Speed Density?
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Speed Density?
I've got a 1994 F250 with a 351W that is speed density. I was wondering what I could do performance wise to this motor? If I ever rebuild it I wouldn't mind putting some better heads and maybe up ing the compression. I just don't know how you would tune it? Does anybody make a MAF complete conversion kit?
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Speed Density vs. Mass-Air
Speed density system is inferior to Mass-Air from all standpoints, but most of all, Mass-Air will work well with most power-adder devices and engine hop-ups; speed density will not.
impish
impish
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Well since I didn't want to go hunting on used parts, the mass air kit includes everything including the trans controller. It was about 4 hours to install, most of the time was trying to run wires so it could stay hidden.
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From: Calhoun GA
I've got a 1994 F250 with a 351W that is speed density. I was wondering what I could do performance wise to this motor? If I ever rebuild it I wouldn't mind putting some better heads and maybe up ing the compression. I just don't know how you would tune it? Does anybody make a MAF complete conversion kit?
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Junior User
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From: Kelowna, B.C
^^more on this.. Havnt heard about adjustable fuel pressure regulators..
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From: Calhoun GA
An adjustable unit can raise the pressure higher than the factory FPR, which will allow more fuel to pass through the injectors under heavy/WOT conditions. The 2 and 3 bolt regulators will bolt right up to the factory flange once the factory regulator is removed. This works fine for many bolt-ons and even some mild heads and/or cam upgrades. The best way to dial one of these in is to have a FP gauge and a wideband to check the A/F ratios.
Fleet Mechanic
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From: New York
Sorry, but I can't agree with that statement at all.
I will however agree that if you are planning on making changes to the engine which will change the volumetric efficiency, the factory MAF system will adapt much more readily than the factory Speed Density.
As it relates to the topic of fuel pressure increase as a means of "tuning", that's not really a very good way to do it as you're applying a monolithic change across all conditions. i.e. Yes, you'll be adding fuel at higher loads where you need it, but you'll also be doing so at lower loads where you don't. Closed-loop would probably be able to clean it up enough once warm if not making a big change in FP though.
I will however agree that if you are planning on making changes to the engine which will change the volumetric efficiency, the factory MAF system will adapt much more readily than the factory Speed Density.
As it relates to the topic of fuel pressure increase as a means of "tuning", that's not really a very good way to do it as you're applying a monolithic change across all conditions. i.e. Yes, you'll be adding fuel at higher loads where you need it, but you'll also be doing so at lower loads where you don't. Closed-loop would probably be able to clean it up enough once warm if not making a big change in FP though.
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