I dont know if you guys have heard of this, but when I was lookin for ways to stiffen my chassis I decided I wanted to get SFCs, but I found another way which might be even cooler to stiffen the chassis, make the car safer, and reduce noise levels. The stuff is called structual foam. It seems like an amazing product, very commonly used in jets and other aircraft some newer cars have started using this technology to gain crazy increases in structual rigidity of the chassis. The new for expidition through use of this foam gained 70% increase in chassis rigidity over last years model. A couple cadillacs and some Benzs also use this technology but more for sound deadening more than chassis stiffening.

Just check out these links.

They foamed the chassis of a 300zx with the least dense foam and increased chassis rigidity by 40%
http://www.sportcompactcarweb.com/p...6scc_proj300zx/
its down towards the bottom

this is an example of the stuff... the foam used in the 300zx was 2lbs per cubic foot density. On this site they have up to 16lbs per cubic foot density which is 1500% stronger than the 2lb stuff.
http://www.shopmaninc.com/foam.html

I could see using this stuff in strategic locations on the car to act like a roll cage and I was thinking about foaming the SFCs that I want to put on.

SO who knows about this stuf. I cant really find any info on it. It doesnt seem like many cars use it. Maybe theres a reason for that, that I'm not aware of.

 

search it. I remember reading a good long thread on it a while ago.

~Alex

 

Hmmm, US Composities instead of ITW or that Japanese company. Good info thanks. Matt93SE did this and liked his results. I was planning on trying it last fall but never made it to Maxus and the idea got shelved for a while.

 

I would suggest against relying on it like a roll cage, I doubt it would protect you very well.

 

agreed....the foam is strong enough to stiffen up the subframe bottom, but I doubt it would have much, if any effect in an accident....first of all, if you get hit from the side, the impact is around the middle of the doors, well above the level that you would foam.....in a front-end or rear-end collision, the crumple zones are (respectively) in front of the firewall and behind the rear wheels.....so the foam really wouldn't come into play, except perhaps a minimal amount of energy transfer.

 

...I would note that, if well-done and the expansion holes plugged/filled afterwards, this would be virtually undetectable if someone wanted to "cheat" SCCA rules.....

There's a chance that I might just do several stiffening things and jump up into SM class, so it's probably legal there.

that said, I'm not sure what the classing rulings would be for this....I'll have to dig around the rulebook and see.

 

SM may be good - 16.1.O reads "Any minor modification...does not provide a weight reduction...intended to allow...strengthening of brackets..." Keep in mind SFC's are only allowed lengthwise on the frame rails without lateral connectors ie. stage 1 vs stage 2.

Of course rules do exist to be bent.

 

What kind of weight gains would be seen from using this?

 

Irish, many cars- including the Q45- use this stuff as a chassis strengthening measure all across the board. they also run it up the door pillars and A and B pillars and along the roofline. it's somewhat of a pain to install in there, but makes noticeable differences for the people that do it- including impact protection in a crash.

essentially, all you have to do it duct tape off all the holes you don't want the stuff oozing out, then go after it from the opposite end of the part.


I would also be very wary of trying to get around SCCA rules by using it.. in the way we are using it, there's absolutely no that it is used as a chassis strengthening measure. As long as chassis braces are allowed in the classes you're running in, then it's not a problem. so far I haven't had any complaints running my car with both stage 2 LTB and SFCs in SM locally, but I'm also near last, behind guys like Teucci...

 

Why the ????? Shouldn't that be a ??

I guess I know with a max, it's unlikely that I will be in any contention for any championship in phillyscca, no matter what I do and what class I'm in. That isn't to say I still won't try, but I could run a SM max against a GS Mini and I wouldn't guarantee a win. The max I think do much better at road courses than auto-x, unless it's really, really fast auto-x with long straights.

 

yeah...I hear you. I think you need to do some other things first though

my plan next season for beating the Minis: siphon all the gas out of their tanks while they're in the staging line....

I actually checked with a local Inifinti dealer to see if they could do it - they "declined" though they did say they "could if they wanted to," which they didn't want to.

My question is related to how much expansion.....is there a risk of bending the frame as the foam expands (i.e. if it clogs up someplace with no expansion holes and pushes subframe pieces outwards).

I personally wouldn't....hell, I'm the guy who ran STU last event because my rear wheels were 8" wide (with 225 tires).....there's really no way they ever would have known, or even thought to look, if I had run STX.....it's really a matter of honesty. Plenty of things you "could" get away with if you really were good at hiding them.

I may just run SM anyways...I want SFC's for daily driving and the fastest STX and STU cars are right up there with the top few SM cars at most of the events I've gone to anyhow.

 

these types of foams are minimally expansive. they will expand to fill the space they're in, but will not keep pushing and bend the metal like the cheap spray can foam will.

 

I think you would have to test the expansion anyway, I think you would want a minimal density if you used the foam. Weigh a simple 1-2 liter beaker, fill it with the foam, I think that would give you a rough idea then just weigh the whole thing. Make your density estimates from that. The volume of space you're filling in your max...I am not sure where to get that information. You could plug it up, fill it with water and measure the water...but I figure someone might have gone through this excersise somewhere before.

 

Yeah, like what?!! get two different color wheels?! well...um..I really haven't done anything anyway, so maybe I should do something..

Eureeka! that's the answer! They're tiny anyway, it would only take a minute.

 

you're over-analyzing it man.. just buy more than you need, fill the car, then sell the rest or save it for later.
this stuff is designed for automotive applications, so it's not going to blow the structure apart like handi-foam. been there, done that. many of these things expand almost instantly after they're mixed, so they're not going to continue to grow once you pump it into the car. mch easier to deal with than the stuff that you squirt in and THEN it expands 50x and you end up popping seams. eek.

