So I plan on running a Keihin FCR on my 16v. I have read that using carbs means your dizzy is now locked, so i wanted to avoid that by running direct ignition coils (maybe splitfire). Now that means I need EDIS stuff, but I will be using a Haltech ECU. Haltech says, "It is capable of controlling sequential injection on engines up to 4 cylinders, or semi-sequential up to 8 cylinders, combined with direct fire ignition for engines up to 4 cylinders or wasted spark ignition on engines up to 8 cylinders." So would that mean that I need just the trigger wheel and a sensor or do I not need any of that because it says the ECU can potentially run the ignition? Or am I in wayyy over my head in stuff that I am totally in the dark about?

If your going to be spending money on a haltech, you should just use injectors and make a better intake manifold, you will get more power that way. But if you are dead set on running carbs and the ignition system of choice (or what i think and probably many other think is best) get yourself a megajolt jr. It is just an ignition ecu to run EDIS.

Im in the same boat as you right now! I have actually been really thinking about the Electromotive XDI system http://www.racetep.com/hpx.htm Its trigger wheel Coil pack style and expensive but it looks awsome!

If you are going to run complex electronics why on earth run carbs?

http://www.youtube.com/watch?v=ropKAFjy ... ture=share

This is why

yoshimitsuspeed wrote:If you are going to run complex electronics why on earth run carbs?

This is beyond correct.

YOTAHOLIC808 wrote:http://www.youtube.com/watch?v=ropKAFjyjyU&feature=share

This is why

If you read the description, he is running a MSD ignition (which i believe is crap). You really need to do some research if you think you have to spend $500 just on a computer and harness.

YOTAHOLIC808 wrote:http://www.youtube.com/watch?v=ropKAFjyjyU&feature=share

This is why

That is not an answer.

EFI makes more power over a broader range of engine and environmental conditions, get better has mileage per hp, is less likely to fail, doesn't care about g forces, and many other benefits.
There is a reason Forumla Atlantic and other race motors have gone EFI. It's flat out better in every way.
If you just want carbs for looks and sounds then who cares if the dizzy doesn't advance timing like it's supposed to?

For out right power EFI all the way. But for most power levels that people run on the street, both can be achieved easily with either carb or EFI. But the one thing i noticed. IF you know what your doing carb can be cheaper, have the same mpgs, and power. But most people don't know what they are doing soo, EFI is the better way to go.

ogdougynutty wrote:For out right power EFI all the way. But for most power levels that people run on the street, both can be achieved easily with either carb or EFI. But the one thing i noticed. IF you know what your doing carb can be cheaper, have the same mpgs, and power. But most people don't know what they are doing soo, EFI is the better way to go.

Almost the same MPG and almost the same power. If tuned right and in the same environment it was tuned in.
You think car companies would have dumped all the time, money, energy and R&D into fitting much more expensive EFI systems if carbs got the same gas mileage, worked as well and had equal or less emissions?
Nope.

EFI can adjust for an infinite range of environmental variables, load, throttle position and much more. With a carb you are trying to tune for all those things with a few fixed components so it's very challenging to get optimal fuel across the range of throttle position, RPM and load. Even if you did manage to get it dialed in any change in temp, humidity, altitude, barometric pressure etc will cause the AFRs to no longer be optimal.
You are right about cost as far as something like swapping A 4AG into a non EFI chassis but that is the only advantage. Once you start buying and installing expensive electronics to control spark you might as well just go EFI and get all the benefits that come with it.

I'm not arguing the fact the EFI is bad, never have. I know it is better, specially now a days that injector technology has gotten way better.

And I'm not talking about Car companies they have much more stuff to deal with, I'm talking to the "tuner". If you compare what you have with carbs and the edis system (i.e. full fuel and spark control) it can be done cheaper than an EFI set-up, and still achieve the same power and (roughly) the same mpgs.

Also with the tuning with carbs it is like EVERY little change in the weather requires a jet change. I change mine with the seasons, every once in a while, and like i said if you don't know what your doing with carbs it will be a lot of work.

Why not MSD 6AL?

Im not saying the 6AL set-up is bad, plenty of people use on the 4age and it works well. But when pricing my every thing for an ignition a new 6AL (about 200) and a new timing retard (about 150). The megajolt jr setup was only like $50 (and could be a lot cheaper because i bought a crankpully with the crank tooth) more and it had many more options. Plus the added benefit of getting rid of that awful distributor lol.

I got a used 6AL for 100 shipped and skipped the timing computer.

Well like i said the edis set-up is a little bit more, the megajolt jr. cost me 165 new. and everything else you need (magnetic pick up, edis, coil pack, and the trigger wheel) can be picked up at a junkyard off a ford escort. I spent a little bit more because i just didn't feel like welding on the trigger wheel and bought a new crank pulley with trigger wheel.

But what justified doing the edis for me was the fact I had WAY more ignition control. My car is running ~11.5:1 with an 83mm bore. So those cylinder walls are thin and my rods had the small end bored a little to fit the 20mm wrist pin. So i wanted to make sure there would be no pinging in that motor.

ogdougynutty wrote: I spent a little bit more because i just didn't feel like welding on the trigger wheel and bought a new crank pulley with trigger wheel..

What did you end up buying? Does the T3 pulley/trigger wheel work with the Megajolt setup?

I agree with ogdougynutty. If you're going to buy all that fancy electronic, then just stay with EFI. You don't really need all that fancy electronic just to run a nice set of carburetors. Either megajolt or a MSD 6AL-2 programmable should suffice. But as for constant rejetting..? I disagree... I ran Mikuni solex for a long time and carburetors aren't that picky.

canyon_carvers wrote:I agree with ogdougynutty. If you're going to buy all that fancy electronic, then just stay with EFI. You don't really need all that fancy electronic just to run a nice set of carburetors. Either megajolt or a MSD 6AL-2 programmable should suffice. But as for constant rejetting..? I disagree... I ran Mikuni solex for a long time and carburetors aren't that picky.

My whole point is that to maintain optimal performance you would. Jet your car and drive it from sea level to 6000 feet and sure it will get around but it will be far from properly jetted. Even basic atmospheric changes can make it sub optimal. This is the whole point is that EFI compensates for these variables and can keep you much closer to optimal over varying conditions. Anyone who is concerned with performance should be concerned with this benefit unless they feel like jetting their car every time they drive it.
It's a slightly different beast but if I take my dirtbike jetted for 7000 feet down to 5000 feet I risk melting holes in the piston or seizing the engine. Cars are not as finiky but that's just an example of how much of an effect small environmental variables can have.

..

Wanna use edis and carbs?
Do like said above and get set up with megajolt/lite/junior whatever.
Edis runs at a fixed setting if wired right. ONE wire controls advance, and you can make it programmable that way.
Using edis and buying a haltech for use with carbs would be kinda...... dumb.