Joe-
I spent a year looking for the "right" system for my 78. I weighed the advantages of using a crate motor with TPI versus an LT1 from a salvage yard, to MAP or not to MAF, and then researched the vast suppliers of systems and set ups.
I went with MAP because of packaging constraints and airflow irregularities that come from a left or right elbowed MAF sensor. Really, as it boils down to it, MAF can compensate for only a little more of a gap in the variances between lab programing and real world operations. False air- the air that slips in after the sensor- will wreck the fuel tables on a MAF and send it sputtering. Why? IT CANNOT ACCOUNT FOR THE AIR. It simply gets the wrong data and uses it as the sole source to meter fuel. The procesor is slower too, so it cannot acount for changes as fast- air charge, detonation, coolant temp, etc. A day at the track is miserable on the MAF cars because of the slow rate to learn. Overall, its very primitive in design and archaic in function.
MAP cars have the faster processor. They run on tighter programing curves, but remember that the MAP sensor takes into consideration EXACTLY what the demand for the engine is for fuel at that snapshot in time. It uses a vacuum source at the rear of the plenum. It needs a stable idle to set its parameters unless it has been programmed to accept a nasty cam. Low vacuum created by a lumpy cam will tell the computer to add fuel, add spark and trim them if the engine lopes too much for the way it was programmed. Thus, big mods from stock only affect it if it dramatically changes the parameters of operation. MAP systems "learn" how to tailor themselves to the engine because the computer knows that its programing is at best a guide. It takes time to cycle but it will figure out the best set up.
Will a monster cam require a non-stock chip? You bet. Will an outrageous stall converter require a new chip? Most likely. Will 40lb an hour injectors and twin turbos need a new chip? Certainly. That is true of BOTH MAF and MAP systems. Will new rockers affect a MAP car adversely? No. Will a 2k stall converter need a new chip? Not unless the TPI is running the TCC.
I personally feel as though the TPI with a MAF sensor is a waste of money. Its expensive, clunky, prone to false readings and damage. A good speed density system is well worth the money. Not only that but false air is a killer on TPI because of all its gaskets in the runner and upper & lower plenum system.
LT1s, that is to say the 94 to 97s, are all MAF and MAP driven. Its more or less MAF with a MAP back up. Redundancy of systems gives a cleaner bill of ecological health. a little more than MAP. However, that system is fine for the LT1 because of its unique 1 piece nature and emmission certifications requirements. No VORTEC system or heads will work with the LT1 block or the LT1 manifold. You need all three of the same family to get the LT1 to work- LT1 block, heads, and manifold.
However, the L-98 TPI works well with the Vortec. The runner design makes for great scavenging coupled to the shape of the heads makes for great power. You will need a TPI to vortec manifold since the heads are different from the previous system. Vortec uses 8 bolts to get the manifold mounted while the earlier blocks use 12.
If you plan on going with a 400+ TPI system here is what I would do-
VORTEC heads
The largest tube runners I could find
A 58mm throttle body
LT4 injectors
1.6 roller rockers
91 F-Body MAP harness from painless set up with out emissions (Why? The sensors are cheaper, its easier to route through the car, and you can stash the CPU under the radio ahead of the HVAC controls!!!)
Get a chip from a company that asks you what makes up the sum total of your engine, car, and driving style. Remember that you need an accurate wieght, gear ratio, tire size, injector size and all the other data to get the chip tailored to what you want. Even if you build the car in stages, a chip should cost less than $150 dollars. I paid $80 for mine.
Good lucK- I hope I have helped you out a bit!
r you can have it reprogrammed in the prom too. Also on the vss,this is what i did,mt 700r4 trans had the vss electrical plug only on the trans. tail no speedo cable,so instead of getting the kit with the pulse generator and a place to mount the speedo cable to it,i went out to the junkyard and got a speed buffer from a 87 firebird(yellow box under the dash pass. side over the computer)and wired the yellow and purple wires from the trans. to it 1 wire to a hot source,1 wire(brown) from computer to it and a ground.The vss now works fine but i still dont have a speedo yet,my plans are all new autometer guages for speedo and tach but in electric versions so i can run the wire from the speedo to the buffer box and everything will work fine.HOpe that helps.
