In reply to frenchyd:
I'm not running it on ethanol though. And with E0 vs E10, they just blend in cheaper (lower octane) gas to get the same octane as an end result.
The only time I've ever had this engine ping was when it was bone stock. And it was only ever at ~2800 rpm and 2/3 - 3/4 throttle. In other words, a bad spot in the stock tune (thanks Chrysler). With a good tune and the current cam, etc. 91 octane E0 is enough to get MBT out of it. It would need timing pulled to run on 87 though.
frenchyd wrote: Ethanol has an octane of 114 (methanol is 116) plus the flame front on alcohol is slower than the flame front on Gasoline both of which improve knock resistance.. If you are having "ping" or knock at 9.1-1 compression it's likely there are some sharp corners in the combustion chamber someplace.
Yeah that's interesting. 9.1 to 1 compression is a low compression engine in my book for being naturally aspirated, even at sea level and hot weather.
9.1:1 static and a tiny cam that only gets 230-250hp out of 5.9 liters with (I'm assuming) decent heads probably leads to a high dynamic compression ratio, which is the actual number of importance when talking about octane requirements.
The stock heads on the 5.9s are ok, but not great. You're dead on about the tiny cam though. Tiny cam, intake that's good at filling cylinders at low / mid RPM, pistons way down in the bore for awful quench, iron heads, etc. all lead to being more knock prone than you'd expect.
For comparison, I now have a somewhat bigger (but still small) cam, an intake more suited to mid / high rpm, better heads (better flowing and slightly better at getting heat out of the chambers) and thinner head gaskets for better quench (still not very good). Higher compression and more aggressive timing than stock, but it's less knock prone...
maybe those of us that get tired of taking little carburetors off of little motors and cleaning them (again) when in fact we were fully expecting said motors to fire off with a pull of the cord... 
759NRNG wrote: maybe those of us that get tired of taking little carburetors off of little motors and cleaning them (again) when in fact we were fully expecting said motors to fire off with a pull of the cord...
If the manufacturers of said small carbs pulled their heads out of their rears, that would be taken care of.
In reply to alfadriver:
What do you figure they need to do? From what I've seen the modern fuel is just too volatile and varnishes up fast, the only solution I can think of it to set up everything with shutoff valves so it's easy to run them dry. I don't think evap standards will allow the old push button float bowl drains some stuff used to have.
BrokenYugo wrote: In reply to alfadriver: What do you figure they need to do? From what I've seen the modern fuel is just too volatile and varnishes up fast, the only solution I can think of it to set up everything with shutoff valves so it's easy to run them dry. I don't think evap standards will allow the old push button float bowl drains some stuff used to have.
Two reasons- older small carbs don't do that, and, most important, cars don't do that.
It's not about being a sealed system that's the problem, they cheapened the hardware to react to ethanol differently. We've had over 30 years of materials research to know what does and does not react to fuel. Choose one that does not. Done.
Modern fuel is actually less volatile than older fuel, so that it evaporates at a slower pace, which does less harm in the long run.
My old mower never once had a problem, and I just ran a power washer I got probably 15 years ago for the first time in at least 5 years with no problem. But my fairly new chipper/shredder- what a POS. This is a new thing, and the crap they give the fuel is total BS. They should be robust to the most common fuel on the market. Period.
It's not rocket science- but it's a sub set of rocket science- material science.
Yeah, the modern fuels are a lot more "heavy" than they used to be, which makes evaporative emissions a lot lower.
Spilled gasoline just doesn't evaporate like it used to. A friend remarked that when he spilled a little E85 on his Miata, it evaporated almost instantly. Gasoline used to do that, doesn't anymore.
OTOH, I believe the emissions levels currently are such that half a gallon of spilled gasoline is equivalent to permissible HC emissions for 200,000 miles of driving. This includes exhaust emissions, evap emissions, and emissions from the rubber/plastic (underhood and interior) deteriorating.
759NRNG wrote: maybe those of us that get tired of taking little carburetors off of little motors and cleaning them (again) when in fact we were fully expecting said motors to fire off with a pull of the cord...Or since it's just push the button on the riding lawnmower maybe you could mow the lawn?
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