Don't want to hijack the other thread so I'll start a new one. I'm looking at something that will support at least 500HP and then some more in the future. I run a pretty healthy solid flat tappet cam, 252/260@ .050 so that may be a problem with some systems. I run the motor to usually about 6500+ rpm. I asked about the www.massfloefi.com system about a year ago and it got some good responses and wonder if anyone has any experience with it. Or what other good systems are out there. I'm not a computer wiz but not afraid of them either. The carb is running very good but with the cam and combo it could be smoother in the low to mid range and give me some better driveability.

 

The Holley C950 will work fine in your application and be the least expensive.

FAST & Accel Gen VII add some bells and whistles but I'd venture to say they're not really needed in your case. They are quite a bit more $$$.

I also hear good things about mega squirt and I'm tempted to try it myself (currently have the Holley C950).

 

The multi port Holley system is over $3000 without a dist. I would like to stay with a multi port system. Nice system though

 

Not sure what Holley system you're looking at, but a small block MPFI system is $2399 from summit (PN 91004101). Add a distributor and a wideband and you're still below $3k.

 

I have been running a MassFlo conversion for most of the summer on my 468. Kit was complete and good quality. I had no issues with install or startup. The motor is a mild BBC build with @575 HP at the flywheel and used for 80% street duty. The biggest problem was repackaging the L88/cold air box to work with it.

I was interested in the mass air approach and was familiar with the EEC IV from running a 5.0 Mustang. Worst case, I could tune it with the Tweecer, but I have had no reason to do so. It seems like the MassFlo site has some over the top marketing, but the system has worked. I am sure it is not tuned to squeeze the best HP/torque numbers, but I was not looking for that, just a reliable driver setup with minimal tinkering.

Holley systems are nice also, but pricing depends on injector sizing as I am sure you are aware.

Phil

 

The system I was looking at had the wide band O2 sensors. I see which one you are looking at now. They have quite a wide selection of 950 systems.

 

Don't forget, you'll also have to upgrade your fuel system. Pump, filters, lines, sump and regulator. You'll have to add these regardless which system you go with - usually about $600 or more for this stuff. I wouldn't consider a system either that wasn't wide band O2. I think a controller and sensor is around 300 bucks or so.

Expensive, but nice to know your system is going to fire up when you twist that key.

 

Yes I already have some plans for the lines and pumps and filters if I go this way. Wide band is for sure

Expensive?? What isn't expensive on these cars.

 

We just put one of those systems on marks 72 pantera,were having a lsight miss problem but other then that its a nice setup,most likely hell get tweecer to program anything else.Its supposed to handle 500 hp and his 392 stroked crate motor was dynoed at 435 before the 180 degree headers,so hes somewhere around 460 probably.Gordon if you want to see the system in person let me know well set something up.

 

PM sent Pat. Thanks

 

Innovate has a wideband controller that's adaptable to the C950 for $200, the LC-1, save $100 over Holley's.

 

I have the Holley Commander 950 on my 69 427 and have retrofitted the MEFI 3 with an Accel Gen 7 on the RamJet 502. Here are my opinions of each.
The Holley Commander is an older more basic system that works fine for the money and is probably all one needs for a standard street performance application. I cut my FI teeth on this one. I was very pleased with the Holley support crew. They upgraded my 950 ECU for the Pro version SW free of charge. Zwede has a pretty good write-up on his home page documenting some of the necessary (IMHO) application mods. For some reason, Holley sized the intake ports smaller than the head ports requiring some considerable porting. The throttle body is a tad to high and positioned slightly to far back to fit a stock GM L-88 hood. Minor air chamber, air filter base, and/or throttle body mods are required for a perfect fit. I also had to ditch the 30 lbs/hr injectors that came with my system for a larger set. The pro version supports wide band O2 which is necessary for the Hooker sidepipe headers I have on the 69. The O2 sensor has to be mounted too far away at the collector for a HEGO to reliably monitor exhaust. It has 2 outputs that can be configured based on rpm, TPS, MAP with one having the additional capability of controlling a electric fan based on ECT. It has the basic 16x16 scalable cell table for spark and fuel.

