before I say anything (and I guess I probably shouldn't if I have preface it with a qualifier) thank you for posting your dyno results whether or not there is a FI comparison it is good info.
I am not a admin advanced or guru-member just a regular guy who has only had my car for a couple of years and I'm not itching for a fight or trying to belittle you or anyone in any way but...

really? you fear posting on this board? really? what are you afraid of? how many of these guys have you met (me only a handful and they were all super cool to me and I know I've posted my share of moronic questions/comments) do you think they will come to your house and beat you up or kick you off the board or ?

again please no one take offense but often all of us need to take a step back, if you or me or anyone posts something they think is earth-shattering info or even mildly interesting or relevant to whatever discussion and it receives less than your desired response -who cares?!?

if someone responds with something that ruffles your feathers (it is very difficult to either write or read tone) read around it (for instance you could skip the first 3 sentences of this post) for the info contained within very few posts on here are just flame jobs with no info contained within

I'm glad you're on the board Darren hell I'm glad everyone here is here because we all love these cars and the collective can keep them on the road much longer than any individual alone, especially me!


cjl

The fastest way to start an argument on a 914 board is to post anything that has to with carbs vs injection.

My previous car was a 74 L-jet car and it ran great but was always unreliable and left me stranded a couple of times. I was always able to diagnose it and get it working again with out a problem but I would rather drive my car than work on it.

My current car came with a set of Dellorto 40s. They were never set up correctly by the previous owner and didn't work very well. The first thing I did was track down a D-jet system with the intention of converting it back. Before I converted it I took some advice from here and changed the vents from 28mm to 34mm,installed smaller idle jets, bigger main jets & smaller air correctors. Didn't take much of a learning curve to get the car running really well. I also spent some time sorting out the anemic Bosch ignition. The car runs great and more important than that to me it is dead reliable. I haven't messed with the settings on the carbs in years. It starts all of the time and it runs at a pretty consistent 275 degrees. I would love to have injection but If it isn't broken why fix it. If there was some kind of turn key modern injection system that I didn't have to build myself I might consider converting it.

Thanks cjl, I'm not fearful, I just said some others with thinner skin may be put off.
Hell, I got a 2 week suspension last month for posting what I thought. No fear here!

Yes, you live in Europe. Silly me for assuming someone living in Europe would have a European car. What was i thinking?

That wasn't the context of the OP. "Did Porsche eff up?" The decision to go that way was made back the the 1960's. So yea...compared to modern injectors...they don't compare. But that was then. Now is now. The OP want to know "what is the best way to go". I'd assume that means now.

Even Jake who I consider has given a wealth of info and has contributed a lot here says either will work fine. Given you have the ability to tune it yourself. So...go for what you know. If not, then get out your wallet to pay someone else...carbs or EFI probably won't matter at that point.

I've had both carbed and EFI cars of several varieties. I kept the D-Jet on my car because that's what it came with. I know how to tune it. It is a highly reliable system and my car fuel mixture is right on the money. From a component standpoint it can be complicated as Jake mentioned. If I was in business...I wouldn't recommend it....too many call backs.

Some great discussion about carbs here but I'm wondering if the OP has decided which "way" he will go?

IMHO for street with a 2056 done right w-Djet....means cam...tuning...ect..can't
be beat from a smile/cost perspective and seat of the pants perspective. Most bang for the buck.

Carry on.

Andy,

That'll be decided on the 23rd

But I see they kick in the use of a big ass fan for the radiator airflow...

Look guy's,

I've got outta my seat and spent hard cash to obtain some (what I consider anyway) good information then willingly shared it free for the world to see on here.
I am asking nothing in return.

I'm not taking sides on the Carb v FI debate.

The data simply shows how jet sizing in a 914 with retro fitted carbs effects:

Air Fuel Ratio (and consequent mpg)
Driveability through rev range shown as torque
and Horsepower.

Whilst showing that factory HP & Torque specs can be met, by having to compromise on mpg.

I searched previously for some hard data, and basically came up with just strong opinions, so sought to obtain impartial facts that can be used to illustrate what's going on when you swap jet sizes, and the quirks in the graphs that you might not necessarily have predicted in response.

That's all folks......