 

I know I am over analyzing a little, but Irish undoubtedly has already thought about what I discussed about expansion.
The other thing is that I've seen it done on tv somewhere, it was less of a worry about busting seams than it was just optimal density for structural improvement.
Plus, I don't think it would take that much effort to test it, AND I am fairly sure you can't redo it after you apply it once, the foam isn't that porous. So, with that in mind, why not make the maybe extra hour or so of effort to at least attempt to get it optimal. It isn't like you can just reweld something, I am fairly sure once it's in there there's no going back.
Irish I would want to ask other dealerships or shops, that way the liability is on them and not you, and I am not sure what kind of equipment (pumps?) you would need to inject this stuff in (syringe type pumps, diaphram, or just air pressure?). It doesn't discuss the application in the article in the beginning of this thread. I would contact the foam company they might know which method works best for the foam you want to use for your max.

 

Matt, in a Maxima, where would you want to foam? I saw this before in road race cars, but didn't know what it did. I assumed it was used to absord energy in a collision. What is the difference btwn 2,4, 16 lbs foam? Is it just strength or does it weigh more as well???

 

According to that first SAE doc, the cornerpoints were most improved and not so much the in-between connections. The denser foam does weigh more and requires more liquid to blend. I'm trying to get my hands on the other 2 SAE docs now...

 

I can kind of answer my own question. SCC foamed the uni-body structure. They used this kit: http://www.foamseal.com/auto_aftermarket.htm . It took them 5 cubic feet to fill everything. Pretty cheap chassis stiffening IMO.

I know that SFC's really stiffen up the Maxima chassis. This would be a nice add-on to the SFC's. It would really create a pretty stiff structure!

 

i saw them use this stuff on a skyline once on the speed channel. sounds like a good idea but i wouldn't know where to start.

 

Can you post the documents when you get them? or at least summarize what areas really made a difference?

 

Frame rails is one thing but i wouldn't recomend applying it all over in a DD vehichle. When you get into an accident your car is designed to break a certain way, by adding this to your A, B C pillars etc etc you change how the car will crash, this could be for the better or could be for the worst, the problem is you dont know which. just my .02

 

Bejay- if you could post up those documents, that would be awesome.

I just searched for the old thread we had about this but came up empty. It had some decent info if I remember correctly. I am very interested in giving this a try, but am unsure as to which density I should use. At first, I would think the stiffer the better, but then I thought about weight differences. Is there a way to know if the 4lb foam weighs twice as much as the 2lb foam? And the 16lb is 4x heavier than the 4lb?
If those SAE documents tell us which are the 'best' locations, or the locations that need it the most, that would be excellent.

North did bring up a good point, which is that stiffening up certain parts of the car could be beneficial in a crash, but it's a possibility that it could lead to unexpected things in a crash as well.

When foaming the frame, is it enough to just put duct tape over the holes, or is something stronger needed?

I may stop by Jim Coleman Infiniti and see what they have to say about doing it....

 

I haven't found a way to get the other 2 tech documents for free w/o paying yet. This was an excellent start though and looked like corners were the most beneficial in that particular case.
http://forums.maxima.org/showpost.ph...45&postcount=2

The weight question is simple. Assuming 5cuft is needed you'd use 10lbs of the 2lb density, 20lbs of the 4lb density, or 40lbs of the 8lb density.

If I were to do it I'd probably choose the 4lb stuff. Twice as stiff as the SCC project (which showed a 40% improvement on the Z), and half the cost of the 8lb stuff.

As for the tape I'd think something strong to resist the endothermic reaction. I thought I read like 200deg when combined somewhere. Definately test it outside the vehicle first.

 

concentrate on not blowing up your motor first


don't you have SFC's already anyhow?

 

You should concentrate on not being over the hill
Yes, stage 2 SFCs....but could always use a stronger frame, right? Can you ever have a frame that is too strong?

 

I read the SCC article with the 300zxtt and i asked about using this on a differnt forum..no one could give be a straight answer..so i am very interested

 

From what I have learned since I posted this topic...
It sounds like a cheap and very effective way to stiffen your chassis while reducing noise in the car.
The downside is that it is flammable.. so dont ever think about welding on your car again
Its permenant - forget ever gettin it outta there if you ever change your mind.
If you crash your car you can forget about fixing the peices that were foamed.

Thats too much downside for my daily driver, if I owned a track or a weekend car though. It would be my first mod

 

i am thinking the same thing.....i use my car all year all the time....i will jsut but soem SFCs and call it a day....

 

Are you saying that every Infinity they have done this to is essentially totalled if you get into a somewhat major accident? Why would they do that if all of your points are accurate?

 

I'd like to know where the information that this polyurethane foam is flammable came from. I'm sure it would burn but it couldn't possibly be explosive. It probably wouldn't burn any more readily than the plastic components in your car, although the air space in the foam would certainly help it burn more quickly.

Still, I will get SFCs welded before foaming just to be safe.

 

Excellent find, this gives us a good start.

Seems like the 8lb stuff has the best bang for the buck. But that can amount to alot of weight increase.

It would be interesting to learn if just applying it into the joints is nearly as effective pumping it thru an entire beam. The only time I saw the use of this stuff was on the Speed channel where they were pouring it into a R32 Skyline's rocker panels. According to that paper the test points (1, 2, and 3) on that SUV's rocker panels showed very little gains, though this would be comparing a SUV chassis to a R32 chassis.

However the more I read about this stuff the more I would like to try it. Seeing as im pulling the engine, Im going to try applying it to "Joint 8" and some other small points in the engine bay area.

 

If one were to strip the interior, remove the sound insulation, and fill just the joints, you could theoretically save weight and stiffen at the same time. Just need a warm day, cold day, warm day...