EFI on our old engines--what to expect

[696pack]

I see these EFI kits available but know little about what to expect from them.

Using my 66 Charger as an example what would the compatibility be and what would be the beneifit?

The car is a 523 stroker with a healthy roller cam, 10.3:1 compression, hipo exhaust manifolds (thinking of changing to headers) I have had two different carbs on the engine. First was a 870 cfm Holley Avenger, currently a Holley 750 double pumper and I plan to go back to the 870.

I expect that the EFI systems are more adjustment free and self adjusting to a certain point after initial set up, should have better throttle response, etc. However what would the performance be like compared to what I currently have?

 

[Meep-Meep]

For my money the EFI will cure that annoying vapor lock symptom that we carb guys get with today's gas. Even a TB system should put a smile on your face when you go to restart your car after a run to the store in that 100 deg Arizona climate. I'm driving my 66 hemi around the last couple of days and it's just annoying to be dealing with not one, but two pots of gas sitting on a hot stove so to speak.

A port system is by far the best but more complex to hook up and plumb. The TB system relies on a good intake and proper velocity to help mix the fuel and air and provide proper fuel distribution (just like a carb).

When I had my 72 911 with mech injection tuning was great. A simple tweak of a screw and I had either a richer or leaner mixture. So for the non self tuning systems the tuning should be similar where you have a pot for "choke" "accel pump" "cruise" and probably WOT and idle. You can make dozens of adjustments in an hour while getting data from your O2 sensor and never spill a drop of gas. I am going in that direction once I get a few other things done and perhaps one day I won't smell gas in the garage two days after I drove one of my relics.

To maximize power with EFI or a carb you will need to spend some time driving with an O2 sensor readout gizmo like the LM1 or LM2 to dial the mixture in under different conditions, and with either system properly tuned there may not be that much of a difference in power. The difference I think will be drivability. If you are one who drives your car regularly - and I know you are - then the EFI will pay off sooner just from the sheer pleasure of consistency and good manners.

 

[696pack]

Thanks for the info. That is pretty much what I expected but not being able to make a corrolation of the cfm of a carb to the EFI system I did not know what to expect if I went that direction.
The MSD system (the only one I have even looked at) in the Summit catalog says it is good for engines up to 525 h.p.
Any suggestions on which system is the best bang for your buck?

 

[Gpuller]

Was doing research on the self tuning EFI's yesterday MSD Atomic, Fast EZ and Holley Avenger. The more I read more I was confused!
MSD and Holley systems have timing controls, Fast doesn't. If your running an MSD or HEI ignition I don't think any of them would be a problem, but couldn't find anybody running a Mopar Performance ignition with EFI. MSD says their system doesn't need a fuel return line, all others do need a return. MSD can be run with a return, most people agree that a return is the way to go. Cooler fuel and less pump troubles. The Holley can be hooked to a laptop and custom tuned, MSD and Fast can't. Holley is upgrade able pretty easy, even to multi port if you wanted.
Saw this on MSD's web site: "Note: If lobe separation angle (LSA) is less than 108° you may need to go to the next larger cam profile. If cam duration is longer than 250° the Atomic EFI will not be suitable for your application."
The FAST is the cheapest, and Holley is on the high end cost wise.
I think a phone call to each manufacture with your exact motor specs would be a must.

 

[dpstark2]

From what I've seen, the "learning" systems have come a long way. I have not looked into the newer systems recently, but I know a lot of people like the FAST stuff. Any EFI system is going to be a slight upgrade (in my mind) compared to a carb. However, I think you're short changing yourself if you don't run a return line. The fact that the fuel is under pressure instead of vacuum will help vapor lock and the like, but the return line is what really keeps fuel circulating and cool. Also, most EFI systems don't like cams with a lot of overlap (i.e., high duration and/or small LSA)- so keep that in mind when you get started. EFI is not a cure-all, but it can help. As far as performance, I would expect slightly better response and smoother transitions- but not much more power or anything like that.

