing to do with o2, it's all about charge density. Whatever charge ends up being compressed and burned has the same chemical composition as it would at sea level or any other altitude. We use engine vacuum as a convenient way to describe the depression in the intaking cylinder, but there's actually no such thing as engine vacuum. It's atmospheric pressure that fills the cylinders on intake, and it rushes in less quickly the higher you go, so you end up with less mass of air to compress, and consequently lower compression and lower heat of combustion and less piston force as a result.

As an example of how dramatic the effect is, at my home altitude of 6500' the pressure is only about 11.5 psi vs. 14.7 at sea level. Already there's 22% less pressure even at this moderate altitude.

Here's a chart of the pressure changes:
http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html

Since pressure is less, air mass per unit volume is also less, and that is what matters in wind resistance, although that's also probably an incorrect framing as an engineer would probably begin with static pressures at surfaces in analyzing drag. But to simplify, there's less air to push out of the way, so aerodynamic drag is also reduced. I'm not up on how to analyse that, but the power losses due to lower cylinder pressure plainly outweight the reduced vehicle drag.

A turbocharger has the effect of transporting the engine instantly to below sea level. I've always looked at it that way.

The term "less oxygen" means less oxygen per given unit of air volume, which is not a common perception but a scientific fact. This fact has been experienced by wheezing emphysemateous Harley riders making their way on foot to the Mt. Mitchell observation tower (Whoa, cigarette break!). I've seen it and it ain't pretty.

The density of air at sea level is about 1.2 kg/m3. Since density is proportional to drag you can deduce the reduction in drag based on the generic chart below.

Oh, yeah, and isn't our atmosphere 21% oxygen?

Tue Jul 22, 2008 2:27 pm

Year: 1987
Type: Westfalia Weekender w/ all the usual stuff under the bench and in the closet (200 lbs or so)
Time: 8.3 seconds (avg of 6 tries. All within 0.5 second)
Engine: 2.2L WBX GoWesty
Miles on engine: 30K
Engine mods: None
Trans: 4-sp manual
Trans mods: none
Fuel tank: 1/2 full
Tires: 225/60-16 @ 42 psi
Altitude: ~700'

Tue Jul 22, 2008 6:54 pm

OK tencent, the gloves are off!
The percentage of o2 is 20.94% and remains constant to 70,000 ft above sea level. This explains the poor performance you observe when driving above 70,000'.
Yes wind resistance decreases with altitude and increases with velocity.
Yet still if your air charge is reduced even though the percentage of o2 remains constant the overall amount of o2 decreases with the reduction in pressure related to altitude. There is a scientific unit of measure for this called 'torr'. Further, the amount of disolved o2 in the gasoline will be reduced because of the lower ambient air pressure.
:roll:
PS I think the winner of this debate should buy the loser a libation at the location of your choice in the event I am within shouting distance of your elevated location.

Wed Jul 23, 2008 5:27 am

riceye wrote: Year: 1987
Type: Westfalia Weekender w/ all the usual stuff under the bench and in the closet (200 lbs or so)
Time: 8.3 seconds (avg of 6 tries. All within 0.5 second)
Engine: 2.2L WBX GoWesty
Miles on engine: 30K
Engine mods: None
Trans: 4-sp manual
Trans mods: none
Fuel tank: 1/2 full
Tires: 225/60-16 @ 42 psi
Altitude: ~700'

Sweet! I updated the results: http://www.knology.net/~vw/30-50challenge.htm

Wed Jul 23, 2008 6:17 pm

Thanks for putting this together -- I think it's a really excellent way to compare engine performance. Also, I like seeing what wheel and tire sizes other people are running. :vw: :vw: :vw:

Year: 1987
Type: Wolfsburg
Time: 9.2 seconds
Engine: 2.1L
Miles on engine: 143,000 -- 60k on head gaskets
Engine mods: None
Trans: 4-sp manual
Trans mods: none
Fuel tank: 1/4
Tires: 185R14; 45/55 psi
Altitude: 500 ft. asl

Wed Jul 23, 2008 7:12 pm

You manual transmission guys have all the fun, but I still want to try it.

finally getting my new 2.2 wbx installed tomorrow and I can't wait to try it - unless it will violate my break-in instructions that is!