Engine Carrier

[randywebb]

I agree with that. Also, 450knot & perhaps Noah, are assuming a very high cost for the item.

That doesn't have to be true. One might even be able to hammer some Ti sheet into the right configuration.

And, prices for Ti are dropping all the time.

Al is another alternative, as is a high strength steel.

The problem with drilling holes in the existing piece (Thom has done that) is that it lets in dirt, but a skin of FG or CF could solve that problem.

[randywebb]

The real question is: Once you have "spent one's money on these cars" -- at what point do you investigate doing a lighter engine carrier?

If it costs $3,000 then that point is very far way.

If it costs $300 (or 5 hours of time for a hobbyist, and most on this bbs are hobbyists to some extent), then that point is not too far.

[450knotOffice]

Point taken, Randy and Bobby. Most of us here are enthusiast and will take any opportunity to work on the car that presents itself. Also, I totally agree that moving the engine forward, even a tiny bit, will produce a big gain.

[Bobboloo]

I threw out the $3000 figure because I recently got a price of $2500 to have a sheet metal fabricator replicate a sport seat rail for me. Just one rail. He said the prototype would be $2500 and then the copies would be cheap afterwards.

Ti is ultra expensive to work with. It takes special liquid cooled tooling just to cut the stuff. Billet Al CNC is great for one-off stuff. There's several guys, like Mark Hargett on this board, that do it.

If you can blue print it they can probably program the data and cut it for you.

[tcar]

That is NOT wrought iron as someone said, it's a steel pressing. Weighs maybe 3 or so pounds. Have one in my garage.

Why spend hundreds of bucks to save a pound or so, for something that might break if you hit a pothole?

[Natchamp]

I've done a couple of designs for this part. One is a machined aluminum version and one is a formed stainless version. I always thought it would be a nice product and still plan on eventually doing it but after the analysis I don't think there would be as much weight savings as you might think.

[RWebb]

Hmmmm... how about forming it (got a hydraforming unit?) with big holes (like the the drill hole Thom put in his) so it is your basic supportive skeleton. Then wrap it in FG (or even CF) to keep out the dirt and grunge...

I suppose it could even be stamped.

If I had access to a mill like I used to, I'd gouge big holes out of one and then wrap it in FG. For a hobbyist machinist, that can't be too hard. The expense come in when you try to send the kids to college or pay your health care premium by selling the things.

[si Banker]

I have tried to make one for the past year the stock one is 17.09 kilos and the criss member is 14.47 kilos. I am working on a design made of 7075 aluminum that will be hard anodized.

I do not for see much of a weight savings but it will make great eye candy. Any interest?

[RWebb]

Interested in a photo...

Unlike "No Ah" I want wt. savings, and want it at the extreme rear of the car, where it is most important for pitch and yaw.

[pieterk]

I wonder if there might also be an additional advantage to be found in a carrier that might also be stiffer than the pressed steel one in there now. When I changed my motor mounts to solids, I was surprised at the relative flexibility of the cross member, and if that's the same metal as the carrier, then perhaps there might be some incremental benefit for a race or track car to have a stiffer carrier, much as the solid mounts impart a benefit. If that's a useful modification, then that would compound the advantage of a pound or two saved in weight.

I've posted before about the possibilities of producing virtually free prototypes by enrolling at local colleges with good CNC classes. It's possible at Glendale Community college at least. Design it, buy the stock, and output it.

Titanium can be welded as well. I've looked into titanium stock for building a muffler. It ain't cheap, but it's doable. When my TIG skills are developed enough, this is a project I might try embarking on.

[Jeff Alton]

I have the "RSR" style cross mount in my car, now I am really going to have to weigh my spare carrier, there is no way is 17.09kg, let alone 17.09 pounds......

Cheers

[Jeff Alton]

Okay, just weighed it, mine is 3.5 pounds....... Plus whatever my cross bar mount weighs.

How much weight do you think you can get rid of?? Even if you get rid of it all (clearly not possible) that saves 3.5lbs...... what about half?? 1.75lbs? at what price???

I will drill a hole in it to get access to the crank pully bolt, but not for weight savings....

Cheers

[jim72911t]

Originally Posted by PBH

That was my thought. Draw it up in CATIA or SolidWorks and send it to a machine shop. CNC work is cheap now.

