Fuel types

Issues pertaining to the TGB/C30X series engine and driveline issues
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aclark79
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Fuel types

Post by aclark79 » Fri Aug 04, 2017 4:51 pm

So, I've been running 92 octane gas with a lead additive, but 100ll AVGAS and "racefuel" at 100 octane with lead are available. Not sure if those are the same or not. There is also 92 and 110 octane ethanol free (but no lead) fuel available near my home.

I'm wondering what everyone else is using in their trucks? Is avgas safe to use in the Volvo? What about "Racefuel"?

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Jimm391730
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Re: Fuel types

Post by Jimm391730 » Fri Aug 04, 2017 9:12 pm

Can't answer for the Volvo, but I was at the track last week and 100 leaded was $11.09 per gallon!
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Garrycol
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Re: Fuel types

Post by Garrycol » Fri Aug 04, 2017 9:17 pm

aclark79 wrote:So, I've been running 92 octane gas with a lead additive, but 100ll AVGAS and "racefuel" at 100 octane with lead are available.
When I was flying, the ll in 100ll Avgas stood for Low Lead (ll).
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rmel
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Re: Fuel types

Post by rmel » Sat Aug 05, 2017 3:47 pm

High Octane is required for high compression ratios so the fuel won't pre-ignite during the compression cycle.
The advance needs to be tweaked accordingly. If you have an engine with a lowish compression ratio your
likely throwing money away going after high octane.

Lead in the fuel is another question, boosts octane but also puts Pb deposits on the valve seats reducing valve
seat recession So depends what your going after, high octane or preserving your seats. The best preventive
measure for seats is to run a little rich, and if you have a head re-build, make sure you get hardened seats.

Octane boosters have additives that boost the Octane but some products claim valve seat protection. IMHO the
best on the market is Lucas, they use MPPT as an octane booster and is a well proven anti-wear additive for
valve seats. Miller Oil in the UK is also MPPT.
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VinceAtReal4x4s
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Re: Fuel types

Post by VinceAtReal4x4s » Sat Aug 05, 2017 4:11 pm

The B30 Volvo engine needs 89 to run smoothly when the timing is set correctly, in general. Anything above 89-91 and you are wasting money. Different parts of North America have different selections but you are usually looking for the middle of the three selections at gas pumps. The B30 has a little higher compression than most older 4x4 motors.

The lead additive is a good idea assuming the heads were never rebuilt with hardened seats, not that it would hurt it then either.
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Garrycol
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Re: Fuel types

Post by Garrycol » Sat Aug 05, 2017 9:58 pm

Lead additives are not legal here so I use FlashLube upper cylinder lubricant which has the same result without the lead.

I agree with the others - hi octane fuel is a waste unless the engine is modified with high compression.

Garry
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Uli-RT
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Re: Fuel types

Post by Uli-RT » Sun Aug 06, 2017 11:49 am

The B30 in the Volvo TGB needs definitely a minimum of 97 Octane (RON in Europe), what should be about 92 Ocatane (PON in the US); if the Ignition is at 10 degree v. OT.
To use lower octane gasoline you can take the ignition back to about 5-7 degree v. OT.
But than you loose a little bit power.
If the engine is not ringing while accerlerating everthing ist good.

To use unleaded fuel (we don´t have leaded fuel in Europe) I put some hardened Valveseats in the Cylinderhead.

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Garrycol
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Re: Fuel types

Post by Garrycol » Sun Aug 06, 2017 7:48 pm

If it needs 97 RON then compression ratio must be up around 10:1 which seems off for a mil vehicle which are usually designed to run on any crappy old fuel out in the field.

I do not know Volvo engines at all and googling doesnt give me an answer - does the B30 have aluminium heads or cast iron heads?

Garry
1973 Haflinger AP700
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1971 Jaguar Series 3 E-Type Conv
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VinceAtReal4x4s
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Re: Fuel types

Post by VinceAtReal4x4s » Sun Aug 06, 2017 11:29 pm

9.3:1 is the B30A compression ratio as fitted to the C303/TGB Volvo's.

I found 89/90 to work fine and that's over 1000's of road miles on a stock motor at typical altitudes, probably from 500-2000ft. My options were usually 87-89, or 90, and 92 or 93. I tested it over time and never could detect a difference between 89 or 90, and 92, and this was a stock engine with rebuilt carbs that were in perfect tune, in my opinion. It ran very strong.

If you live at, say 5000ft, you can use lower octanes. If your head was reworked/shaved, you may benefit from a little higher number as the ratio would increase.

Specs from my old website: http://www.real4x4.com/303specs.shtml
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Uli-RT
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Re: Fuel types

Post by Uli-RT » Mon Aug 07, 2017 11:22 am

The cylinderhead is cast iron. The reason for using high octan fuel is not the compression ratio rather the shape of the combustion chamber; it does not have the optimal shape.

My experience using 95 Octan (RON) is not very good. Engine was ringing very bad running up hills with full throttle. If you take throttle back its gone.
So I use 98 Octan or LPG (over 100 Octan)

Ringing can cause a big damage to the engine. So listen carefully and take care :)

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