When you put a supercharger on a 05 5.4L F-150 can you run regular 87 octane fuel or will this cause detonation? Thanks for your help

 

Is that the 3v? The ROUSHcharger requires 91 octane or higher. You could probably ask if they could tune it for lower...but...that's kind of like buying a bag of M&M's, and then only eating the wrapper .

 

Yeah its the 3 valve. I think the roush is the lowest boost i've seen with only 6 psi, i've seen others like the whipple with 8-9 psi boost.

 

Pulling back the timing to allow use of 87 octane makes the blower hardly worthwhile. You're killing the gains that the blower gives you, though overall it should have more power than without the blower. How much more...that is the question.

You generally want to run the highest octane you can find with any forced induction setup.

For what it's worth, you can run a bit more boost with an intercooler.

I run 10.5 psi on my stock 1997 5.4L, though my power levels aren't near what the newer trucks get due to my lack of PI heads. Also, I've got a procharger, so there's little boost until the rpm rise.

 

Like stated above, it would basically be useless to run on 87 octane, with a pulley. We run 91 octane on ours. The last thing you want is detonation.

 

2020,
have you already installed your s/c or are you just gathering info on it?

 

The supercharger will add a lot of heat to the intake charge, plus the added compression will make detonation much more likely. For example, the M90 adds approx 15-20 degrees F to the air temperature per each psi boost. I'm seeing around 70 degree rise for 4 psi currently.

Making the engine run without detonation at those higher compression temperatures will require crazy amounts of retard to the timing which takes away from the power adder you are wanting.

The only possible way around this is with water injection to cool the intake charge and combustion temperatures. Its theoretically possible, but very hard to make a tune for this, so most don't even try.

When I first put on my blower, I was trying to tune for mid-grade fuel, but after a couple of weeks I gave up after I realized how much timing I was taking out to try to accomplish that.

 

You could but it would have to be tuned for 87....lots of timing retard....would equal loss of power....

Wouldn't be worth it....if you're getting a supercharger, you are pretty much expected to buy the best octane possible...91 or 93...that way you can take advantage of the added power the supercharger will add....

Just look at the Cobras or Shelby GT500's...they REQUIRE 91/93 octane....

 

On boosted vehicles, good fuel is the cheapest form of power adder anyway.