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Thread: Emulating Low Gears
Emulating Low Gears
By extending the air intake, you get more low end.
You will get the SAME effect from using a larger intake mount, as long as the internal cylindrical volume is the same.
I typed this up last night and fell asleep at the desk. Here it is...
I just finished extending my intake! I got about the 8.5" extension, and SWEET MERCIFUL TROUT, it's like a whole new world is opened up to me.
You know on old diesel trucks how you start off the line in second? After this mod, I feel like I've been in second gear on my bike it's entire life. This mod brought me down to below first gear. Now, I only took it about a quarter mile to see the initial results, as it's 10:30 at night and it's cold. Tomorrow in the daylight I'll jump and take it on a mile and see where it does in the long haul. There is SO much throttle response it's seriously crazy. It's going to take about 30 minutes to dial everything in, my throttle is right on the brink of screaming and sputtering out at the same time. But like I said, WOW. It's handling so delicately! I want to just go find a huge hill and just climb it over and over again!
I know what I'm doing tomorrow, and that's tinkering!!! There's something here and I can't quite place my finger on it, but I know I'm onto something big. It's not just the distance! That's a part of it, but that's not everything here, it's all about the hose diameter. A smaller hose means there is less distance for the fuel vapor to travel.
Okay, now wrap your minds around this...
Instead of just playing with standard hosing extensions, what we should be doing is calibrating this with MULTIPLE hoses.
Standard intake is .75" ID and 2.5" long. That means it's got a volume of 1.1039 sq inches (estimate). An intake at 8.5 inches long is 3.7533 sq inches. Collective, we've got a total volume of 4.8571875 square inches for an 11 inch intake pipe at .75" ID (which is what I'm running now, VERY VERY low end).
Now, that's awesome, right? Lots of numbers. But, this is where it gets good. If you use only a half inch intake pipe at only a total of 8.5 inches long, you get 1.668125 sq inches of distance. Running two simultaneous intake pipes will get you 3.3625 sq inches. A third hose will bring that up to 5.030625 sq inches.
In theory, we're looking at basically one point seven square inches for your closest to stock setting, which as I said, feels like second gear on an old truck off the line. Say we were to use two intake pipes now! We're looking at three point four square inches, which is double the intake. Running both of these intakes at the same time should yield a decrease in top speed, but an increase in acceleration. That's basically your "First Gear". A third intake hose brings it up to 5 square inches, which is where I'm at currently tonight, this would be the "MegaDrive" gear. Lastly, we have a fourth hose, which is 3/8ths hose.
"MegaDrive" = All three hoses ON.
"First Gear" = Two hoses ON, One hose OFF.
"Second Gear" = One hose ON, Two hoses OFF.
Like I said, I was tired when I was doing this and I know there ARE other variables, but this is just kinda the foundation.
Also, this is going to be part of my dual carb setup down the line, but until they are both done, they will remain separate projects.
im having a hard time wrapping my head around this.. concept sketch? dont mean to sound ignorant.
Just picture the stock intake tube, now picture it with a Y on the end, but meeting up at the carb with a valve on each tube.
Then just add extra tubes, like one that forks into 3, 4 intakes which all meet up at carb.
ohhh! i get it! thats a really good idea!
I know! It's gonna take some time to get all the parts I'm going to need to make a prototype. It sucks that there's no way to get it working to emulate higher gears, if you tried you'd be making a way too complex choke. But just for the hill climbing aspect, it's a very worth while thing.
you my friend, will revolutionize MBing, really, ive been here for like what.. a week, and ive already overflowed my brains float valve with your ideas! ^_^, hurry up and proto already!
I got paid today, so I'm going to start hunting around for parts. It's gonna take a while to get everything, tough parts are going to be customizing the intake tube and finding valves that are the right size to keep flow proper.
why not just get a bike with a shiftkit and derailuer?
they relly are fun... believe it or not, i actully have a first and second gear.... and five others to with them.
@ DTG, sweet! hmm, me thinks a cheap pipe brazer would be sufficient to join the intakes.. least for a proto anyways.
@ G M Vtch, im not sure about duct tape goat, but to me, half the fun of this hobby is DIY. sure, you could buy parts, but... making another way is so rewarding.
VTec - http://www.sickbikeparts.com/catalog/index.php?cPath=21
Tubing is cheaper than 150 bucks! If I had the money, I'd do it in a heartbeat. But, I don't have that much - heck, for 150 I could buy a second motor for a rackmount. I'm seeing what can be made for less than 25.
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