Fuel switch

I have a Gillis in and was wondering if that Regular/Premium fuel switch still does anything at all and what position I should leave it in. Thanks!

Mike

It still effects the timing. I leave mine in thye premium mode when ever I have the boost cranked up. And of course it is always cranked up! Too bad the gas prices are also in full boost mode!
Wes

In prem mode, timing is between 1 and 4 deg (depending where you are in the timing map) advanced over the reg setting.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 00 Windstar (wifes vehicle)

Lets say I'm doing about 15 or 16 psi max, but just average around 5 or so. Should I just leave it in Regular mode to save gas and/or be able to get regular unleaded? Or am I just better off leaving it in Premium?

I experienced something interesting when I recently detuned the daily driver to see if I could get it to run on regular. Prior to detuning I was running about 13* advance and 17-18 psi (but the overboost buzzer didn't go off) I set the timing back to 10*, sprout out and backed off the boost valve (old Hallmon) by several turns, figuring this would take me to 15 psi or less. I took it for a test drive and it didn't run for s--t but it kept boosting to 18+, enough to set off the over boost buzzer! WTF. It did this a few times and as I was taking it home I remembered that I forgot to put the sprout back in (gee, I never did that before - not) So I put the sprout back in and went for another drive. Car ran much better but only developed 15 to 16 psi and I didn't change the valve setting.


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NATO Member. it's not a vice, it's an obsession
Good judgement comes from bad experience, and a lot of that comes from bad judgment.
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm

Originally posted by 88BirdOfPrey:
Lets say I'm doing about 15 or 16 psi max, but just average around 5 or so. Should I just leave it in Regular mode to save gas and/or be able to get regular unleaded? Or am I just better off leaving it in Premium?

I did an unscientific test of this a while back. With 93 octane in the tank, and cruise control set at 70 mph on a straight, flat level rural interstate, I put the trip comp in INST MPG mode. With the switch in PREM, MPG stayed rock steady at 31 MPG. With the switch in REG, still a constant 31 MPG. COnclusion: At least at steady state cruise, no difference in MPG.


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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 00 Windstar (wifes vehicle)