Octane Question

[SHOoffST]

I have installed a custom ram air system to the stock MAF intake tube and have noticed an excellent bump in power. Here is my question. Sometimes it feels like it has more power than other times. I was wondering if I have potentially increased the cylinder pressures enough at 60-80MPH for the computer to pull timing?

Its not all the time, but there are times its extremely healthy and then others... just healthy... It seems noticable and this is the only thing I can think of. So what if I bump it to 90 octane...?

I have a very large collector under neath the bumper connected to the stock intake system...

Here is a picture of the can...

[Z63R]

I was wondering if I have potentially increased the cylinder pressures enough at 60-80MPH for the computer to pull timing?

Welcome to [FJ]focaljet.

That's a "Randy from FocusSport" question... depending on the drop in ambient air at 70 MPH, your iat's will drop meaning the engine is inhaling denser air and therefore there'd be a slight increase in cylinder pressure...

The differences in the spark timing changes' effective torque you feel are more than likely a result of the spark tables associated with charge motion control (idle-emissions tumble flaps) and imrc (intake manifold runner control). But I'm no digital tuner.

Also, and I realize this is Duratec Tuning, but, SVT Zetecs have been know to have "overactive" knock sensors... and with the gasoline octane rating discussions we've had here in Duratec Tuning it leads me to belive that some PZEV Duratecs may run better on a mid-grade gasoline (89) than 87...

I've never tried anything other than 87 in my 2003 2.3 Duratec PZEV ZX3 (with only a CAI, flex and 2.25" exhaust) because it runs so well. It's so smooth and incredibly torquey for a four banger.

[SHOoffST]

Originally Posted by Z63R

Welcome to [FJ]focaljet.

That's a "Randy from FocusSport" question... depending on the drop in ambient air at 70 MPH, your iat's will drop meaning the engine is inhaling denser air and therefore there'd be a slight increase in cylinder pressure...

The differences in the spark timing changes' effective torque you feel are more than likely a result of the spark tables associated with charge motion control (idle-emissions tumble flaps) and imrc (intake manifold runner control). But I'm no digital tuner.

Also, and I realize this is Duratec Tuning, but, SVT Zetecs have been know to have "overactive" knock sensors... and with the gasoline octane rating discussions we've had here in Duratec Tuning it leads me to belive that some PZEV Duratecs may run better on a mid-grade gasoline (89) than 87...

I've never tried anything other than 87 in my 2003 2.3 Duratec PZEV ZX3 (with only a CAI, flex and 2.25" exhaust) because it runs so well. It's so smooth and incredibly torquey for a four banger.

I just think if there is a case of detotenation, then the timing will drop out on all cylinders reducing power. I would think that timing being pulled would be really noticable. My 60-80mph pull is just awsome. This same car tracked 15.4 1/4 with a lesser ram air design at the time. The car now has the hard core ram air unit and a slightly ported head. There are just times when you stomp and it and it really pulls hard.