In my project I finally found a 90° down part that fits.  The gap between the 90 and the firewall is about 0.700".  If I wrap the 90 will that be enough of a heat reduction so I don't discolor the paint (or damage it) for that gap?  Or do I need to create a bigger space behind that?

It might be hard to get an exhaust wrap in that tight of space to be effective.  The wrap could contact the firewall under certain operating conditions.  If it did,  there would be wear on the exhaust wrap and the associated noise could be annoying.

 

What about forming a heat shield to fit in the space without contacting the exhaust or the fire wall?  It would be easy to monitor for effectiveness.  An effective heat shield can dissipate a lot of heat.

 

- John

How much movement can I expect (under certain operating conditins)?  Torsionally or front to back?  What gap is really needed?  There are bosses on the 90 that I can stick a heat shield on, how much gap between all that?  The orginal 90 had a warp on it, about 1/4" thick, woudl I need more?  Now is the time for me to nail this down as I'm going into paint later this summer.  

I would think that there would be very little engine movement axially.  Torsional movement (left or right) shouldn't have any adverse effect.

 

Maybe a combination of a heat shield and exhaust wrap would work the best.  Modify the firewall to gain as much clearance as possible, wrap the exhaust, use the bosses to mount a heat shield.  Wouldn't matter if the exhaust wrap contacted the heat shield.  Just allow at least 1/2"  inch or more between the heat shield and the firewall for air flow.

 

Of course, these are just my thoughts - I have no real expertise - just my own experiences.

 

From the photo it looks like the lower boss is the closest to the firewall.  It would be this area that will need the most attention to gain more more clearance by modifying the firewall.  The head of a heat shield mounting bolt would consume some of that clearance.

 

- John

Edited May 22, 2024May 22 by Tractorman

Thanks for the input! 

 

The lower boss is also about 3/4" away from the firewall.   I'll start to poke at what I can do, kinda figured I'd need to do SOMETHING more....biggest problem I have is behind the firewall is my Vintage Aire (AC) box and I'm pretty tight for space, but might be able to squeek out an inch possibly with some non-"standard" placement of stuff to get it all in there (put stuff at angles).

 

EDIT:  the lower boss is about 1/2"...but I think I have enought meat there to trim is down a bit and still have plenty of thread space for a heat sheild.  Good eye BTW!

 

Edited May 23, 2024May 23 by PilotHouse2500

For heat shielding projects I use the heat shielding that car manufacturers use between the car body and the catalytic convertor.  I can get it for next to nothing at a junk yard.  It is made with up to seven layers of very thin aluminum sandwich between two thicker outer layers.  It is very easy to bend and cut to fit or wrap.   

7 hours ago, IBMobile said:

For heat shielding projects I use the heat shielding that car manufacturers use between the car body and the catalytic convertor.  I can get it for next to nothing at a junk yard.  It is made with up to seven layers of very thin aluminum sandwich between two thicker outer layers.  It is very easy to bend and cut to fit or wrap.   

 

good idea!  I'm hitting a yard or two this weekend so I'll see what I can find!

Where I'm currently sitting...thoughts?  1" of depth added.

Something looks different in the bottom photo versus the top photo.

 

It appears that you made a large cavity in the firewall?  Sometimes photos are deceptive - I may not be interpreting the photo right.

 

Are you still going to add a heat deflector on the turbo elbow?

 

- John

Yah cut out a section and planning a fill panel to weld in.  Still plan on a wrap and heat shield.

 

Top pic is the fabbed fill panel, second I'd cut out and third is that panel set in the cutout.

I think it should work.

 

- John

@PilotHouse2500That sure is a nice panel. Did you form it with a wood buck?

OK great, I'll finish fit up and weld this week.  

 

Hammer formed on a wood bock, frame rail on my 51 COE (unstarted future 6bt conversion project), and two pieces of steel I have to help make curves and rounded areas.

the results, 1.5" at the bend now and 1.25" at the 4" outlet....more pics on the build thread I have if curious.

 

thanks all!

 

 

Edited June 5, 2024Jun 5 by PilotHouse2500