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Old 05-07-2008, 03:59 PM   #76
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Originally Posted by Maximo View Post
Well a LRP Spec 3 is a sport motor made in Taiwan.... it has decent power but lacks top end RPM , it is designed as a MT motor, but they made a so called Truggy version, but at heart its still a 13 mm crank sport motor..........Most good .21 engines will outperform it !
What does MT stand for? I do think this is s truggy engine, just the power it has, it spins the wheels no matter what speed im doing, its nuts, almost too much power, very hard to keep straight without "fishtailing" everywhere. and yes im light on the steering, it still goes sideways.

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Ok, let's address several of your comments/questions:

1) Faster and quicker are not the same. 1/8 scale buggies RARELY see a track where they will top out... but they see a lot of tight tracks that need instant acceleration to clear jumps or make a quick burst down a short straigtht between corners. Even if you are 10 mph faster on the top end, you'll NEVER use that on anything but the very largest tracks, and then only on one long straight. Even if there is a huge straight, a car that accelerates quicker but doesn't top out as high will probably finish the straight ahead of one that accelerates slowely but has a faster top speed. It is about the AVERAGE speed down the straight.

2) Without knowing what the other gears are in your car, it is impossible to say what your final gear ratio is. Simply saying "I have an 18t bell" is like saying "I have a 5 speed" in a real car. The final drive ratio is the important part, and that relates to the clutch bell, spur gear, pinion gears, and ring gears.

3) Going from a 18t to 12t is about as drastic of a change as you can get without other changes. A change of 1 tooth on a clutch bell is a noticeable change! 12 is 2/3 of 18... so... in the simplest terms possible, you will have 1/3 more torque to the wheels than you did, so it will accelerate faster by 1/3, BUT, you will also lose 1/3 of your top speed. Say your buggy topped out at 48 mph before. (Not likely, but possible...) And say you were hitting the top RPM the engine was capable of. Going to a 12t bell will mean your top speed is now 32 mph! Even if it could hit 51 mph (I'm keeping the numbers round so the math is simple) your top speed would be 34 mph.

4) In addition to the issue with bearing sizes, you're going to have to move the motor mount a bit to get the gear mesh right... and that big of a change may be outside the range of adjustment available to you. It may REQUIRE a bigger spur gear just to get within the range of adjustment... which increases the torque even more... but also reduces the top speed even more.

5) The issue of the motor has already been addressed... but bigger isn't always better. A good quality .21 will make more power than your motor, especially on the top end... and you aren't class legal for racing with a .28 even if it doesn't make as much power. Besides, I've seen someone put an .18 in a buggy and lay the smack down on a bunch of .21s. It is all about having what suits your car, the track conditions, and your driving style.
DAMN that was a helpful post!!

1. I realize what you said there, but keep in mind I dont race. Just wide open fields and gravel roads for me, so acceleration isint a big deal... I have an unlimited amount in front of me to accelerate... Its the absolute max top speed im trying to get.

2. The only gear I know for sure is the clutch (duh). The gear that goes up against the clutch (spur gear?) Is stock in a Mugen mbx5, which I believe is 44T. Thats very interesting math, ive never thought of it that way.

3. I know its a drastic change, thats why I bought it :P. I think ive switched before from a 13-14T clutch and didnt really feel a difference, cant wait to try this change! Thats very interesting math, ive never thought of it that way.

4.Please dont tell me youre talking about my 12t / 5x8MM bearing problem . If I have to adjust my motor mount im screwed, its barely working as it is, and if I have to change it, ill just sell this 12t clutch I have, along with the bearings I ordered. Like I said, I dont even care about torque/acceleration so its def not worth it. Maybe if I was racing, and serious about it I would consider this change.

5. Yes, I knew that .28 wasnt race legal, do they race in just a .28 class, or is only .21s that are allowed to race "legally". Im not sure if this engine suits my car or not, I dont think it does. my tires are too small the are constantly fighting to get traction, but I still have fun nonetheless. But is it safe to say that .28 engines are the most powerful? or will a top of the line, completely modded, perfectly tuned .21 beat a .28? when its time for a new engine in my other car, id like to stick with a .28, maybe one even more powerful than my LRP.

ps: I have a second car that didnt have its engine broken in, pretty much took it out of the package and had it WOT down the street... for about 2 tanks. Now its got about a gallon through it, It sat for about 3 or 4 months, and it still runs awesome, still has lots of compression, im very impressed with this junk japan SH motor that wasnt broken in at all, its a nice engine. Am I going to see any long term effects of not breaking it in? It might lost ALL compression around the 3-4 gallon mark? whereas a properly broken in engine will start to lose compression at around 7-8?? (im just picking random numbers)
Thanks A LOT for all the help guys, im learning a lot here
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Old 05-07-2008, 04:06 PM   #77
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Originally Posted by blowpopracer View Post
I would STRONGLY suggest staying away form go techs and vspec. Both are cheap and both are ok engines but reality is they just dont last long.

I would recommend for your price to look at

1)grp,ninja(old version) or my personal favorite falcon
2)Any RB or NovaRossi
3)os engines just not the vspec

Just trust me stay away from go tech and vspecs. If you ignore my advice let me know when you hit the 10+ gallon mark how well you like them.


