Hi folks,

I just ordered and received a stockpile of APC pylon props for my Magnum and Whiplash as nobody around these parts carries them.

Question: what is the reason for both 8.75" and 8.8" props? Is there a difference in basic design, or is it for another reason? I ended up ordering 8.8" diameter in 8.5" through 9.25" pitch. I don't have any 8.75" for comparison.

I'll be running these stock or slightly clipped on my SJ50, and clipped to 8" or so for my West .50.

Thx,

MJD

The small differences in the props is for fine tuning the engine for absolute
maximum performance and rpm.

FBD.

The 8 3/4" props were the original pylon props and had a slightly wider blade. The 8.8" are the newer design and primarily used on the Nelson Q500 engines. Both seem to work fine, although I think the best top speed can be gotten with the 8.8" props.

I figured it was a design change, with the choice of 8.8 versus 8.75 to distinguish the difference.

Good - I bought the 8.8's with the goal of going fast. Not much other reason to buy these props though, I guess, is there?

Thanks folks,

MJD

Not really

Good selection of props.

No need to clip any of them on the SJ50 - except for maybe the 9.25 pitch. Then only a little.

Two of my all time favoite props are the 8.75x8.25 and the 8.75x9W.

Which muffler are you using ?

Hi Bob,

I have the SS muffler, so I was not planning to clip any of them for the SJ50 unless the higher pitches like the 9.25 seemed to be a bit much of a load. But for the SS muffler maybe not, right? Darn it I should have bought the other muffler, but oh well.

Based on the .50V1 prop recommendations I was going to look at the 8.75/9/9.25 range clipped down to around 8" on the stock pipe length for that motor. I chickened out on running APC 8" sport props despite the fact that many people seem to be doing so. Now I have a collection of those with no purpose..

MJD

you will be fine with the SS muffler and any of those props (except the 9.25 pitch as noted)

in fact, if you want something scarey, get the 8.5x7.25 prop A little magic occurs.

Say what? For which motor? Seems light for the SJ50/SS combo. Looks like the right load factor for the .50V1 though. Whatchoo talkin' about this magic? Don't tease me like that!

I guess Bob didn't see this to reply but while in the pylon forums I found this posted by Bob27s.

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While breaking-in the early version of the SS-40 engines using the apc 8.5x7 props, quite by accident/luck we found that the SS-40 had a secondary sweet spot just over 20K rpm as well. The 8.5" props ended up working great for the sport class racing. Racing the SS combination you would use an APC 8.5x7 up to 8.5x7.5 pylon prop. Peak RPM is up around 20K on the ground. Find peak rpm, back off 600-800 from there, and go

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Thanks Mike. Actually, Bob wrote me a PM on the subject so I found out what the deal was. I have yet to try this out as the weather has gone for a dump up here.

MJD

Yeah, I got back to him with the little 'magic' story The SS-50 responds about the same as the SS-40 engines did with the 8.5" props.