vitos fat basterd

[sierrahotel]

i may not own a dyno in my shop but i do testing on them and test in the real world at the strip ,the times tell the whole story ,its true everyone has different ways they like ot test things and i wont knock anyone for their beliefs but I will stand by my point that the roller dyno tests only what is set against it and its parameters and also its inaccurate below 5 grand and in reality that often represnts 50% of the total rpm curve on a typical blaster motor ,look at where the dyno curves start on a dyno i would not choose a surgeon who has only been tested at medical school for half the time or less .i would not watch half a football game or read the last half of novel and make a bold summary statement of it .in my opinion what happens below 5 grand is just as critical, a race is often won within the first 20 feet out of the gate

It has been a couple of months now that I've been reading this forum.... I've read many posts, some are accurate, and others are not. It is to be expected that a lot of information from a forum such as this may not be entirely factual.... it is all part of the learning process. Posts by people on this forum are in different phases of this learning process and are at different levels in their understanding.

There has been a lot of controversy about dynamometers these past months, what they can do and what they can't. Without going into the physics of inertial dyno’s, I can say without reservation, the types of equipment these posts are commenting on are in fact more accurate at lower RPM readings than they are at the top end of the RPM range. The subject dynos have an extremely low sample rate due to their data acquisition systems. The software packages just are not state of the art! This is why they will be more accurate down low. The dyno's in question will probably be lucky to sample at 10 HZ (10 times a second). State of the art data systems will have a sample rate of at least 100,000 HZ! Better ones will sample at over 250,000 HZ! I could go into the explanation why this is so, but I'll save that of another day.

Bottom line, don't believe everything you read - use you head. Don't be afraid to change your opinion as you continue your quest for the truth, its all part of the learning process!
These comments are based on my 35 years of engine development, utilizing all different types of dynamometers and are meant only to enlighten those that seek the truth!

 

[Kennedy_Power]

Great input Sierrahotel
The Vito pipe is a Great mid to top end power pipe, Shearer pipe is killer trail pipe
PM me if you are intested in a Vito or Shearer pipe
Thanks
Flickr: kennedy_power's Photostream

 

[BLASTER HP]

i have a friend thats had a dyno for like 10 years. me and my friends take all our quads to his dyno. what he does for me on my trail bike is dyno my bike in 1st gear through 6th gear all at once. the graph shows all the shift points, torque and peak rpm not to mention air/fuel in every gear, with all that info its easy for us to tune every gear at every rpm range. so without owning a dyno you really shouldn't comment on what they can and can't do. after a day at the dyno our bikes always run like never before wheather it be the track or trail. also since conditions of the trail or dunes are obviously different then what its like in his shop he always suggests minor tuning depending on the situation. when i go to the dunes he always fattens up the jets because of the extra load the paddles and sand add. with out a dyno and air/fuel meter your merely guessing when you make a modification, the seat of ur pants cant 100% tell you if your lean or rich at the low or top end, you cant tell if your peak rpm is at peak hp. with my limited time on the dyno its clear to me that its the best way to tune a bike properly and completly.

 

[burnin'_oil_2001]

Well I am going to chime in...

I think what Flotek was saying is that while a dyno is beneficial there are other ways to tune. I have ridden Banshees with similar dyno peak horsepower and the one that had 3-5 less horsepower was more rideable and faster. The dyno sheet did not show this. I do know that the better dynos do chart acceleration, speed, and I have seen charts that point out clutch slippage. You can simply test for tuning via welding a bung on the exhaust and sticking an O^2 sensor in there and reading what it has to say (now I believe DynoJet has a wide band fuel controller that can adjust itself). I also agree that track testing is a good way to test as the most important number is who one and how fast- it is just that a dyno moves that testing into a controlled environment (raceteams while owning some of the best dynos on earth still track and record track times and conditions). Just because Flotek does not HAVE a dyno it does not mean the he does not USE a dyno. I imagine that if the customer wants to pay then Flotek will deliver. In my neck of the woods many people/companies rent dynos as needed. I personally think dyno sheets are useless w/o a build and tuning sheet. In the 70-80s Honda used to kisk everyones ass in motorcross racing- but there was now way anyone could buy the stuff they had (that is why the production rule came into being). It comes down to a cost/benefit ratio on whether or not to own a dyno-- and dyno numbers can be misleading or flat out tampered with as Kennedy has pointed out many times on this site. However, I do enjoy the friendly sparing as it looks at both sides of the issue and helps me to learn and to make the best decision that I can. Now if we could just get the press and politicians to do the same instead rope-a-doping us!

 

[FLOTEK]

It has been a couple of months now that I've been reading this forum.... I've read many posts, some are accurate, and others are not. It is to be expected that a lot of information from a forum such as this may not be entirely factual.... it is all part of the learning process. Posts by people on this forum are in different phases of this learning process and are at different levels in their understanding.

