Out of Curiosity... 4360 Question

[GRNDP51]

For all you round engine guys... Was the 4360 geared properly so any type of "slow nose" wouldn't be necessary for the power it put out? Basically, in a finely tuned race-prepped Furias, the propellors stay at a 'safe' RPM when ran at high power, correct?

[W J Pearce]

Re: Out of Curiosity... 4360 Question

The R-3350 was not exactly geared incorrectly, it just did not have the best gearing when used in a role for which it was never designed to fulfill (air racing). If I have me info straight, the most common propeller gear reduction ratio used on the R-4360 was .375, but .381 and .425 were also used. The .375 reduction is fairly close to the coveted R-3350 EA-2 slow nose case ratio of .355, especially when you consider a “normal” R-3350 has a .4375 reduction. Early R-3350s did have a .35 reduction, but those cases cannot be used on the redesigned, later (better) engines. So, an R-4360 with the common .375 reduction would probably work fine, and there is no low-speed alternative anyway.

[Race5]

Re: Out of Curiosity... 4360 Question

The 4360 can't run at the high rpm numbers that a race prepped 3350 can either.

[W J Pearce]

Re: Out of Curiosity... 4360 Question

The 4360 can't run at the high rpm numbers that a race prepped 3350 can either.

Excellent point.

[RAD2LTR]

Re: Out of Curiosity... 4360 Question

I'll say this much, shooting Dreadnought at full race power at 1/125 doesn't come close to a perfect prop circle. I think I'd find it about 1/80 sec. I've got some shots of Sawbones at 1/125 that have it at pretty close to a full circle. I'll have to go revisit my 232 and 77 shots to see how much prop blur I have at what setting.

Its funny I was just talking about shooting Dreadnought, 77 and 232 at slow shutter speeds last night with a friend. 4360s and slow case 3350s are really hard to shoot and get a perfect prop circle since they are usually moving at a good clip, and they turn so slowly that shutter speed becomes a serious issue.

Will

[88SC]

Re: Out of Curiosity... 4360 Question

Excellent point.

I read an article/interview with Dennis Sanders once, where he said that they experimented with an engine speed of 3,200 rpm. He said that they discovered that the valves were just barely kissing the reliefs in the pistons, when they pulled a jug.

Shouldn’t be too hard to find the article.