Stay with a carburetor or go EFI

[67 gt]

Don't need peer approval but this is a forum. If we’re not bouncing these ideas off each other then what are forums for?

This is not an emotional decision, trust me. The car is apart. I can go one way or another. If I ever want to go EFI, now is the time.

Carburetors work, don’t have to make it seem like I believe they don’t. I also understand fuel injection is a better mousetrap. But, there are certain things that it can do that no mechanical fuel delivery system can which is datalog and tune itself of the fly. Obviously things need to be optimized for the self tuning aspect to bear fruit but again, EFI is all about real time evidence based off data. Not sure why that’s such a contentious point.

Despite what the marketing may lead you to believe, converting a car from carb to EFI is a lot of work and the initial money outlay is far greater than it would be if I just keep the carburetor.

The other idea the marketing promotes is that you just set it and forget it. That could not be further from the truth. Sure you can rely on a general base calibration to start but once you’re beyond that, things get pretty involved. The software provides the ability to fine tune every point within a range of data and then allows you to switch tunes with a few keystrokes for particular applications. Is that a bad thing? You’re on some sort of computer while you’re viewing this thread. Is that the only thing microchips and programming are good for? Its just another tool, thats all.

But to your point - carburetors can be tuned to a razor sharp edge but instead of software providing a visual representation of what the motor is seeing, you’d be relying on physical testing testing testing and more testing and if you kept notes, log books (aka data) for guidance. Nothing wrong with that at all, I’ve done it. I’m telling you that all the ideas to achieve your “tune” are the same, its just done with software.

The visual representation of the data is key.

As stated I’ve been using the FI for 3 years and I thought it ran well . Well I had a guy over and fine tuned it mate night and day difference I knew there was more in it but wow torque and top end HP was very noticeable and fuel economy is better can be said with a carburettor but I will never go back .

 

[rmchrgr]

Thanks mate! Still waffling about this but getting closer to a decision. This is just my own observation but if you look through Holley's website it sure seems like they are all-in on EFI products. It's eye opening when the most ubiquitous carburetor company is basically saying they're done with carbs.

I have been looking at their Stealth offering because it looks like a carburetor but they don't offer it in a return style. With the Stealth I believe I'd have to use an external bypass regulator with that particular system unless they have an internally regulated fuel pump module. Could be OK I guess but for whatever reason my brain is stuck on the idea that a retrofit EFI system is better with a return-style delivery system. I don't think there would be too much issue with fuel boiling since it's already at a high pressure. I don't know, this is the one thing that's kind of holding me up.

Like I stated already in a previous post, Holley offers in-tank pump modules for carburetors but it's on intergalactic back-order. If those units were available now, I might consider going that route to get the car running and then do the EFI down the road. I'd be waiting until at least June though, my impatient *** can't wait that long.

I took out my aluminum fuel tank the other day trying to see what needs to happen with it to install an in-tank pump. I believe it will cost me almost the same amount of money or more to have the tank modified for an in tank pump than it would be to just buy one already set up. EFI tanks by themselves are pretty cheap right now and are readily available from anywhere.

It's funny too because I bought the aluminum tank for the weight savings (18lbs) but declined to have it set up for an in-tank module which I regret. That was in 2015 though so things are different now, shite happens. Thing is when you look at it from a weight distribution angle the rear of the car might actually be too light now.

If you all don't know this about me by now, I tend to overthink stuff.

 

[EdM]

A somewhat recent install of the Edelbrock Pro-Flo 4 in my 427 Windsor Mach 1 just works in every regard. Night and day.

 

[rmchrgr]

OK, so for those keeping score at home - I pulled the trigger on the EFI. I went with the Stealth throttle body because it looks like a 4150 hp carb. To feed it I got a 340lph in-tank fuel pump. That particular pump has no regulator so I hadda get a filter/regulator thing that installs right off the pump module outlet. It's a cool solution because it's a return which I preferred but its short. The internal regulator is preset to 59.5 psi. This allows me to to keep the existing 3/8" single line to the front without having to get an extra regulator or run a second return line. I may not even have to buy too much in the way of hose or fittings either since I have a bunch on hand already.

