Formula SAE pics

93forestpearl · Post by **93forestpearl** » Fri Sep 23, 2005 7:36 pm

Here are some pics of where we are at right now. I'm still trying to perfect the suspension geometry, since we are low on cash right now.

http://www.d.umn.edu/~pidd0002/pics/P1010731.JPG
http://www.d.umn.edu/~pidd0002/pics/P1010732.JPG
http://www.d.umn.edu/~pidd0002/pics/P1010734.JPG
http://www.d.umn.edu/~pidd0002/pics/P1010737.JPG
http://www.d.umn.edu/~pidd0002/pics/P1010746.JPG
http://www.d.umn.edu/~pidd0002/pics/P1010747.JPG
http://www.d.umn.edu/~pidd0002/pics/P1010748.JPG
http://www.d.umn.edu/~pidd0002/pics/P1010749.JPG
http://www.d.umn.edu/~pidd0002/pics/P1010751.JPG
http://www.d.umn.edu/~pidd0002/pics/P1010756.JPG
http://www.d.umn.edu/~pidd0002/pics/Scr ... tation.bmp

The frame is mild steel since it our first year, and I had nothing to do with the design. The motor is from an '02 GSXR 600. The wheels are 3-piece with magnesium centers and spun aluminum shells. Weight ~ 6.5lbs. The second to last pic is of our vaccum bagging system, which we'll get plenty of use out of. THe last pic is a screen-shot from our Bill Mitchell suspension geometry software, which has helped alot. It would take me months to do all of the ride, roll, steering, and pitch iterations by hand. Enjoy.

206er · Post by **206er** » Sat Sep 24, 2005 12:14 am

when are you going carbon tub?

skid542 · Post by **skid542** » Sat Sep 24, 2005 12:28 am

That looks pretty nice so far. Keep us posted, I've know a couple people on VT's SAE team, I'm an aero guy so no worries

.

93forestpearl · Post by **93forestpearl** » Sat Sep 24, 2005 9:35 am

The carbon tub depends on the loot, if you know what I mean. Its our first year, and our faculty advisor won't listen to my ideas of rebuilding the frame out of chro-moly. Since soooooooo many of the guys are completely green to the concept of cars, I'm just trying to get us all on the same page to build a decent car.

But, since the suspension is MY baby, we are going with carbon tubes and 7075 T6 outside ends, (email me if you want CATIA drawings), stainless inside inserts, and a fairly low roll center(.397in below ground to be exact). We have that vaccum-bagging sys. so it won't take alot to fab some tubes that will handle the stress and strain. I'm focusing on unsprung weight and finding money to fund this project. All of these guys don't have the balls to approach a $200 million plus company like AMSOIL or Cirrus Design for a couple grand. Bunch of weenies.

I just want to get there and not be a dumb ass group who is assembling their car on the way. For next year, the frame will be built around the CG, suspension, and packaging, and will save 50 lbs in the process. (This one weighs 92 lbs as it sits:shock:). My goal is to keep the car under 550lb with the driver. Some teams are under 370.

I've got three guys and our fluids genious, Dr. Pope, going on a tuned port intake for this beotch. If they do a good job, we'll get 60+ HP out of it, which is not bad for a 500lb car..

I could rant forever, but I'll stop.

91White-T · Post by **91White-T** » Sat Sep 24, 2005 3:11 pm

Nice! I wanted to join formula SAE but have 0 time this semester...

LaureltheQueen · Post by **LaureltheQueen** » Sat Sep 24, 2005 4:59 pm

The UW formula SAE team "funds" autocrosses. It's a great way to make revenue, because you don't have to pay pretty much anybody, all you have to pay for is announcing equipment. They get a fair bit of money doing these, I think, and have a chance to test and tweak their cars for free.

$.02

BAC5.2 · Post by **BAC5.2** » Sat Sep 24, 2005 5:05 pm

What are the regulations on engines?

FG!! · Post by **FG!!** » Sat Sep 24, 2005 6:22 pm

610cc and a 20mm restrictor plate.

BAC5.2 · Post by **BAC5.2** » Sat Sep 24, 2005 7:15 pm

That's it? Just 610cc and 20mm restrictor plate?

So no rules against forced induction? A turbo setup wouldn't weigh very much, maybe 30 pounds at the most for what you need. With a 20mm restrictor plate, what's left but to force air through it?

