Deboring cylinders
Dec 5, 2005 | 11:01 PM
#21
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Trailblazer
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Deboring cylinders
Update on the situation guys. Weber got back to me, told me it wouldn't be a good idea to debore the engine....I don't want to take this as truth because they never answered my specific question on what the combustion chamber bore is. Polairs is very keen on helping me out but I have to wait till after the hectic snowmobile season to get one of their snowmobile engineers helpin me out. now the situation has come down to a couple options on this....
option one: debore....this will only work if the combustion chamber bore>76.7mm. If it is smaller than it would require indepth work with Polaris to figure out which I am definately not opposed to doing...there is nothing I would like to do more than develop a competition legal engine alongside Polaris Industries but I'll have to wait to hear back on this one once I somehow find the combustion chamber bore.....anybody have any ideas on how I can get this critical dimension?
Option two: Destroke? The FST uses two piece con-rods and if we could somehow get ourselves some nice new shorter ones (one-off no doubt) it would lower our compression and decease our displacement....with this in mind, the FS (non-turbo engine) would be favorable because it has the same internals as the FST but higher compression stock I believe and shorter con-rods would lower the compression to an acceptable level to run something like a garrett GT15
Option three: No more FST, use a sportman 600 engine and boost it. Use clutching similar to a snowmobile set up (ie dark blue or almond primary spring with 52 gram weights and a light blue spring and R12 helix in the secondary) rather than the very soft set up normally in the quad.....I know a sportsman 700 engine with the sportman 500 clutch configuration will catwalk.....dont ask how I know this [img]i/expressions/face-icon-small-happy.gif[/img]. Now running a sportman 600 engine under boost with a TEC 3 will require less development time and Could be definately ready for the 07 season
What do you guys think. There have been alot of great ideas going around here so far and I know there are tons of knowledgable people on here. any opinions?
option one: debore....this will only work if the combustion chamber bore>76.7mm. If it is smaller than it would require indepth work with Polaris to figure out which I am definately not opposed to doing...there is nothing I would like to do more than develop a competition legal engine alongside Polaris Industries but I'll have to wait to hear back on this one once I somehow find the combustion chamber bore.....anybody have any ideas on how I can get this critical dimension?
Option two: Destroke? The FST uses two piece con-rods and if we could somehow get ourselves some nice new shorter ones (one-off no doubt) it would lower our compression and decease our displacement....with this in mind, the FS (non-turbo engine) would be favorable because it has the same internals as the FST but higher compression stock I believe and shorter con-rods would lower the compression to an acceptable level to run something like a garrett GT15
Option three: No more FST, use a sportman 600 engine and boost it. Use clutching similar to a snowmobile set up (ie dark blue or almond primary spring with 52 gram weights and a light blue spring and R12 helix in the secondary) rather than the very soft set up normally in the quad.....I know a sportsman 700 engine with the sportman 500 clutch configuration will catwalk.....dont ask how I know this [img]i/expressions/face-icon-small-happy.gif[/img]. Now running a sportman 600 engine under boost with a TEC 3 will require less development time and Could be definately ready for the 07 season
What do you guys think. There have been alot of great ideas going around here so far and I know there are tons of knowledgable people on here. any opinions?
Dec 6, 2005 | 12:42 AM
#22
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Deboring cylinders
I would go with #3. But again, I would have to study the rules over and over to see any advantage for any choice.
IMHO a short rod is bad news for many reasons.
Good luck with your comp. Hope you win.
IMHO a short rod is bad news for many reasons.
Good luck with your comp. Hope you win.
Dec 6, 2005 | 01:04 AM
#24
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Deboring cylinders
Short rod = bad rod angle. A bad angle on the rod will want to push the piston into the side of the bore.
The longer the rod the better the rod angle. A better rod angle will want to push the piston down on a straighter angle.
You always want the longest rod you can stick in an engine package. Longer is better in this case!!! [img]i/expressions/face-icon-small-wink.gif[/img]
The longer the rod the better the rod angle. A better rod angle will want to push the piston down on a straighter angle.
You always want the longest rod you can stick in an engine package. Longer is better in this case!!! [img]i/expressions/face-icon-small-wink.gif[/img]
Dec 7, 2005 | 02:42 AM
#25
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Deboring cylinders
Okey guys, tell me where I am wrong. I understand how a shorter connecting rod would decrease the compresson, but I don't see how it would decrease the displacement. The travel distance of the piston would be the same.
Now if you were to get a <u>crank</u> with a <u>shorter throw</u>, then the displacement would be decreased (as well as compresson).
Now if you were to get a <u>crank</u> with a <u>shorter throw</u>, then the displacement would be decreased (as well as compresson).