After all the fuel tank waffling I did here, I took my slickster Hot Rod City Garage aluminum tank down to a welding place and described to them how I wanted it modified. Let's just say it was a wash between that and buying a new stock-style EFI tank so that's that, they got the job, tank will be ready next week all st for the pump module.

I suppose some of this choice was because of our recent weather here in Southern CT. I was out walking our dog and it struck me how humid it is which by itself sort of makes EFI the clear choice. While I generally won't be driving the car in the rain, it's been quite humid here and as always, it will be all summer. Yes, carbs run fine in humid weather but if it's bad enough it can throw the tune off and then the tinkering starts. But then the next time I take it out the weather might be different and then I'm under the hood again. And on and on.

Yeah, the tinkering is all part of the "experience" of owning an old car/street machine but it does not have to be. There's still plenty of tuning to do with EFI so that part does not disappear, it's just done on a laptop. I know that many don't think a computer has any place in an old muscle Mopar but that's OK, I can't worry about things like that. If you use an MSD then you have things with digital components in it. It's almost unavoidable these days, you have to be pretty stubborn to keep your Mopar free of modern technology.

I also believe the idea of a consistent 60psi of fuel pressure (even just into an open plenum intake) and a digitally controlled ignition can only improve the combustion process over older mechanical components. I could be wrong about that but again, why be stubborn and rely on 6 psi to get the fuel into the engine? Guys have been running loud external electric fuel pumps since the dawn of time trying to ensure the proper amount of fuel is available. As for spark, I probably wouldn't go for a full modern coil on plug ignition but points and even the now 50 year old Mopar transistorized ignitions are kinda things of the past now.

Well, that's my reasoning for now. Don't get me wrong, it's a big layout of money and I'm sure there will be instances where I am cursing the decision. Additionally, I don't believe EFI is magic and will make more power just by having it but the hope is that maybe it will run cleaner and perhaps a little leaner. My long-view theory on that is consistency at the track. Long ways away on that but that's what I see down the road.

When all the shiny new stuff comes and it starts going in the car I'll update my Great Pumpkin thread.

Thanks for the input.

Greg

 

[rumblefish360]

Ahhhhhhhhhhh, the “Great Pumpkin” thread returns....

 

[yellow rose]

OK, so for those keeping score at home - I pulled the trigger on the EFI. I went with the Stealth throttle body because it looks like a 4150 hp carb. To feed it I got a 340lph in-tank fuel pump. That particular pump has no regulator so I hadda get a filter/regulator thing that installs right off the pump module outlet. It's a cool solution because it's a return which I preferred but its short. The internal regulator is preset to 59.5 psi. This allows me to to keep the existing 3/8" single line to the front without having to get an extra regulator or run a second return line. I may not even have to buy too much in the way of hose or fittings either since I have a bunch on hand already.

After all the fuel tank waffling I did here, I took my slickster Hot Rod City Garage aluminum tank down to a welding place and described to them how I wanted it modified. Let's just say it was a wash between that and buying a new stock-style EFI tank so that's that, they got the job, tank will be ready next week all st for the pump module.

I suppose some of this choice was because of our recent weather here in Southern CT. I was out walking our dog and it struck me how humid it is which by itself sort of makes EFI the clear choice. While I generally won't be driving the car in the rain, it's been quite humid here and as always, it will be all summer. Yes, carbs run fine in humid weather but if it's bad enough it can throw the tune off and then the tinkering starts. But then the next time I take it out the weather might be different and then I'm under the hood again. And on and on.

Yeah, the tinkering is all part of the "experience" of owning an old car/street machine but it does not have to be. There's still plenty of tuning to do with EFI so that part does not disappear, it's just done on a laptop. I know that many don't think a computer has any place in an old muscle Mopar but that's OK, I can't worry about things like that. If you use an MSD then you have things with digital components in it. It's almost unavoidable these days, you have to be pretty stubborn to keep your Mopar free of modern technology.

