timing and 87 octane...or even 89

Decipha's custom GUFX strategy covers all 89-93 foxbody ecu's including the 88 mass-air california ecus.
88351stang
Posts: 3
Joined: 2021 Dec 02, 11:02
Location: Franklin, GA
Vehicle Information: 1988 Mustang GT
351W
GT-40X305 heads
X303 Cam
GT-40 tubular intake
70 mm throttle body
Pro-M 77 mm mass air meter
3.73 rear gear

timing and 87 octane...or even 89

Unread post by 88351stang »

Hey guys

I have searched and found varying results and opinions on this. 351W flat top pistons (10:1 static compression ratio), GT40 X305 aluminum heads, X303 cam and GT40 intake. All my timing is set up for 92 octane right now. Is it possible to lower it enough to run 87 octane? I have seen where some have said don't even try it, so wondering if yall have tried something similar. Been driving the car a little more lately with diesel prices the way they are, but premium is not saving me alot.
decipha
Posts: 4957
Joined: 2021 Feb 15, 12:23
Location: Metairie, LA
Vehicle Information: Work Truck
'19 F-150 3.3L

Re: timing and 87 octane...or even 89

Unread post by decipha »

yeah no problem

start by yanking out 8 degrees over 3/8 throttle ~typically 50 load.

The dial it in from there.
88351stang
Posts: 3
Joined: 2021 Dec 02, 11:02
Location: Franklin, GA
Vehicle Information: 1988 Mustang GT
351W
GT-40X305 heads
X303 Cam
GT-40 tubular intake
70 mm throttle body
Pro-M 77 mm mass air meter
3.73 rear gear

Re: timing and 87 octane...or even 89

Unread post by 88351stang »

Thanks decipha
jhine5588
Posts: 11
Joined: 2021 Jul 16, 17:37
Location: Binghamton, NY
Vehicle Information: 1983 LTD wagon- 302 HO swapped with EFI and bolt-ons

Re: timing and 87 octane...or even 89

Unread post by jhine5588 »

Just curious, has the OP tried this yet?

Any major difference on the butt-dyno?

This market sucks to own things that get less than 20mpg...



Jeremy
88351stang
Posts: 3
Joined: 2021 Dec 02, 11:02
Location: Franklin, GA
Vehicle Information: 1988 Mustang GT
351W
GT-40X305 heads
X303 Cam
GT-40 tubular intake
70 mm throttle body
Pro-M 77 mm mass air meter
3.73 rear gear

Re: timing and 87 octane...or even 89

Unread post by 88351stang »

I haven't yet, but definitely going to. I will post back with results
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