[SKIPS69]

I'm preparing to install a Holley Commander 950 MPFI on my 502 and I am sure that I am going to have a ton of questions.

Here's my first question.

Can I use a stock fuel sending unit with the factory type return line?

If not, has anyone used the Moroso fuel neck that has the return line in it that you have to cut the filler neck?

Or? Any other suggestions for a return line spot in the tank?

I've been looking at the DSE tank with the internal pump. Man, that's a nice unit, but, not quite what I had in mind cost wise.

Thanks in advance for the replies!

[SKIPS69]

One more question.

Where is the best place to find the Pro 3.0 software and cable for the ECU interface?

I see that Summit has it. Pricing seems...reasonable, but, I'm always looking for a better deal.

[Mark .L.W.]

We have two cars with this system and just think they are great , both cars have rock valley tanks with the holley pumps inside . Jody here suggested putting our return lines off to the side rather than having the bubbles being stirred up right at the pump . We installed ares on the passenger side of the tank about an inch from the bottom so it doesn't flow in and cause aeration .If you want to ask more questions i could pm you my number and you could call me .
Mark.

[JimM]

have fun with your new system!

As far as the s/w for your laptop, I'm sure a number of us could email it to you.

The commander 950 has to be flashed with the v3 firmware. This can only be done by Holley. I think they charge $75 to do it. The member I bought my used system from talked them into doing it for free.

The cable is a standard 9 pin serial. My laptop only has usb ports, so I'll be using a usb to 9 pin cable I picked up at a computer store (tigerdirect) it comes with driver software that lets me asign it to "be" a particular serial port.

One of these days I'll need to cable it up and power up the controller and see if my laptop will talk to it, but I've used this cable for some pretty wierd stuff without a problem. I just tell it to be com1 and even really old dos s/w running in a command prompt box on xp has been happy with it.

I'll be using a stock (3/8") sender / pickup, with an additional 3/8" return line welded in. We'll see how it works. Trying to use the oem 5/16" vapor connection will be a problem. I tried that on my last one, it was unable to dump enough fuel to maintain the correct pressure at idle, car ran stinky rich till Doug at Holley told me to run a bigger return.

[paulm]

Originally Posted by JimM

The cable is a standard 9 pin serial. My laptop only has usb ports, so I'll be using a usb to 9 pin cable I picked up at a computer store (tigerdirect) it comes with driver software that lets me asign it to "be" a particular serial port.

Per Holley, some serial to usb cables do not work well and cause strange things to happen. The preferred method is to connect to serial, but not all laptops have a serial port. If I could only remember the "bad" brands and "good" brands.....Damned brain turning to mush....

[JimM]

Originally Posted by paulm

Per Holley, some serial to usb cables do not work well and cause strange things to happen. The preferred method is to connect to serial, but not all laptops have a serial port. If I could only remember the "bad" brands and "good" brands.....Damned brain turning to mush....

Very true.

The one that I have is from "sabrent", it's tigerdirect part # M501-1032

I haven't verified it with the c950 s/w yet, but I'm VERY confident it will work. I use it to run a diagnostic program which, according to the manufaturer, must use com1, and must run on DOS, not a dos window in windows. works fine in a dos window with this cable.

[SKIPS69]

I'll take a look at the rock valley fuel tank, but, I was kind of hoping to use my current fuel tank and sending unit.

Any comments on the fuel line diameter? I was told that the reason that the motor would not run well before with the super charger was because it needed a 1/2" fuel line. At what horsepower level does a car need a 1/2" fuel line?

Oh, and is a 3/8" return line too big?

My plan is still to get the motor running without the supercharger, and then eventully put the supercharger on.

[JimM]

I tried talking to my c950 saturday, without success. Laptop is running Vista and using the cable described above.

At some point I'm gonna try straight serial into a desktop pc. If that works, I'll try from an xp laptop, and go on from there.

I have the question also posted on chevytalk, hoping to hear from DougF soon.

The return really should be the same size line as the supply. A few years ago, I tried doing one using a stock 3/8 sender as the supply, and the stock 1/4" vapor line as the return. It did NOT work, the system was unable to bypass enough fuel to control the pressure at idle.

[paulm]

Originally Posted by SKIPS69

I'll take a look at the rock valley fuel tank, but, I was kind of hoping to use my current fuel tank and sending unit.

Any comments on the fuel line diameter? I was told that the reason that the motor would not run well before with the super charger was because it needed a 1/2" fuel line. At what horsepower level does a car need a 1/2" fuel line?

Oh, and is a 3/8" return line too big?

I have run 3/8 supply and 3/8 return in all (three total) of my EFI cars. Try the stock tank/sender and see how it works, it can't hurt and it doesn't cost much. You have to run fuel lines regardless, worst case if it doesn't work out you can swap the tank later.

I have zero experience with forced induction or high horsepower applications so I will be of no help in deciding what fuel line size to use.

Originally Posted by JimM

I tried talking to my c950 saturday, without success. Laptop is running Vista and using the cable described above.

At some point I'm gonna try straight serial into a desktop pc. If that works, I'll try from an xp laptop, and go on from there.

I have the question also posted on chevytalk, hoping to hear from DougF soon.

All I have ever done (while using a USB/serial cable) is looked in the device manager to determine what COM it is assigned to. Once I determined that I changed the COM setting in the C950 software to match. There have been times when I have had it assigned to a certain COM and then unplugged the cable or restarted the machine and it quite communicating. I just had to change the COM setting in the software to match what the computer said it was assigned to.

[JimM]

my usb cable worked with an xp machine, it seems vista is the problem.
When I connect the cable, the new hardware wizard says it's a "prologic"

[Doug F.]

I don't know what HP your engine will have buy my BB is about 640 and I run 3/8 everywhere and have no pressure drop at WOT.

EFI and carb line sizing is different due to the pressure.

If you go large anywhere, go big on the inlet of the pump. I run 3/8 on mine there even, but have a good gravity feed.

I'd run 700 HP with 3/8 and ideally a -8 feed to the pump.

I know the fuel systems people say -10, etc, but I think that is overkill on EFI.

Take a look at what some of the 2000+ HP EFI drag cars run. A lot of -8.

[SKIPS69]

I'm starting with an engine that's 502 HP and then adding MPFI and a Pro Charger.

What do you guys think? Is 700 HP possible?

I agree that going to 1/2" line for the fuel supply is quite large, which was one of the reasons for the post.

Thanks for all the replies!

[Mark .L.W.]

700 is easy , i have a 427 small block and i'm adding a F1 and intercooler i'm looking for around 750 at the rear wheels , i'm running the holley comander 950 MPFI with 65 lb fuel injectors , we are also going to run a water injection with methonol and water .
Mark.

[JimM]

you'll get 700 at the crank on 3 lb boost!
I think you'll be revising your expectations upward, substantially.

[MStennes]

When I was running my Commander 950 pro I bought a Dell lap top off of Ebay. I cant remember the specific model number but could get it pretty easy if you want it. I went with this model as it had a serial port and being a older model it was pretty cheap. Do you have the wide band conversion? That really made a difference for me. I also ran the Holley inline pump with no problems, I also used the factory lines 3/8's for the inlet and 1/4 for the return. We tried diffent USB to Serial connectors and found one that worked on a friends lap top but it was running XP and not Vista. I ended up buying one as borrowing his was a pain, and using my desk unit was not a option. I have a extra contoller that has the 950 Pro hardware on it if your interested. The reason I got rid of the Holley was I'm installing a LS7 now.