Retserof

iTrader: (1)

I just installed the RB dual tip catback on my 94. The installation was easy. I let the car idle to warm up while I checked for leaks, then drove it around the block. I put it back on the ramps and noticed that the floor of the hatch was very warm.

Underneath the car I could tell that heat was rising from the new catback pipe into the spaces above the differential and up around the rear sway bar, the fuel lines and the top of the gas tank near the pump. It got very hot up under there and I'm worried.

The car is stock except for a downpipe, and there was no exhaust leaking from the system.

I never checked to see how hot that area used to get with the stock catback -- is it normally very hot under the floor of the hatch, or is the RB catback in fact radiating a lot more heat? The surface area of the new pipe is 40% to 50% greater than stock so it could radiate a lot more heat, and it is tucked up tighter against the bottom of the car.

Has anyone else with an aftermarket catback noticed this too, or is it just me.

technonovice

If for some reason your EGTs are much higher than they should it would not be because of the catback. Not sure about the properties of the SS RB versus stock though.

d0 Luck

RB mufflers are generally restrictive. why do you think they're so quiet in comparison with any other aftermarket muffs?

Retserof

iTrader: (1)

Thanks for the feedback.

The fuel pump cover (next to the spare) was getting pretty hot. So was the floor of the hatch forward and left of the spare tire well. The heat from the section of exhaust pipe between the cat and the muffler must have risen into the drive shaft tunnel and the space over the rear axel and differential, and then made its way to the highest point - around the sway bar, fuel lines and pump cover. The brake lines are up under there too. These are things that do not like heat.

The RB must be less restrictive than the stock setup. I'd hate to have to put the stock unit back in just to make a comparison.

Does this area of the hatch floor normally get hot with just the stock catback?

technonovice

I can't answer your question, but I'd guess that the stock would be the same if not hotter than the RB. The RB is less restirctive than stock if not as free flowing as others. Give Racing Beat a call. I'm sure they can help you calm your worries.

Retserof

iTrader: (1)

Thanks. The surface area of the RB catback pipe is quite a bit greater than stock pipe, and it is positioned much closer to the bottom of the car, so it will radiate more heat than stock and not be as easily cooled by ambient air. I just wonder if this is normal.

I'll call them Monday, but I was hoping somebody here would have the answer. This is a great forum. I've been visiting it for years but only registered this year, since my car was stock and had no problems to speak of.

bajaman

First of all, sound suppression and exhaust restriction do not necessarily go hand in hand. Muffler technology is now such that an exhaust can be "quiet" but still flow as well as some piece of **** 'fart-cannon'. ANY exhaust short of a straight-pipe has "restriction". And also keep in mind that SOME restriction is necessary for proper engine operation. Even "straight-pipes" are NOT straight and have exhaust runners 'tuned' for optimum performance.

Now, having said all THAT and as an owner of a RB dual-tip catback, I have to say that I have found there to be a LITTLE more heat in general than what I noticed with the stock unit. I always associated it to the lighter, stainless steel construction of the RB unit over the heavy stock unit. But never have I noticed anything even remotely approaching high or excessive heat in the hatch area.

Have you ever experienced the over-temp warning light for the catalytic converter going off? Does it work (as in, light up when you turn the key to 'on')? If the light is not working then you may be experiencing overall excessively high exhaust system temperatures, which is NOT good! Danger danger, Will Robinson!

GoodfellaFD3S

iTrader: (213)

I wouldn't worry about it. In all my years of being around and working on FDs, have never heard of anything like this leading to a problem.

TpCpLaYa

iTrader: (10)

isnt there an exhaust shield that curves above the muffler? Is that still there?

Mazda99Nikon

Something worth checking out the next time you have the car up on ramps is to look at the seal between the converter and the pipe leading to the muffler. If there is some distortion of the normal layout, it is possible that the bend is forcing some leakage between the two pipe flanges. There should be a stainless gasket in between there, as well. If there were a leak due to the bend, you might have a blow torch aimed at the bottom of your car. My estimate of temperatures in the exhaust at that point would be in the area of 600 degrees F. or higher.

cewrx7r1

iTrader: (2)

Just a case of newb paranoia.

