Fuel requirements for B21 engine

[Blt2Lst]

This is regarding my 1980 volvo 242Gt with B21 engine.

The owners manual say's I should run 91 octane unleaded fuel.

The guy I got the car from said he always used 91 octane premium gas.

However, I have been using 89 octane since I got the car back in april due to the high gas prices here in Calif. The car seems to run the same without any sign of detonation.

My question is can I run 87 regular gas without harming the engine. I realize if the engine does ping I can retard timing some but will probably make the car sluggish.

Other than that, is there some reason why the factory would reccomend 91 octane gas for this model?

Thanks for the input

Al

[Cyberr]

We drive on 95, 96 or 98 octane. You should only loose some high rmp power. If it doesn’t sound like knocking when you do a kick down, there shouldn’t be any problem.

Don’t know why factory recommended 91 octanes; don’t remember if we had 91 to choose on either. However – more octane – safer run on every car.

They might have modified the cars for you octane when they shipped them over. Don’t think they dared to sell them otherwise, however these engines are strong! Can handle much!

Since our gas price is a lot more then your, so are even we trying to find other options. So, many drives on Ethanol. E85 as we call it. Could be compared as like 105 octane petrol. So some modifications must be done to get a stable idle and full high rmp power. There are some special made parts for carburettors, and if you have injection you could just change the parts which I don’t know what you call them, raw translation “spreaders” the 4 little thing which injects the fuel – to larger. You need 25% fuel to compensate ethanol.


In short, if you don’t notice any rare sound or loose of effect (so it gets annoying) so isn’t there any problem. You can drive these engines without oil and water, almost. :-)