Fuel Injection

5177 is still in restoration.   a "sniper" throttle body system has been installed.   I sure HOPE it will run.   Now, my desire is driveabilty vs performance

One of the quirks the shop hit me with I don't fully understand was that a dual plane intake would cause problems.

I converted mine to the FAST EZ EFI 2.0 8 years ago and have been very happy with it.

I have used the FAST XFI 2.05 sequential port fuel injection system on my engine for years. It was one of the best modifications that I have ever done to the car. Aftermarket EFI systems have come a long way since the time when they first became available. There are also a lot more shops that know how to set up and tune them now. There is nothing about a Cleveland engine that can cause a problem with fuel injection not working correctly. If you want to just have your Pantera as an occasional driver, then a fuel injection system will not be worth the cost. The nice thing about fuel injection is that cold starts and warm up is like a modern vehicle. Changes in altitude have no effect on how the engine starts and runs. Improved gas mileage is a given that EFI will do better than a carburetor.

Steve at PI Motorsports should just admit EFI conversions are beyond his knowledge or capability. In fact, it seems like he has problems with electrical systems in general. I’ve had 2 different EFI systems over the years and they both worked great. The first was a simple system based on a converted 4 bbl manifold and my current system is an 8 stack with drive-by-wire, controllled by a Holley ECU. With EFI, the engine just runs better in all conditions although it won’t necessarily make more power. I could never have pulled it off myself though. A successful conversion requires the involvement of a specialist. I use Autotrend EFI in Northern California.

I have used both EFI and carbs, and found that each have their benefits and drawbacks.  Carbs are relatively inexpensive and simple to install but they dry out and get gummed up if not used frequently.  EFI is pricier and can be a project to install (electric fuel pump and return line to gas tank as examples) but does not dry out and cold starts well as mentioned above.  EFI uses less fuel.  You may have to take the car to an EFI specialist with a dyno to get the most out of it.

At this point I am using Holley carbs, in particular their 750 with vacuum secondaries.  After some minor tuning of the carb, the car works quite well once warmed up.  I cannot be happier with the amount of power I get from the carb.  I don't think EFI would produce any more power or drivability although it will probably use less gas.

EFI can change the sound of the engine.  Since it squanders less fuel, the engine's sound is truncated a little but still makes good power.

As expected from this group, really great input with valuable information.  Thank you.

@jfb05177 posted:

5177 is still in restoration.   a "sniper" throttle body system has been installed.   I sure HOPE it will run.   Now, my desire is driveabilty vs performance

One of the quirks the shop hit me with I don't fully understand was that a dual plane intake would cause problems.

I have heard the same thing about a dual plane intake manifold not working well with fuel injection. I don't think that is true if you are using a throttle body injection system because it only duplicates what a carburetor does, except with a far greater degree of precision. Perhaps if you were to use a dual plane intake manifold with sequential port fuel injection there could be an air flow problem, but the system would still work.

Even with a sequential system, it should work although you would need to take steps to even out the airflow between the two plenum halves. Some dual plane manifolds have a small notch removed from the divider which would solve the problem. If the DP manifold didn't have that notch, one could be cut out or an open plenum spacer could be used. You just need to ensure that the same amount of air is flowing to all cylinders. An alternative would be to use dual O² sensors; one per bank. Then you could tune each side of the engine separately.

@davidnunn posted:

Even with a sequential system, it should work although you would need to take steps to even out the airflow between the two plenum halves. Some dual plane manifolds have a small notch removed from the divider which would solve the problem. If the DP manifold didn't have that notch, one could be cut out or an open plenum spacer could be used. You just need to ensure that the same amount of air is flowing to all cylinders. An alternative would be to use dual O² sensors; one per bank. Then you could tune each side of the engine separately.

Sequential firing is only for OEM. It is for emissions reasons because it is cleaner at idle, but you don't need it and in fact is actually detrimental for performance applications.

There are no injectors made that can keep up with a V8 much over 3,000 rpm if sequentially fired.

Batch fired isn't as clean at idle since there is unburned fuel momentarily sitting on the closed intake valve. It is also slightly susceptible to fuel reversion as a result but nothing like carbs create on an IR manifold.

An interesting side effect to EFI is it calms down the idle on radical or marginal cams. In fact, the largest complaint against switching from carbs to efi is that the engine looses much of the rumpy-rump idle the long overlap cam creates.

The horse power is a function of how much atomized air the engine can pump. EFI does not increase that but particularly in eight stacks it distributes it evenly.

As an FYI, one member I know converted his P to FI.  Forgot which system, but he loves it.  He has the later design fuel tank and used the bottom bung as the tap for the fuel feed to my recollection.  He said the drivability, starting, etc. is far better.

@panteradoug posted:

Sequential firing is only for OEM. It is for emissions reasons because it is cleaner at idle, but you don't need it and in fact is actually detrimental for performance applications.