There has been a lot of controversy about dynamometers these past months, what they can do and what they can't. Without going into the physics of inertial dyno’s, I can say without reservation, the types of equipment these posts are commenting on are in fact more accurate at lower RPM readings than they are at the top end of the RPM range. The subject dynos have an extremely low sample rate due to their data acquisition systems. The software packages just are not state of the art! This is why they will be more accurate down low. The dyno's in question will probably be lucky to sample at 10 HZ (10 times a second). State of the art data systems will have a sample rate of at least 100,000 HZ! Better ones will sample at over 250,000 HZ! I could go into the explanation why this is so, but I'll save that of another day.

Bottom line, don't believe everything you read - use you head. Don't be afraid to change your opinion as you continue your quest for the truth, its all part of the learning process!
These comments are based on my 35 years of engine development, utilizing all different types of dynamometers and are meant only to enlighten those that seek the truth!

welcome to the site ,i dont claim to know everything about dynamomoeters or have infinite knowledge concerning data aquistion but it stands to reason if it is so accurate and state of the art down below as you say why is the chart never displayed at these low levels ,any logical person would agree 60% is alot not to be reveiled ..at best it seems a terrible injustice is being done especially for the average rider who wants to know how his setup performs for the the bulk of the riding his engine performs in like the technical stuff and off idle torque the response , seems that cutoff problem may be the output of the engine being tested hasnt reached the capability yet in the curve to drive the load presented against it in an accurate manner and last i checked blasters dont idle at 5 grand ,i imagine the bulk of these guys on here would benefit greatly seeing how their performance is *before the last 20% of the powercurve,testing a trailpipe at 8,000 rpms seems to me a bit counterproductive to the cause in my estimation,no doubt about it a dyno is a useful tool in the right hands
but as i said before it has its limitations and is often only a good as the operator running it . my post was not meant to knock any ones work or testing but thats my 2 pennies

 

[sierrahotel]

welcome to the site ,i dont claim to know everything about dynamomoeters or have infinite knowledge concerning data aquistion but it stands to reason if it is so accurate and state of the art down below as you say why is the chart never displayed at these low levels ,any logical person would agree 60% is alot not to be reveiled ..at best it seems a terrible injustice is being done especially for the average rider who wants to know how his setup performs for the the bulk of the riding his engine performs in like the technical stuff and off idle torque the response , seems that cutoff problem may be the output of the engine being tested hasnt reached the capability yet in the curve to drive the load presented against it in an accurate manner and last i checked blasters dont idle at 5 grand ,i imagine the bulk of these guys on here would benefit greatly seeing how their performance is *before the last 20% of the powercurve,testing a trailpipe at 8,000 rpms seems to me a bit counterproductive to the cause in my estimation,no doubt about it a dyno is a useful tool in the right hands
but as i said before it has its limitations and is often only a good as the operator running it . my post was not meant to knock any ones work or testing but thats my 2 pennies

I will respond .... just not enough room here.

 

[sierrahotel]

Yes, you are correct that the engines performance off idle is important to many riders. That is the reason top engine builders ask so many questions when putting an engine package together for a customer. They must know how you intend to use it so they can build an engine that does what you want. I can not say for sure, because I have not tested this myself, but I would guess a stock everything blaster would out perform any modified engine from off-idle to say.... 3 or 4 thousand RPM. At that point a trail type engine would start to pull away rapidly, a dune type engine would lag behind, and a race type engine would still be flat on it's face! At about 6000 RPM the dune will finally catch the trail and continue upward as the trail flattens out. At about 7000 to 7500 RPM the race will zoom past the dune as it flattens out. The race has been a dud up to this point. I would estimate that a stock engine is all done around 5500 - 6000 RPM, the trail all done by 7000 RPM, the dune by 8000 RPM, and the race by 9000 plus RPM. See next post

 

[sierrahotel]

The point to all of this is you must be honest with your builder as to how you are going to be riding. I would guess the reason most of the dyno sheets you see does not show anything below 4 to 5 KRPM is because the stock stuff is kicking ass off idle to 3 or 4 KRPM. I believe the builders are trying to show how the different packages are superior to the stock set up, not prove the stock set up beats the pants off them below 4000 RPM. Not all, but most modifications from the builders will move the engine's power band to the right on the dyno chart, as does pipe changes, etc. See next post

 

[sierrahotel]

Most people that look at the posted dyno charts see only the peak numbers, this is not what you want to look at. Look at the area under the curves and compare, the more area, the higher the average power. You don't even need the numbers!

I would say you are being somewhat dramatic in the statement "terrible injustice". I agree these engines do not idle at 5000 RPM. Your so called "average rider" with a stock set up I would guess is 3 to 4 KRPM just tooling around and shifting at 6000 RPM. If he's happy, great! If not, this type of rider would benefit from mild mods up to a good trail package.

My point is this, the power below 3000 RPM is of little importance. 1st, the engine is not used in this RPM range when being ridden hard. 2nd, the stock stuff is better in this range.

I do agree with you that a lower RPM recording point is in order.... I would say to the builders, start your recording @ 3.5 to 4 KRPM and show what your packages lose down low.