Darren C,

I was just attempting to point out that even if you ran a stock, well running D-Jet 2.0 on the dyno, comparing your dyno numbers to this stock engine would not prove one way or another as there are too many variables changing in the engine that can't be easily quantified, and thus the discussion would not be resolved. It was not meant to be personal.

As for FI and emissions, agree emissions played a role but here in the US carbs were used up until around 1990. But I was attempting to point out that many factors (both internal and external) come into play (such as emissions) in the design of any product, and that has to be considered.

this is the stupidest thread i have ever seen. from op question to the responses. i have been flamed for many of my query. this is a tough group, but at the end and beginning, is the central question posed by somebody that does not have basic understanding of fuel delivery whether fi or carbs, let alone how those systems work. i think rabys response covers the controversy pretty eloquently.

Huh, and yet "this is the stupidest thread (you've) ever seen...

Thanks to everyone for contributing to this thread.

I do apologize if I ruffled some feathers, but really appreciate all of the technical data and opinions that were given on both sides.

Honestly did not know the Carb versus EFI question was Taboo. (I saw nothing in the rules about not being able to discuss it!)

If I would have simply posed the question, Carbs or EFI?....... how many responses do you suppose the post would have gotten? probably not all that many, and the responses would probably have been more of the yes/no/very little and general informational replies.

On the other hand by asking the same question only in a more provocative manner, it likely elicited many more in depth responses with a great deal of expanded information, actually more information than I ever thought.

As for my personal choice, for now I'm going to go with the stock EFI. Probably use the carb set up on one of my other 1.7 or 1.8 liters in a V rod setup, but that's another subject.

Hope I didn't upset to many of you, I can say one things for sure you are all quite knowledgeable and very passionate about your Cars, what's in them and I am glad to be able to take part in it.

In the future I will do better regarding the question and how it is posed.

Thanks again

hey corndogger, blow me , yeah it is

Now that we beat this dead horse , its time to move on to 4 versus 6!!

your right, is it a hate crime or terrrtism? what if its both?

IBTL

Your welcome to your own opinion, but The fact there were so many replies with really great data proves anything but it being The stupidest thread you've ever seen.

Just because people disagree doesn't mean their point of view is stupid

you are the op , obviously you are a retard, corndoggfhohole, a retard, where we going with this ?

I would say your crossing the line bud.

I have a niece that has Down's syndrome. People have used that word to describe her.
That is a vile description of someone that has a learning disability.

Using that type of language is not acceptable.

I think you need to apologize

No relevant data was posted, (the dynamometer graph has nothing to do with the factory using EFI)

Jakes comment has nothing to do with the factory using EFI. Even my comments do not answer it completely, it is pure speculation until we see something in writing or a video from someone at Porsche (or perhaps Bosch) saying why the switch to EFI.

what data? one guy from england posted a dyne sheet from england with carbs
. vague on the build, this is your proof?

I got a lot out of it,

Thanks

Thanks Brant. I think I will lower my float levels a bit and then keep on keeping on.

This board can be a bit harsh at times, but Injin seems out of srts...should crawl back under his rock or back into his bottle

Thanks all and thanks again Darren

Those graphs were great, thanks.

Not sure they answered the mail on 'why' or driveability, but that was good data and makes total sense as I am trying to dial in my Dellortos. I'm using that data to go a bit smaller on my main jets and larger on my accel pump jets. LOVE this forum.

Not related to your graphs, I find the comments about this board being 'harsh' a bit amusing. I've been on BB's since the early 90's with SAAB NET and the XS11 Forum and from Jeep to SAAB, to G Body to COG, FJR, Subaru and a couple others, 914 world is total chill, and has been the best community so far and virtually troll and moron free. A bunch of cool guys, helpful and absolutely generous and gracious. IMO, the person who encounters troubles here brought them............

https://www.youtube.com/watch?v=60Lb3-kYvc8

https://www.youtube.com/watch?v=vK8OX8xbka0


/
https://www.google.ca/?ion=1&espv=2#q=k...mp%20for%20sale
Since 1968,efi has been the way.
Retro-fitting carbs to an injected T4 can be made to work tho.
Mapping egt back to back on a dyno is one way to make a valid comparison,quickly.
Another is time consuming trial and error testing,one change at a time,a seat of the pants,'feel' method.
The factory abandoned the mechanical carbs over injection 5 decades ago,so,
the question the op should have asked is 'Which efi system is most suitable for my application?'
http://www.total911.com/technology-explain...fuel-injection/
/
Gee,I wonder who will be the first to offer a DFI system for the TFour.
Get sum soon.
https://www.google.ca/search?q=direct+fuel+...gwvt4uUakTUM%3A
http://www.hotrod.com/how-to/engine/1501-d...-future-of-efi/

Too Funny Veekry

Here is my dyno chart from when my 914 2.0L was bone stock with newly fitted Djet.

