DRIVESHAFT

I realize individual cylinder tuning is possible, but what do you use for feedback to guide your adjustments?
Since O2 sensers are typically installed in the collectors, and not the primary tubes, you will get an average readout of all 4 cylinders on that bank.

not a '76

if you have a knock sensor or two, you can correlate a knock event with an individual cylender pretty easily.

The O2 sensors respond pretty quickly too, especially at lower speed you can pick up a problem from a individual sensor.

these two facts and some other tricks allow for check engine codes like "misfire on cylender 3"

nevermind high tech stuff like SAAB trionic that fires the sparkplug a second time and uses some feature of the spark signial to identify burn quality.

DRIVESHAFT

I seems like you would need a sensor for each cylinder for that to work.
Are you say that isnt the case?

not a '76

A good EFI always knows which cylender its firing. So it just needs one knock sensor. when it fires a cylender and hears knock right afterwards, it can retard timing or add more fuel to that cylender for the next firing event.

you can hear knock throughout the block, just like a mechanic's stethoscope can hear a rod knock anywhere in the block, even if it might be louder and quieter at certain locations

billla

It's not going to be all that long until there are sensors at each cylinder, and actually within the cylinder itself. Many high-performance general aviation aircraft already have EGT sensors in each exhaust.

We'll clearly end up at some point with direct injection fuel injection with the injector in the combustion chamber - the Cadillac CTS already has this and there are likely others I don't know about. Virtually all diesels use direct injection.

The technology path is pretty clear - EFI, including aftermarket EFI gets better and cheaper all the time. I worked with the early aftermarket stuff, and it was - in a word - junk. And it's not like all the early Detroit stuff was a lot better. But the factory stuff now is pretty impressive and the aftermarket stuff is getting better all the time. This latest generation of aftermarket EFI is pretty impressive as well.

69427

Unless I'm mistaken, Saab doesn't actually fire the plug a second time (outside of cranking conditions), it merely looks at the ION current immediately after the plug fires.
I am open to correction if the newer ones actually fire the plug twice.

nitronick

I notice Herr Gruber has completely vacated this thread after being pwned by his own link

Golden

Maybe he's out walking Dino...............

billla

I can't imagine that quote being used out of context to try and "prove" exactly the opposite of what the article found.

But it just shows how important it is to check sources and read articles fully.

63mako

Just read the article completely. It's findings are the exact opposite of the original post. What amazed me was the difference on the chassis dyno. Peak HP increased by 10 and Peak Tq by 20. This is on an engine with well under 200 HP to begin with and about a 30% increase in fuel mileage.

MotorHead

So what are we looking at here, converting to EFI for 10hp if that, maybe the other way around an lose 10hp ?

Buy an LM-1 and tune your carb correctly and you will be surprised how well it works. Like I said before not many know much about carbs anymore, they are gone or going. Anyone ever change their emulsion bleeds, anyone even know what they are. ( I know only a little about them so don't worry about it )

As for the European and his superior EFI setup if I was going to spend 2 -3 grand to change over I would expect this superior setup to net me some real power, not something you wouldn't even feel in the seat of your pants.

As for throttle response and drive-ability, I again have to go back and say get the correct carb for your motor and get it tuned correctly. As far as I am concerned there would be little advantage for someone like me driving around the same area in the same weather every year.

I do like that Dual Throttle body FAST EFI setup though

tt 383

Timing and fuel are two different entities, and a timing computer could be added to benefit a good carb setup for cheap, and someone else seems to think that the term "carb" dictates a common plenum 4 barrel and cannot compensate for individual runner, not true either. Like any efi vs carb discussion this is riddled with to many generalizations. This was about making the most power, and carbs in any form of racing that is about the most power, win hands down. As always the EFI guys want to muddy the conversation up with the advantages of EFI, not the topic, WOT power..... Pro stock, bonneville, any class that efi isnt banned in carbs dominate when ultimate power wins the race.
When tuned properly a carb is the peerfect atomization/emulsion machine.An injection system is a proper air to fuel delivery ratio machine. When a carb is tuned to do both things at the correct time its desgn is an inherent advantage at making peak power. Golden, save your book worm EFI seminars for a different forum preferably one only the UK can access. Out

MotorHead

I don't buy this EFI; Great, Carb; poopy stuff either.

