Toluene as a fuel additive

[Tony S.]

I've been doing some research on fuel additives for my '65 396 car. From my limited web search, it seems that Toluene seems pretty effective. I'm curious if anyone on the board has had any experiences with Toluene, and what are your impressions of it.

Thanks.
Tony

[Stuart F.]

Re: Toluene as a fuel additive

Anthony;

What have you determined to be it's good attributes? Can't say I know much about it.

Stu Fox

[Tony S.]

Re: Toluene as a fuel additive

Stu: From what I've read, it seems to be a very good choice for increasing octane. It's supposed to make our high compression engines run much better. It is readily available at paint and hardware stores. There are several websites that discuss it. It seems to be a good choice, but before I put some in my tank, I want to see how other NCRS members have done with it.

Tony

[Clem Z.]

Re: Toluene as a fuel additive

i would check to see if it will damage the rubber parts of your fuel system.

[John N.]

Re: Toluene as a fuel additive

I've been doing some research on fuel additives for my '65 396 car. From my limited web search, it seems that Toluene seems pretty effective. I'm curious if anyone on the board has had any experiences with Toluene, and what are your impressions of it.

Thanks.
Tony

Toluene is a key blending block in formulating av gas and racing fuels. To a lesser extent it is used in other gasolines to help it meet octane specs. It is a octane improver with low or no reid vapor pressure. It is considered a aromatic because of it sweet odor (along with benzene and cyclohexane). As Dick points out it is a effective solvent and can disolve rubber lines, paint etc. Yes one can use it to raise octane but for the average hobbyist the use of av gas or racing gas possibly blended with some super unleaded would be the easier route.
Regards

[Duke W.]

Re: Toluene as a fuel additive

Toluene is a component in most gasoline blends. It has a Research Octane Number (RON) of somewhere between about 110-115 - I don't recall exactly, and the Pump Octane Number (PON) would be 4-5 points lower. Xylene is another high octane component, but slightly lower.

It's okay to use if you are in a pinch - like on the road, but if you absolutely need higher octane than what's available at the pump I recommend blending in whatever proportion of 100LL avgas or race gas is necessary to quell detonation.

100LL avgas octane number is measured by the "aviation method", which yields an octane rating very close to the Motor Octane Number (MON) , so the PON is about 104-105 - about the same as toluene.

Whenever dealing with octane numbers keep in mind which measurement method is being used and the approximate conversion between them. Most guys toss these numbers around without knowing which method they're dealing with, and, in many cases, have no idea what they're talking about.

PON = (RON + MON)/2, and the difference between MON and RON, known as "sensitivity", is typically about 8-10, and the aviation method yields as stated above - something very close to the MON.

All octane numbers at commercial filling stations in the USA are PON. Europe uses RON, so their "98 octane" is about the same as our 93.

Duke

[Dick W.]

Re: Toluene as a fuel additive

Many, many moons ago we added toluene to pump gas before racing gas was readily available. When we raced micro midgets inside we were limited to gasoline and had to do what we had to do. Outside we ran alky with a little (10%-20%) nitro added. Now talk about aromatics

[Gary S.]

Re: Toluene as a fuel additive

If you plan on doing this yourself, try Googling toluene and read about some of its more nasty side effects.

[Richard F.]

Re: Toluene as a fuel additive

I remember when you could buy toluene at motorcycle shops as an octane booster. I use to mix it for my MX bikes. Years later I read how it is one of the most evil chemicals known to man. I still wonder exactly how it's long term effects are going to kill me.

[Brad M.]

Re: Toluene as a fuel additive

A colleague of mine worked on a project for a company that makes toluene. Apparently one of the Company's main revenues related to sales to soft drink producers (maybe specific to diet ones).

I think the preservative potassium benzoate is somehow derrived from toluene. I drink quite a bit of diet pepsi/diet coke and my colleague tells me that I am drinking oil (as toluene somehow ultimately comes from crude oil apparently).

Clearly this has nothing to do with octane, but maybe an area that me and others who drink diet soft drinks should be concerned about regarding the harmful effects of toluene that were mentioned above.

[Ted S.]

Re: Toluene as a fuel additive

I've been doing some research on fuel additives for my '65 396 car. From my limited web search, it seems that Toluene seems pretty effective. I'm curious if anyone on the board has had any experiences with Toluene, and what are your impressions of it.

Thanks.
Tony

Tony,

If you want to bump the octane you may want to look at the price of race gas verses toluene. Many folks have said race gas is more economical and you can mix it with regular gas just like toluene to get the desired octane. If I remember right Toluene is 114 octane.

I used to run toluene blended with gas in my '60 vette because the "dynamic compression ratio" came in around 8.3:1 with iron heads. The static compression ratio was around 11:1. I would get quite a bit of pinging running on 91 or 92 octane. Usually I would mix about 1 gallon of toluene with 9 gallons of 91 to get the octane up around 94. Then it would run fine.