So......


Flatter torque curve with FI with aprox. a 5 hp gain with carbs.

For my street car I.ll take FI for a stock config.

Wow Geoff, thats great info. opening two tabs on my PC I can bring up my graph and yours and flit between to write this post. To make it easy for others I've edited it in here so you can just scroll up and down for comparison...



914_teener, the torque curve is about the same no flatter or curved between the D-Jet and the Weber 40 IDF's.
Take a look at the RPM scale at the foot of the graph, mine starts at a lower RPM, so by the time I'm at 2000rpm I'm making Torque about 118, peaking at about 122 whereas Geoff's D-jet torque peaks at 108 and his RPM trace starts at 2000 which is why it first appears flatter. (eggs & eggs scenario) if you could see Geoffs trace pre 2000 rpm it's gonna curve like mine. In fact you can just see it curve down, so if it were extrapolated I'd guess you'd be around 90-95 torque at 2000rpm Geoff....I'm making 118 torque at 2000 rpm on a 135 jet! (105 torque on a 125 jet and 108 torque on a 140 jet both at 2000 RPM both above the stock D-jet which is kinda curious too)

Brilliant data to show some "basic" comparisons Geoff. Thanks so much for sharing it's really made my day to see this real newly fitted D-jet data.....

Taking into consideration the US and Europe DIN & SAE scales I'm still up by 6% on peak torque WOW, I'm up by 15% on torque at lower RPM (2000rpm) and that's a real driveability bonus. Wow, Wow!

Don't suppose you have an AFR trace do you Geoff? I'd like to see what the trade off in mpg looks like between the two.

Thanks again Geoff, this thread just got a whole lot more interesting.

Carbs vs EFI sounds surprisingly like this:


https://www.youtube.com/watch?v=FL7yD-0pqZg

And here is a question that I pose whenever this comes up:

IF EFI is superior AND Porsche had EFI on the 911T & 911E (both MFI & EFI) then why did they opt for carbs on the 914-6?

The answer is: They intended to race the 914-6 from it's inception, and they knew that carbs provided more adjust-ability than the EFI did at the time.


Now if you want The tuneability of modern EFI with the "vintage" appeal of the stock EFI, then you can use 100% stock EFI parts from the D-Jet and add a Megasquirt for the ECU.

Two guys in my vintage racing group did exactly this.
They use 4X stock throttle bodies for ITBs and run E85 controlled via Megasquirt.

I am not positive, but I think they use aftermarket MAP sensors in place of the MPS.
Although I could make a circuit that would use the stock MPS and provide an analog output that the megasquirt can read and mimics a MAP but that just sounds like a lot of work.

The EFI system being more tunable is both a pro and a con for some people. The benefit comes from the ability to dial in fuel every couple hundred RPM, BUT the issue with this is that all of those increments require perfect tuning.

Again, this is why PEFI is not for everyone, but its also why some people love it.

I have cars with stock EFI, CIS, PEFI and carbs. They all have pros and cons, but at the end of the day I like whats simple.

Couldn't agree more Jake. I have cars with all manner of fuel delivery too, but the simplest always give me less trouble and when and if I get trouble, they're normally easy cheap fixes.

I like carbs and they have a place for the appropiate application. But, I've never really thought of them as more than a somewhat metered fuel leak.

Carbs only have a few inputs which AFM is adjusted. FI simply has more.

One person's 'simple' is another person's 'complex'.

Which is more 'simple'?:

Plugin in a laptop to an OBDII port, download ROM from ECU, edit a table using a hex editor, reflash ROM to ECU?
OR
Pulling off an air filter, removing a mainjet holder with a screwdriver, swapping main jet, then repeating this 3 more times and replacing air filters?

Ask 5 people and you will probably get 3 different answers.

I totally agree with you Stu.

