Cool soluton for hot problem

[Chuck]

One of the header pipes virtually touches the clip. Something about a hot pipe almost touching fiberglass . . . . not a good thing.

So we put a nice bit of exhaust wrap on the offending pipe. Put two layers of relflective heat mat on the bottom side of the clip. It actually burned through the outer layer, the contact point being visible in the picture.

After a thirty minute drive the fiberglass was noticeably soft in the area above the headers. It did not distort or lose its shape, but one could feel a difference. And the fiberglass was really HOT.

So I am looking for ideas. I might be able to squeeze a metal plate and stand it off about an eighth inch, except for the lip around the opening which is right up against the pipe. But that would be a challenge.

I could add another layer of exhaust wrap. That would be an easy solution, but I am not sure how much it would help.

I have seen perforated metal heat shields and was also wondering if that might be a better option.

Or maybe hot fiberglass is not a problem as long as it does not distort.

Any one else confronted this issue?

 

[Doc Kaler]

Hi Chuck,

First, are your headers ceramic coated? Aftermarket headers on Vipers can literally melt through the plastic heater core housing unless they either use Iconel heat shields OR are ceramic coated (I used ceramic coated Belanger headers on my Viper with no problems). Using both would be even better.

 

[Chuck]

Doc:

Nope. Stainless steel. No coating. I would prefer to leave them that way if possible.

 

[Randy V]

Chuck - You must have changed from the first set of headers (same as I have)..

If in your position, I would add these sleeves to the headers;
Design Engineering DEI 010114 - DEI Speed Sleeves Exhaust Wrap Jackets - Overview - SummitRacing.com

and then put a layer of the Gold Foil shield over the top of what you already have on the body (which is what I'm also planning)
Design Engineering DEI 010392 - DEI Reflect-A-GOLD Heat Barriers - Overview - SummitRacing.com

I'd be wrapping the adjacent tubes as well as the radiant heat from them has to be substantial as well..

 

[Chuck]

Randy:

Thanks for the good tips. Yes, we changed headers when the tranny was changed. These set higher than the headers used with the 016.

Would the sleeves be better than the wrap? Any benefit to one over the other?

Covering at least the top four tubes does make sense, even though the other three are an inch or more clear of the fiberglass. The heat from all those pipes together is substantial.

Is the gold shield better than the reflective - silver - heat barrier material? Any reason for one over the other?

 

[Lynn Erickson]

Fiberfrax is what I use on the fiber glass aircraft engine cowling to shield from the exhaust pipe heat. it comes in 1/16" or 1/8" thick and can withstand 2300 degrees f. it can be glued to the inside of the fiber glass and then covered with a thin .016 stainless steel sheet metal. works much better then the racing heat shield and is much less expensive and much lighter in weight. can also be used to make separate heat shields by sandwiching between a piece of stainless steel and aluminum with pop rivets. stainless steel side facing the heat source FIBERFRAX from Aircraft Spruce

 

[Cliff Beer]

Chuck, I know that the place that did the ceramic coating on my headers indicated that they can (optionally) also coat the inside of the headers. I'm not sure how they do that....perhaps with a dip process, which suggest the exterior needs to be coated as well unless somehow masked off. In any case, perhaps such a place in your area could ceramic coat the inside of your headers...??

 

[Randy V]

Randy:

Thanks for the good tips. Yes, we changed headers when the tranny was changed. These set higher than the headers used with the 016.

Gotcha.. Okay - that makes sense.. I guess I didn't know that you needed to change headers for the ZF, but probably required as the crossmember is taller for the ZF.

Would the sleeves be better than the wrap? Any benefit to one over the other?

I would put the sleeves on over the top of the wrap - only because the sleeves are somewhat of a lower profile and only overlap in one place (hence thinner).

Covering at least the top four tubes does make sense, even though the other three are an inch or more clear of the fiberglass. The heat from all those pipes together is substantial.

Is the gold shield better than the reflective - silver - heat barrier material? Any reason for one over the other?

The Gold shielding reflects 80% or more of the heat. I'm searching for a reasonable price on the same gold foil that NASA uses on Satellites which reflects up to 95% of heat and is good to 1,000+ degrees F rather than the ~850F that the DEI gold barrier does..

I'd put the gold foil on right over the top of the silver barrier. At least that's the route I'm headed with mine.

