super victor EFI intake

90lxcoupe said:

a bigger intake is only going to make good power at higher rpms, it has alot do do with port velocity and the volume of air being moved... that being said, comparing intakes to fuel systems is completly irrelevant, there is a regulator on a fuelsystem to make it possible to run larger injectors and fuel pumps.

a victor 5.0 on stock heads would be like running 96lb injectors with a stock pump

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What he said. Port cross section size has to be chosen carefully to maintain good flow velocity in the intended RPM range of a given motor. Smaller ports have the virtue of higher velocity but at the risk of not flowing enough air to feed the cylinders at higher RPM. Larger ports, of course, have the capacity to flow large amounts of air, but if the engine doesn't demand it (small displacement or low RPM), then velocity suffers and the cylinder actually wouldn't be filled with air effectively when the valve is open. Also, characteristics like swirl would suffer, resulting in inconsistent A/F mix and poor combustion efficiency.

Another thing to consider is intake runner length, which can be tuned to support performance in various RPM ranges due to the pressure-wave effect of the opening and closing of the intake valve. Some new cars take full advantage of this by means of variable-length intake runners.

90stang5speed said:

Thanks for trying to clear that up. I looked into some other intakes on the summit website and it looks like the TFS intake has an RPM range that I can work with a lot better than a super victor

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I think you'd see much better gains spending money on a good set of heads right now than buying another intake. The Explorer right now isn't your bottleneck- its the stock heads.

Not mentioned anywhere in the above 'velocity' arguments is the MAJOR importance of cam timing.

The piston motivates the air to move.
The valve timing is what dictates potential air speeds, but this often glossed over.

Custom cams from guys who know what they are doing can make a large intake work very well on a 'small' engine.
The entire combo would need to be worked in unison though....

cam selection involves careful consideration on both the intake (inlet) and exhaust (outlet) side. In an ideal situation, the exhaust system flow charactaristics are tuned to the valve events as are the intake valve events.

The exhaust has the capability of positively affecting cylinder fill. If the timing is right, there is not a lot of "pull" or "signal" on the opening intake valve as the piston is near TDC and piston speed is very low - no draw. If the ehaust system is designed correctly, it still has mass moving down the system and draws a vacuum or once again "signal" on the chamber. Since the cylinder volume is small, the vacuum the exhaust gass creates, (which is not great in relative terms to CID) is still very effective in getting the intake air moving to start sweeping fresh air into the cylinder. At some point, the piston starts to move at greater speed and the ability of the exhaust system to exert much effective gas movement on the intake port is lost, but that's OK as the piton is now moving the air.

If you vary from ideal by restricting the exhaust, the cylinder is not completely empty and some burned gasses remain in the chamber as the exhaust valve closes which dilutes or displaces fresh feul and air and power will be diminished. If the exhaust system overscavanges and/or injector timing is not right, some of injected fuel unburned may be drawn into the exhaust and power will be diminished - this is much more of a problem on carb cars where fuel is always suspended in the air charge.

On the intake side, if you open the intake valve too soon, exhaust gasses will be blown back out the intake valve in what is called "reversion". It is sucked back into the chamber as the piston continues on it journey, but that is a waste of time and the ability to get fresh air into the chamber. Open the intake too late and you inhibit the ability of the cylinder to fill based soley on the time you have to do it.

Now consider that the ideal valve events and system design paramters will need to vary with rpm and you get a feel for why you pay a good cam desinger for the benefit of his knowledge and services.