Also remember that when someone makes a recommendation, and they have that recommendation listed as a sponsor on their signature line, that maybe they arent giving you true factual unbiased info.
well said i take my hat off to you your 100% correct
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Old 05-08-2008, 10:36 AM   #78
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Originally Posted by German Muscle View Post
Dynos will tell you everything you need to know except fuel milage...... just like in real racing.
right...and i can come up with every single variable there is when it comes to these 2 stroke nitro engines...so many variables its almost a watse of time to list.

a manually adjusted carb alone is enough to flaw most dynos.

Like i said, the only test for me is on the track, against the clock, in race conditions. A dyno cannot do that for me, sorry.

in scale sized dynos its all controlled, and even then, its still not 100% accurate. In NASCAR, at the end, it all comes down to how it performs 500 miles into the race...no Dyno can test race conditions...none.

I rather burn fuel on the track, not on a dyno jmho.

its a tool, but i personally think it should never be the end all when it comes to performance.
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Old 05-08-2008, 01:34 PM   #79
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lets see some of these variables. You tune the engine for the dyno just like you do on a car. you can tell if its tuned incorrectly as well.
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Old 05-08-2008, 04:40 PM   #80
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Originally Posted by German Muscle View Post
lets see some of these variables. You tune the engine for the dyno just like you do on a car. you can tell if its tuned incorrectly as well.
Lets just start paying out awards for the guy with the best dyno results.

I said it in another post i will say it in this one. We dont race dynos, we race rc cars. Leave your dyno talk to the bench racers that for some reason cant make the a-main with the motor that has the best dyno results.
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Old 05-08-2008, 04:54 PM   #81
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lets see some of these variables. You tune the engine for the dyno just like you do on a car. you can tell if its tuned incorrectly as well.
Some people have a very hard time when you get into dyno talk as they just cant grasp the concept of how it relates. I agree with you German Muscle a dyno is a excellent way of comparing apples to apples. If a guy like me cant drive and wants to have the most powerful motor on the market the only way to really know that is with a dyno. Once you drop it in a vehicle there are alot of variables that determine how fast the buggy will look with that motor in it. Examples include poor driving, and wheel spin but in the end the most powerful motor can only be proved and verified with a dyno.

In other words I buy the engine with the most horsepower ever proven on a dyno and I put it on my buggy, this doesnt mean my buggy will be faster than all other buggies in speed or lap times but it does mean I have the most motor! Wes I hope this info helps you understand why people discuss dyno results.
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Old 05-08-2008, 05:00 PM   #82
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Guarnatee I Can lean the hell outta my $125 second hand RB S5 and put out some whoping numbers on a dyno.

Means nothing. At all. Full scale dynos are for bragging rights and thats it. When you are talking about a .21 motor. The biggest difference between the top motors is .1-.2 horsepower. Im not gonna be bragging to much about that. Dyno results mean nothing. I my motor usually comes off the track at about 260*. Where as someone whos motor dynos at .1 horsepower more than mine comes off at 210*. I can tell you right now, my motor was making more power. No dyno needed.
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Old 05-08-2008, 05:09 PM   #83
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Originally Posted by wes95_z28 View Post
Guarnatee I Can lean the hell outta my $125 second hand RB S5 and put out some whoping numbers on a dyno.

Means nothing. At all. Full scale dynos are for bragging rights and thats it. When you are talking about a .21 motor. The biggest difference between the top motors is .1-.2 horsepower. Im not gonna be bragging to much about that. Dyno results mean nothing. I my motor usually comes off the track at about 260*. Where as someone whos motor dynos at .1 horsepower more than mine comes off at 210*. I can tell you right now, my motor was making more power. No dyno needed.
Wes I dont want to be rude but once again it seems like you can not grasp the concept of a dyno. If that is how you think thats fine and Im not going to waste anymore of this thread trying to educate you. If dyno results mean nothing lean out your s5 and send it to me in which I will send in that and my new os .28 modded motor from maximo(once I send him the money) and we can dyno them both then Ill put both of them in my buggy and have them clocked at the end of the straight. Im sure your s5 will keep up reguardless of the dyno results.

I better stop now before I say something I will regret, its just very hard reading posts from people who obviously dont understand what they are talking about.
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Old 05-08-2008, 05:17 PM   #84
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Originally Posted by blowpopracer View Post
Wes I dont want to be rude but once again it seems like you can not grasp the concept of a dyno. If that is how you think thats fine and Im not going to waste anymore of this thread trying to educate you. If dyno results mean nothing lean out your s5 and send it to me in which I will send in that and my new os .28 modded motor from maximo(once I send him the money) and we can dyno them both then Ill put both of them in my buggy and have them clocked at the end of the straight. Im sure your s5 will keep up reguardless of the dyno results.

I better stop now before I say something I will regret, its just very hard reading posts from people who obviously dont understand what they are talking about.

