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View Full Version : Skid plate traps so much heat i may start a fire.


Mach2nh
August 23rd, 2017, 04:33
Made a flat skid that spans the long arm cross member to the rear cross member for the traction bar its only about 18" long and the width of the uni rails.
Thing holds so much heat in from the cat its amazing. I pulled the lower shield off to get the plate close to the cat so i knew that part would get hot but the upper shield i left in place and the distance between the cat the floor is still stock. I no longer have the carpet but it i did it would %100 welt or catch fire. Having the rear seats folded down the seat its about 9" from the floor and the vinyl part of the seat gets so hot. Anyone else have this problem? I keep the seat folded down all the time so no one is ever going to sit in the back so im going to make a heat shield on the floor. Just use the sheet steel and space it off the floor an inch. May even drill some holes in the skit to let some air in around the cat. I knew it would get warmer covering up the bottom more but just cant get over how much so.

Green XJ Jeep
August 23rd, 2017, 06:32
JCR skidplates have the area below the cat cut out. Might have to do that

Mach2nh
August 23rd, 2017, 19:28
I did see that. My skid covers more area so i think i just may cut out just under the cat and run a double wall baking sheet in the cab on the floor. Not much else to do other than omit the cat.

trippled
August 23rd, 2017, 19:41
Could you add another heat shield between the floor and the cat? Some kind of dei brand type thing comes to mind.

Mach2nh
August 23rd, 2017, 19:49
I was thinking of using the baking sheet on both sides. Just dont know if i can clear it. The double wall baking sheets work really well and many are SS or alum so its almost cheating. Im going to put a spot temp gun on it and see what its really showing for temps. But given the fact i can smell the hot floor im going to say its close to hell.

denverd1
August 24th, 2017, 09:01
can you cat delete? would flow better for sure

David_Bricker
August 24th, 2017, 09:16
Deleting the cat is not a wise idea, for a variety of reasons.

I have a flat belly pan that is probably 36" long, rail to rail. I relocated the cat to in front of the pan, immediately after the exhaust makes the turn towards the rear. In theory, that would actually make the cat slightly more efficient.

The muffler is just before the rear axle, where the floor pan climbs to clear the axle. The exhaust pipe wraps over the top of the spring, and then exits out the back.

David Bricker / SYR

mcguyver_xj
August 24th, 2017, 10:58
can you cat delete? would flow better for sure

cats don't reduce flow and its illegal to delete factory emissions equipment and pretty sure against forum rules to discuss

Mach2nh
August 24th, 2017, 15:39
Ya wont be taking the cat out. So with the outside temps at 70* and a 30 min drive at 50mph the floor in the area of the cat got to 270*. The skid was only 220* so ya warm. haha Good think i dont have the carpet or it would be stuck to the floor smoking.

RCP Phx
August 24th, 2017, 16:02
Have you considered making your skid out of aluminum?

JohnX
August 24th, 2017, 16:13
JCR skidplates have the area below the cat cut out. Might have to do that

Nailed it. Cut out some "vents".

It won't make much difference in strength.

techno1154
August 24th, 2017, 17:31
Ya wont be taking the cat out. So with the outside temps at 70* and a 30 min drive at 50mph the floor in the area of the cat got to 270*. The skid was only 220* so ya warm. haha Good think i dont have the carpet or it would be stuck to the floor smoking.

Why is the cat getting that hot? Is your XJ burning oil or perhaps using more fuel than it should? The cat is designed to heat up and burn off any of these things so they are not released into the atmosphere.

My XJ also have a full skid plate from DPG. Yes, it do get hotter over the cat and the entire exhaust piping for that matter but not that dangerous.

Could the cat be partially plugged? IDK.

Mach2nh
August 24th, 2017, 17:39
No the motor is running fine. The cat just gets hot to do its job and with the flat belly its just trapping a bit more heat and the plate is reflecting more heat up. I know cutting a vent wont change much in the skid strength wise, just really didnt want a hole in a nice flat skid. But i will deal with it vs heating up the cab so much. Will make a shield for it this weekend in the cab and if i can clear it i will do the same over the cat under the body.

All the skids you guys bring up have way more breathing room so i can see things not getting so hot for you.

dan1977p
August 25th, 2017, 06:57
Since you don't want to cut vents in the skid, what about running a fan in front of the cat to blow the heat back or an exhaust fan to draw the heat out depending on how much room you may have.

Boostwerks.com
August 25th, 2017, 12:03
https://static.summitracing.com/global/images/prod/xlarge/hsp-177201_xl.jpg?rep=True

Cat's will typically have a heatshield on one side only (top side). It helps to shield the bottom side as well like shown above. They will get hot enough to produce IR radiation which is what can heat up everything in the area around them. Shielding either the cat, or the area around it may be enough, although adequate air gaps are still going to be needed.

Mach2nh
August 25th, 2017, 19:12
Ya it comes with shielding on both sides. On the way home i stopped at the store and picked up a cookie baking pan and just placed it face down over the hot spot. It was a world of difference. Going to tac weld it or bolt it to the floor and that should be the end of that. I may stick a 2nd under the floor over the cat to.

I mean i knew the thing would get hot with the skid in place. Its just amazing how much heat is reflected by it.

trippled
August 25th, 2017, 19:22
If you can fit it I would definitely throw one underneath

rockclimber
August 25th, 2017, 23:38
when I did my flat belly I had no choice but to raise the exhaust as high as it would go.

the OEM cat touched the floor, although it never melted the carpet it was noticeable.

I swapped to a magnaflow cat and it is considerably smaller, so there is about a 1" airgap and the skid cutout underneath it, my floor still gets too hot to touch.

I would suggest an additional heat shield between the cat and the floor.

techno1154
August 26th, 2017, 05:29
I got a complete heat shield from a Grand Cherokee the fit over the length of exhaust from the bend up front to just before the diff. A few self tapping screws keep it firmly in place.