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-   -   what engine should I put on my 57" p51 to make it a fast ? (https://www.rcuniverse.com/forum/pylon-universe-rc-pylon-racing-323/11617757-what-engine-should-i-put-my-57-p51-make-fast.html)

EBGFLIGHT 05-28-2015 01:14 PM

what engine should I put on my 57" p51 to make it a competitive racer ?
Was thinkin a Saito 150. My other plane has a saito .91 and its pretty fast but I want to build a screemer. Any opionions are appreciated!

EBGFLIGHT 05-29-2015 10:15 PM

I can get a good deal on an OS FS-90. Any opinions? Or objections? IS this is good engine? Will it drain my fuel tank faster than I can get it off the ground? Let me know!

foodstick 05-30-2015 05:52 AM

I am not a pylon racer or expert... but all the guys I knew that liked to go fast years ago put on a Rossi engine with a tuned pipe... That was the typical method in the past around here.

EBGFLIGHT 05-30-2015 09:10 AM

Thanks! That helps a lot

MFLOOD3800 05-30-2015 12:07 PM

There is one engine used today that dominates every other engine used - YS115 WS. You wont find another engine that compares - period.

JohnBuckner 05-30-2015 12:44 PM

What rules planning to race under??? The SAM's group out in California? RC Pro in the south west or elsewhere? All this will have a direct effect on what you can use.


EBGFLIGHT 06-02-2015 11:06 PM

The rules go by times. Gold silver and bronze class. I just came across a Super tigre s75 with a tuned pipe. Also got a new ring and cylinder sleeve. I plan to increase compression and maybe open up the ports a bit. Also going to get a slightly bigger carb. Does anybody know what carb may be slightly larger? Any way it should be a cheap screamer for this 6 lb plane. I think the 115 would be over kill lol. Ive heard these st75 engines pull 10lb plus planes around so my power to weight should be plenty. I also have the same plane with a saito 91 and it rips.

speedracerntrixie 06-03-2015 04:53 AM

It all depends on what you want to do. If you plan to race the airplane then the ST may fall slightly short of silver speeds. A YS 91 AC would be minimum for silver, a 110 puts you in the zone. I tried the piped 2 stroke path for a while. Had a purpose built airplane running an enclosed pipe Rossi 61Setup. This combo would run an APC 11x11 but was only a fast silver airplane. If you want to go gold speed the 115 is the only real option and then if you are going ARF then strengthening mods ars nesessary.

EBGFLIGHT 06-03-2015 09:55 AM

Thanks for the advice! Yea I will probably go with that engine in the end. Just seems a bit big for such a small plane haha but I guess thats what it takes to go fast. Why didn't you use a larger rossi?

speedracerntrixie 06-03-2015 10:07 AM

I strongly considered a Rossi 90 and actually had one in hand, its a very heavy engine and after running the numbers for the engine, header and pipe I realized that going to the YS was a better path. The 2 strokes have the potential but not the consistency to compete with the YS. You seem to.recognise that as you mentioned mods to the ST from the get go.

EBGFLIGHT 06-03-2015 10:20 AM

Yea the consistency of 2 strokes is difficult. I considered a st90 because it is built off a 60 case. But then the pipe I have would probably have too low of a volume. So for consistency issues would you know if anybody has an os 8b carb anywhere I can purchase? I figured that is the correct carb for my set up

EBGFLIGHT 06-03-2015 04:33 PM

Found an 8b carb. Should be at least able to make silver class but well see. I've never raced before and barley practiced so whichever plane ends up being slower will be my practice plane. Thanks for the help I will keep posted

EBGFLIGHT 06-03-2015 04:33 PM

Found an 8b carb. Should be at least able to make silver class but well see. I've never raced before and barley practiced so whichever plane ends up being slower will be my practice plane. Thanks for the help I will keep posted

MFLOOD3800 06-03-2015 05:29 PM

There is no such thing as "over kill" when it comes to racing. You need to go wash your mouth out and never use those words again, ever...

Seriously why re invent the wheel? Get a YS110 for silver and a 115 for Gold. By the time you buy the 2 stroke, the pipe and a series of props, you have exceeded the cost of a used YS.

