Why EFI?, maybe excellence was expected and they came as close as they could.. |
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Why EFI?, maybe excellence was expected and they came as close as they could.. |
Gunn1 |
Jun 11 2016, 03:59 PM
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#1
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Senior Member Group: Members Posts: 1,021 Joined: 14-February 16 From: Minnesota Member No.: 19,670 Region Association: None |
Did Porsche eff up?
No they didn't eff up, they did the best they could with the new technology they had. It seems as though the technology was purchased by the folks at Bosch from the aviation component of Bendix. That said most Injection systems were originally good at idle and full open throttle, so primarily racing applications. So in there infancy not well suited for automobile applications. Been reading on different types of fuel delivery systems and their pro and cons. There are very few con's to todays EFI systems, there were however performance and reliability issues with the original designs. Even today Claims of increased HP, Fuel economy, drivability, reliability and so on....some still dispute how much these differences really mean. It appears the main thing EFI does extremely well over Carbs is in the pollution factor, or in this case the ability to pollute less. Carbs are a some what open system allowing hydro carbons to escape/vent in to our atmosphere even when the engine is at rest, where as the EFI is essentially a closed system releasing no vapors or gases unless the engine is running and those gases are then coming out of the tailpipe from the exhaust cycle. Many of the Guru's (about 5 to 1) prefer carburation. The above Statement isn't correct, although what confuses this OP is the sheer amount of photographic evidence on this site and others including evilbay and CL showing most engine compartments with Carbs installed. Many here have spent thousands on their cars, and what do you see when the lid is lifted? a Carburated engine..... So while my intentions will be keeping my cars in their stock or near stock form, with EFI, I cannot understand why so many Carburated cars. (Because its easy isn't an answer, because its simple isn't an answer and because its cheap isn't an answer) With this being the case, Did Porsche mess up when they went the EFI route with the 914? I do not believe they messed up, I believe they did the best they could with the available technology they had. Granted they did sort of use the end user as of a kind of a guinea pig/test bed, but what manufacturer doesn't in some way. WHY DID THEY DO IT????? I think that just as much as seeing the Ljet and Djet as a performance and platform to develop future EFI systems off of, Porsche and others also incorporated EFI into there products to show they were progressive company's in design and practicality. EFI, Unibody, Targa, Mid engine, four wheel disc, and many more attributes can be cited as Porsches View into the future. I would like to keep my car stock with the factory EFI, but increasingly getting more difficult to do with so little information backing it up. Above statement is also incorrect. In my case I think I am fortunate because I believe I have most the parts needed to reinstall the factory EFI's on all three of my cars. There is a plethora of info on both sides, but for now.... just for originalities sake, EFI will be the way I go. To those that added constructive comments and or facts to this thread... it is much appreciated...to those that took this thread as some sort of attack on their beliefs, or way to "clutter" the site, I can appreciate how you feel, but I just see those arguments as shutting down the free flow of ideas and the give and take of facts that get each of us to arrive at our own understanding of the information. |
Darren C |
Jun 13 2016, 07:42 AM
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#2
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Member Group: Members Posts: 392 Joined: 26-December 14 From: Chichester UK Member No.: 18,255 Region Association: England |
Sitting on the fence watching this thread unfold, it just seems to be another differing opinion of ego’s with little or no hard facts displayed in this thread (albeit the facts are numerous and available elsewhere on 914 world).
It’s unfortunately this type of thread that clogs up the ease at which I’ve been able to seek out useful and meaning information on this site. The net result is that I simply go and find out for myself rather than trying to wade through all the opinionated drivel. My latest task was to see what happens when you fit carbs to a 2.0L FI stock engine. The only way I know how to get hard facts (rather than opinion) was to go do it, and get the car on a Dyno. I spent a whole day on the dyno, did 12 runs with various jet settings (increasing in steps of 5) and graphed Air Fuel ratio, torque and Horsepower through the rev ranges. For clarity the 12 graph overlays have been thinned out to 3 runs showing a fuel band where best driveability v jet range was found. Interpret this data as you will, it shows the pros and cons of fitting carbs over the whole rev ranges. It’s not heated opinion its hard fact. (IMG:http://www.914world.com/bbs2/uploads_offsite/i265.photobucket.com-18255-1465825340.1.jpg) This information is worth far more than the 4 pages that proceed my post. |
DBCooper |
Jun 13 2016, 10:58 AM
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#3
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14's in the 13's with ATTITUDE Group: Members Posts: 3,079 Joined: 25-August 04 From: Dazed and Confused Member No.: 2,618 Region Association: Northern California |
Interpret this data as you will, it shows the pros and cons of fitting carbs over the whole rev ranges. It’s not heated opinion its hard fact. This information is worth far more than the 4 pages that proceed my post. Sorry to disagree, but I don't think this information lends anything to the discussion. You were jetting carbs for power. So were any of your dyno runs done at part throttle? Then the results are applicable for full throttle situations, and how often do you drive your car at full throttle, what percentage of the time? So how is that related to "drivability"? And except at full throttle how does it shed any light in any way on "the pros and cons of fitting carbs", or any comparison of fuel injection vs. carburetors? The reason no manufacturer uses carburetors any more is that carburetors are primitive and only fuel injection will give them the control they need to meet emissions standards. Fuel injection will meter the correct fuel/air mixture for ANY driving situation. Carburetors can't do that, simply can't, and that control isn't only emissions, it gives the same control over every aspect that affects "drivability". That was as true back then when Porsche/VW installed injection on these engines as it is now. Fuel injection is better today than it was then, but it's always been better than carbs. That's not a baseless "claim" because empirical evidence is easy enough to find, just do a google search of "performance comparison fuel injection vs. carbs" or anything similar and look for actual test results. For peak power, as in the dyno charts above, once jetted there's little difference between carbs and F.I., but for every other measurement that affects "drivability" fuel injection is better. Excuse me for being undiplomatic but this isn't secret information, and to imply that Porsche "effed up" by choosing fuel injection is simply ridiculous. |
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