Retserof

iTrader: (1)

Thanks for the suggestions and reassurance. I probably am being paranoid, but then I've helped put out a couple of car fires (not my own), so maybe I'm justified.

There are no exhaust gas leaks that I could find - all new gaskets were used and the flange bolts torqued to FSM specs.

The cat overheat warning light is ok, and has never had cause to come on. The heat problem is rearward of the sensor and clearly is comming from the new stainless steel connecting pipe that runs from the rear cat flange to the muffler body. The floor above the cat isn't getting any hotter - it is the floor all the way back in the trunk, near the fuel pump, that I'm worried about.

The muffler body itself has a heat shield above it, which works fine. Besides, the muffler body is on the opposite side of the spare tire well from the fuel pump and is also too far to the rear of the car to cause this problem.

I'll start it up again tonite, take some temp readings on the fuel lines, sway bar, etc., above the rear axel, and call RB tomorrow.

In order to relieve the paranoia, I can always put the stock unit back on for comparison, but it would be a hassle.

Would switching to slightly longer muffler hangers and/or wrapping the connecting pipe in insulating tape keep things any cooler?

POS7

Its funny that so many people call it "quiet", but I don't think its that quiet at all. It has a throaty growl, even at lower rpms, which is very noticable, but not extremely annoying. Even the stock cat is pretty loud at WOT. In some ways I liked the stock cat better. Because its so quiet, the turbo spool was very noticable on the car.

I disagree. The reason why they're so quiet "in comparison with any other aftermarket muffs" as you put it, is because it utilizes a muffler design.

Most "fartcan" aftermarket cb exhausts utilize a canister design. In other words, they utilize 3" straight thru piping out, with a small canister to muffle the sould. For this reason they're loud & called fart cans as well. The RB design utilizes the same 3" piping, but either splits the piping (straight through y design) or straignt out design. The muffler surrounding the piping is the reason why its quiet.

The disadvantage of the rb is that its heavier than fartcan exhausts, but still much lighter than stock.

It is not restrictive at all because it utilizes "straight through piping". There was a very noticable power increase throughout the powerband.

I think you're being paranoid. Unless you have an exhaust leak, there shouldn't be a problem. Pretty much the entire fuel system is on the left side of the car, the entire exhaust system is on the right side of the car. Look at it this way, the fuel filter and lines are above the diff. The temperature of the diff probably has a greater effect on the fuel system than the exhaust system which is somewhat farter away from the fuel system (unless you have massive problems with the exhaust system). Also, the gas powers the engine right? The fuel system must deal with the under the hood heat as well. There is a lot of heat coming off everything from the turbos all the way back to the catback exhaust. Its normal. Some of these components are 600-800F I believe.

Kento

You're being way too paranoid. If anything, the stock exhaust system is positioned "closer to the bottom of the car", because the larger diameter of the RB exhaust causes it to hang lower into the underbody airflow. The heat radiation and airflow cooling differences you speak of are inconsequential.

Unless you see the entire rear section of your exhaust glowing red at night (and even then it wouldn't be the RB dual's fault), I wouldn't worry about it.

Retserof

iTrader: (1)

The RB connecting pipe actually is closer to the bottom of the car than the factory connecting pipe was. Because of its larger diameter and the way they bent it, it is tucked up to preserve ground clearance under the vehicle.

I spoke to RB on the phone today, and the guy said they never heard of a problem developing, but he agreed that the RB connecting pipe would throw more heat because it has more surface area.

I will double check to see if either of the gaskets might be leaking exhaust gasses, but otherwise I will write this off to paranoia and just drive it.

adam c

iTrader: (2)

When a car sits at idle, there is no airflow in, around, or UNDER the car. When you drive your car, airflow will pass under the car, and remove most of the radiant heat from the exhaust.

That being said, any car will get radiant exhaust heat from sitting at idle. The heat has to go somewhere, and "up" is where hot air goes. I would not give it another thought

Retserof

iTrader: (1)

Thanks, I'll try not to worry about it, but the next time I'm stopped in construction traffic on the Edens Expressway into Chicago, I'll keep one hand on the fire extinguisher and the other on the door handle.

Or maybe I need to install an auxiliary fan on the back of the car.