If your 396 is running at a stock compression ratio and stock cam it very well may run on today's 91 or 92 octane. Many of the high performance engines of yesteryear bled off a lot of compression because of the duration and assocated overlap of the cams. It's interesting to look at the cranking psi of a high performance engine verses a "lower" performance engine. Many times the "lower" performance engine will have higher cranking cylinder pressure than the "high" performance engine.

I have a 396 in a Camaro that's around 11:1 and calculates to 8.3:1 dynamic with aluminum heads that is running fine on pump gas.

Hope this helps, Ted

[Duke W.]

Re: Toluene as a fuel additive

DCR and compression bleed-off have nothing to do with overlap. It's purely a function of the inlet valve closing point. Long duration cams usually have both high overlap and a late closing inlet valve - not all, but this was typical of the SHP cams of the sixties.

The modern LS7 camshaft has medium duration and low overlap (211/230 degs. at .050" lifter rise, 121 degrees LSA), but is phased very late (inlet POML is 124 deg. ATDC). Compare to the L-79 cam, 222/222, 114 LSA, 110 deg ATDC POML.

The later the inlet valve closes the lower the cranking compression pressure and low end torque due to reversion, and this also mitigates low rev detontion. The piston pushes mixture back up the inlet tract up to the mid RPM range, but allows the inlet process to continue well after BDC at high revs due to the inlet mixture's high kinetic energy, which keeps it flowing even with the piston is past BDC and on the compression stroke.

Duke

[Clem Z.]

Re: Toluene as a fuel additive

DCR and compression bleed-off have nothing to do with overlap. It's purely a function of the inlet valve closing point. Long duration cams usually have both high overlap and a late closing inlet valve - not all, but this was typical of the SHP cams of the sixties.

The modern LS7 camshaft has medium duration and low overlap (211/230 degs. at .050" lifter rise, 121 degrees LSA), but is phased very late (inlet POML is 124 deg. ATDC). Compare to the L-79 cam, 222/222, 114 LSA, 110 deg ATDC POML.

The later the inlet valve closes the lower the cranking compression pressure and low end torque due to reversion, and this also mitigates low rev detontion. The piston pushes mixture back up the inlet tract up to the mid RPM range, but allows the inlet process to continue well after BDC at high revs due to the inlet mixture's high kinetic energy, which keeps it flowing even with the piston is past BDC and on the compression stroke.

Duke

will this change with the coming of direct injection on the newer gasoline engines since all the intake track will be moving is air ????

[Duke W.]

Re: Toluene as a fuel additive

Not really. A fuel-air mixture has greater density than air only, so the inertia effect is a little less.

The inertia effect can be enhanced with variable cam phasing. On DOHC engines with variable phasing on the exhaust side only, the cam is usually retarded at cruise, which increases exhaust residual to control NOx and eliminates the need for a separate EGR system.

If variable inlet phasing is incorporated, the cam is usually advanced at low revs (closes the inlet valve early) to enhance low end torque, then retarded at high revs to close the inlet valve later and enhance top end power. This yields a commendably flat torque curve from just off idle to max revs.

I don't know of any single cam engines that have variable cam phasing. About five years ago, GM publically discussed a "dual-cam" SB that they were testing, and I thought this would be the C6 Z06 engine, but that turned out not to be the case.

The only reason to have two in-block cams on a pushrod V-8 would be to implement independent variable cam phasing on both sides, and we may yet see this version SB go into production, but I'm not holding my breathe.

Duke

[Clem Z.]

Re: Toluene as a fuel additive

Not really. A fuel-air mixture has greater density than air only, so the inertia effect is a little less.

The inertia effect can be enhanced with variable cam phasing. On DOHC engines with variable phasing on the exhaust side only, the cam is usually retarded at cruise, which increases exhaust residual to control NOx and eliminates the need for a separate EGR system.

If variable inlet phasing is incorporated, the cam is usually advanced at low revs (closes the inlet valve early) to enhance low end torque, then retarded at high revs to close the inlet valve later and enhance top end power. This yields a commendably flat torque curve from just off idle to max revs.

I don't know of any single cam engines that have variable cam phasing. About five years ago, GM publically discussed a "dual-cam" SB that they were testing, and I thought this would be the C6 Z06 engine, but that turned out not to be the case.

The only reason to have two in-block cams on a pushrod V-8 would be to implement independent variable cam phasing on both sides, and we may yet see this version SB go into production, but I'm not holding my breathe.

Duke

the 500 cu in viper engine uses a single cam that has a way of variable cam timing as it has the cam in 2 pieces. http://www.sae.org/automag/technewsl...ertrain/04.htm