Rudeboy

Hey guys,

I mostly fly planes and heli's but I'm thinking about getting a truck (Savage X SS + LRP Z.28R Spec3) to fill the winter months.

Now, for my planes I normally mix my own fuel, because I've got a bunch of different engines that all seem to like their own blends.
And for my heli's I use Wildcat 15% heli fuel which contains 18% synthetic oil.

How much oil do you normally use in these car engines? I've read all sorts of things, but the general impression I get is that it's more in the 12 to 14% range for cars.
Would it be ok to just take my heli fuel and dilute it with the appropriate amounts of methanol and nitro to get the oil content right?

What's the effect of running 18% oil in a car engine? Will it load up and get hard to tune or what?

Thanks

Snaut Rocket

Some where betweem 8 and 12 should be good enough.

Sugafree

Car Fuel Facts
If you read the R/C car magazines, engine instruction manuals or talk to local racers, you'll likely find conflicting information about car fuels. The main controversy seems to focus on how much and what type of oil is needed for a car fuel.

Here the straight scoop based on over 15 years of experience that includes working closely with engine manufactures, industry experts, top-level racers and the results of testing literally hundreds of formulas in all types of car engines and conditions.

Why Not Airplane Fuel

Car engines operate in a totally different environment than do airplane engines. Airplane engines spend a great deal of their running life at full rpm, they have a constant airflow from the prop to aid in cooling and instant throttle response and acceleration is not as critical as with a car engine.

Car engines spend most of their life accelerating from one corner to the next and are seldom at full RPM for more than a few seconds. They rely on an oversize heat sink head to dissipate combustion heat and racers actually tune car engines based on throttle response.

Fuel designed for airplanes typically have from 15 to 20% oil. While the manufactures that truly understand the requirements of car engines typically put 8 to 12% oil in their car fuel.

Why 8% to 12% Oil

Using high oil content fuels (above 15%) in gas car engines won't provide improved engine life, as some would expect. Through extensive testing we've discovered the point of diminishing return as far as oil content to engine life is actually around 8% for most car engines. In other words any more oil than 8% in the fuel does noting to improve the life of a car engine. In fact the secondary effects of high oil content fuels can actually cause engine damage by encouraging over lean runs. Here's how.

Using high oil content fuel causes a car engine to be unresponsive during acceleration acting as if the engine were running rich. Typically when using high oil content fuel, in order to get crisp acceleration and response, an engine will need to be adjusted overly lean. In addition the high oil content prevents lean bog when an engine is over-leaned thus allowing the engine to run at this lean setting without the customary telltale lean bog warning letting you know the engine is overheating.

In summary, high oil content fuels don't give added protection. The point of diminishing return from a protection standpoint in a gas car application is about 8% oil depending on the oil type and engine. Anymore oil than this doesn't offer added protection and has potential secondary effects that reduce performance and can actually cause you to over lean your engine in an attempt to get crisp throttle response and acceleration. Do yourself a favor and follow these two rules:

Rule #1- Always use a high quality fresh fuel designed specifically for gas car use that has between 8% and 12% oil preferably with at least some castor in it. (We recommend Blue Thunder Sport or Race Formula)

Rule #2 - Don't use airplane fuels or any other type of fuels that have over 15% oil in your gas car engine.



http://www.horizonhobby.com/Articles...ArticleID=1318

cheiro

I'm in the same situation as you... If you got the fuel ready mixed it won't hurt your engine. But performace wise will be less. Big block car engines run on 20%-30% nitro.

As for myself I mix my fuel to this ratio... 15%-18% oil 20%-30% nitro... You'll also find that car engines tend to heat up, lean out alot more than helis... poor fuel tank placement/designs, Hot days, no wind, dust mud stuck on the cooling head.

If you're asking whether having 15% oil will damage the engine my answer would be no.... I've got two savage and one revo between the 3 of them they've gone through almost 40L of fuel with no adverse effect. Maybe I'm lucky

BuzzBomber

My Feedback: (4)

I'm mostly a flyer too, and I've been known to use air fuel (15% nitro 18% 80/20 oil) when I'm out of car fuel. I've done this for several years and never had an issue with doing so--I just accept that power will be down somewhat due to the lower nitro and higher oil content and make sure the engine is tuned appropriately(temp. within spec, smoke plume @ WOT, etc.) instead of trying to eke out every last RPM.

Part of the controversy arises from the fact that most of the published info about what fuel to use where in the hobby world comes from the guys trying to market 15 different blends of fuel......There is no magic fairy dust in car fuel so if you're blending your own, then yes, by all means, add back in some methanol and nitromethane to bring the oil content down to around 14%.

ttoks

theres something being missed here, it is a very good idea if you plan to run your plane/heli fuel in a land engine to add at least some caster oil, caster protects at much higher temp then synthetic, you don't want to run full synthetic in a car engine, particularly if you start tuning for performance.

normally a 50/50 blend of caster and synthetic is good, if not a little more caster.

BuzzBomber

My Feedback: (4)

Interesting you mention that. I like to use fuel with some castor oil content for the very reason you mention, but the car fuel I usually buy (O'Donnell race blend) doesn't mention ANY castor in their blend, just a "special synthetic oil package". Haven't burned an engine out on it yet. Also, the Saito four-strokes I run urge in the manual to use an all-synth lube in the fuel because castor residue can cause problems in the valvetrain, yet I use 80/20 synth-castor wildcat Omega blend with no problems. I realise these are different scenarios, just thought I'd mention it to further obfuscate things. Anyway, the rest of my air engines get at least some castor, and I put a little extra dollop in the fuel for the 1/2A size engines to be safe.

Rudeboy

Most of my plane engines get full synthetic. Only the racing engines and high revving sport engines are run on castor, because it gets a lot thinner when hot compared to the synthetic I use, so the oil film produces less drag.

I guess I'll be putting some castor in this car fuel too. It certainly won't hurt anything.

Dil

i mix my fuel,, 14% oil,, and only 5% nitro,, cos i cant get my hands on proper nitro fuel,, my fuel works well,, i use and oil from shell called castor 927,, which is a castor based synthetic oil, has worked well for me,, the oil is designed for kart engines, which run on alcohol but works for my lil trucks as well,