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Discussion Starter · #1 ·
Its a 88.I have:
Cobra Intake
Gt40 heads with 1.7 rockers
B303 cam
ford racing shorty headers
High flow catted h-pipe w/flowmaster mufflers

Everything else is stock.If it will work with the speed density then I'll start putting it together.If it will work with maybe a couple other things please let me know.If I definitly need mass air and anything else I'll hate to do it but I will.I already have the A9L computer(not installed).I am hoping to keep it speed density.I am new to the whole Fuel injection mess.Thanks for any help you could give me and I'm sorry if this subject has been beat to death but I couldn't find any info on the exact setup I have.Steve
 

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The bcam does not play well with SD. I know there are a couple of cams out there that get along with the SD but the bcam is not one of them.

SD system relies on idle vacuum.
 

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I have a theory, but it's just a theory, that if you keep the idle smooth enough for the vacuum to remain stable, you can put just about anything into an SD system (non-boost), so long as you compensate with injector size/fuel pressure.

The SD adds fuel based on a chart, increasing the engine's power output amounts to adding more fuel and air. The air is increased with the parts you bolt on, but the fuel is only increased (without changing the computer's charts) by increasing injector size and/or fuel pressure.

The thing is though, that you need to be fairly precise in your injector mods to make this work. The fuel charts in the computer can only be compensated by a few percent either way. So if you are not very close in your choices, you can easily run outside the computer's perameters, and be overly rich/lean.

The SD programming is very rigid, and is actually better than MAF, but you have to be dead on. The reason MAF is so popular is that it is user friendly.

The reason rough cams don't work well with SD is that the MAP sensor works based on vacuum. The MAP sensor is THE key sensor that the computer reads on an SD system. Since the MAP is so sensitive to vacuum, and a cam makes for wandering vacuum, they do not get along.

Smoother vacuum comes from lower cam duration numbers @.050" lift and/or a higher cam LCA.
The higher your duration @.050" lift goes, the higher your LCA needs to be, to a point... The point that the LCA gets too high comes quickly. You can get up to 114, or maybe 116 LCA, then you are done.

Think of it this way, if you are going with an 'off the shelf' cam grind:
If it won't work with a stock torque converter auto tranny, it won't work with SD/MAP.
 

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Discussion Starter · #5 ·
Thats some good info.If I was going to all the trouble of changing the cam,It doesn't sound like it would benefit too much with just a bit more than the stock cam.I also heard from somebody that using 1.7 rockers on the stock cam will increase lift and not mess with the SD.I just don't know how much more HP this is worth?
 

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Discussion Starter · #7 ·
Wow,that eliminates doing that.That is also good reading.I'm learning as I go along.Thankfully the people on this forum know and thats why I joined it.So it sounds like if I want to use what I had listed, I' m going to have to go mass air.Do I need bigger injectors?
 

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19# injectors are pretty much running at 100% when you reach 300 horsepower.

As for cam, you can find good cams with a wide LCA.
Some really quick ramps, wide LCA, and duration @.050" at or below 215ish should be great. You won't hear much, but smooth idle is what gives you stable vacuum signal to the MAP sensor.
 
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