I opted for the Accel Gen VII for RamJet primarily because (at that time), it provided state of the art capability for the lowest cost. It supports sequential injection, dual fan control for my Spals, second alternate fuel map for performance vs economy, powerful nitrous capability if I ever opt to use it :*****: and more sophisticated sensor input monitoring and precision control I believed necessary for that big Ramjet intake. One of the major advantages Accel has over the Holley is that they use a fuel control algorithm that interpolates a value between the cell settings in the fuel table. The holley just bang bangs between the cells while the Accel has a nice smooth transition. Not sure if the FAST XFI system has this capability but it does incorporate a 17x16 table for added resolution. The Accel DFI is far and away better and easier to tune and calibrate the tables. It also has a more sophisticated acceleration and idle control fuel modification algorithms which the faster micro controller allows
From a electronics design packaging viewpoint, all the aftermarket systems don't hold a candle to GM's/ MSD's MEFI 4b. If you have a need for a rugged race or off road application, It is probably your best choice. The MEFI 4 does not support sequential injection (MEFI 5 does) but it has all the capability of the others and more. It's has much more cell table resolution, and now that you can program it, it is one of your better choices. I know I bad mouthed the MEFI in the past but that was mainly due to the poor GM tune and the fact that you couldn't program it.

There is more, but I am running out of wind, so for what it is worth, these are my opinions.....:cheers:

Bullshark

 

I agree with most of bullsharks comments except that Holley "bangs between the fuel cells". It does interpolate between cells, it's just not visible on their rather crude laptop SW. I don't doubt the Gen 7 is a more capable system, though.

BTW, seems there's a new Holley EFI in the works, but no ETA yet.

 

I understand it's less than 4 mo. or greater than 6...

 

Any info or is it just speculation?

 

Markus, I was probably to hard on the Holley by saying it bangs between fuel cells, but some where I seem to remember reading or hearing that the Holley incorporated a simple crude calculation for cell transition. Probably an Accel marketing guy Anyway, do you happen to know any details on how they calculate between cells? Do they just pick one point or linearize the calculation for both rpm and kpa axises. Accel does the later with a nice graphical bar indicating the amount of correction. Makes it easier to make tuning corrections on the fly.

Bullshark

 

There's a thread going on over at chevytalk's EFI section where Doug Flynn (Holley R&D manager) is asking for a wish-list for their next system.

 

I don't know any details but remember Doug F stating that the C950 does look at the surrounding cells and bases the current injector DC on all those cells, not just the closest. But I don't know the exact algorithm used. It would be fairly simple to used a weighted system so I'd think that's what they do...

 

IMO, the method for interpolation between cells is not that important. Why? Because the user is encouraged to smooth out the fuel and spark graph. This minimizes the rate of transition between cells. If the transition is not smooth enough (very rare) the user can change the scale between cells allow the system to "focus" on a certain range for more accuracy. I'm guessing it's just a straight weighted interpolation between cells - nothing fancier is needed.

 

Jerry, I agree the smoothing and map scaling is an important element of FI tuning and absolutely needs to be done as a part of any calibration. All to often so called dyno tuners dial in full throttle acceleration and short-cut the rest of the map. However, we will have to agree to disagree on the cell transition interpolation importance issue. If all your focusing on is a full throttle rapid transition, then we agree, it's not as important.

The GM MEFI 4 has a set of 4 fuel and 4 spark tables equally divided up in 200rpm steps 400 to 9000 in 10 kpa per cell steps, That is in addition to linear interpolation between cells. Makes for much better engine control resolution. I guess they feel rpm resolution is more important than map? If by straight weighted interpolation, you mean a linear line drawn between cells with more than one sampled data point, then we are saying the same thing.

Bullshark