So you are trying to steal their speed secrets hu? LOL.
I have read various things over the years about flame travel. I don't have any of those articles. I try to look at ever new combustion chamber design that the big 3 put out. I also have practical experiance in seeing what happens when you put a big lump of aluminum in front of a flame. It's not a good deal.
If I was starting from scratch and wanted to win this deal I would look for the biggest HP I could find in a 600cc engine (Yammie R600?). If I was really serious I would build a 2 stroke. A 4 stroke can't even come close to the power to weight of a 2 stroke. Then I would buy that engine and form fit it to the rules. What I mean by that is shave the pistons down to 7 to 1 and add about 30 PSI of boost or so from a turbo or supercharger. You need to get as close to the edge of the rules as you can. If you don't your are not going to win.
Whatever you do, I wish you good luck in your endeavor.

 

FST, wander what that stands for?[img]i/expressions/face-icon-small-shocked.gif[/img]

Sorry about that. I guess my mind just happened to skip right over that one.[img]i/expressions/face-icon-small-blush.gif[/img]

 

Bubba: FST=four stroke turbo.....mmmmm boost

We are currently running a cbr 600 f4i engine but 80% of the teams run a motorcycle engine and I want to do something different (it is a design competition) and my main desire to run this 750 is because I want to use a CVT (smoother running and less turbo lag) so Its not really about making the most power, its about making it usable which i think the CVT's accomplish nicely

 

modedwarrior one thing you might want to think about is power loss through a CVT. Your thoughts are right about the turbo and the CVT; but you are also going to loose about 20% of your power through the CVT. 20% is a bunch!!!!!
Will the smoothness overcome the 20% loss in power? Only you can answer that question.
One more thing to think about is CVT's and turbo's. They are kind of like oil and water. They don't really mix to well. A turbo will put out a ton of low end torque if designed properly. If the 750 CVT was designed for X amount of HP at Y amount of RPM and you change those parameters outside of the limits of CVT you will have big problems.
If geared wrong, I can smoke an automotive hydraulic transmission, let alone a rubber band.
Just something to think about if you haven't already.
Maybe you can build a 2 stroke that sounds like a 4 stroke?!!!! [img]i/expressions/face-icon-small-wink.gif[/img]

 

I dont think the loss will end up being 20% but in any case in a track where you hit wideopen twice and your average speed is 50mph i think the smoothness is well worth it. Smooth driving will win an autocross though. I know that a larger squish band width will increase torque and a smaller squish band width will increase higher RPM power but what happens with a negative squish band? I assume a swirling effect will occur but my knowledge of CFD is not sufficient to analyse this problem

 

why not weld the edges of the chamber to re-size it,i know theres machine shops that can repaire damaged heads when valves break/ect so they should be able to close up the chamber a tad[img]i/expressions/face-icon-small-wink.gif[/img] keep the shape simaler to oem and all should be good.the only problem would be how close the valves are to the edge of the chamber,you might have interfance problems or may shroud the valves more causing some power loss[img]i/expressions/face-icon-small-confused.gif[/img]

 

More research needs to be done regarding 2 strokes for emissions and power output, etc.
Oil formulations too (for you Chem E's out there)

Too bad your university won't allow you to tinker with the 2 smoker!!

 

If you average speed is 50mph and you only need "speed" at certian times, than I wouldn't turbo your motor. Just use Nitrous for when you need acceleration. Then you can consentrate on making the motor you choose effiecient when it comes to fuel mileage. you can cryo-treat all the internal parts of the engine,and also coat the parts with performance coatings(that reduce friction) for maximium fuel mileage,and strength!


If you want to be different than use other forms of technlogy.





Bigger.

 

hey guys, I would love to run a 2 stroke. Specifically polaris's 600 HO two stroke but rules forbid it. Nitrous is also not permitted. I've emailed weber about the 750 but no response yet. Its not looking too promising yet, does anybody else have any other ideas?

 

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