The power to weight gains would FAR outweigh the weight sacrifices.

Your target of 550lbs now gets bumped to 600lbs, but a 600lb-car with 100hp would be more competitive than a 550lb-car with 60hp, right?

93forestpearl · Post by **93forestpearl** » Sat Sep 24, 2005 9:38 pm

Some teams do go with forced induction, and Garrett has two options with a gt12 or gt15. But the problem is that the restrictor must be before the compressor. From what I've read on the fsae forums, there isn't a major gain in hp but you can get alot more torque out of it with a turbo. THen there is the packaging issue of finding a spot for an intercooler and all the plumbing.

I'm not discounting the idea, but since this is our first car, we need to get the basics down before we go too nuts on it. It also depends on how many guys stay involved. Next year when the frame is designed around everything else, as opposed to vice versa, our options will be much more open.

Right now I feel like I should have the Project Manager label. Our guy is a grad student who doesn't know a whole lot, but he has keys for the labs. I'm the one who goes out begging for money and trying to find deals and donations. For instance, we need four rear shocks and springs from a mountain bike. They must have adjustable compression and rebound dampning. Something like the Fox DHX would be perfect, but they are $400 apiece. So yesterday Iwent to two bike shops in town and got the business cards of who I need to talk to in order to get them donated or at least a deal. And on and on.

Laurel, I really like that idea of putting on Auto-x's to make money. Now I just need to find enough tarmack.

BAC5.2 · Post by **BAC5.2** » Sat Sep 24, 2005 10:16 pm

You should have asked me about the rear shocks. I could have gotten you the numbers you need to call, without any problem.

Why did you choose the Fox DHX?

I'd reconsider.

Fox has problems. I blew a Vanilla RC, twice.

If you are looking for high performance, and durability, contact Avalanche. They are a smaller company, but make some incredibly reliable and durable shocks. Better than Fox in every way.

The DHX is also a bit heavier than the Avalanche.

You could also look into the Manitou Swinger 6-way. You'd then have external preload and rebound control, Pedalling Platform adjustments (not necessary for your application really, but you could use it to adjust dynamic preload. I.E. you could set preload, then set a threshold for the shock to activate. You can use that to help balance roll, in that setting the threshold will require certain leverage before activating the shock. Or you can leave it empty, and have no assist). You also get volume adjustments (progressiveness of shock stroke), and high and low speed compression adjustment.

Expensive, but worth it. AND, Manitou (owned by Answer Products) has motor sport devisions (Motorex lubrication, and saftey equipment).

The 6-way weighs 500 grams, and you can get a Ti Spring. You could tune EVERYTHING with this shock, AND it would be more durable than the Fox.

93forestpearl · Post by **93forestpearl** » Sat Sep 24, 2005 11:29 pm

Really. I'm very interested then. I just saw the Fox DHX because it does what we need. I know very little about the mt. bike world so I definately didn't know that about Fox. I gotta go to work though.

BAC5.2 · Post by **BAC5.2** » Sun Sep 25, 2005 1:03 am

Yea, check out the Manitou.

The Fox will do what you are looking to do.

Without the spring, the Swinger is 500 grams (per unit). The Fox, without the spring, is 400 grams.

I was going to get a DHX for my downhill bike, but had decided to use a Swinger 6-way instead. The DHX could never break, but I know the Swinger would be durable for me. Plus, I like how Manitou sets up its seals. They have very little stiction, which is nice. They are favored among most OE specs, which is kind of cool, considering Fox used to OWN the OE market.

FG!! · Post by **FG!!** » Sun Sep 25, 2005 2:46 am

I wish I could talk shop, but it's been too long since i've been involved. I like wathing this video though from last year. The engine tunning sounds great and the driver doesn't suck.

http://students.washington.edu/auto/Media/2005.mpg

BAC5.2 · Post by **BAC5.2** » Sun Sep 25, 2005 3:33 am

That looks sweet, and brings up another question...

What are you doing for brakes?

I assume your using the bike motor and it's stock tranny, right? You have the benefit of not having to shift often. IIRC, the Gixxer600 tops 1st at 70mph.

Actually, you have a few benefits using the bike gearbox. For one thing, all motorcycles have dogboxes, so you can use the clutch simply to get going, and clunk through the gears without MUCH worry. Your car won't weigh THAT much more than a bike.

