Vibration damping for differential mounts

[nvpF1crazy]

We're running a CBR250R single cylinder engine (first time anybody is doing that at FSAE or FS) and after it was cranked it doesn't seem like any vibration damping might be required. The original bike didn't have any either.

So is vibration dampening for a chassis mounted differential required? Does any team use bushings made of polyurethane or any other material for dampening vibrations to the differential mounts? We're mounting our differential (Torsen T1 Univ Special) on to the chassis.

[nvpF1crazy]

We're running a CBR250R single cylinder engine (first time anybody is doing that at FSAE or FS) and after it was cranked it doesn't seem like any vibration damping might be required. The original bike didn't have any either.

So is vibration dampening for a chassis mounted differential required? Does any team use bushings made of polyurethane or any other material for dampening vibrations to the differential mounts? We're mounting our differential (Torsen T1 Univ Special) on to the chassis.

[whiltebeitel]

Many teams do not run any type of intentionally flexible bushing or mount between their engine and the differential. The rules do not mandate it, so it is not required.

[shark.ashwa]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by nvpF1crazy:
We're running a CBR250R single cylinder engine (first time anybody is doing that at FSAE or FS) and after it was cranked it doesn't seem like any vibration damping might be required. The original bike didn't have any either.

So is vibration dampening for a chassis mounted differential required? Does any team use bushings made of polyurethane or any other material for dampening vibrations to the differential mounts? We're mounting our differential (Torsen T1 Univ Special) on to the chassis. </div></BLOCKQUOTE>

I dont think so, UTA ran a turbo 250 in 2010. Also, a team from Delhi (NSIT?) used a Honda 250 for their car intended to participate in FSAE-A.....I dont know what happened to that though http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif
There is no need for vibration dampeners for the differential mounts. More importantly, you need very stiff mounts (think shock loads while changing gear! http://fsae.com/groupee_common/emoticons/icon_eek.gif)for the diff mounts.....

Sharath

[kcapitano]

I think UTA used the CRF250X; in any case, it couldn't have been the CBR250R because that engine wasn't on the market in 2010. The CBR250R is also a much different engine to the 250 motocross engines.

@nvpF1crazy, will you guys be at FSAE michigan? I'm interested to see how the CBR250R does in FSAE. Off topic, I know, but what what made you guys decide on that engine?

[nvpF1crazy]

@kcapitano: Not Michigan. We tried for UK this year and are on the reserve list. Hoping to get through to Hungary.

We're a first year team from India and this engine was chosen largely because of the financial and serviceability constraints posed by the standard 600cc engines. There is absolutely NOTHING between 250cc and 650cc here in India http://fsae.com/groupee_common/emoticons/icon_frown.gif

Our aim is to design and manufacture a good car around it, clear tech and endurance and win fuel economy.

Right now we're learning so much new everyday that engine mods and turbos are really not worth it. Maybe next year!

[Markus]

With new fuel economy rules in FSH and FSUK including CO2 conversions and again excluding effiency (fuel or in this case emissions relative to lap time) any combustion powered car will face snowball's chance in hell to win fuel economy if an electric car is attending the competition.

Fast electric cars are consuming around 4kWh of energy during endurance which equals to 2,6kg of CO2.
Fast (and efficient) combustion cars are consuming around 3l of fuel during endurance which equals to 7,8kg of CO2.

In other words you have to finish endurance with less than 1 liter of fuel used which I think is an impossible task (gasoline doesn't really combust above lambda 1,3). Even if it would be possible it would mean losing a lot of points from endurance scoring.

Don't want to put you down but that's how it unfortunately is. Put your full emphasis in getting the car ready in time and make it reliable. Testing time is valuable in scoring high, and finishing endurance is a good start for a new team.

[nvpF1crazy]

So I guess we should be the only competitors among the combustion teams challenging the electric ones in this category! All the more reason to get our car in proper shape!!!

[Markus]

I was being quite conservative... For example 2011 FSG winners translated to FSUK emission rules:
Fuel efficiency (combustion): 1,9l which equals to 4,9kg of CO2.
Energy effiency (electric): 2,6kWh which equals to 1,69kg of CO2.

Which equals to 0,65l of fuel used. Which is what you might have to beat. And you must finish endurance to score fuel economy.