At first I thought it would work, now I look at this as a thermal expansion issue as the length of the tube from the brace to the fulcrum (the upper and lower manifold bolts) is roughly 1 foot horizontal and one foot vertical. I would like a second opinion because I see nowhere else to easily make a brace that will allow some flexibility without exceeding it's yield strength.

 

Make the upper mount flexible

 

Not possible. The upper end is fastened to a tranny bolt just in front of the shift linkage. - If that is what you're referring to...

 

it needs some way to flex as the downpipe changes length during heat/cooling cycles

 

Yeah, that's what I'm trying to achieve. Obviously, the beefy bracket must be ditched and a longer, more flexible one made. Any ideas?

 

how about this.





http://vertexnow.com/Verocious...rts_2

 

I just copy honda and use a strap of thin steel. this provides lots of support to prevent vibration but is flexible enough (in one direction) to account for any expansion.

 

I think you should use "ROTARY"s idea. Sturdy yet flexible Just like stock.

 

OK so I had "fabricators block" and had to take a whole day to get this issue rectified. Please let me know of any discrepancies you see before I weld this up.

Stock brace with adapter and should be rigid sided to side and vertically only. Should I apply one continuous bead (TIGed) or do several?





I felt it wold be good to lightly brace the front end. The marks indicate the area to be welded. To the best of my judgment, this would allow maximum flexibility with sufficient weld surface on the pipe. The material is .125" SS




Let me throw this in to get a second opinion as well. The down pipe is the lowest point on the car. I want something to take the hit other than the DP if I run over something at speed. This will be welded in the corners only of the base plate. It's the only idea I could come up with for protection. I have 40-50 hours of work in this DP and will be a bit ill if it gets bent to hades.

 

I like the way you think, I think this is the most overlooked part of an FI / NA car.

 

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thats what i did for my homemade dp. i used 2, one at each of the large bolt holes, been 10k and not problems yet. i just put a flex joint after the engine/trans area..

 

I'm surprised no one else gets involved with this type of thing. What is everyone else doing? I don't even think you can leave it unbraced and get by with it. I mean, that is a lot of stress for 4 bolts to hold under that kind of vibration and I don't know of any production 3" downpipes with a recirculating dump.

Anyway, here's the verdict. Heat shields will be added later, which will be stainless elevated about .250" above the pipe. Hope this works

 

Not many people get involved because they're too busy looking at other things - and buying prefabbed 'universal' DP's.

I like the rear mount, but the front mount should have been made from thinner stainless IMO. Just don't weld it up on the pipe further. BTW the thing I like about no heat sheilds is less time to getting oil to opperating temp...I only drive 7 mins to work, so I can only boost up the on ramp if I preheat the motor.

The DP's I make for my cars use the oem hanger, and its enough. My recent 'sink trap' mani has the SP braced below to the mani due to a rigid mount via the wastegate (similar to your recirc setup). To make a long story short, I've had no issues (no cracking) from expansion, which is great considering I was my own welding instructor BTW I just ordered some 1.75" flex pipes for such recirculated WG attachments, which will help even more. You should look into it too, you cna get them from ebay for $20/shipped.

 

Actually, I did use a flex, not sure if it's going to do much though.

I've got 9 hours seat time on this new tig since 10 years ago when I was in school for welding. Today I still suck terribly.

 

u risk tearing your tranny mount if you hit something, and i think you might feel a lot more vibration as the direct bolt on to the chassis will transfer quite a lot of vibration.

 

Exactly what i did, worked beautiful

 

It would be better for the solid portion of the pipe to vibrate with the engine and let the flex section take the vibration movement. However, in the real world, who knows what the resonant frequencies are of that terrible mass hanging down.

 

this is very similar to what i do on every downpipe i make.no problems so far,with some of them being in use as long as 5-6 years.i've also done this to fix cars who's downpipe or manifold broke due to not having any kind of bracing(which most kit downpipes don't).copying the factory setup seems to allow it to move some,but keeps stress off the turbo/manifold when the engine torques.i wouldn't bother with the brace in front.also,of course,have some type of movement capability in the exhaust after that brace-either a stock style ball socket flange,or a flexpipe.
chris

 

I had a downpipe braced like that and my factory hanger part (that black metal) ended up cracking down the road. Probably something that I did.....there was no pre-stress when bolted and tightened to the turbo.

I've been making a new one and am wondering what to do about bracing. It is going to be a 3" side exit/dump with 2.5" going under the oil pan. I'm wondering if I should use hiem joints on it.

Can we brace anything to the block like the factory does?....maybe use the 14mm bolt on the lower front that helps hold the stock manifold (I don't know how much movement it would allow) ?

 

"Can we brace anything to the block like the factory does?...."

did you see the pics i posted? that black piece is a rubber........sigh........nevermind.

 

The factory does not use anything made of rubber for any exhaust mounted to the block.

Go sigh somewhere else.

 

"The factory does not use anything made of rubber for any exhaust mounted to the block."

sorry.. i never worked on a honda before so i don't know how the stock brace looks but you have so whats the problem?

greasemonkee, Bailhatch, and myself all posted different options yet you still cant figure out how to make a simple exhaust brace.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ROTARY &raquo;</TD></TR><TR><TD CLASS="quote">
sorry.. i never worked on a honda before so i don't know how the stock brace looks but you have so whats the problem?

greasemonkee, Bailhatch, and myself all posted different options yet you still cant figure out how to make a simple exhaust brace.
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Wow....I'm sorry if you get all worked up by someone asking a question or for more possible suggestions. And yes, I have seen what others have posted....but is more information from people with experience a bad thing?

I am going to try heim joints to brace my downpipe, turbo, etc. Hopefully it works out ok.....if it doesn't, no big deal.

 

Im using the factory mounting bracket for the header, its not much, but anything will help, there arent any places to make a bracket like you b series FWD guys have room for




I spent 4 hours on mine


Modified by MidwestAutoWorks at 6:37 AM 8/3/2007

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by greasemonkee &raquo;</TD></TR><TR><TD CLASS="quote">I have 40-50 hours of work in this DP and will be a bit ill if it gets bent to hades.

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That's gotta be the worlds most expensive honda downpipe!!! lol

What in the hell took 40 hours to build a downpipe?