Also, before you drop that thing into the car, get a new clutch in it. Bike clutches are fairly reliable, and you can use them very effectively to control output from the motor to the ground. Preferred bike launching is to rev it up, slip the clutch, pull the clutch back in, bring engine revs up, and slip the clutch to control the front end. That's a lot of clutch slipping, and you could do this ALLLLL day long without worry. They are durable.

If you can, try to pick up some brakes from a bike. If you can get 2 front brake setups, that'd be the perfect brake setup. Solid, drilled rotors, 4 piston calipers, the car won't be heavy enough to significantly overheat the brakes. One at each corner, and manually actuated. Don't have anything drag on the engine. That'd be a hell of a stopping machine (using HH pads too would be great). For the rear, assuming rear drive, have the brakes inboard for less unsprung weight (a-la Jaguar and Hummer). The axles will be short enough that you won't really have to worry much about having the problems usually associated with inboard brakes.

What is the shock orientation going to be? I can tell your not to excited about your frame layout, and that you're just trying to build a car, and wait till next year to pull out the stops. But what are you doing for this year? Are you planning on trying to be competitive, or just trying to have a car to race?

I've always been a fan of lay-down setups. They seem extremely efficient, and sensitive. Plus, packaging helps keep CG low

. Kinda neat, Koenigsegg implimented this design really well.

I want to do Formula SAE. I wonder if the University of Maryland has a team. I should ask RallySam, he went there.

FG!! · Post by **FG!!** » Sun Sep 25, 2005 4:16 am

Good predictions. Yup, the stock tranny and clutch is used. The chain goes back to torsen diffential that's held in a custom diff housing that each team makes. Alotta teams include a single disc brake on this housing. The control configuration that most teams use is probably the most interesting part. At your feat are gas and brake. One hand lever by your right hand contols the clutch and gearbox. Push forward to upshift. Pull back to downshift and disengage the clutch. The clutch is staged in the stroke to disengage before the downshift. You can really bang quickly between the gears. To launch, release slowly from the pulled back position.

We used off the shelf wilwood brakes. It made replacement easy.

Most teams did lay down set-ups, and the lower the better.

Each team has to build up a knowledge base. It takes years to really pull out the stops. I'm really impressed that they have a frame built this early in the year though.

93forestpearl · Post by **93forestpearl** » Sun Sep 25, 2005 11:46 am

We had a senior D group do the frame, although I put together alot of it. That is why it isn't built around anything and we are now trying to figure out how to mount shit like the motor and what not. But I digress.

I already got brakes from a '03 gsxr front. 4 piston tokicos(sp). They should provide plenty of stopping power. Plus, we can use a real thin solid rotor to save unsprung weight like mentioned. We will be geting the Torsen diff as mentioned. It is a heilical lim. slip. It is sourced from an Audi center diff and is modified by torsen. $360 or so isn't bad at all. I know of plenty of teams that put a brake rotor on the diff, but it makes me worry. Gear oil doesn't like being above about 280 degrees. Putting a rotor and caliper on a thin aluminum housing doesn't sound good to me. Plus, I'm not shure how a helical diff would react to said braking forces.

We have to run two master cylinders to have two independent braking systems, as per rules. Basically one pedal with a balance bar.

I didn't know most bikes could be used like a dog box. I lijke that idea. We get to set what kind of final drive we have with the size of our rear sprocket.

As for our shock setup, it will be inboard, horzontally mounted coil-overs, being pushrod actuated. Being inboard, I have huge leeway as far as shock travel and spring rates go, cause I can play with the rocker.

Oh. And we have a new clutch on the way. One of the guys has been involved with bike racing for a long time. He can tune that bitch up in his sleep. I guess all of the valves were within spec. THe clutch was on the low side though. THe clutch is from some place local, here in MN. Sam said it is good. I'll take his word for it.

But him and myself have gotten into some dissagreement. He feels that getting afuel injected motor was a mistake because of his carb tuning experience. I say arbs don't have the control that injector do, especially with a restricted intake as such. How else can you adjust feul and timing for individual EGT's and AFR relaibly, even when someone else doesn't have the feel for carbs. Arrrr. anyways

p.s. I'm wasted right now and it is 5:45 am. fyi

jamal · Post by **jamal** » Sun Sep 25, 2005 12:04 pm

This is really neat. I'm seriously considering joining my school's team instead of doing the ASCE bridge/canoe stuff. I think I'll go to the meeting this week and see what's up.