I also believe the idea of a consistent 60psi of fuel pressure (even just into an open plenum intake) and a digitally controlled ignition can only improve the combustion process over older mechanical components. I could be wrong about that but again, why be stubborn and rely on 6 psi to get the fuel into the engine? Guys have been running loud external electric fuel pumps since the dawn of time trying to ensure the proper amount of fuel is available. As for spark, I probably wouldn't go for a full modern coil on plug ignition but points and even the now 50 year old Mopar transistorized ignitions are kinda things of the past now.

Well, that's my reasoning for now. Don't get me wrong, it's a big layout of money and I'm sure there will be instances where I am cursing the decision. Additionally, I don't believe EFI is magic and will make more power just by having it but the hope is that maybe it will run cleaner and perhaps a little leaner. My long-view theory on that is consistency at the track. Long ways away on that but that's what I see down the road.

When all the shiny new stuff comes and it starts going in the car I'll update my Great Pumpkin thread.

Thanks for the input.

Greg

Just remember that since you are introducing the fuel essentially in the same location as a carb, you will have the same wall flow and plenum fuel flow issues. The EFI guys love to claim how superior their injectors are at atomizing the fuel, but I call BS on that.

Any time there is fuel in the plenum there is a puddle. At steady state RPM (relatively steady state RPM anyway) the engine is running mostly off that puddle.

The fuel along the surfaces is a liquid. Any time there is a change in MAP, any fuel in suspension becomes a liquid again, and somehow you need to get as much of that liquid back into atomized form as you can.

Soooooo...port shape is much more critical when you have fuel in the air. Surface finish is much more critical when you have fuel in the air. There isn’t a computer on the planet that can change the physics of what happens in a wet manifold. Anything you do to address those issues will make more power, run cleaner and get better economy.

Just an FYI.

LOL...I knew you were going EFI. I don’t blame you. I just new where you were headed. I think it was the best choice for you.

I think you should start a thread on this project. I’ll certainly follow along.

 

[rumblefish360]

As long as the injector operates within in its parameters and is a clean injector, it should be superior in atomizing the fuel because it is under pressure.

 

[rmchrgr]

Any time there is fuel in the plenum
LOL...I knew you were going EFI. I don’t amu blame you. I just new where you were headed. I think it was the best choice for you.

I can’t help but feel the incredulousness dripping from that statement...

Again, I don’t think there will be any noticeable performance advantage. The thing I like about it is the data logging aspect and the ability to change parameters precisely within a given range.

Let’s face it, retrofit, throttle body EFI is just a better mousetrap. I’m just into that sort of thing, I don’t really have any sort of rational explanation for that.

I am curious about BSFC and if EFI would have any effect in that area but I’d have to do back to back dyno sessions to figure that out. When I had my motor on the dyno, the BSFC numbers were not that great. I tend to think that’s related to mechanical “issues” like maybe the cam is not timed right or like has been suggested bu someone who knows way more than me that the dyno was not calibrated correctly. We made a few power pulls and did some basic tuning; it was going in the right direction. Basically we leaned out the jetting and added a few degrees of timing but the numbers didn’t change that much so we stopped.

My hope is that the EFI will help it run good on the leaner side which I believe would be easier to achieve with the software, there is only so much you can do with a carb to get it to run exactly how you want in every situation.

 

[yellow rose]

I can’t help but feel the incredulousness dripping from that statement...

Again, I don’t think there will be any noticeable performance advantage. The thing I like about it is the data logging aspect and the ability to change parameters precisely within a given range.

Let’s face it, retrofit, throttle body EFI is just a better mousetrap. I’m just into that sort of thing, I don’t really have any sort of rational explanation for that.

