Porting, what does it mean to you?

[Kennedy_Power]

I am curious to hear from you. So many people look into a cylinder and come up with their own conclusion, it looks good and should run great, or it looks bad and it won’t work correctly. What do you look for? It can be difficult to come up with a conclusion before taking certain measurements, but most of the world does not understand the function between the exhaust port and pipe design duties. Then the transfers become even more confusing; timing, window area, tunnel cross sectional area, back flow angles and so on.

 

[LoSeR]

I am curious to hear from you. So many people look into a cylinder and come up with their own conclusion, it looks good and should run great, or it looks bad and it won’t work correctly. What do you look for? It can be difficult to come up with a conclusion before taking certain measurements, but most of the world does not understand the function between the exhaust port and pipe design duties. Then the transfers become even more confusing; timing, window area, tunnel cross sectional area, back flow angles and so on.

I personally don't think you can tell much by just looking at a cylinder. I know port windows and exhaust ports can be raised or lowered to change where your engine makes power, by altering port timing, kind of like a four stroke engines upgraded camshaft changer when the intake port is opened, and how long it is open, that alot of work needs to be done to the transfers and exhaust to make a fast drag motor. And I also know that it is a very time consuming process to rework the transfer ports properly. :">

 

[hickskateboarder]

Kennedy, you've been doin this for a while right? it would be awesome if you could do a in-depth diy on porting. i did my own port job, looked at a BUNCH of pics on the internet and stuff, just basically widened the intake, widened the exhaust port a little and opened it up to match the size of the opening in the pipe, and polished everything. made a good difference up top, but i would like to make a little more power on low end, is there anything i can do to the transfers to do so? i didn't move my exhaust up any cause i know that pushes the powerband up.

 

[LoSeR]

Kennedy, you've been doin this for a while right? it would be awesome if you could do a in-depth diy on porting. i did my own port job, looked at a BUNCH of pics on the internet and stuff, just basically widened the intake, widened the exhaust port a little and opened it up to match the size of the opening in the pipe, and polished everything. made a good difference up top, but i would like to make a little more power on low end, is there anything i can do to the transfers to do so? i didn't move my exhaust up any cause i know that pushes the powerband up.

I've drilled some wormholes (1/4" bit) on either side of the intake near the bottom(look in the for sale section under haulers, 240 kit at the pics I have of my ported 240, you can see the worm holes..)

 

[Kennedy_Power]

The worm holes will not show any gain on the dyno; there are rare caes when they will. One example is; certain pistons being used in banshee stroker cranks. The intake windows are too low on some set ups. Then the worm holes make up the differnce in the lack of window area in the piston. Blasters do not have this problem.

 

[LoSeR]

So I guess whoever set up my 240 cylinder didn't know what they were doing
http://i270.photobucket.com/albums/jj108/meganblynn/100_1316.jpg
http://i270.photobucket.com/albums/jj108/meganblynn/105_0081.jpg
http://i270.photobucket.com/albums/jj108/meganblynn/105_0082.jpg
http://i270.photobucket.com/albums/jj108/meganblynn/100_1317.jpg
http://i270.photobucket.com/albums/jj108/meganblynn/105_0083.jpg

 

[hickskateboarder]

yeah i took it apart again a few weeks later and very carefully put 1/4" worm holes in. it might have made a very minor difference, but it's probably all in my head lol.

 

[pittboss45]

When it comes to porting and or engine building, I found this on another site and might need moved to another topic, but I'll stick it here for now.


"Lately it has been brought to my attention that some engine builders have been making some rather outrageous claims as to the HP output of the motors which they can build for you, both 2-strokes and 4-strokes. Some are even claiming these numbers are dyno proven (one snake in the grass even quotes hp numbers for his dyno, even though it is nothing more than a water pump set up to drain a 55 gallon barrel, he says the faster it can be drained, the more power the engine is producing, pretty dang shakey). A lot of builders don't want you heading off to an independent dyno service (such as GT Thunder) for this reason. BTW, GT Thunder is used by many of the top builders to accurately see how their engines stand among the rest, as many dynos (homemade and boughten ones) are terribly inaccurate. Let some common sense prevail when chosing which engine builder to use. You are not going to get 45 hp out of a blaster on pump gas.... period. Nor will you get 75 hp out of you're 450 on 93 octain. I have seen where one certain engine builder went as far as to set up an engine on a dyno to pull the numbers straight off the crank, that's right, no clutch, trany chain, carrier bearings, etc. to rob horsepower and then publicily quoted those numbers as an accurate representation of the performance of his engines. Do you ride without your transmission? Unfortunately, there is no clearing house to weed out these people and fancy websites and a line which almost sounds believable has reeled in many people to spend their hard earned cash at these places resulting in some very disappointed customers, whom then go to a noted engine builder crying the blues as to how they got ripped off by XXXX and that there was no after the sale support to work out issues with the engine and wanting the next engine builder to fix what has been done and to give them the HP that they are looking for.....at a discount. Good engine builders do not sell porting jobs for $125, nor do they build 450s that produce 55hp for $500. Use your common sense when chosing your next engine builder, ask about championship records, verifiable ones, like AMA, ATVA, WORCS, CRA and NEATV, county fair races do not count. Maybe you'll get what you actually wanted in the first place. "