I am an engine builder, I build high performance offshore marine engines. Most the engines I build are Merlin 540 ci+. They make anywhere from 750-1200 horsepower depending on how much the customer wants to spend. As an engine builder I am telling you dyno results are for bragging rights only. Thats it. Ask any engine builder.
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Old 05-08-2008, 05:39 PM   #85
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Originally Posted by wes95_z28 View Post
Guarnatee I Can lean the hell outta my $125 second hand RB S5 and put out some whoping numbers on a dyno.

Means nothing. At all. Full scale dynos are for bragging rights and thats it. When you are talking about a .21 motor. The biggest difference between the top motors is .1-.2 horsepower. Im not gonna be bragging to much about that. Dyno results mean nothing. I my motor usually comes off the track at about 260*. Where as someone whos motor dynos at .1 horsepower more than mine comes off at 210*. I can tell you right now, my motor was making more power. No dyno needed.
actually no you cant, when you lean the engine out it will loose power and shows on the dyno. It also does the same thing when to rich, youll get a tune where it likes and its right on and itll make the highest numbers and smoothest graph over and over again. You can see how you need to gear your car with a dyno where you need to have the gear change and where you need to set your clutch to enguage. The dyno is far from bragging rights. Its meant to be a standard to see where all engines tested stand and what kind of power and how broad of a power curve the engine makes for the money. Its definatly a useful took in everything above and deciding on what engine fits your application. Everyone who knows something knows that with dynos its not about how big the peak numbers are.... its all about area under the curve. And when your dealing with top of the line engines anything can happen. RBs claim to fame engine only makes 1.4HP and then there are plenty of other .21s that make 1.6HP with alot beter powercurve. The two top on road engines out right now: the Picco P9R Evo 2 and the novarossi 35+21 is almost a .4HP difference in power.

NEXT!
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Old 05-08-2008, 06:11 PM   #86
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dyno's are not just bragging rights. I must ask, how do you set and develop you ignition curves on your marine motors if you dont use a dyno? by feel?

ignition curve
AF ratio (airfuel)
torque curve
clutch engagement or torque converter
varibles between different engine parts using previous set points includ AF ratio


these are just a couple things the dyno can do, which you can not by feel. you might think you can but you cant beat a computer doing the maths for you.

sorry to chime in but I have used and sometimes not used dyno's for years now and spent more money then most of big horsepower engines. I can say the dyno is very useful in developing the combinations. once its sorted, well yes then its just bragging rights... my 2c.
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Old 05-08-2008, 06:13 PM   #87
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the dyno is fun but definitely not a replacement for on track testing to see how you can change your useable powerband with all the different chassis tuning , clutch (very important), pipe (very important), throttle curve (for the finger) , turbo or standard , heat range of plug and on and on and on and on and on ......................... get the drift ? LOL hey german muscle try this one on your dyno ; plus 21 block (tko ceramic bearings)with 421b(821b) piston/sleeve set ,odonnell 77t plug,dynamite 086 pipe/header set , 8mm carb insert .
monty
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Old 05-08-2008, 06:50 PM   #88
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the dyno is fun but definitely not a replacement for on track testing to see how you can change your useable powerband with all the different chassis tuning , clutch (very important), pipe (very important), throttle curve (for the finger) , turbo or standard , heat range of plug and on and on and on and on and on ......................... get the drift ? LOL hey german muscle try this one on your dyno ; plus 21 block (tko ceramic bearings)with 421b(821b) piston/sleeve set ,odonnell 77t plug,dynamite 086 pipe/header set , 8mm carb insert .
monty
which 21+ block? 5 or 7? Also what rod? 821b? i can source everything except the 821B parts i think.
BTW its not my dyno but its a friends that i have access to. Hes already dyno'd the NR 421B and S821B.
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Old 05-08-2008, 06:53 PM   #89
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actually no you cant, when you lean the engine out it will loose power and shows on the dyno. It also does the same thing when to rich, youll get a tune where it likes and its right on and itll make the highest numbers and smoothest graph over and over again. You can see how you need to gear your car with a dyno where you need to have the gear change and where you need to set your clutch to enguage. The dyno is far from bragging rights. Its meant to be a standard to see where all engines tested stand and what kind of power and how broad of a power curve the engine makes for the money. Its definatly a useful took in everything above and deciding on what engine fits your application. Everyone who knows something knows that with dynos its not about how big the peak numbers are.... its all about area under the curve. And when your dealing with top of the line engines anything can happen. RBs claim to fame engine only makes 1.4HP and then there are plenty of other .21s that make 1.6HP with alot beter powercurve. The two top on road engines out right now: the Picco P9R Evo 2 and the novarossi 35+21 is almost a .4HP difference in power.

NEXT!
im next sir, My LRP .28 PS claims to have 3.8 HP... Im being lied to right?

they also claim the starter box version has 3.9 HP... that seems too much if yours are 1.6 and 1.4?
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Old 05-08-2008, 07:07 PM   #90
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im next sir, My LRP .28 PS claims to have 3.8 HP... Im being lied to right?

they also claim the starter box version has 3.9 HP... that seems too much if yours are 1.6 and 1.4?
Yes all manufacturer power claims are extreme lies. This was the main reason the X-Dyno was made. Which LRP .28 engine do you have? Should be a Spec 1, 2, or 3
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