But at a guess I'd say that most folk on here would find it easier to lay their hands on a screwdriver at the side of the road than a laptop to an OBDII port, download ROM from ECU, edit a table using a hex editor, reflash ROM to ECU. :-)

Using that kind of logic would lead one to believe that the 910, 907, 908, 917 and so on were never intended to be raced. Because those cars were all fuel injected. The 914/4 and 914/6 were too good, giving the 911 fits remember. The 914 got the 2.0 911T to keep it slower than the 911, so the FIA homologation required it to race with carbs. In SCCA, Porsche and SCCA made a deal to allow the 914/4 to race with carbs instead of the OG fuel injection…

Why would you ever have to do the "on the side of the road" with a laptop? I've had plenty of idle screws come lose on my carb setups, but i never had to fix a broken FI by plugging in a laptop on the side of the road. That's not how FI works.

It's not like driving around somehow shakes the bytes around in your ECU mapping tables ...



I think you're really grasping for straws here ...

Click to view attachment
BMW-X6M

What kind of carb yuh runnin?
https://www.google.ca/search?q=setting+carb...DmZLsrOniHBM%3A
https://www.google.ca/webhp?sourceid=chrome...ing+weber+carbs
https://www.google.ca/webhp?sourceid=chrome...0fuel%20mixture
https://www.google.ca/search?q=constant+vel...vyNyXRYfd_WM%3A
https://www.google.ca/search?q=constant+vel...SWHBgEQ_AUICCgB
https://www.google.ca/search?q=su+cv+carbs&...ygA&dpr=1.5
https://www.google.ca/webhp?sourceid=chrome...on%20cv%20carbs
https://www.google.ca/search?q=mikuni+cv+ca...UWDAQcQ_AUIBigB
https://www.google.ca/webhp?sourceid=chrome...retor+vs.+slide
https://www.google.ca/search?q=kendig+const...SgA&dpr=1.5
https://www.google.ca/webhp?sourceid=chrome...ator+carburetor
Synchronizing carbs:
https://www.youtube.com/watch?v=GaTRyHxvneY
https://www.youtube.com/watch?v=Y_WDF6glD5k
https://www.youtube.com/watch?v=2PiQBr20kM8

https://www.sema.org/sema-enews/2011/19/cre...dig-passes-away

Sir Andy, et all,

Technology is fine, but everything has its limits. I’m not championing Carbs or FI here, but I’ll share a little experience I had last winter.
I was driving home from work alone on a back road and I suffered a TIA stroke while at the wheel, in seconds I was totally blind, and had no control of my left side. I was doing 50 mph at the time, and managed to bring the car to a stop using the grass verge and its feel through my right hand on the steering wheel. My first reaction was to feel for my phone to dial 911 (999 in UK).
But I had a smart phone.
Ever tried to dial 911 when you’re blinded by a stroke on a locked smart phone?
I thought I was gonna die there and then at the side of this empty road alone.
I opened the door and fell out the car into the road as I couldn’t stand up, blind and trying to shout for help with slurred speech.
Fortunately a passing car stopped and got me to the local Hospital ER (A & E in UK).
Smart phones are great, but I now have a Nokia 105 with buttons, so I can feel where the 9 & 1 are.
As has been said previously in this thread it’s what the individual feels comfortable with. The graphs I’ve posted along with Geoff are great to show what’s going on in a technical capacity, but everyone’s free to go with what they like.

Don’t lambast each other.

Don't try to be clever and nit pick each other.

If we all simply liked the same things the world would be a boring place.

Sure I get sh*t for my Nokia phone….but I’m not going to change it because it gives me a comfort that a smart phone can't ever do.


Hopefully you can get the meaning I'm trying to convey here...



Stu, your iphone 4 movie sure did make me smile.
Neither cartoon character need a damn up to date phone, it's just "stuff" that clogs our lives. All we need is a little understanding and each other.

Well, with 7 pages of replies, you've certainly opened up a can of worms!

My perspective as a buyer in 1974-75:

IMHO - the Porsche 914 was the superior solution with state of the art EFI - & NOT dual/multiple Carbs to screw with - over the competing set of late 60's - early 70's sports cars & coupes in my budget which I looked at, including: MGB & C, Triumph Spitfire & TR4A & TR6, Austin Healy/MG Sprite/Midget, Fiat 124 Spider & Coupe, Alpha Spider & Coupe, Karmann Ghia, Porsche 912 (76 912E was the same 914 2.0L Djet), BMW 2002 (ti & tii were EFI), etc.