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[LoSeR]

You could get 45hp out of a Blaster on pump gas.
Don't know about the 450
I got 93hp out of my Banshee on pump gas at 6,000 ft elevation
Porting makes a huge difference in 2 stroke motors.
I paid 250 bux to RB racing for a port job and I was EXTREMELY happy with the power, still utilizing a stock carb.
Ps, what do you think of the pics in my post #6

 

[Kennedy_Power]

Most automotive test facilities use dynamometers coupled to the crankshaft for development work. In the ATV/power sports world the majority use dyno jet inertia chassis dynamometers. The reason is simple, cost and knowledge. Most ATV performance shops do not have thousands to invest in hardware, low inertia eddy current dynamometers and instrumentation needed to run high speed data acquisition software, and the lack of understating how and what to look for. I would not use a dyno jet dynamometer to develop two cycle exhaust pipes, for several reasons. The software is very limited, slow, and almost impossible to capture the exhaust pulses using high speed dynamic pressure transducers on a acceleration dynamometer. I use both; a engine dynamometer for exhaust pipe development, transient and steady state evaluations. The dyno jet is a great tool for calibration. I use it to tune customer’s bikes; help them with jetting, ignition timing, or whatever the case may be.
As far as different shops dynamometers being off; you most calibrate the load cell at least twice a year.
A easy way to tell if someone’s dynamometer is off, do the math and figure out the BMEP(Brake Mean Effective Pressure) of the engine that’s being tested.
Brake Mean Effective Pressure (BMEP) is another very effective yardstick for comparing the performance of one engine to another, and for evaluating the reasonableness of performance claims or requirements.
BMEP= (HP X 6500) / L X rpm
6500=constant
HP= Horsepower
L= engine displacement in liters
RPM= crankshaft speed
Example= Blaster 195cc or 0.195 liters
BMEP= 40X6500 / .195 X 10,300= 129.44 psi
BMEP ranges from 90 to 240 PSI
If you do the calculations on someone’s claimed power numbers and the BMEP is over 180 PSI. Something is probably wrong with the load cell. It takes hours of pipe and engine development to get those numbers. NASCAR engine are in the 230 PSI ball park and money is no issue for those race teams.
I hope this helps you guys out
Good luck and as always feel free to ask any questions.

 

[LoSeR]

Slightly off topic...I was told by Jim at Passion Racing that by reworking the exhaust port on my stock Cheetah powervalve cylinders, that I can gain a more "violent" drag engine powerband, as opposed to the 4 stroke turbo like powerband I am experiencing. Do you have experience with these cylinders?

 

[Kennedy_Power]

Happy to see you get those Trinity pipes off and put on a set that will produce great power, and has a nice over rev. Matt Shearer is a friendly and awesome person to work with. There are two minor issues that affect the performance of those cylinders. I will not mention them on a chat forum.
I can make a change to the cylinder without modifying the exhaust port; and it will come on hard. Whenever you raise the exhaust port, you will raise peek power and loose power down low. I would widen the exhaust and leave the port roof alone. If you want more details email me at kennedypowerports@gmail.com
Thanks

 

[quam]

damn, kennedy, you know a lot more about this sh*t than i do!
do you do p&p jobs? you build 2stroke pipes? nice dude!
i'm thinkin maybe i'll have my cylinder p&p either this or next winter depending on how much i wind up spending rebuilding the bottom half and finishin up my bike.....if you p&p blasters, shoot me some prices.

 

[LoSeR]

If he's a builder I'm sure he does P&P.