EBGFLIGHT 06-03-2015 05:54 PM

Should have said something before I bought all this junk! Jk I do it for the fun factor. I will still probably end up with an ys 110 though to mount once I start getting consistent times

Prop_Washer2 06-03-2015 06:55 PM

This one will make it go...


EBGFLIGHT 06-03-2015 07:05 PM

That would be insane haha

Prop_Washer2 06-03-2015 07:39 PM

You want to go fast or not..??? Let's start with how fast do you want to go..in a measureable MPH or Kmph...You call it...I'll tell you which power plant to use...or are you 16 years old..??

EBGFLIGHT 06-03-2015 09:18 PM

Yea I want to go fast I mean how fast is silver class? Maybe break 100 mph? Anyway when I first started this thread I was planning to use a thumper maybe the ys 110 or 115 if it was mentioned earlier. but, when foodstick mentioned a tuned pipe I knew I had to do a 2 stroke build. I remember seeing those things rip around when I was younger and they seemed super cool and fast. sorry I kinda turned this thread from what engine to use into my 2stroke build. But I am thinking a tuned pipe, larger carb, slight porting, polishing, raised compression, and maybe make a billet piston running 30% nitro will get me to 100 on a 6 pound plane if the engine holds up. If all else fails and it ends up sucking I'll chuck it and buy a ys. Or what engine would you recommend for this 6 pound p51 to break 100mph?

speedracerntrixie 06-04-2015 06:55 AM

Do more reading, the compression ratio as it is now will not allow more then 15% nitro. Dont get carried away with porting other then a longer exhaust duration. Set the pipe up for about 13K and then start with a 12x10 APC.

EBGFLIGHT 06-04-2015 11:16 AM

Thanks speedracerntrixie your absolutely right about the comp ratios. Any other more suggestions from your experience? It all helps a ton.

Axle Al 06-04-2015 02:21 PM

If you only want to do 100mph? almost any .60 two stroke nitro with tuned pipe or tuned muffler will do that. If you get it set up right and the right prop. Even though I am no OS fan, if you are new to the speed thrill, get an os .55 ax and the evolution tuned muffler, $60 or the jett tuned muffler. apc 11x7 for break in then try apc 10x8. 10% nitro and depending on what P51 you got you may get as much as 115 mph. the trouble starts when you want to get over 120+ Check out the Rossi .61 speed 13. great price, There are many engine choices but the supertigre is in my opinion not the ones to mess with. Unless it is some older rear exhaust pylon motos from the old days when two stroke nitro was in it's prime time. Good luck

speedracerntrixie 06-04-2015 04:09 PM

The ST is not the best choice however if he takes avantage of the engines torque I think it will be faster then with a screaming .61 in the nose. An ARF P-51 is pretty much a drag bucket. That's why I reccomended a 12" prop. The ST will be able to spin a 10" pitch prop with a little tuning. The speed 13 is set up to spin an 11x7 or 11x8 at high rpm. That small of a prop is just not going to work on a draggy airplane. I have seen many WM Mustang .46 ARFs with YS 110 doing about 130 mph. The ST 91 should get to 110.

airraptor 06-04-2015 04:39 PM

EB flight The St75 is a good engine and can be made in to a power house. all engines of the same size can be made to run the same rpm on the same prop. some just need more work than others.
I would stick with the ST carb as they are the best carbs out there on stock engines. you can open the carb up some. I would also run a Jett tuned muffler over a full tuned pipe as it much simpler to set up and run on the plane where as the full tuned pipe has to have mounts and clamps for the coupler. you will only lose 200 or so over the full tuned pipe by going with the Jett muffler. I can check on what can be done to this engine but i think you should be able to do a 12x10 around 13500 not 100% but should be close. it can be set up to run on 5% nitro and run that number.

EBGFLIGHT 06-05-2015 06:55 PM

Airraptor thanks for the support. I already have a tuned pipe and mounting wont be a problem, I love to fabricate stuff like this. If you can check what to can be done that would be fantastic. I have two of these engine and want to race one and use the other for an aerobatic plane.

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