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

Ceramic coating - yes, you can have just the insides of the pipes coated. I'm not sure how effective it is just on the inside. When I had the pipes done for my Factory Five Challenge racecar, they were done inside and out. They were a lot cooler than un-coated, but not as cool as wrapped. I ended up wrapping the tubes as well.

 

[Frank Catt]

Another easier solution is to take away the glass fibre in the immediate area and build a turkey pan under it, it will look good and solve the problem

 

[Jim Rosenthal]

The gold foil is what McLaren used on the F1; supposedly very effective, although (obviously) expensive. Is there any way to modify the fiberglass in that area so it isn't as close to the pipe? Plus wrapping the pipe and using the foil?

 

[Chuck]

Frank, Jim: I think you are on to something. Got some ideas may try to pull together tonight after my day job.

In the meantime, before I do a search, has anyone seen for sale that perforated metal the new car manufacturers are using to shield the mufflers and cats from the car? Looks very formable, should be easy to work with. I am also guessing it is pretty cheap.

 

[Lynn Erickson]

MICRO LOUVER AIR SHIELD from Aircraft Spruce
MUFFLER/CAT HEAT SHIELD KIT from Aircraft Spruce
http://www.aircraftspruce.com/catalog/eppages/kevlarheatshield.php

 

[Chuck]

Lynn

Thanks. That looks like the stuff.

 

[Keith]

Chuck,
I had the same problem, although mine was self imposed as I made my own pipes. I ended up remaking the top pipe and moving it toward the rear of the car so I could drop it down some. That said, it was still less than a finger width from the clip when the clip was closed and locked. I made a "radiant shield" from some old Harley pipe shields. It works well as area of the rear clip above the pipe is barley warm to the touch after a five mile run.
I believe I still have some remaining pieces the chrome shield material if you would like to try it.
Keith

 

[Ron McCall]

Chuck,
I had the same problem, although mine was self imposed as I made my own pipes. I ended up remaking the top pipe and moving it toward the rear of the car so I could drop it down some. That said, it was still less than a finger width from the clip when the clip was closed and locked. I made a "radiant shield" from some old Harley pipe shields. It works well as area of the rear clip above the pipe is barley warm to the touch after a five mile run.
I believe I still have some remaining pieces the chrome shield material if you would like to try it.
Keith

Keith,

How did you attach the shield to the pipe?

 

[Bill Musarra]

Chuck,
You might want to consider what Dimi did with his rear clip. With his exhaust system I think he has more of a heat problem than the rest of us, and I don't think he has had a problem at all.

http://www.gt40s.com/forum/gt40-build-logs/21100-dimis-build-drb-68-a-3.html

Go down to post #56 and he explains it. You might not have as much room but any air flow should keep it fairly cool.

Bil

 

[Chuck]

I am thinking about three options. Interested in thoughts and comments.

Option Number 1.

Taper the lip adjacent to the pipe back to give about 1/4" to 1/2" clearance and than add a heatshield with at least a 1/8" spacer on the underside of the clip.

Anal view showing the clearance is attached. All the pipes but one clear the clip by about 2 inches. Just one is the problem.

This would probably be the least visible modification with the clip either up or down.

 

[Chuck]

Option Number 2

Cut out a secton about 10 inches wide and 5 inches deep from the clip and insert a section of aluminum fit to match, painted with engine black. Perhaps leave a 1/8" seam between the aluminum plate and the adjoinint glass so the heat absorbed by the plate would not affect the adjoining fiberglass.

The size of the cut out would be dictated by wanting to avoid the curved corner. This woudl be big enough to cover the pipes.

This would be visible through the rear glass with a close inspection, but hopefully not to obvious.

A picture of a pattern of the aluminum plate in position is attached.

 

[Chuck]

Option Number 3.

Fab a cover to go over the collectors. This is not an original idea. Note the picture taken at Road American attached.

This would be an easy mod and indeed could be used in additon to one of the foregoing options.

With all of these options reflective material or insulation would also be used. May also wrap the pipes where they pass close to the clip even with the shields.

Any thoughts or comments before I start cutting and bending and gluing?

 

[Bill Musarra]

Chuck,
How about extend the cutout to the rear of the tray and insulate the pipes. Would that give too much heat to the rear glass? Maybe two screened computer fans at the front outside edge of the tray, or the upper side vents that would be thermostatically driven to keep air flow going over the pipes?? That is basicly what Lotus did or does with their heat problem.

Bill