My decision to go the with Megasquirt was due to flexibility and my own electronics hobby. I don't recommend it to everyone. At this point, I'm still stuck on getting a crank position sensor to work reliably. I hope to wrap that up soon. However, you only need the CPS to run ignition from the box- I could have used the output of my MSD and been done by now. I also went with an in-tank pump, which was completely non-trivial. Neat, but not easy.

 

[Gpuller]

After I read about the cams on the MSD site I kind of stopped researching. My car is running the old MP 284/484 cam with 108 overlap. Its not much fun to tune with a carb, figured an EFI wouldn't be much of an improvement. I'd have to rethink my motor combo from cam it ignition to make them work. Just not in the budget. Always good to learn though.
One of the complaints on these self tuning deals was the pump was too loud. Some guys switching to in tank pump.

 

[67 coronet]

about the only things you get from those fi systems is slightly improved fuel economy and easyer starting.a well tuned carb will have the same throttle response.as far as fuel vaporisation issues,why not set up an electric pump with regulator and return line fuel system.you can get almost the same benefits as the fuel injection at a much lower cost.

 

[SwedCharger67]

After I read about the cams on the MSD site I kind of stopped researching. My car is running the old MP 284/484 cam with 108 overlap. Its not much fun to tune with a carb, figured an EFI wouldn't be much of an improvement. I'd have to rethink my motor combo from cam it ignition to make them work. Just not in the budget. Always good to learn though.
One of the complaints on these self tuning deals was the pump was too loud. Some guys switching to in tank pump.

I think one has to distinguish between throttle body injection and intake port injection.
I'm guessing that Throttle Body Injection with a big cam + big intake and corresponding slow air speed would probably be just as problematic as a big carb to get to behave well on low rpms (fuel separation etc.).
But a port injected engine shouldn't suffer from that, considering the fuel is sprayed to the back of the intake valves, and the intake is dry.

 

[GrabberOrange69]

I'll caveat my experience with EFI is hot rodding with Ford EEC IV multi-port 5.0s, but as a general rule for camshafts/heads: EFI multi-port likes more lift and less duration/overlap and big ports in the heads.

Personally, if the engine is highly modified, I'd stick with carbs.

 

[SwedCharger67]

...
Personally, if the engine is highly modified, I'd stick with carbs.

My opinion is completely the opposite...assuming of course you have an engine management system that you can control yourself...

 

[kb67mopar]

From all that I have read it seems to me if you want to go fuel injection and not take an electronics course contact your local dyno, talk to them about their experiences with different systems and get some recommendations and find out what they know how to tune. Install the system, take it to them and have it professionally tuned by guys who know what the spark curves and fuel maps should look like. This is about the only way to get it really dialed in and then I bet you will find better response, easy starts, good street manners and raging drag strip savageness.

If you like to tinker and change jets and all that stuff....walk away and keep your carb, you can do more harm then good on a hunch.

*I base the response solely on hours of mindless reading from magazines, the internet, and countless car shows and is not based on my experiences installing any.

 

[SwedCharger67]

From all that I have read it seems to me if you want to go fuel injection and not take an electronics course contact your local dyno, talk to them about their experiences with different systems and get some recommendations and find out what they know how to tune. Install the system, take it to them and have it professionally tuned by guys who know what the spark curves and fuel maps should look like. This is about the only way to get it really dialed in and then I bet you will find better response, easy starts, good street manners and raging drag strip savageness.

If you like to tinker and change jets and all that stuff....walk away and keep your carb, you can do more harm then good on a hunch.

*I base the response solely on hours of mindless reading from magazines, the internet, and countless car shows and is not based on my experiences installing any.

Well said, the only thing I would like to add is that if you like tinkering you can do a lot more of that with an engine management system which you are in control of!!

 

[Meep-Meep]

I have two older Holley ProJection systems that I got for cheap and can't wait to try them on something. Because I drive my cars I'm sick and tired of dealing with carburetors fed by that swill they peddle at the pump.