There are no injectors made that can keep up with a V8 much over 3,000 rpm if sequentially fired.

Batch fired isn't as clean at idle since there is unburned fuel momentarily sitting on the closed intake valve. It is also slightly susceptible to fuel reversion as a result but nothing like carbs create on an IR manifold.

An interesting side effect to EFI is it calms down the idle on radical or marginal cams. In fact, the largest complaint against switching from carbs to efi is that the engine looses much of the rumpy-rump idle the long overlap cam creates.

The horse power is a function of how much atomized air the engine can pump. EFI does not increase that but particularly in eight stacks it distributes it evenly.

Sequential port fuel injection produces the same amount of power at wide open throttle as bank fired fuel injection. Sequential port does produce better fuel mileage and is smoother through most of the rpm range.  I have run my engine both ways and it runs much better in sequential mode. My engine is also making about 550 horsepower at the flywheel and was tuned on an engine dyno. At idle, the big hydraulic roller camshaft still has of lope, although perhaps not as much as it would if I was using a carburetor.

My motor was also tuned on a dyno; first with a 4 bbl carb and single plane manifold, then with my IR EFI system. It actually made a bit more power at 6,500 rpm with a carb but the power curve was steeper. The power curve was flatter with EFI. Up to about 4,500 rpm, EFI made more power. As far as drivability is concerned, there’s no comparison. EFI is better hands down.

Great stuff.  How often do I take my engine to 6,500 rpm...never really.  Most of time it doesn't see 5,000 rpm, and if it does, it is for a split second.  I have never raced or tracked mine.  It actually drives very well with the carbs, but my mechanic has mentioned going EFI to me several times, so I am considering it.  I guess one of the things I am weighing is how much satisfaction and better drivability will I get out of it compared to the cost of conversion.  If it is lightyears ahead, I would do it.  But if it is limited all-around performance increase, is it worth it?

@Fuzz posted:

Great stuff.  How often do I take my engine to 6,500 rpm...never really.  Most of time it doesn't see 5,000 rpm, and if it does, it is for a split second.  I have never raced or tracked mine.  It actually drives very well with the carbs, but my mechanic has mentioned going EFI to me several times, so I am considering it.  I guess one of the things I am weighing is how much satisfaction and better drivability will I get out of it compared to the cost of conversion.  If it is lightyears ahead, I would do it.  But if it is limited all-around performance increase, is it worth it?

If you are happy with the way your Pantera runs with a carburetor and it does everything that you want it to do, then don't bother with fuel injection. It is doubtful that the fuel mileage increase that you would get with fuel injection  would every pay for itself. I am totally satisfied with the fuel injection system on my Pantera and would never consider going back to using a carburetor. I also have an on dash monitor that tells me everything that is going on with the EFI system, which in the event of a problem, I won't be guessing at what is wrong.

Here's a read on the subject of batch v. sequential firing. I did not write this so don't blame me. it is pertinent to the discussion I think?

https://www.enginebasics.com/E...vs%20Sequential.html

Here is a discussion of how EFI affects idle quality (from camshaft timing).

https://www.onallcylinders.com...you-may-not-like-it/

The only thing I would add that was not mentioned is that idle quality change would be more noticeable on an 8 stack system. An IR manifold plays havoc with the idle to begin with and the EFI reduces the effect of the overlap of the cam timing.

How much? I don't know.

A self learning EFI system is the current desired system. Using a laptop to tune the EFI is now close to obsolete, less desirable, old school thinking, self flagellation and probably not as accurate as the efi's cpu can do.

Let the EFI's cpu adjust everything. Essentially all you need to do is plug it in, set the idle rpm that you want, identify the firing order and engine displacement.

It is batch fired so you don't need a crank sensor. Finding the space to install a crank sensor in a Pantera is a challenge to begin with.

The "self learning" efi cpu takes some of the rough idle out of the engine depending on the cam timing. The self learning cpu balances the fuel fed to the engine at idle (and all rpm's)  by balancing the a/f it reads from the oxygen sensor in the exhaust.

That a/f is pre-determined from a programed "script" it reads from. That is pre-loaded into the self learning cpu. So what happens is that if the roughness in the idle is read as an a/f balance issue, usually a "too lean idle" reading, the cpu compensates for that at idle by adding fuel to the extent it is capable of. That happens automatically.

The effect with some cam profiles is to take out some of the leaning in the intake manifold at idle caused by  "overlap". I would describe that as it looks like it is calming down the engine somewhere around what taking 10° of intake/exhaust overlap would do?

If that leaning from overlap was already compensated for by something like the timing design of "George's cam" or the CompCams "Weber" profile, it won't have much effect on the idle quality.

Don't shoot me. I'm only the messenger.