cutting firewall
 

hey guys, sorry for the long absence. 2yr professional obligation left me garageless and broke. hey but i'm slowly restarting my 20b-rx8 build.

my biggest problem is as some of you already know, intake manifold. so... i decided to cut my firewall and just use oem manifold. i asked JIC in california who's the only ones i've seen cut firewall on our beloved rx8, but they were being pretty secretitive about this process.

this being said, isn't firewall just a two sheets of sheet metal? my thought was just cut the firewall where it's hitting the manifold, spot weld the two sheets together and weld a metal box around the hole.

any feedback will be much appreciated.

thanks in advance.

yo, wondered what ever happened with you

you have to consider what may be on the other side under the dash etc. and need to be removed or relocated, typically you would pull everything in that interior area out of the way to do it especially if cutting and welding are involved

Are you sure that you can't just clearance it with a BFH and some elbow grease?

A porter power would be better used , I don't know if a BFH would be as esthetically appealing

Never underestimate a proper BFH. Personally I'd try that first, if it's terrible go to plan B.
But like team said, need to know what is behind where your cutting if you go that route.

yes, nobody ever used a hammer to make something beautiful out of metal

it ultimately depends on how much we are talking about, the car mentioned

it's a lot easier to do with a stripped racecar than trying to maintain creature comforts for the street (shown around 0:48 in the vid below)




such a shame to put that kind of power in just to take the slow way through the turns


.

Nice way of undermining 100 centuries of blacksmiths.
For a long time, the ONLY way to make something beautiful out of metal was with a hammer.

That said, there isn't much room between the firewall and a lot of plastic on the inside. The back of the HVAC system comes right up-to and through the firewall in the center of the engine compartment, directly adjacent to where the rear lift hook on the stock engine would be. It is nearly constant contact from there to the heater core and evaporator inlet/outlet.
Pulling the dash is only a 2 or 3 hour job, so I would just pull it first and see what you can and can't do.

I suppose you never knew I started my career as one, thanks for undermining 100 centuries of sarcasm. It did actually exist before the facepalm you know? :lol:


:)


.

yea tried the hammer. firewall easily gives at some spots, but the part i need to expand near the most posterior rotor on passenger side (the last air intake channel), there's exactly 2 inches of clearance from the intake manifold gasket and the firewall. when i banged on this spot with a sledge hammer, there's absolutely no give at all. felt like the whole car was shaking. there must be something behind it. i guess i need to have the dash taken down... manifold that was made for this fits, but the flange is sooo thin that i think it's a huge fire hazard. i decided to trash it for a shortened oem one.

i must say i learned so much from working on this car... i didn't know how to change spark plugs before this project. now i can tig weld, do pipe work, own a small milling machine that i used a few times already. :) anyhoo, probably another month or two before i get a weekend off to take the dash down. thanks guys. btw is scott still around or is he gone for good?

This isn't the middle adges anymore, we have this thing called technology, hammers have their uses but are not the be all and end all.

Stick,
If I read it correctly, you laid into it with a sledge before knowing or looking to see whats behind it ?

Technology only means automation tooling wise. What you call "cnc mill" was a pantograph.
The Romans used drills to to brain surgery, go figure. Indians welded metals... with hammers and fire.
Watchmakers still use hammers.

I know still use my hammer when I can't fit things in my car btw :rofl:

@stick: Welcome back! I agree with who says that you should inspect what's behind your "hot" working area.
Have you considered moving the engine just a little so that it will clear?

Where are you located now?

You just missed the latest drama. Apparently SG has started a new RX8 company and snuck in as a vendor for several days before being outed and given the boot.

Indeed, I did not know that and yes - I totally missed the sarcasm in that one, seeing how it was so well nuanced.

Sorry, got it backwards. We symbolized long before we spoke ...

glad to know the ancient members are keeping the newbies safe ;)

will update when the dash's down. i'm in jax, FL these days, busy with new job. looks like i'll be relocating soon though. don't know where. i will stay away from tampa in case i see someone i will want to run over haha. it's for the best. i met a good group of people through this journey i would have never met otherwise (ironically mostly in sti forums), so i got over it. once my rx8'd done, hopefully i can meet some here as well.

You should probably keep the manifold that he made for your car, instead of banging and cutting. All you have to do is buy a ready made 20B
for example:
http://www.mazdatrix.com/R-INTAKEFAB.HTM
cut off the old one and weld on the new one(nice and thick).
Or you have it water jet cut by someone.

if you saw it you might not agree, he tried to hand fabricate it all from flat stock and did a rather poor job. I was a bit shocked when I first saw it because it was not up to the quality level some of his other fabrications. I think it could have been done much better regardless.

Wish I had known where you were, Stick. I was out of work from July-Oct. and needed something to do besides race and lay around :suspect:

I remember seeing the pics of the intake a looooong time ago, but I bet it would be much easier than cutting the firewall.

it's always easier to do a half-@ss job

Yeah, but I have learned it's not cheaper that is for sure.

Jax, Fl., huh? I live there as well, if you need a hand let me know.

On the intake issue, you can always go here:
http://www.definedautoworks.com/
go to the parts section, the actually have a LIM modification that shortens it significantly, and may help it clear the firewall.

Pretty sure he already has that or something similar. The engine is in the firewall tunnel. It was a tight fit for the Renesis, let alone a 20B.

I would agree with the tight fit. The only reason I thought it may work is when I consider the LIM pineapple racing makes; it lowers the UIM enough to fit the rew into stock position in the 8, so in theory defined autoworks could cut enough out to replicate that effect. Since he is local I am gonna try to contact him so I can look at it in person...

I'm sorry, but all I can think of is a 2031 episode of "Wheeler Dealers" where Mike tells Edd "oh and there's one other thing; at some point, some fool decided to cut a hole in the firewall," to which Edd replies "thanks Mike, for always finding new ways to make my life easier".

; )

You missed the point entirely. First, he already did this per my quoted reply where he stated this. Second, they have shortened it as much as possible, as shown in their pictures you can only cut out the section where the runners are straight and align up with each other when the two pieces are mated back up. Third, if it was that easy Scott would have gone that route rather than attempt a custom manifold. He may make some dumb choices, but he's not entirely stupid. So go ahead and look. We'll be waiting for you to come back and tell us how impossible it will be with one more rotor depth further back in the decreasing-slope tunnel.