List of basic design goals

[Mechanicaldan]

I know there is a post that has a couple of numbered lists regarding basic design goals for a first year team, but I can find it. I've been searching for a while. Anyone have the post bookmarked? It's something like the following:

Simple and Cheap first year car
1. Steel frame
2. Fuel injected 4 cylinder motorcycle engine with stock muffler (steel, multichamber, ie Honda F3) to pass noise tech on first try. Don't use stock aluminum Suziki mufflers as teams have failed to pass noise tech with these mufflers.

3. Power commander for tuning fuel injection
4. 6.5" x 20" tires w/ 13" rims
5. 3 brake rotors and calipers
6. Spool with chain drive
7. Mountain bike dampers
8. No traction control
9. No launch control
10. No turbo
11. Mechanical shifting
12. No aerodynamic package

Basically, keep it simple, learn concepts, document design, finish manufacturing early, learn to drive car, fix broken parts and retest before going to competition.

[Mechanicaldan]

I know there is a post that has a couple of numbered lists regarding basic design goals for a first year team, but I can find it. I've been searching for a while. Anyone have the post bookmarked? It's something like the following:

Simple and Cheap first year car
1. Steel frame
2. Fuel injected 4 cylinder motorcycle engine with stock muffler (steel, multichamber, ie Honda F3) to pass noise tech on first try. Don't use stock aluminum Suziki mufflers as teams have failed to pass noise tech with these mufflers.

3. Power commander for tuning fuel injection
4. 6.5" x 20" tires w/ 13" rims
5. 3 brake rotors and calipers
6. Spool with chain drive
7. Mountain bike dampers
8. No traction control
9. No launch control
10. No turbo
11. Mechanical shifting
12. No aerodynamic package

Basically, keep it simple, learn concepts, document design, finish manufacturing early, learn to drive car, fix broken parts and retest before going to competition.

[Mark TMV]

oh man, we got most of it wrong with our first-year car then...

[Chris Allbee]

just curious....why do you assume that the stock muffler will automatically pass sound?

[Kenny T Cornett]

Hmm... we have 1 of the things on your list for our first year attempt (due at competition in 2008 due to the freakin fire)

[Drew Price]

Ha, we have 5, counting the three "No's" on the list....

Drew

[BrendonD]

Yeah Drew, but I think we took a much much different approach to the simple and light with our motor selection. You and me have some shop-time dates this week :shifty:

[Mechanicaldan]

Stock mufflers are sometimes stamped with 85 dB. I've been around motorcycles for a decade, so stock sportbike mufflers will pass the 110 dB requirement. There are thousands of other things on the car that you can impress the judges with more than the fact that you designed you own muffler. I always feel sorry for all the teams that have a hard time making it through Noise testing at competiton, because it really is easy to get through.

For all you naysayers that want to build your own muffler, or use a Yoshimura muffler, bring a stock muffler as a backup. It'll make you life a LOT easier at competiton.

[Bill Kunst]

Its not just the stock muffler that makes it quiet. If i bolt the stock muffler directly to the exhaust port of a one cylinder motor, the noise levels are going to be different then a full stock exhaust system. The reality of it is that the stock systems are not designed for our use, and unless you design your entire exhaust system together, bolting on a part is likely going to do jack squat.

[markocosic]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mechanicaldan:
3. Power commander for tuning fuel injection
</div></BLOCKQUOTE>

We'll match 11 of those 12 http://fsae.com/groupee_common/emoticons/icon_smile.gif but contest the 3rd...

On a bike, the plug and play of a power commander is undoubtedly easier. On an FSAE car, installing a MegaSquirt (or the PE ecu) appears to take less time than butchering the bike loom to fit the car. Sure, tuning will take longer to get started, but I think forcing you to go from scratch in terms of maps and working out what the sensors are/do,what you need you'll end up with a better understanding of powertrain tuning/mapping and ultimately a more reliable first-year package. The support for both is great too, and neither really cost the earth.

[drivetrainUW-Platt]

We had the same suzuki stock all aluminum muffler that everyone runs...we didnt pass sound the first time till we baffled it.