Even the fuel injected 911E of that period was considered the more tractable 911 model, and the 917 was MFI or EFI - NOT carbed, so go figure! Also the top powered 60's 427 Vette was the "Porcupine Head" fuel injected version. However, it was a time of transition to the newer FI, EFI & MFI technology, & most serious race teams made the switch to some for of FI.

I'd had enough of messing with & rebuilding carbs on my 1st 2 cars - a 68 Opel Kadett 2DR Notchback Coupe 1.1L & 69 Pontiac Ventura 4DR HT 400ci V8 - as well as with my folks', brother's, & uncle's & buddies' cars! And I certainly did NOT want to get into the royal PITA of synchronizing dual/multi carbs, constantly rejetting them for different altitudes, weather & other conditions, not to mention rebuilding more than one of the suckers per car!!

So I'm in agreement with the majority on here - emphatically NO - Porsche didn't eff up - then or now!!!!

My perspective as a new/used car buyer today:

New/Recent Cars - First off - try to name one car made today with carbs!? EFI is clearly superior fuel management for power, torque, mpg, emissions control, power/torque bands control over the range of RPMs, weather, altitude, etc. - so nobody does them on the new cars today, nor will they!

Classic Cars - No Carbs, unless that was they way they came as new & it's a restored or to be done as a classic build. For a Resto Mod - whether American Iron or Imports, most everyone is going with EFI Crate Engines, Mega-squirt, etc. EFIs for the reasons above & that others have said.

914 with Carbs:

So who is using carb conversions on 914 engines? Again there are some classic builds with carbed Porsche flat 6s, the Euro version of the 1.8L 914 (a cost saving measure for RoW by Porsche BTW, since they didn't need to meet Smog Tests for CA & the US), & as a cost saver on some 914 2.0L's built over 2056-ish, where the OE Djet doesn't work well.

Who else? Those who are too cheap to buy the proper OEM parts to fix their stock EFI, those who are either too lazy to mess with the more complex EFI &/or "...just don't know how to make these cars run properly" in the words of my Austrian born Porsche mechanic who was factory trained on the 914 in 1969-72 & has had his own shop since 72 (I've gone to him since he did the PPIs on 10-20 914s before I got my 73 2L back in 1975) - so a REAL GURU! .... not an online wannabe!!

Also note that our 914s are usually worth far more with either their original EFI (914-6 excluded cuz they were stock carbed), as well as on the better EFI "built" flat-4 resto-mods.

So, make your own choice!
Tom
///////

If indeed a 914 is NARP I guess it could be said Porsche didn't eff up?

Are you still implying that someone did eff up?

Wake up and smell the hydrocarbons.

Now that's some of the dumbest bullshit I've seen in a while, and then, just when you think that one could never be topped it (good God!) just keeps on coming:

No, no one effed up.

I think EFI is the way to go, especially with a stock or near stock displacement engine.

Carbs would probably be more viable and useful on a "Big Four"
Type situation.

Are you drinking again?

Since I've been sitting in front of my computer doing number crunching all day anyways, I thought I'd take a little time and use a little code to pull numbers from both the carb and FI plots and compare the two...

This plot compares the max power case from Darren (carb with 135 mains) with the FI case from Geoff. All that has been done here is pulling the curves off each plot and putting them all on the same chart. It might look a little different due to the axis dimensions. Note that I'm assuming Darren's power axis is reading in DIN HP so I corrected it to SAE HP.

Click to view attachment

At first glance, it looks like the carb'd car has both more power and a power band which is shifted lower in the rev range.

This next plot is the previous data normalized (ie: the data is divided by it's max value to force it to lie within a range of 0-1). Ignore the y-axis label, I just forgot to change it. Normalizing allows you to compare the trends. I did this because 1) no two dynos will read the same absolute values and 2) a correction factor for drive line losses is always applied, but the actual number is unknown since it's not recorded on these plots.

The curves look almost identical. Since they show the same trends and relative power differences, this leads me to believe that there is really little appreciable maximum power/engine speed difference between the two induction methods. Perhaps the carbs fall off faster but who knows... Just some things to think about.

Click to view attachment