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Date:         Sun, 8 Mar 2009 21:58:58 -0700
Reply-To:     Keith Hughes <keithahughes@Q.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Keith Hughes <keithahughes@Q.COM>
Subject:      Re: Replacing FI with Carbs on WBX 2.1L
In-Reply-To:  <BAY0-PAMC1-F15mhbuo00024cc8@bay0-pamc1-f1.bay0.hotmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

> Date: Sat, 7 Mar 2009 23:32:15 -0600 > From: John Rodgers <inua@CHARTER.NET> > Subject: Re: Replacing FI with Carbs on WBX 2.1L > > There is, obviously, a lot to be said in favor of the electronics in > modern automobiles, and there doesn't seem to be anything said bad about > the ever forward creeping expansion of electronics i cars and other > things to the point that no one can work on anything because of the > technology, unless it is taken to a special facility that has the > specialized technology to test all these systems. That is a bit scary. > The more technology that gets incorporated, the more vulnerable that > technology becomes to all sort of unexpected events. Like - what happens > to all those fancy electronics if there is - God forbid - an atomic > related electromagnetic pulse anywhere near where we live. All the > electronics get fried. On occassions in the geological past there have > been astrological events that apparently have produces such > electromagnetic pulses, and it could happen again. Kinda far out, but > possible to happen. And of some concern is the Mayan Calendar and the > year 2012. Some anticipate some sort of spectacular event that may > include the EMP. That's not far away. Some worry about such. For me it > is only passing concern. But what if it happens. All but the few > vehicles with mechanical fuel delivery systems would be stalled on the > side of the road. I definitely believe in the KISS principle in most > things. And keeping it that way in vehicles is important to me. FI is > great. But it still begs the question - why just accept the declaration > by the powers that be that modern electronic FI is the best and can > never be replaced by anything better. That is where I am. If an > alternative to FI can be found that is better, and more simple, you bet > your bippy I'm gonna jump on it. I don't want to get locked into a > narrow mode of thought on this. I watched a really good show on physics > tonight. It reminded me that Albert Einstein worked out his theory of > general relativity with nothing more than a paper pad, a pencil, and his > brain, and with that provided the basis for modern Quantum Physics and > just about everything else in science today. Pretty extraordinary, I > would say. So, whose to say - perhaps it can be done where carburetors > are concerned. Pencil, paper, and some deep thinking. Sometimes all that > is necessary is simply looking at the problem from a different angle. > > Who knows, there may be a fully carbureted 100/mpg Vanagon in the wings > out there already, just waiting for it's debut!! > > Regards, > > John Rodgers > 88 GL Driver > Wow, that's a *lot* of angst for a carburetor discussion! A couple of points: Assuming you make it through your nuclear EMP, or Mayan mystery apocalypse, you'll still be dead in the water unless you go back to points and condenser as well (none of those nasty ICU's and Hall sensors), with all the charming issues they present. So now, you're looking at poor spark control as well as degraded fuel delivery control. Additionally, when talking about carbs, Bernoulli is the relevant genius, and he predated Einstein by a couple of centuries. Whatever miracles one might believe carburetors to be capable of performing, they are still limited because of the principle upon which they're based. Given the affect that temperature, varying fuel pressure, and air pressure has on the Bernoulli effect, and the extremely non-linear response at low air velocities, carburetors have to be equipped with multiple interdependent/interacting mechanical systems to augment their operation - anti-percolation devices, altitude compensation, variable orifice jetting, WOT enrichment, accelerator pumps, separate idle circuits, cold start enrichment, etc. The principles a carb is based on is relatively simple, the implementation however is another matter.

While several of these ancillary systems can fail, and still leave a functional vehicle, any failure of the many interdependent mechanical systems will result in significantly reduced performance (and hence, mileage). And, you still have no way of adjusting for engine load (e.g. RPM vs throttle position), nor do you have the ability to inject fuel on a per-cylinder basis instead of in a common manifold (granted, Bosch CIS doesn't quite accomplish this either - but its much closer). So if you want simplicity, and ease of field repair, then a carb and spare carb kit will get you there. If you want peak performance, efficiency, and driveability, FI gets the cookie.

And as for:

"But it still begs the question - why just accept the declaration by the powers that be that modern electronic FI is the best and can never be replaced by anything better."

You might be accepting that "declaration" (assuming for the sake of argument that such a declaration exists), but some of use (or many) don't need anyones' opinion, merely our own experience. I've built/rebuilt/tuned hundreds of carbs over the years (from Hitachi and SU sidedrafts, to 1,2,4 bbl, up to 1050 cfm downdrafts), and none can compare in performance or economy with FI. Even the old Rochester, Crower, Hillborn injection systems beat the carbs of the time for maximum horsepower, and the Rochester could even beat them on driveability when tuned properly (granted, that wasn't very often...and you couldn't live anywhere *really* cold, but still...). Carbs can run great - many millions of miles have been driven on carbs, but *performance* issues killed them, not some engineering conspiracy. The more process variables you adjust for, the better the performance, and FI has it hands down in that department.

And, if I'm close enough to the EMP to need to worry about my EFI, I'll be much too worried about my "tan" to care about my Motronic :-)

Keith Hughes '86 Westy Tiico (Marvin)


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