It has a lot to do with your headers to. Also, our engine wouldnt quite rev to redline due to lack of tuning, so that prob made it run rough and make more noise.

[Chris Allbee]

I feel sorry for those teams who think that designing your own is a waste of time. Seriously, if you have everything else taken care of then feel free to dabble in designing your own muffler. You will learn a lot and last I checked that was the point of this competition.

As far as your decade of sports bike expertise, did you ever look up the procedure by which those mufflers are assigned a 85dB rating? Its not like the sound test we go through at competition.

And again the tuning aspects are different as well. Have you looked into the effect the restrictor has on volumetric efficiency at high RPMs? Given that, did you then consider the effects of the exhaust "back-pressure" on trying to improve that VE?

Next, what is the exact set-up you are running? Engine? Runner lengths? Exhaust configuration? Plenum size? any head modifications? These all play a part in the sounds emitted from the engine (i'm sure there are others).

Point is, just because it works on one application doesn't mean that it will have the same effect on another system. So don't feel bad for the rest of us.

[afroney]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">For all you naysayers that want to build your own muffler, or use a Yoshimura muffler, bring a stock muffler as a backup. It'll make you life a LOT easier at competiton </div></BLOCKQUOTE>


Also, take into consideration things that aren't directly muffler related, but can cause a team to fail noise. Our aluminum firewall last year rattled pretty badly against the chassis, causing us to nearly fail noise. We even had a nice stock Yoshi muffler

[Mechanicaldan]

Chris -

You make a LOT of valid points, but my original point of the post is for a SIMPLE and BASIC design list for 1st year teams. I would think that on a list of 50 important items to a judge, that designing your own muffler is pretty low on that list. Yes, you need to understand what the lengths and diameters of the exhaust system have to do with the curve of your powerband. If designing your own muffler were a TOP 10 item for the design judges, then more top placing teams would do so, but they don't, they buy one.

Mike - I'll take your word for it, but I find it really difficult to believe that a stock multichambered muffler (Honda F3) won't pass the noise test. Of course, that's a steel muffler, not an aluminum one, and you said it might have had a lot to do with your header and tuning. I've been to competition and talked to other teams that have been very happy when they passed noise with a stock muffler. One team I remember used a 600RR oval undertail muffler. Anyone else NOT pass noise tech with a stock muffler? Mike, I think your team is the one exception.

I understand that there is a LOT to consider. I was trying to make a basic list for 1st year teams to consider. The point is to get a car built from scratch. No starting point other than a blank screen and an empty chassis table. Team members that struggle with the difference between caster and camber. THAT'S A HUGE UNDERTAKING. It's easier when you have a car that has been to competion, and you can refine it. Members then understand concepts and can apply them more thoroughly for improvements.

I am VERY open to suggestions for a 2nd year team list. I would agree that designing a complete exhaust system would be on this list, along with a MegaSquirt ECU, or any other fully adjustable ECU.

Regarding building on concepts, I will point to my team specifically from 2002 when I joined in the Spring semester to last year. We did not have a running car at competiton for 2002. It was a 600 lb beast with a lame attempt at aero. It sucked. I helped my team work on the car for 4 days trying to get it to run. We placed 1XX something, as I don't even remember. Our team pledged to never have that happen again. We went back to basics. No aero. No traction control. No electronic shifting. The next year I was engine team leader, and our team finished 22nd. The next year's car was even better, but DNFed endurance because of a leaky differential. (Design with o-rings to seal it!) The following year ISU placed 18th. Last year ISU placed 7th. Building and improving upon concepts that work, instead of going crazy with complicated systems. Last years team still didn't have aero, or electronic shifting, or traction control. They did have a team that understood concepts, and could drive a car well.

I feel that if a 1st year team were to follow this list and score in every event, then they would have been one of only 44 teams at the 2006 FSAE competition to do so.

Why aren't there more teams finishing every event? It's because there is so much to do in so little time. So, for a 1st year team, I think SIMPLE and BASIC is best. Slap a stock muffler on the car, and tell the judges you justified the decision for it because it didn't break and allowed the few remaining members in the Spring to learn to test and drive the car weeks before coming to competiton for the 1st time.

