r.gault at sbcglobal.net
Mon Oct 10 19:40:33 EDT 2005
So, let's see.. Regular is $0.15 cheaper than premium here. That's 5%, or
in my case equivalent to a little more than 1 MPG. For that cost (about
$65/year), I get way more fun at close to 10:1 CR. Actually, I might be
getting more than an additional 1 MPG due to increased efficiency at the
higer CR. I'll be interested to see if the 3.6L engine is much different
when I get it in.
Hopefully, next winter, I'll be putting on a Megasquirt EFI using 6
motorcycle throttle bodies. Way too much fun. Maybe $1500 by the time I
get through. Maybe 2-3 MPG improvement (optimistic). Hmmm.... Can't use $
as an excuse for that mod - just have to admit it's a hobby.
As for the economics of trading up for a new car.... There's a minefield
there. Assuming that you pay $15,000 cash for the car, at $1000 a year it
will take a little over 21 years to pay back the $15K and the lost interest.
If you finance the car, it will be worse because of the fine deal you'll get
on the loan - say 25 years to pay back.
Gas prices aren't anywhere near high enough to make economics a reason to do
much of anything. It's not the price that makes us do stuff, it's the rate
of change of the price. SUV sales are in the tank (sorry), but it won't
last. The elephant herds will return when we get used to $3 gas.
There are only a couple of reasons to make any kind of car change:
1) Your wife wants a new one.
2) It's a cooler car
----- Original Message -----
From: "Padgett" <pp2 at 6007.us>
To: <virtualvairs at corvair.org>
Sent: Monday, October 10, 2005 3:46 PM
Subject: Re: <VV> MPG
> >It's odd to me.......someone posted last week suggesting a subject of
> >"getting higher gas mileage" from your Vair.....NO ONE responded!
> Well the first and most obvious cost savings is to be able to run regular
> instead of premium.
> Other than that if the primary goal is MPG and cannot begin with a turbo
> then the best start with a 110 hp engine, accept the cost of premium, and
> learn to drive for economy which is specific.
> Had posted a number of possibilities for DFI (digital fuel injection)
> has the most potential for improvement that is the "poorly controlled
> that is the HV carb. Does not even have any metering rods (e.g. Carter AFB
> or Rochester "M" series which includes the monojet which is very crude but
> there) to lean out the cruise. Even a variable venturi SU HD-4 would be
> better but is a sidedraft.
> Next issue is the driving conditions. Best is a steady state cruise at the
> minimum rpm you can get into top gear. PGs have an advantage there since
> are at 1:1 as low as 15 mph (with some slip, have not plotted actual rpm
> yet, one of the things I have planned.
> For Interstates obviously the best choice is a 3.08 gear for minimum rpm,
> 3.27 is next and tall rear tires make possible for the rest. Ideal would
> 2400-2600 rpm at 70 mph but is hard to achieve with a 3.55.
> Next, everything related to tuning needs to be optimized. Need to find
> "sweet spot" for advance for your car (is a little different for each).
> Invest in a manifold vacuum gauge and find settings that provide the
> highest reading at steady state cruise.
> Worst thing about driving for maximum MPG is the constant attention,
> requires as much as any race, for any advantage such as turning the engine
> off & coasting as much as possible (my wife thinks it amusing when coming
> up to a known light that is going to be red awhile that I shift to neutral
> and when a/c is not required, turn off the engine. Of course it helps to
> confident that the engine will fire back up on the first 1/2 turn of the
> Biggest factor is not no accelleration but no sudden changes (just like
> racing). If in a 45 mph zone then holding the throttle constant and
> allowing variations in speed will give better results than holding 45
> exactly. Get to speed as quickly as possible without engaging "power
> enrichment" and then try to stay smooth and constant with minimum braking
> (turns the momentum you spent gas to achieve into heat).
> I don't know what the drag coefficient is for the Corvair (expect LM is
> better than EM but really only important over about 60 mph) but the car
> a low profile and (to me) smooth lines. Best is a coupe. Worst is a
> for two reasons, one curable. First the roofline is not as smooth. Second,
> the cocktail shakers represent over 50 lbs of extra weight.
> Biggest factor in MPG is where you drive. Five mile hops to the store and
> such with lots of traffic is terrible. Steady state at a "sweet" speed
> (needs to be enough to be operating efficiently in top gear but no faster)
> is best. Have no numbers on Corvair as yet (still getting it right) but
> last weekend the 3800 (231 cid, 3300 lbs) that was reading 17.2 mpg 20
> miles from fillup due to stop and go was up to 23.6 after 120 mile round
> trip to picnic. Long stretches at 60 mph (sweet spot) over 30 mpg. On
> cruise. Without trying. I *know* the Corvair can do better with 90 cubic
> inches and 1000 lbs less.
> I really like digital feedback FI because it does not require tuning once
> programmed properly. Can do the same with carbs just requires periodic
> Anyone try Clark's variable fan pulley, seems to make sense ?
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