206er · Post by **206er** » Sun Sep 25, 2005 5:12 pm

you should look into air shocks. much lighter and more tunable for spring rate than coils. though coils are generally available in more lengths, travels, and damping options. but for playing around with spring rate, air shocks would be even easier to adjust than unbolting a coil shock. just use a shock pump.
are shocks considered unsprung weight? I imagine with a steel chassis you may be looking to shave weight in other areas.
look on www.MTBR.com classifieds, they are the best for mountain bike stuff. you might be waiting a while to find a matching set of air shocks though.
what is the weight bias like on those things?
do you think 8" rotor mountain bike disc brakes would be up to the job of stopping the car? if so you could save some serious weight there. there are 6 piston setups available

93forestpearl · Post by **93forestpearl** » Sun Sep 25, 2005 7:09 pm

Since the car will tip the scales at over 500lb with the driver, mountain bike disk brakes wouldn't be nearly enough, I think. I guess I'd have to do more research. Its nice that we'll have a similar weight to a motorcycle so those brakes should do just fine up front with the right pads. For the rear, I'm trying to find some light two piston calipers. I've been told to stay away from willwood. AP racing is kinda spendy. Archer told me to get in touch with stoptech. When we get our website up, there will be pictures of their shop. $300k vipers are pretty sweet, even if they are american.

My friend might be filament winding us some axel shafts, which would be tits.

The shocks will be sprung weight since they will be mounted inboard. Things like a-arms are partially unsprung weight. The outside is unsprung and the inside is sprung. A little statics would tell what it is exactly,

BAC5.2 · Post by **BAC5.2** » Mon Sep 26, 2005 1:48 am

Don't use air shocks from a mountain bike.

They won't have NEARLY the capability to control something as heavy as this car. Air shocks also have an added downside of... being air based. Under cyclic load, the air likes to expand and you effectively get a varying spring rate. Not to mention, that most air shocks can hold a max of 225psi, which is about enough to support a 200lb individual on a mountain bike. This vehcile will put a MUCH higher load on the suspension than a mountain biker would put on it with a bike. I've serviced a TON of blown air shocks.

With a coil shock, it would be much more reliable and consistant performance. Plus, with the suspension tuning software, he should be able to estimate spring rates with that, if it won't do that, I can give some advice based on lots of suspension tuning experience.

Definately stick with fuel injection. With carbs, you can save weight, because you don't need things like a fuel pump, or an ECU. But you can definately tune MUCH better with the fuel injection. Yea, your friend can tune carbs. But YOU can tune an ECU. Control it with a standalone computer (Megasquirt), and voila, you will be able to do just about everything. Plus, you could tune for forced induction if you so desire to go that route. The flexability with fuel injection will pay immensely on race day. Monitor with Wideband O2, and individual EGT. Flyin Miata sells 2-in-1 EGT gauges. Get 2 gauges, 4 sensors, and hook it all up. Get a tach, 4 EGT readings, maybe a speedometer, a light connected to the knock sensor (or a knock sensor from a Legacy should work fine), and a digital readout for A/F readings. I bet that would cover just about all the monitoring bases, and you should be able to tune really well from that.

For a rear brake, why not use 2 sets of rear brakes from a motorcycle? I would imagine a brake influence on a helical diff would be interesting. Slow one side down, and it would force the other side to slow down as well (one side would slow down, and the helical gears would force outwards and attempt to spin each output at the same speed, so it would slow the other axle as well). But it would probably wear the SHIT out of the diff. If you get an Audi on snow or ice, and grab the e-brake, all 4 wheels will try to lock. Helical diffs are cool.

For the heat issue, you could consider using gear oil designed for heavy duty truck use. That should help handle any extra heat.

206er · Post by **206er** » Mon Sep 26, 2005 4:19 am

BAC5.2 wrote:Don't use air shocks from a mountain bike.