 

[RustyRatRod]

I think if I could get an EFI setup that I KNEW I could tune and make work, I would do it. Only problem is, I think I know which one(s) that is and they are out of my reach. Only way I would do it would be some kinda dedicated port system. Hell, one of them Hilborn lookalikes that are modern EFI would be cool......but not for 5K.

 

[696pack]

My car already has 1/2" fuel line with return line, electric pump and regulator. Sounds like I should stick with the carb.

I went through hell with the fuel pumps both the new (supposedly quiter) Holley pump and the Aeroflow pumps would not pick up the fuel with the pum at the tank. After more research I fund that the Magnaflow pump works but it is really noisey.

 

[moparmarkk]

hey meep-meep why dont we try one on a str?,mark

 

[pturner]

i have spent much hours on the web, and talking to MSD, and Fast. you need to keep digging. Fast is introducing a EX 2.0 that uses a new user interface with more options, even timing and transmission control. it is not sold yet but seems to be just a few months away. Fast also has a new distributor to work with their system and your Mopar. i think they also can do timing with a MSD Box. the Edelbrock and fast look just alike except the operator programming interface. You can also put an edelbrock intake that is drilled and ready for for SFI injectors on the intake. as i said keep digging as there is much information out there. Fast is owned by Comp Cams and in Memphis, they seem to have tech support people that seem more knowledgeable about their product.
OH, no way i would use the non-return system, it too can percolate the fuel as it would be setting in the line, there is also somewhere a web page or instruction page in the MSD manual that helps you calculate a number that relates to choosing a non or return system, look for it as it explains several factors about both systems.
i am going to put someones EFI on my 68 Roadrunner, but just now doing bodywork so no rush.
PT in Tennessee

 

[Meep-Meep]

hey meep-meep why dont we try one on a str?,mark

I think we'll need both for that! But I have a plan and I think you'll approve.

 

[SwedCharger67]

...
So for the non self tuning systems the tuning should be similar where you have a pot for "choke" "accel pump" "cruise" and probably WOT and idle. You can make dozens of adjustments in an hour while getting data from your O2 sensor and never spill a drop of gas. I am going in that direction once I get a few other things done and perhaps one day I won't smell gas in the garage two days after I drove one of my relics.

To maximize power with EFI or a carb you will need to spend some time driving with an O2 sensor readout gizmo like the LM1 or LM2 to dial the mixture in under different conditions, and with either system properly tuned there may not be that much of a difference in power. The difference I think will be drivability.

Well said.

I think it's a good idea to choose a system which you can run both in "closed loop" (self tuning, the system is reading the O2 sensor and adjust the amount of fuel supplied) and in "open loop" (you read the O2 sensor value yourself and set the air/fuel map yourself).

But it's a difficult area, how well the self tuning (closed loop) works is a matter of the software in the box (and also the quality of the O2 sensor, air temp sensor, engine temp sensor, air pressure sensor...). A lousy software/hardware and you get a lousy result.

If you have anything else than a stock engine, I think it's unlikely you'll find an A/F map that will fit your engine.
To help in creating an A/F map it might be possible to start in the self learning mode to get a base map that is at least somewhat close to a good map. Then switch over to "open loop" and manually do the final adjustments to fine tune the A/F map, at least at critical rpms and load levels.

Of course, if you don't like tinkering, the "open loop" system may not be an attractive option.

 

[Greg Ducato]

My advice here would be to choose a cam profile compatible with aftermarket EFI if you are contemplating going with that over a carb. Most aftermarket EFI will require a certain vacuum level at idle for best performance with the systems operating parameters. Even the tuneable systems will have trouble with a cam that doesn't produce at least 12 inches at idle. I fought an Accel Digital VII system on my Hemi for nearly two years before I got it reliable enough to drive, and it was a sequential system with wide band Oxygen sensor which should have made it a bit easier. My big mistake was that I chose a cam ground on a 108 center, should have gone 112 to even 114 for best results. Check any modern engine cam profile and check the centerline, you will see they all stick to this principle.