Speed density nerds only please!

THere are a couple of good horse power cars running speed density,but they have unlimited electronic resources.Switch to masss air.Thats the best i can do for ya.

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because I am not sure if the SD ecu operates the same as the MAF strategy for Adaptive Fuel....

From what I've read, the SD's adaptive limit is about 12-15% max.

But that being said, the ECU ignores O2 readings at WFO, it runs open loop which uses known stored values.

However, the values it refers to for open loop operation are modified by the learning strategy during closed loop.

Some people seem to have good luck with HCI SD setups using a cam from one of the many SD safe charts. I have a feeling that many of these setups work by accident.

The SD ECU can only determine how much fuel to inject by measuring MAP vs RPM vs Temp and TPS. It has tables from the factory, and can only deviate so much from these values to adapt (12-15%). The ECU baseline tables were established by ford for the bone stock 5.0L.

A stock 5.0L vs a modified one could have the same vacuum at a given rpm, but the modified motor would be moving a lot more air. Therefore the modified engine would run lean. The ECU would read the lean O2 sensors, and add fuel. But it can only adapt so much (the "Adaptive Limit"). You can play with this level with fuel pressure tweaks to some point i'd imagine.

Now back to my theory about it working by accident.

Some ppl do the HCI, throw in a cam that has a little more duration and overlap than the ECU is used to, therefore lower vacuum.


The change in MAP reading compared to the stock cam can at some points through the curve cause the ECU to compensate fuel, but not for the right reason.

This last part is all speculation by me and may be completely wrong.


All in all, I'd say if you stay conservative with the cam, and play with the fuel pressure you should be able to get it to work for you.


There are quite a few people who know much more about this stuff than me, try s b f t e c h

Here's a speed density cam chart. That site has a lot of SD info.

http://www.50tech.com/viewtopic.php?t=50694

From what i've read as long as you keep a sd friendly cam that supplies enough vacuum you can swap heads, super charge or add nitrous. One of the mustang mag editors had a supercharged 347 running SD. The big knock i heard was once you pass 300 HP an need bigger injectors you need a custom chip.

lang williams said:

From what i've read as long as you keep a sd friendly cam that supplies enough vacuum you can swap heads, super charge or add nitrous. One of the mustang mag editors had a supercharged 347 running SD. The big knock i heard was once you pass 300 HP an need bigger injectors you need a custom chip.

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give me more info on your combo, pm me .. i am pushing 400+ rwhp on a sd system and yes upgrade the injectors , rob them from a s/c or lighting depending on the cam you want to run.

I know a lot of boosted LS1 guys run SD once they max out the air flow that a MAF is capable of reading.

Im not familiar with 5.0 SD vs a late model GM SD tune.

If adaptive strategy is used in the logic, it does affect any "open loop" condition....... including WOT. Old school '88 setup with an AOD I've worked on, requires a system KAM reset at the track every time, in order to obtain the best ET's.

joel5.0 said:

Old school '88 setup with an AOD I've worked on, requires a system KAM reset at the track every time, in order to obtain the best ET's.

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Absolutely, auto or manual. Do it before a dyno too.