fuel injection

mee_doo · 12-07-2001, 01:54 PM

I am about to do a 5l conversion and I was wondering which fuel injecting system is better. Mass air or speed density?

Chevyguy · 12-07-2001, 02:15 PM

Mass air is more adaptable and tuneable. The 86-88 guys will tell you the Speed density system can work fine, and may pump a few ponies more than a stock Mass Air system, but the Speed Density is pre-programmed for a known setup and will eventually give you problems as you deviate from the known values.

If you are converting a Mustang, you can swap in the engine harness and computer from a FI mustang, just make sure you get the complete system from the same car as Ford changed the setup each year, and sometimes during the year. For a non Mustang swap, stick with a universal kit like Ron Francis or FMS etc..

84_GT350 · 12-08-2001, 02:41 AM

If you're looking to modify the engine at all, Mass Air is the only way to go. True...you can modify a speed density motor, but the state of tune becomes much more important. Like Chevyguy said...a speed density system might make a few more horsepower stock, but the adjustability of Mass Air is it's selling point.

12-07-2001, 01:54 PM	#1
mee_doo Registered Member Join Date: Sep 2001 Location: Abbotsford,B.C,Canada Posts: 4	fuel injection I am about to do a 5l conversion and I was wondering which fuel injecting system is better. Mass air or speed density?

12-07-2001, 02:15 PM	#2
Chevyguy Backyard Mechanic/Chemist Join Date: Feb 2001 Location: Acton MA USA Posts: 435	Mass air is more adaptable and tuneable. The 86-88 guys will tell you the Speed density system can work fine, and may pump a few ponies more than a stock Mass Air system, but the Speed Density is pre-programmed for a known setup and will eventually give you problems as you deviate from the known values. If you are converting a Mustang, you can swap in the engine harness and computer from a FI mustang, just make sure you get the complete system from the same car as Ford changed the setup each year, and sometimes during the year. For a non Mustang swap, stick with a universal kit like Ron Francis or FMS etc.. __________________ 2001 Crown Vic Maurader Airbox/MAF, DR chip Edel IAS shocks Single exhaust :wtf: 93 P-71 Vic interceptor Backup car now 90 5.0 LX Notch SOLD 74 Chevy Laguna type S-3 454 under construction Currently apart undergoing bodywork.

12-08-2001, 02:41 AM	#3
84_GT350 Registered Member Join Date: Apr 1999 Location: Overland Park, KS, USA Posts: 1,631	If you're looking to modify the engine at all, Mass Air is the only way to go. True...you can modify a speed density motor, but the state of tune becomes much more important. Like Chevyguy said...a speed density system might make a few more horsepower stock, but the adjustability of Mass Air is it's selling point. __________________ 1984 1/2 GT350 (#842 Hatchback w/ T-tops)

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