Sign in to follow this  
Followers 0

Firewall

21 posts in this topic

Posted

Did anybody get a factory supplied firewall with their Avid+ kit? I'm ready to order some 304 Stainless .018 for firewall and need to confirm the size. Will 3' x 2' be enough, or do I need to order a 4' x 3' sheet? Looks real close but I don't have a cowl on hand yet, planning on using a Kitfox Series 5/6 smooth cowl for Rotax. Thanks.

Share this post


Link to post
Share on other sites

Posted

Doug,

I made my own firewall and it turned out to be about 27" tall, with about 1 1/2" wrapped around the bottom and about 34" wide.  So, a piece 30"x 36" should do it.  I used an old C model firewall to get the general size and bent aluminum to make the flange. 

Jack

Share this post


Link to post
Share on other sites

Posted

Thanks for the help Jack, I knew it was close and didn't want to order small. Maybe I'll compare weight and price vs. galvanized with FireStop paint, and try to find a lightweight heat/cold insulation and sound dampener material while I'm at it.

Share this post


Link to post
Share on other sites

Posted

Sounds like a plan.  What is firestop paint?  I'm using galvanized and didn't think you needed to treat it.

Jack

Share this post


Link to post
Share on other sites

Posted

Jack - re: fire stop paint, see link in my prior post. You don't need to treat galv., but my thought was since you typically have to use a heavier gauge of galv. vs stainless to get equal fire resistance, using a thinner gauge galv. with the fire stop paint might provide protection equal to stainless at the same or less weight at a lessor price altogether. Most important if I can source the galv. locally because .018 and .020 304 SS sheet seems to missing in action around here.

Share this post


Link to post
Share on other sites

Posted

Thanks Doug, looks like some interesting stuff. 

Jack

Share this post


Link to post
Share on other sites

Posted

Doug,

You better stop all that serious progress. Very distressing for us ner do wells trying to lounge on the sick bed. Might just agrivate me enough to get off my keister and start moving again  :lol:

:beerchug:

CM

Share this post


Link to post
Share on other sites

Posted

Jack-

How thick is your firewall SS in inches please? And, it is 304 SS, right?

Thanks  :-[

I'll be more specific for the metal experts...

I know ACS recommends/sells .018" (3/16") 304 SS firewall material, but I just found a local line on super cheap 1/8" 316 marine SS.

Can I substitute 1/8" (0.125") 316 SS for 3/16" (0.18") 304 SS for firewall material?

316 SS is thinner and stronger, but strong enough?

Weight difference?

Thoughts anybody?

------------------

304 Stainless Steel

T-304 is the most commonly used stainless in the world. You can find it in everything from forks and knives to backsplashes. It is weldable, machinable with the right techniques, and has good corrosion resistance, but is not for use in salt water environments. This material is hardenable by cold work.

304 Stainless Steel (annealed condition)

Minimum Properties    Ultimate Tensile Strength, psi    73,200

Yield Strength, psi    31,200

Elongation    70%

Rockwell Hardness    B70

Chemistry    Iron (Fe)    66.5 - 74%

Carbon ©    0.08% max

Chrome (Cr)    18 - 20%

Manganese (Mn)    2% max

Nickel (Ni)    8 - 10.5%

Phosphorus (P)    0.045% max

Sulphur (S)    0.03% max

Silicon (Si)    1% max

-----------------------------

316 Stainless Steel

Also known as marine-grade stainless steel, T-316 is similar in machinability and weldability to T-304, but has far superior corrosion resistance. It has a far higher yield strength than both 303 and 304, meaning that it will not bend as easily. This material is hardenable by cold work.

316 stainless steel (annealed condition)

Minimum Properties    Ultimate Tensile Strength, psi    89,900

Yield Strength, psi    60,200

Elongation    45%

Rockwell Hardness    B91

Chemistry    Iron (Fe)    65%

Carbon ©    0.08% max

Chrome (Cr)    17%

Manganese (Mn)    2%

Molybdenum (Mo)    2.5%

Nickel (Ni)    12%

Phosphorus (P)    0.045%

Sulphur (S)    0.03% min

Silicon (Si)    1%

Share this post


Link to post
Share on other sites

Posted

Doug,

I used galvanized material for my firewall.  It's only around .030" thick.  .125 stainless is very heavy isn't it?  I can't imagine needing anything over .030" to .035", you could darn near hang the engine off of 3/16" stainless.  What does your construction manual call for? 