[Biggy72]

We couldn't pass with a suzuki muffler.... we were anywhere between 115 and 118 db pretty much no matter what we did. A super trap system is great for a 1st year team because it is adjustable if you can't pass sound.

[Mechanicaldan]

OK, I was wrong, and wasn't specific enough. Let me restate number two.

2. Fuel injected 4 cylinder motorcycle engine with stock muffler (steel, multichamber, ie Honda F3) to pass noise tech on first try. Don't use stock aluminum Suziki mufflers as teams have failed to pass noise tech with these mufflers.

[Chris Allbee]

Missing the mark again there Dan. It wasn't about just the Suzuki being insufficient to pass tech. The argument revolved around the complex interactions of the entire induction and exhaust systems and how those affect the final sound pressure levels of the system. If your system is different from stock then your noise levels and spectra will be different as well. It may so happen that the system you guys came up with still worked well with the stock system, but that doesn't mean it will work with everyone else. There is more than one way to approach each problem. Your way isn't the only way.

2. Fuel injected 4 cylinder motorcycle engine with stock muffler (steel, multichamber, ie Honda F3), Iowa State's intake, exhaust, fuel/ignition map, frame (and anything that would rattle because of the motor), and the exact weather conditions on the day Iowa State passed tech to pass noise tech on first try. Don't use stock aluminum Suziki mufflers as teams have failed to pass noise tech with these mufflers.

That should just about cover it. you're welcome for the clarification.

[mtg]

I think Dan's on the right track- his point was to suggest first year cars are ridiculously simple and use general design basics that have a high probably of working on the first try.

On the subject of details, I'll vouch for a stock Suzuki muff by itself not necessarily passing tech. It seemed to me that there is a strong correlation between exhaust loudness and the length of pipe between the collector and the muff.

[Buckingham]

From my experience the Suzuki engine itself is hard to pass sound with. When our team switched from a FZR to GSXR many years ago we were amazed at how the GSXR was 10-15 dB louder across the board (with no muffler, the same muffler, just about every combination we measured).

[Hot Rod JayRad]

I also think Dan has the right idea. Our 2nd year car has been hard to pull off because we tried too many design improvements for the number of people on the team.

Regarding the mufflers:
I suggest using the stock muffler because it was originally tuned to the motor headers/exhaustpipe. If engine hasnt undergone much change it makes alot of sense to use the stock chambered muffler.
But yes, you will usually have to modify your exhaust a bit to pass sound. Muffling can be simplified by the understanding that the more material there is to absorb the energy of the exhaust, the less energy it will have when it leaves the tailpipe; therefore, quieter exhaust readings. Use this to come up with a simple solution for your first year or even second year car. Bill, I completely agree with you as well, but I think there is an easier, quicker solution for teams that have different design priorities (i.e. getting a first running car by comp.)

[drivetrainUW-Platt]

Heres our muffler, I am pretty sure it is a Suzuki, its def aluminum.
Like I said before, our engine was sputtering and cracking at 10000rpm due to tuning so that probably made more noise then a good running engine.

http://i22.photobucket.com/albums/b309/duwem/Muffler.jpg

[Wesley]

I completely agree that simplicity is best for a new team - in fact, I would tend to argue that simplicity is best for all teams. Widget A may generate buzz at competition, but if Widget A goes in Trashcan C during competition, who cares?

While there are books full of equations on how to calculate what header lengths result in what power peaks, not many books give you a step-by-step method of building a working muffler. It actually teaches some new concepts and is a good engineering exercise.

That doesn't only apply to mufflers, but to a pneumatic shifting system, etc, etc.

I think first year teams should definitely concern themselves more with putting a decent frame together, getting a solid engine and braking system, and engineering an effective suspension. But there will be those on the team that may want to work on Widget X, and those are the ones that will make improving tweaks in the future.

[raitinger]

side note ....

How long has cris albee been in this FSAE hell

2003 dang!

[Wesley]

Apparently the man is a masochist. We expect 2 more years out of him before he starts crying and runs away for good.

Good to have him while he is still mostly sane though. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif