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Recently, I have been receiving a lot of PMs regarding basic questions regarding 2.5L / SVT / 3.0L / F/I questions. Since I know a little bit about each, I'll try to answer them in a public forum so that all will be able to benefit. Newbies and beginners, please read before posting. Questions can be basic, some more in-depth.

Please PM me with questions you don't necessarily want to ask in public, and I will post them and the answers anonymously. Should anyone find fault with the answers I've posted, please PM me and I will correct information.

Here goes!

Q: If I add SVT cams alone to a non-SVT 2.5L engine, will I need the ECU? (I assume yes - different timing on the cam = different programming)
A: Need? No. Benefit from? Yes- However, there are downfalls to this. You'll need to have the PATS re-keyed before the car will think about starting. The SVT ECU needs to match your car's fuel system type ('98-'99 SVTs are return-style, only 2000 SVTs were returnless). Take the car to the dealer with the stock ECU, then have them re-key the SVT computer to your car's PATS (DO NOT LET THEM FLASH IT!!!) Secondly, the timing (though still "tame"), will require you to run 91 or better octane fuel. Another option is to have your car dyno tuned. The tuner can load values from any ECU into your current ECU so a ECU swap isn't necessary. Generally a dyno tune is about $500. Go to and search for dealers to get more info on a shop in your area that can dyno tune your car.

Q: Will I need the cam followers from the SVT heads (or are the cams acting directly on the valves)?
A: No- The RFFs (see 2.5L FAQ) and HLAs are identical between the 2.5L, 2.5L SVT, and non-VVT 3.0L (Ford Escape, Ford Taurus, Mazda Tribute).

Q: If I add the ECU, will it work with the 2000 stock Cougar injectors?
A: No. All SVT ECUs have an injector constant of 19#/hr @ 40psi. Stock ECUs are coded for 17#/hr injectors. You must have the correct style (return or returnless, depends on your car) 19# injectors installed before you install and re-key the SVT ECU. Your engine will run rich on the way to the dealer, it's okay for a little while.

Q: If I add the SVT injectors, is there a way to keep the returnless fuel system?
A: Of course. But I re-iterate- Injector "upgrades" should only be performed when an appropriate ECU change is made (SVT ECU, ADC chip, other chip). The injectors that you buy need to match the fuel system type of your vehicle so that you can use your stock wiring harness. Return-style injectors have squared connectors, returnless have rounded connectors. The ECU/chip is coded for the fuel system type and injector size- That's why you can't mix them up without serious issues.

Q: Is there a benefit to the SVT injectors (is this something I shouldn't worry about)?
A: I refer you to the 2.5L FAQ. The short answer is "only if you've upgraded/chipped the ECU or actually find that you're running out of fuel up top with the 17#/hr stockies".

Q: At this point, Intake, Cams, ECU - is premium fuel necessary? Compression has not changed (prepared for flame here)
A: See above. The ECU timing tables necessitate 91 or better octane fuel.

Q: I assume the heads and pistons increase compression - it that the case? Is there any benefit to the SVT heads - flow?
A: The 2.5L SVT engine has higher compression pistons- There is no change in casting between 2.5L and 2.5L SVT heads. Just the Extrude Honing of the primary intake ports ('98, '99, 2000) and the secondary ports (2000).

More to come...
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