Jack 

Share this post


Link to post
Share on other sites

Posted

no way I would go with a 3/16 firewall.  WAY too heavy.  .018 is plenty.  The firewall on a cub or 12 or 20 or most of the rag wing pipers is .020 aluminum (atleast the ones I have owned or worked on).

:beerchug:

Share this post


Link to post
Share on other sites

Posted

My (Mk-IV) manual simply refers to "firewall material". My Mk-IV kit supplied firewall was galvanized, but the pullsheet only says "Mk-IV Firewall" and I don't recall the the gauge. My Avid+ kit was FWB and no mention of firewall is made on that pullsheet.

I found a local source of large scrap 304 and 316 SS in both 1/16" and 1/8" thickness and I'm trying to determine if either is appropriate. Aside from not knowing what either kit is normally supplied with, my big problem is that different metal sheet is referred to using three different standards and further different thickness measures ie., decimal thousandths (sometimes metric), gauge, inches etc. While Galv. is usually sold by gauge, SS is by decimal thousandths but... I'm just trying to convert everything into plain ol' inches ie., decimal inches into fractional inches (1/16ths or 1/32nds etc.)

Bottom line is I've managed to get myself all confused up!      :banghead:

re: weight- ACS sells Galvanized Sheet, 26 Ga., .022", 2.718lb per 12"x48" and 304 Stainless Sheet, ?? Ga., .018", 2.173lb per 12"x48"

re: recommended firewall thickness- following is from a 3/95 Experimenter Magazine article titled Firewalls By Tony Bingelis

Acceptable Firewall Materials

The following materials may be used in firewalls WITHOUT BEING TESTED;

     • Stainless steel sheet - .015 inch thick (.284 lb./cu. in.)

     • Mild steel sheet (coated with aluminum or otherwise corrosion protected) - .018 inch thick

     • Terne plate - .018 inch thick

     • Steel or copper base alloy fittings

     • Other materials may be used if they can pass the fireproof test.

Ok, I see where I got goofed up (ACS recommends/sells .018" (3/16") 304 SS - in my last post ain't right) but what the hell do I need in fractional inches please. Sounds like even the 1/16 thick SS is 4x as thick/heavy as necessary? Wow, I thought the last SS firewall I looked at was more than 1/64 thick? That doesn't sound right!

1/64 = 0.015 625

1/32 = 0.031 25

3/64 = 0.046 875

1/16 = 0.062 5

5/64 = 0.078 125

3/32 = 0.093 75

7/64 = 0.109 375

1/8   = 0.125 0

1016_3d3afb40775e698521b116db939fc6e3ef8

Share this post


Link to post
Share on other sites

Posted

[engineer / machinist hat = on]

316 SS would be more prone to cracking than the 304.  303 would be even better, but harder to find and more $$.

[/hat]

Share this post


Link to post
Share on other sites

Posted

yeah thanks, makes sense... harder = more brittle. Lol, I feel like I must be having some kind of senior moment or something on this. IIRC your mangy fox had a galv. wall under the blanket. What about that 1050... Galv. or SS? If SS, how thick?

Share this post


Link to post
Share on other sites

Posted

Going flying on Friday in it, I'll check it out...  :buttrock:

Share this post


Link to post
Share on other sites

Posted

Doug,

I've still got the original firewall off my C model.  I'll measure it and send you the number. 

Jack

Share this post


Link to post
Share on other sites

Posted

Doug,

I mic'd the firewall off the C model, it's .018" galvanized.

Jack

Share this post


Link to post
Share on other sites

Posted

Thanks much Jack, for some reason I thought it looked thicker than 1/64".

Share this post


Link to post
Share on other sites

Posted

Doug,

No problem.  A little thicker probably doesn't hurt.  Mine is about .025-.030", and I feel comfortable hanging things off it like the radiator hoses and overflow bottle, coils, etc.  Much over that probably isn't needed. Randy used stainless on his firewall, about .018-.020", I don't have the exact size, but it sure looks good.

Jack

Share this post


Link to post
Share on other sites

Posted

I got overly excited there for a moment, coulda bought a sheet of 1/16" 304 twice as big as needed for all of $10.

Hehe, I love a good bargain...  :)

Share this post


Link to post
Share on other sites

Posted

Doug,

The firewall on my 1050 appears to be that same .015-.020" stainless material.  It is not galvanized and is not aluminum.

Larry

Share this post


Link to post
Share on other sites

Posted

thanks Larry

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0