Dec 7, 2005 | 01:51 PM
#26
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Deboring cylinders
Originally posted by: hondabilleturbomugenracing
listen up ladies,
give tex a break. or maybe anyone just doesnt pay enough attention. he can't run two stroke, so stop mentioning it. he can't run nitrous, so stop mentioning it. anyone who needs nitrous to build an exciting engine doesn't really have what it takes anyway. he's not going to use a hemi, he's not going to weld the gap on his combustion chamber. stop talking about other motors. he's a university kid in a competition in which he sacrifices his free time to build a racecar, so he can't afford to choose the wrong motor. this means stop mentioning other motors. he knows what he can build, and he knows what he wants to build, and he knows whats out there.
from investigating the competition, it seems that the most common motor by far is the f4, with some r6s and gsx-r's in there too. these are big heavy roadbike motors that can only make about 80 horse when you choke them through a 20mm restrictor. yes you can turbo those but with gears you need a good driver to hold the rpm in the powerband, and then you have to shift gears many many times (ever driven autoX, didn't think so). so yes you get losses from a cvt, but if you can hold 90+ horse with a CVT and an oversized turbo on a turbo ready motor (FST) the driveability and power delivery will far exceed that of the 4 bangers and you'll have a faster car. even the acceleration event shows this, when the top teams are near the 4 second for 75m range, and shift times in the 0.1s range. Shifting 3 or 4 times gives you nearly a 10% loss in acceleration time compared to a powerful cvt backed motor.
now lets try answering the guys question he's ACTUALLY asking, instead of shoveling BS at him. i don't have any wise comments on deboring and the flame propagation and swirl effects as its not like i'm a second year mech eng student at queen's as well. have you thought of destroking and decking the head/case enough on those fancy Haas's you crazy kids got there to compensate for the compression loss? either that or what about machining a new head? i assume since you're only in second year you have a bit of time to get this fairly innovative idea into your car you have some design time. WWU machined their own bottom end for a custom 500cc V8 and melbourne machined their own inline twin, which they turboed in 05. i don't think a new head is out of the question. besides, it seems like you'll have all summer working with a decently qualified machinist to get it working. but let me know what you think about the destroking and decking idea as its slightly more feasible.
j diddy out
listen up ladies,
give tex a break. or maybe anyone just doesnt pay enough attention. he can't run two stroke, so stop mentioning it. he can't run nitrous, so stop mentioning it. anyone who needs nitrous to build an exciting engine doesn't really have what it takes anyway. he's not going to use a hemi, he's not going to weld the gap on his combustion chamber. stop talking about other motors. he's a university kid in a competition in which he sacrifices his free time to build a racecar, so he can't afford to choose the wrong motor. this means stop mentioning other motors. he knows what he can build, and he knows what he wants to build, and he knows whats out there.
from investigating the competition, it seems that the most common motor by far is the f4, with some r6s and gsx-r's in there too. these are big heavy roadbike motors that can only make about 80 horse when you choke them through a 20mm restrictor. yes you can turbo those but with gears you need a good driver to hold the rpm in the powerband, and then you have to shift gears many many times (ever driven autoX, didn't think so). so yes you get losses from a cvt, but if you can hold 90+ horse with a CVT and an oversized turbo on a turbo ready motor (FST) the driveability and power delivery will far exceed that of the 4 bangers and you'll have a faster car. even the acceleration event shows this, when the top teams are near the 4 second for 75m range, and shift times in the 0.1s range. Shifting 3 or 4 times gives you nearly a 10% loss in acceleration time compared to a powerful cvt backed motor.
now lets try answering the guys question he's ACTUALLY asking, instead of shoveling BS at him. i don't have any wise comments on deboring and the flame propagation and swirl effects as its not like i'm a second year mech eng student at queen's as well. have you thought of destroking and decking the head/case enough on those fancy Haas's you crazy kids got there to compensate for the compression loss? either that or what about machining a new head? i assume since you're only in second year you have a bit of time to get this fairly innovative idea into your car you have some design time. WWU machined their own bottom end for a custom 500cc V8 and melbourne machined their own inline twin, which they turboed in 05. i don't think a new head is out of the question. besides, it seems like you'll have all summer working with a decently qualified machinist to get it working. but let me know what you think about the destroking and decking idea as its slightly more feasible.
j diddy out
WOW! What a great first post!
[img]i/expressions/face-icon-small-frown.gif[/img]
Sometimes talking openly about things can get new ideas generated. AND IF YOU WOULD PAY ATTENTION........ He didnt mention he could not run a 2-stroke until the post right before you. Go back and read it again.
Dec 7, 2005 | 02:16 PM
#27
Weekend Warrior
Joined: Dec 2005
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Deboring cylinders
oh i'm sorry bubba, maybe i like to know what i'm talking about before i speak. maybe everybody else just likes throwing nonsense out into a discussion without being able to back it up. as you can see by reading my post (which i'm impressed you're able to do since i did use some multi-syllabic words in there) that i know something about the competition in question that moddedwarrior is involved in. i didn't just happen to come across this information, i went and checked it out. now, if everyone else was so inclined, moddedwarrior wouldn't have to keep coming back and posting "no i can't to that" or "no that's against the rules".
come on ladies.
come on ladies.
