GM crate 350 HO runs fine on regular 87? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ozkiwi · 11-22-2021, 08:47 AM

The recommended fuel for my crate engine is 91 premium which is our 95 here in Australia but it runs fine on regular 87 with no pinging.
Does that motor really require premium?

S10Fan · 11-22-2021, 09:29 AM

A TV show on the Motor Trend network here in the states, "Engine Masters" did a fuel test using different octane levels. The test basically showed little to no difference between grades of gasoline. If you're not racing and not pinging, go for it was their conclusion.

ozkiwi · 11-22-2021, 06:47 PM

Quote:

Originally Posted by S10Fan

A TV show on the Motor Trend network here in the states, "Engine Masters" did a fuel test using different octane levels. The test basically showed little to no difference between grades of gasoline. If you're not racing and not pinging, go for it was their conclusion.

Thanks I think my experience confirms that but nice to know someone has done it in a controlled way.

**hatzie** · 11-22-2021, 11:43 AM

If it's not pinging run it.
Pay attention in the hot months when you're running it under heavy load like uphill towing at lower RPMs. It may ping under those conditions and not at all otherwise.

Nick_R_23 · 11-23-2021, 07:46 AM

If it’s only recommended, then no, it’s not completely required, but you may run into high load situations like hill climbing, towing, hauling heavy loads, etc that may push you into detonation territory. Running conservative timing will help suppress that, but you also may not be getting full potential from your engine.

In a previous industry I was in, it was advertised as 87 min/91 rec. This means you could run as low as 87, but the ECM would pull timing using fuel rated below 91. 87 was just the max it would compensate to.

ozkiwi · 11-23-2021, 06:58 PM

No pinging even in hot weather underload on regular. The mechanic who installed the motor said he set the timing conservatively which I assume is slightly retarded. It starts instantly and makes more than enough power for my use.
It replaced a tired 305 so I guess thats why it has more than met my expectations.

11-22-2021, 08:47 AM	#1
ozkiwi Registered User Join Date: Nov 2012 Location: melbourne australia Posts: 196	GM crate 350 HO runs fine on regular 87? The recommended fuel for my crate engine is 91 premium which is our 95 here in Australia but it runs fine on regular 87 with no pinging. Does that motor really require premium?

11-22-2021, 09:29 AM	#2
S10Fan Old Heap Driver Join Date: Mar 2008 Location: Newport News, Va Posts: 2,642	Re: GM crate 350 HO runs fine on regular 87? A TV show on the Motor Trend network here in the states, "Engine Masters" did a fuel test using different octane levels. The test basically showed little to no difference between grades of gasoline. If you're not racing and not pinging, go for it was their conclusion. __________________ _____________________________ Bryan '99 Silverado 1500, 4.3, 5-speed, reg cab, short bed '50 Chevy 2DR Hard Top, 350/350, M2 Front End, 3:08 gear, cruiser. '40 F**d Sedan, all Chevy power, Heidt's front end, TCI rear, nice driver.

11-22-2021, 11:43 AM	#4
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: GM crate 350 HO runs fine on regular 87? If it's not pinging run it. Pay attention in the hot months when you're running it under heavy load like uphill towing at lower RPMs. It may ping under those conditions and not at all otherwise. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

11-23-2021, 07:46 AM	#5
Nick_R_23 Registered User Join Date: May 2016 Location: Willow, Alaska Posts: 881	Re: GM crate 350 HO runs fine on regular 87? If it’s only recommended, then no, it’s not completely required, but you may run into high load situations like hill climbing, towing, hauling heavy loads, etc that may push you into detonation territory. Running conservative timing will help suppress that, but you also may not be getting full potential from your engine. In a previous industry I was in, it was advertised as 87 min/91 rec. This means you could run as low as 87, but the ECM would pull timing using fuel rated below 91. 87 was just the max it would compensate to.

11-23-2021, 06:58 PM	#6
ozkiwi Registered User Join Date: Nov 2012 Location: melbourne australia Posts: 196	Re: GM crate 350 HO runs fine on regular 87? No pinging even in hot weather underload on regular. The mechanic who installed the motor said he set the timing conservatively which I assume is slightly retarded. It starts instantly and makes more than enough power for my use. It replaced a tired 305 so I guess thats why it has more than met my expectations.



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