PBH, I'm not trying to single you out, but I thought your quote summed up some of the thoughts that have been presented on this thread.

As a manufacturing engineer with many years designing and making stuff like this (the parts I work with every day are smaller, but the same basic principles apply), I don't see how either the cross bar or the engine support piece could be CNC machined cost effectively.

I just took a few basic measurements on my car, and the cross bar would have to be machined from a piece of AL stock roughly 30" x 6" x 1". Not cheap even for 6061, and probably triple the price for 7075 or 2011. The engine support would need to be machined from an equally expensive billet, albeit with different dimensions.

Add in the costs of design, programming, fixturing, tooling, QC, liability, etc., plus the actual machining time (I'd estimate at least an hour per part), and these things start to get expensive.

$3000 for a prototype actually seems a bit low, IMO. Once you've actually figured out the potential market, there isn't a whole lot of room for profit, or it would have been done before.

The steel parts actually are well designed for the purpose, but certainly aren't eye candy. Form follows function.

Jim

[Jeff Alton]

I would wager our mill could make the cross bar in about 20mins or so, maybe less?? But one may need to do more than one "operation" on it. Same goes for the carrier... More time in that part I think, plus save maybe 1 puond. 1.43 a minute + material + design amortization+ fixture cost+ setup costs +profit = no market.....

Cheers

[jim72911t]

Originally Posted by Jeff Alton

I would wager our mill could make the cross bar in about 20mins or so, maybe less?? But one may need to do more than one "operation" on it. Same goes for the carrier... More time in that part I think, plus save maybe 1 puond. 1.43 a minute + material + design amortization+ fixture cost+ setup costs +profit = no market.....

Cheers

Jeff,
I want that mill! Actually, now that I think about it, you are probably closer to right as far as machining time goes for the cross bar. I'd figure two ops, but the second would be minimal. The carrier will require some serious mat'l removal, so a bit more machining time.

BTW, you quote a bit less for machine time than I would, but I tend to do more high production stuff and wrap engineering and prototype time into the quote.

Anyway, I think we agree on the final point: No market (=no profit)

Cheers,
Jim

[RWebb]

Jeff - my guess is yo might be able to save ~2 of the 3.5 lbs. Admittedly that is not a lot.

But, it is much more than is saved by drilling holes in the lid support hinges and other such operations.

In part my "functional aesthetics" are offended -- Porsche goes to great lengths to use alloy this and alloy that everywhere in the motor and transmission. They use alloy lug nuts. They get awards from the Mg industry for using Mg castings for the motors and transmissions. And then - right on the back of the beautiful ultra-alloy engine, they hang... what? A big chunk of low grade steel.

It's like designing a bird with intricate strut bracings inside the air filled bones and then hanging a rock on it...

[Natchamp]

Without repeating myself or Jeff and Jim, who are spot on. There is one simple question that will put this to rest.

RWebb, what price do you have in mind for a complete setup of the carrier and cross mount? Be honest as to what you think it should sell for.

[304065]

Why do you guys assume that removing weight from the tail of the engine NECESSARILY translates into improved lap times?

It's like the whole "move the battery to the smuggler's box" project that, from an engineering standpoint, makes sense because it reduces the polar moment bla bla bla, but it doesn't necessarily make the car HANDLE any better, particularly in the hands of an inexperienced driver. (We are ALL inexperienced drivers until one gets to the Hurley Haywood level.)

The engine carrier is a critical part that is responsible for taking pretty big loads, both in holding the engine in place when the car is going through various accelerations, and in reacting to engine torque. I wouldn't monkey with it unless it were an all-out Turbo race application and then I would take guidance from the Factory. . . photo credit www.gunnarracing.com. . .

[}{arlequin]

LMAO john/noah!

this is clearly a case of, we've run out of our 101 projects, we know how to adjust valves, and apparently our cis ain't acting up anymore, so now i'm bored and gotta do something to the car.

how about thanking someone that your car is healthy and simply droving and enjoying it instead??

you wanna engineer something guys? i have just the item that will make you loads of cash. ready? alu hats for the early turbo rotors to be used on a 911. at $100/pair you won't be able to keep up w/ the manufacture. just make sure you don't make mine by hammering things over a dolly.

[Jeff Alton]

Dave, I already have that on the go....

Cheers