How many RPMs on the ground for a West .50V1 with an 8X10?
 

Hi guys,

How many RPMs should I be turning on the ground for a West .50V1 with an 8X10 prop? (when the engine is properly tuned, with the standard tuned pipe that comes from West)


What about an 8X8 prop?

The 8X10 is the prop that I really the need the answer for (as that is what I'm going to run).

Thanks,

Mike

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

If you get no response, try [email protected], though he's not fast at e-mail responses.

Their comment was that on the 8x10 they got the best top speed, but the launches could be tricky, and to run the stock pipe length. I never asked about ground rpm on that prop.

MJD

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

Mike what you need is an APC 8x9 , on the ground you should get arround 20000 to 20500 rpm with a 10% cool power and 1/2 inc. off the engine manifold.
I'm flying the magnum since 2000 so is a friend of mine and we did tried any conbination including the 8x10 prop wich did produce 18250 rpm and it was noticeably slower.

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

Thanks MJD and Av8or48!

I was looking at an earlier post from MJD where he quotes Alan at Weston saying that 8X10 gave the best top speed:


But if Av8or48 has run both an 8X10 and 8X9 against each other in a challenge, it looks like I'll have to bring both props to the field this weekend and see. I'll try and record video and post it (too bad I don't have a radar gun though [:o])


Thanks for the input everybody! :)

-Mike

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

Flew the Magnum on Saturday with both a 8X10 and a 8X9. Speed difference was negligible, launches a bit exciting with both props (versus the 9-7). Suprisingly the top speed appeared to be the same as with the 9x7. For some reason I was only able to turn 17200 RPMs with the 8x9 (not even close to the 20000-21000 RPM that others claim). What's going on? As I leaned it out, the engine would die when the throttle was moved from low to high. Who knows, maybe the low end needs some adjustment too. I hate tuning :(

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

More engines have been fried fron a too lean low speed needle than most realize. The low speed needle is contributing to fuel flow all the way up to 75-80% of WOT on some engines.

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

Yep! Been there done that. The mixture might be fine at WOT (look at all the smoke!), but then goes to seed at mid throttle settings (where's the exhaust trail?). It's worth paying careful attention to the low speed mixture. Sure there's less heat being produced at mid settings but too lean is still too lean.

MJD

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

Fortunately, my Magnum spends all it's time at WOT.....so maybe I don't have to worry about the low end mixture at all :D

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

WOT?

What does that mean?

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

WOT = Wide Open Throttle (Full Throttle baby :D )

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

Ok! ;) :eek:

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

Men, I really dont know what you guys are doing but I am getting 20K RPM´s with a APC 9x7 using 10% fuel.

Also, I have not cut my header but when I join it with the pipe using the rubber cupler I make sure that the gap between the pipe and the header is minimun............So maybe here is the clue!
What is your gap between the pipe and the header? Also make sure the pipe and the header does not touch inside the rubber because this can cause RF noise since there be metal to metal contac and the vibration can make RF noise causeing glitch.

Isaac

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

If you don't like tuning, you're in the wrong hobby ;). That is what this speed stuff is all about. There are not many off the shelf combos that are optimal, especially with the various pipe / prop combos out there. I tested a piped WEBRA .50 with 9x8, 8x9 and 8x10 props, and found that it handled the 8x9 the best for speed [155 mph on a delta], but the 9x8 gave twice the thrust for carefree launches and the speed only went down 3 mph. I got more speed from shaving the prop blades, but that APC plastic has its' limits.......it's time to switch to carbon. I have seen my WEBRA .50 turn an APC 8x10 sport prop close to 20,000, then throw both blades before I could shut it down. This engine is stock except for ditching the carb and using a fixed venturi with a high pressure bladder feed.

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

Hey Dude, I have 2 Webra Speed 50GT. Can you explain what is ditching the carb and using a fixed venturi with a high pressure bladder feed. Maybe I will interested in this mod for my Webras:D

THX,

Isaac

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

Here is a look at the entire fuel system, if you are serious about going fast, and don't care about a throttle, then a fixed venturi is the only way to go. The venturi was made on a lathe, but I used to make them on a drill press, with a chisel or sharpened screwdriver for a cutting tool. The needle valve is from an OS .10 or .15 FSR, it has a fine thread and will control bladder pressure. The bladder is latex tubing, you use a syringe to load it with fuel. Bladder systems are more work and can be a pain, but when everything is working right, they can't be beat

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

So the Bladder is like your fuel tank???How many ounzes of fuel you can put on the blader?? How long you can fly with this system? Also, I dont undertand how you keep "CONSTANT" presure on the bladder. I undertand that when the bladder is full there has to be more pressure than when the bladder is half full.

THX,

Isaac

RE: How many RPMs on the ground for a West .50V1 with an 8X10?
 

A bladder of this size will allow almost 4 ozs of fuel, without bursting........most of the time. how long can a 40 sized engine run, running at 24,000 on almost 4 ozs of fuel? Just long enough to be started, launched and run through a 315 foot long [1/16th mile] timing zone about 3 or 4 times. I would guess the burn rate is close to 2 ozs per minute. The pressure remains constant enough, if you don't over fill them. At the very end of the run, the wall thickness of the tubing goes back to its' original thickness and the engine goes rich for a few seconds, signalling the end of the run and cooling the engine slightly.