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Old 12-18-2003, 08:14 PM   #1
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Default Dyno numbers don't mean anything!

Every time i call or go to a shop to look at motors the guy behind the counter says, the numbers dont mean anything after you cut the comm. yes. but i havent cut the comm yet, I am comparing data that the manufacturer got, so if i get a motor with 50 watts 50tq 50 rpm & 50 eff, when I cut the comm it will have the same power as a motor that read 100 watts 100 tq 100 rpm & 100 eff? after i cut the comm on that one to! someone doesent understand! is it me? or them. for my money i would gamble with the one with better numbers.
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Old 12-18-2003, 08:32 PM   #2
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Default Re: Dyno numbers don't mean anything!

Quote:
Originally posted by Charlie O
Every time i call or go to a shop to look at motors the guy behind the counter says, the numbers dont mean anything after you cut the comm. yes. but i havent cut the comm yet, I am comparing data that the manufacturer got, so if i get a motor with 50 watts 50tq 50 rpm & 50 eff, when I cut the comm it will have the same power as a motor that read 100 watts 100 tq 100 rpm & 100 eff? after i cut the comm on that one to! someone doesent understand! is it me? or them. for my money i would gamble with the one with better numbers.
I would find a new place to buy motors from. Most pro motors have been diamond trued already
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Old 12-18-2003, 11:13 PM   #3
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The numbers that come with most motors don't mean anything. Also, maybe he was trying to say that you shouldn't dyno a motor just after you have trued the comm unless it has been properly broken in.
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Old 12-19-2003, 12:34 AM   #4
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I have just bought a CS Dyno and don't fully understand how to interpret the read-outs.

I haven't connected it to a PC but the dyno has its own screen and shows three read outs : max revs, max efficiency and max power. Not sure how to read the figues under each heading.

Anyone using a CS that can help.

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Old 12-19-2003, 12:52 AM   #5
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The guy who said that dyno numbers dont mean anything dont know what dyno numbers mean.
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Old 12-19-2003, 03:15 AM   #6
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Dyno numbers do mean something, they just don't mean EVERYTHING.

If there is a motor in the shop with a power rating a few watts higher than the others - I would DEFINITELY buy that one.

Yes, tweaking/rebuilding a motor will make a difference - and most of the manufacturers just throw the motor on the dyno without even bedding in the brushes - so a motor that performs well untweaked can surely only get better.
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Old 12-19-2003, 05:09 AM   #7
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I'm quite sure, that different manufacturers dyno motors in different ways. The dynos themselves are different. The motor truing are different too. But as long as you are comparing the same motor from the same manufacturer, you can trust the data. So looking at two Monsters, I would definately go with the one with the best numbers. But comparing a Peak stock with a Reedy stock, I wouldnt even compare the numbers.

About trueing a motor; ALigning the brush hoods, is the single-most important step.
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Old 12-19-2003, 04:44 PM   #8
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Cole - no, you can't really. When I used to race stock, I would buy two motors, and test them, often times the one with the better numbers would come out worse, and this was before I did anything to them.

Until the brushes have been properly broken in and seated, dyno numbers aren't going to be very good performance indicators. Most motor companies don't spent the time to break the motor in for a few minutes at 2.5 volts. I also have doubts that some companies even dyno motors that they include a data sheet with.

Anyone who has a dyno can tell you that far more often than not, the numbers that come with a motor are a load of bull.
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Old 12-19-2003, 05:41 PM   #9
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dyno numbers on new motors seem to only be REALLY useful to seperate out the 'obvious' dogs.

as previously mentioned, brush wrap (break-in), comm size, bushing polishing/wear, hood alignment, stack centering...all can change the #'s a motor will make on the dyno. once a motor is fully broken in, it usually doesn't not change too much until the comm gets down a ways. obviously if given the choice between 2 motors, go for the one with better numbers.

a new motors dyno number is like measuring how much you can bench press at age 12. not long after that the performance is going to change (like till you're 20), but then it's going to stay consistent for most of the rest of the life of the motor.
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Old 12-19-2003, 06:00 PM   #10
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The problem is you can't rely on peak numbers... I've been working with engines both big and small for years, I've raced 1/4 mile and also into mud bogging and sportbikes... Too many people want to be awed by this really high peak number but forget to look at what the motor does across it's full RMP range... While doing work on my 2002 R1's engine I took a lot into consideration. How often would I really be doing 11,000 RPM? Not much... I gave up on building the motor to be a high HP engine, though it is anyway... I built it to give me more HP across the entire RPM range... I had to sacrifice some bottom and top end but ended up with an average of 20 extra ponies through the mid range where I'm spending most of my tiime...

You need to look at the track your running and figure out how much you're really going to wind the motor to it's max... I run on an extremely tight track... I have an Axiom P2K2 with excellent mid range numbers and it shows...
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Old 12-19-2003, 08:39 PM   #11
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What Speedo said is correct, you can't get a proper reading unless you fully seat/break in the brushes. If you pull the brush out of a "pro" version you can see that they are not broke in. Its just another gimmik to get a few extra bucks out of ya.
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Old 12-20-2003, 07:32 AM   #12
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First... it depends on what motor tuner's motors your talking about.

If it's a small local guy, and he's doing things with integrity, always uses one dyno and that is not a Fantom, and breakes the burshes in fully... Then comparing numbers from that tunner would likely be meanigfull and your proformance after you cut the comm should be more or less identical to the proformance on the lable. (realtively speaking)

If it's Trinity... It's extreemly rare they run the 'pro' motors long enough to seat the brushes before the test. They use a Fantom which basicly is untrustworth to begin with... All in all... the numbers aren't worth the paper they are printed on... before or after you cut the comm.


Bottom line is... find a motor tuner you trust and then the lable shouldn't matter anyway...

Short answer is... ingnore the lable, or better yet... buy a motor that has not been tuned and do it yourself.

A shorter answer might be... buy a Putnam... he'll admit that his Fantom lables don't mean a thing...
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Old 12-20-2003, 08:41 AM   #13
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DynoMoHum- first of all who are you? Second, you are way off by saying a Fantom dyno is worthless. Eric Anderson is Todd Putnam's right hand man and tunes the majority of the winning motors at big races that he attends and he uses a Fantom dyno. And in reference to your coments on Trinity stock motor dyno numbers I previously would have agreed with you but not since they went to the Fantom dyno. And if you will notice the brushes are much more broken in than they used to be. I'm not a Trinity lover by far, but I know what I see, and I've seen proof that the motors with better sticker numbers are better motors these days. You say you can't tell anything about a motor until it's been properly broken-in, well then how is it that we can tell if a motor is strong by watching the amps @ 2 volts on tha T35 with brand new fresh brushes?

I'm sorry DynoMo, you might be a nice guy and all, but I've been watching a lot of the stuff you post and some of it is good, some is questionable, but you have discredited yourself with that last post.

Guys this is a perfect example of why you can't always believe or trust everything you read on the forums just because someone seems as if they know what they are talking about.
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Old 12-20-2003, 08:49 AM   #14
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so big dog... what are you looking for when you look at amp numbers with no load on a t35 @ 2 volts ?

if you want high numbers, just drop some glue in the bushings/bearings, the numbers will go thru the roof lol
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Old 12-20-2003, 09:39 AM   #15
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True dyno numbers aren't worth anything!!!! let's face it at the level most of us drive on 2-4 extra watts or 1,000 extra RPM aren't gonna matter because it's all neglegable after we stuff it in the wall the first time..... and once or if we ever reach the level of a Johnson, Hirosaka, or Cyrul you could dominate almost any track across the country with any motor on the shelf untuned and unprepared.........
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