Ive noticed that 3rd Gen fbody owners prefer the Speed Density as an upgrade for their TPI 305 or 350, this seems the opposite of the Ford 5.0 faithful Ive run into.


I own a 1986 Mark VII LSC with the Ford 5.0 HO and from 86 to 88? Ford used Speed Density for these cars, then switched to MAF which with 3rd Gens it seems GM went the opposite route switching to MAP.

The Ford guys say the MAF system allows them more flexibility with modding the motor since the MAF adjusts itself according to what the sensor says, they say the Speed Density is restricted by the programming in the computer and is less mod friendly, but also state a slight edge in stock power vs MAF cars.

Im aware the differences between GM and Ford ecm's might be great but these 2 induction styles (MAF and MAP) are somewhat similar between Ford and GM, why the differences in opinion?

you have to look at other factors. the ford has larger mafs that can be bought as the power level goes up, the gm doesnt.

the gm ecm is easily cracked to make upgrading with a SD system very easy, the ford isnt. most people that switch to SD do it when they get to a point where the maf is slowing them down and since in gms case the maf system is limited unlike the ford the only route to go is SD.

GM does go back to MAF, but that happens outside of the scope of third generation F-bodies. So that leaves the 90-92 SD system as the best CC system available in thirdgens before the change in body style. That, in combination with what was said above is the reason for the switch.

yup the lt1 and ls1's have larger mafs available that will read and flow better then the bosch on a 3rd gen.

Ah now I see, thanks for clearing this up guys... funny thing is Im stuck with the lesser prefered system on my lincoln and my GTA lol.. well I can always convert

Whats nice about Fords wirng harness is that to change to MAF from SD all you have to add is the correct ECM, and four wires to the MAF. Splice in power, ground, and add signal in and out at the correct location is all you have to do. Unlike GM, Ford doesn't need the harness changed and the pinout is the same, with the exception of the signal in and out. I did this with my 86 GT. cheers, Bob

Unless I'm mistaken, Ford ECMs are not as well "hacked" as our ECMs, most notabily the SD TPI ECM.

Until the ECMs for 3rd Gen cars were fully hacked, you WERE better off with a 3rd Gen MAF car. But once "eprom tuning" became commonplace on 3rd Gens, then the "fine tuning" capabilities of the SD system allowed it to shine.

FYI, there are guys with 4th Gen LT1s with the 8051 ECM that run faster in "SD Mode only" than "both MAF and SD". Go figure.