Not to mention, that most air shocks can hold a max of 225psi, which is about enough to support a 200lb individual on a mountain bike. This vehcile will put a MUCH higher load on the suspension than a mountain biker would put on it with a bike. I've serviced a TON of blown air shocks.

most bike frames using air shocks have what, a ~2.5:1 leverage ratio? not sure what leverage ratio you will be going fo rwith cantilever suspension but I'd assume its close.
Offroad terrain produces more hard hits to bottom the suspension, and generally a lot more harsh shock movement than a FSAE car will see on nice smooth tarmac. seems to me that the main suspension movement will be a lot less harsh of hits than a mtb will see, and mainly from braking and cornering forces.
the car will weigh ~500lbs/4=125 pounds per corner. so the air shock will be running at a lot less than maximum psi, and under less harsh conditions than normal, so durability is *probably* not going to be an issue.
so I disagree that the vehicle will be putting a higher load on the shock than the typical mountain bike. the coil vs air battle more seems to be an issue of weight, tunability, and cyclic load affecting spring rate as you mentioned. but for an autocross of like 30 seconds, I would doubt that excessive heat is going to come into play. now for something like the baja cars, coil suspension is going to be far superior.
93forestpearl, what are the autocross times, and what is your opinion of the suspension hits the car will take? what is the weight bias of the car?
BAC5.2, what kind of weight savings could actually be seen by using air shocks over coils? I dont really keep track of the weight of air shocks. both my bikes have progressive 5th elements, hell Im not even sure what they weigh.

93forestpearl · Post by **93forestpearl** » Mon Sep 26, 2005 5:05 am

I'm thinking I'll need something with a linear spring rate. Since we are going inboard with a pushrod and a rocker, I can change the leverage ratio and the amout of travel seen by the shock and spring. The program (Bill Mitchell) can work with all of that, but since we aren't completely set on exactly where the shocks will be mounted, I'm still tweaking the geometry while I'm waiting for some info from a guy at goodyear on camber angles for the tires.

The shocks will see full travel, which will be 2" at the wheels. About an inch bump, maybe more. I don't want much roll when cornering hard, less than one degree. We can play with that with swaybars, but it shouldn't take much with such a low roll center. When cornering at 1.5g, there will be plenty of wieght on the outside.

I think that the suspension will take some decent hits, especially when we are tuning this thing because our biggest lot isn't butter smooth. The competition will be at Ford's proving grounds in romeo, and I'm guessing where we race will be rather nice. But Duluth is an extremely rough town. The lake seems to keep the air temp in that range that kills roads in the spring.

The wieght bias will be pretty good but not perfect. It will be more rear biased, a little bit. The weight we'll save from air shocks will be minor compared to the rest of the car. I can see it being beneficial on a 24lb bike though.

As for the engine tuning, we're looking at the Dynojet Power Commander, and definately with a wideband and egt's. Archer has a two wheel mustang dyno, and I hope our car will be wide enough.

I'll have to check out Flyin Miata. I was looking at the Zeitronixs setup, but I don't think that will read EGTs from four cylinders. We are gonna keep the 4-2-1 design for the header, since this thing will run out of breath at about 10 grand. I would love to get the Motec system, but at somewhere near $5k, I think we'll need to pass. I hope we get the grant to get that highspeed camera. During the summer, a rep came into school with the same one used on Mythbusters. It can do 200k frames per secong. 12k was too fast for the mill which was spinning at 2k. We could watch our wheel frequencies and tune the shocks accordingly, which would be really sweet. The camera setup runs about $80-100k.

As for the rear brakes, I'll need to look around some more on ebay. I just need to find ones with mounting points I can work with. The Tokicos I got will work well. Did I mention I got them for $45 shipped? I don't want to mess with the new radial mount stuff I've seen, like on my buddies '05 gsxr. I don't know what I was smokin before thinking I'm gonna spend $600-700 plus on brakes for my car. I can get 4 or 6 pot brembos from a porche for about three bills and make my own brakets.

Hmmm. What else. We get to use 100 octane or E85 at the competition. With E85, the restrictor has to be 19mm.

I would love to use composite metal matrix for the rotors, but I don't know if we'll go that far right away. My professor has three buckets of the powdered material. We have a big ass rotor from some race car that weighs about 6-7lbs. Crazyness.

I think I'm just rambling now so I'll wait for the return.

FG!! · Post by **FG!!** » Mon Sep 26, 2005 5:11 am

There's a 22km endurance event. I would stick with automotive or motorcycle brakes.

Here's the rules if anyone is interested : http://www.sae.org/students/fsaerules.pdf

206er · Post by **206er** » Mon Sep 26, 2005 5:39 am

what about megasquirt for the EFI?

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Formula SAE pics

Formula SAE pics