I am curious about BSFC and if EFI would have any effect in that area but I’d have to do back to back dyno sessions to figure that out. When I had my motor on the dyno, the BSFC numbers were not that great. I tend to think that’s related to mechanical “issues” like maybe the cam is not timed right or like has been suggested bu someone who knows way more than me that the dyno was not calibrated correctly. We made a few power pulls and did some basic tuning; it was going in the right direction. Basically we leaned out the jetting and added a few degrees of timing but the numbers didn’t change that much so we stopped.

My hope is that the EFI will help it run good on the leaner side which I believe would be easier to achieve with the software, there is only so much you can do with a carb to get it to run exactly how you want in every situation.

Oh no...I wasn’t trying to be incredulous at all. My typing doesn’t translate well sometimes. I just meant I knew you were leaning and you were pretty much tipped over that way far enough it would take a Crane to pull you back up. I hope that translated well, but probably not. Again, not my intention so I apologize.

BSFC is an efficiency measure. I don’t know that EFI can correct that. I know a carb can’t fix it IF its something other than a carb issue. If you have an issue with over scavenging the chamber, or let’s say you have some serious stratification issues the BAFC will always be higher. Even wall flow makes the BSFC go up. I’m going to be testing my burr finish once the dyno is up and running.

I’m sure if you tune it long enough you can get the engine to run at 16, maybe 17:1 A/F ratio. You have to work at it though. It will take the proper fuel, at the proper time with the proper ignition curve (that may be the longest tuning process you have...dialing in the advance curve) to do it, but it is possible.

My mentor told me another guy he helps put some EFI system on his GMC Suburban. He has two kids...the boy was 13 or 14 and the girl was 10 or so at the time. Anyway, he hooked both of their laptops up to the EFI and went on some 700 mile one way trip to some big park somewhere I’ve never heard of.

Anyway, he made it into a game for the kids. The game was to have each one optimize the A/F ratio and fuel consumption. IIRC the daughter was tuning the fuel map and the son worked on the timing map. By about 400 miles in they had it cruising at a touch over 17:1 with some outer world timing...like 61 degrees. And it got some incredible fuel mileage number too.

He is supposed to stop by sometime today so I’ll ask him again for the solid numbers. So it can be done. And I’d say if you went to the trouble of EFI, it’s worth the time you invest to get it there.

 

[yellow rose]

As long as the injector operates within in its parameters and is a clean injector, it should be superior in atomizing the fuel because it is under pressure.

I wish, but you still have fuel that hits the walls, floor and roof. In fact, the last webinar I heard Darin Morgan give he said that you should burr finish the ports even with EFI, and that to do it correctly you needed to burr finish the port 3-4 inches ABOVE the injector.

As I’ve pointed out before, even an injected engine (EFI or MFI) will make more power the further you move the injector away from the valve.

You can lose some bottom end drivability, but I’m not sure that loss would be enough to deter me from moving them up as far as I could.

Managing fuel in an intake manifold is a real mother bear.

 

[rumblefish360]

I call the plenum (& runners to an extent) the hole of chaos!

 

[EdM]

Just remember that since you are introducing the fuel essentially in the same location as a carb, you will have the same wall flow and plenum fuel flow issues. The EFI guys love to claim how superior their injectors are at atomizing the fuel, but I call BS on that.

Any time there is fuel in the plenum there is a puddle. At steady state RPM (relatively steady state RPM anyway) the engine is running mostly off that puddle.

The fuel along the surfaces is a liquid. Any time there is a change in MAP, any fuel in suspension becomes a liquid again, and somehow you need to get as much of that liquid back into atomized form as you can.

Soooooo...port shape is much more critical when you have fuel in the air. Surface finish is much more critical when you have fuel in the air. There isn’t a computer on the planet that can change the physics of what happens in a wet manifold. Anything you do to address those issues will make more power, run cleaner and get better economy.

Just an FYI.

LOL...I knew you were going EFI. I don’t blame you. I just new where you were headed. I think it was the best choice for you.

I think you should start a thread on this project. I’ll certainly follow along.

Hence my choice of the Edelbrock Pro Flo 4.