Don't get me wrong though EFI is here to stay and the future
When I want to get groceries on a cold night I jump into my fuel injected daily driver, don't even warm it up.

But when I go to the track I want to take something with a carb, unless I take a rental again

Bullshark

We use thermal couples at each exhaust header tube as well as multiplexed O2 sensors. A special header setup for our engine types support the engine dyno tuning setup.

427Hotrod

Hey guys...I'm going to be testing this soon. My 540 will be getting some neat EFI stuff and it will be dyno tested as well as street evaluated.

It's going to be fun...because my 'ole Dominator actually works well...but I know EFI can do better overall.

Look out for upcoming reports!

JIM

Golden

Why would you lose 10 bhp?

EFI is always going to at least equal a carb at the top of it's game, if not beat it, for about the 4th or 5th time, if EFI doesn't out perform a carb, you've either fitted the wrong system or not tuned it properly.

As far as gains go, even if EFI gives a smallish PEAK gain over what's probably a reasonably expensive carb with dyno time. It's not just about PEAK, it's about BHP and torque across the rev range and that's where EFI really kicks a carbs ***.

Also what about guys who want to junk their 30 year old, 250,000mile carbs. I suspect the gains there are going to be a lot more than 10bhp, the driveability will by like night and day, plus they'll have a system capable of accepting much more future development than a carb.

As for cost, I've said all the way through this thread that a good, bolt on carb is good value for money, that's if it works out the box. Some people though keep comparing EFI to tests done with carbs that cost 2 or 3 times a basic Holley or Edlebrock. The thing is that a 600cfm carb that's perfect for a mild SB won't cope with a fast road 383 conversion, where as a 750cfm EFI system will run both.

As for your comments on atmospheric change, in Toronto you have a annual temperature range of 30-35 degrees, a variation of 15% in air density and as much as a 45% change in humidity in a single day! Do you really believe your carb is optimised for all those conditions? Drag racers will change their fuelling for as little as a couple of degrees temp change.

Here's a quote taken from jetting specialist http://www.jetsrus.com showing how many vairiables drag racers allow for. These are vairiables that a good EFI system adjusts for 24/7 365 days a year.

Bullshark

Hey Jim, you going to try out that new Holley EFI?

FB007

Maybe because a Rainbird Sprinkler works better than an SU Carb.

Matt Gruber

Thanks for the replies! I was away yesterday, and i figured if i was completely off base, this topic would go to the bottom of the page. I am pleasantly surprised to see solid points made on both sides. Keep up the good responses! I'm reading and learning.
.
To correct the public record, i should have stated the 4165-6210, not a 4165. It is a Double Pumper, my street favorite, because Holley has tuned it for 327, 350 and 402 Chevy engines 1965-1970. The primarys do not need oxygen sensor tuning. Just put it on and drive, as long as it idles at 800 or lower and has 12" vacuum or higher.
I agree a generic carb that needs tuning is a big waste of time; the holley catalog is full of application specfic carbs; I'd not put a "universal performance" carb on any street car. Common mistake. Reports here on CF are that they run too rich. here is my article http://community-2.webtv.net/MATTGRU/carb/page2.html

Just checked the mpg in my 355 61 4.11/ no overdrive.
got 19.0 mpg. What mpg could i expect with EFI(be specific as to what system) ?
I am listening closely. and what would my payback period be? My insurance limits me to 1,000mi/yr, and i rarely go 500.
Thanks for the lively discussion

zwede

So you're going for it! Great! One or two throttle bodies?