Dec 7, 2005 | 05:44 PM
#28
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Trailblazer
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Deboring cylinders
whoa whoa everybody...no need for people to get upset with everyone else.
Lets remember, ATVconnection is about helping other people with questions. Nobody claims to know all the answers but between everybody there is a lot of great knowledge and information going around. I should have been a little bit more specific about the rules of the competition and thats why I was not upset when people posted alternate engine solutions. Now the rules are out there and my question is proposed so theres no need for anybody to fight.
I'm thinking very strongly on the sportsman 600 after seeing lentechs(spelling?) turbo sportsman 700. but I would really like to make the four valve overhead cam FST engine work because its a little more technologically advanced than the sportsman 600. regardless of the engine choice I will still have to fabricate a custom intake, exhaust and gear reduction + diff housing to work with this new engine (I'll probably turn these into class projects so I can recieve credit on them). these changes require a complete redesign of the midframe and rear frame of the car......but well worth it in my opinion.
Lets remember, ATVconnection is about helping other people with questions. Nobody claims to know all the answers but between everybody there is a lot of great knowledge and information going around. I should have been a little bit more specific about the rules of the competition and thats why I was not upset when people posted alternate engine solutions. Now the rules are out there and my question is proposed so theres no need for anybody to fight.
I'm thinking very strongly on the sportsman 600 after seeing lentechs(spelling?) turbo sportsman 700. but I would really like to make the four valve overhead cam FST engine work because its a little more technologically advanced than the sportsman 600. regardless of the engine choice I will still have to fabricate a custom intake, exhaust and gear reduction + diff housing to work with this new engine (I'll probably turn these into class projects so I can recieve credit on them). these changes require a complete redesign of the midframe and rear frame of the car......but well worth it in my opinion.
Dec 7, 2005 | 10:53 PM
#29
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Deboring cylinders
Don't rule out a manual tranny Motor outfitted with an AutoClutch. These auto clutches have came along way,and they make them to fit most all popular trail bikes. By using a single-cylinder, lightwieght aircooled 500cc motor,and boring/stroking it to 600cc, you will save 60lbs over a heavy polaris CVT motor.
Also the head design will already have smaller intake ports and valves,so when you turbo through the 20mm throttle-bodies the head design will be much more efficient(sp)Than a head that is designed for 36mm+ carbs. This should make for great HP(quicker), and with the right cam profile LOTS of torque. Which as you know means ACCELERATION!!
In 1985/86 Honda made a great aircooled single cylinder(2 carb,4 valve head) dirt bike. They sold a million of them, so I am sure you can find this motor just about anywhere for nearly nothing.
Good luck.
Bigger.
Also the head design will already have smaller intake ports and valves,so when you turbo through the 20mm throttle-bodies the head design will be much more efficient(sp)Than a head that is designed for 36mm+ carbs. This should make for great HP(quicker), and with the right cam profile LOTS of torque. Which as you know means ACCELERATION!!
In 1985/86 Honda made a great aircooled single cylinder(2 carb,4 valve head) dirt bike. They sold a million of them, so I am sure you can find this motor just about anywhere for nearly nothing.
Good luck.
Bigger.
Dec 7, 2005 | 11:01 PM
#30
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Deboring cylinders
I thought of doing a slipper clutch set up but $1300 USD is a little pricy. I know that seems contradictory to my post about custom sleeves and pistons but with custom sleeves and pistons its more "innovative" (i hate that word).
Which honda motor would you be talking about? the XR600? those are quite awesome motors. lots of power and I dont think even the xr650 can touch em. A air-cooled motor would reduce tons of weight but I just don't think its a viable option for a 20lap endurance race. I've ridden thourghly on moded air-cooled (such as my warrior) and after short distances you produce alot of heat and power output decreases at what is seemingly a exponential manner. If I do recall correctly the 500-600 aircooled singles with twin carbs ran something to the effect of dual 28-30mm carbs (correct me if im wrong) and our limitation is a single 20mm restriction in the intake. But i definately see where your coming from with the smaller ports suggestion.
Which honda motor would you be talking about? the XR600? those are quite awesome motors. lots of power and I dont think even the xr650 can touch em. A air-cooled motor would reduce tons of weight but I just don't think its a viable option for a 20lap endurance race. I've ridden thourghly on moded air-cooled (such as my warrior) and after short distances you produce alot of heat and power output decreases at what is seemingly a exponential manner. If I do recall correctly the 500-600 aircooled singles with twin carbs ran something to the effect of dual 28-30mm carbs (correct me if im wrong) and our limitation is a single 20mm restriction in the intake. But i definately see where your coming from with the smaller ports suggestion.