Driving with no cat back on...
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Joined: Apr 2001
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From: Dallas TX
Driving with no cat back on...
Ok, I've done this before but only for about 5 minutes or so (just cuz I wanted to see how obnoxiously loud was when I had my exhaust off :) ), but is this bad on the engine? I remember some people talking about burning a valve when driving without exhaust on. I know that the lack of backpressure will cause loss of torque, but I don't see how it would be bad for the engine. I mean headers that dump right to the side of the car seems to be alright.
The reason I am wanting to do this is to pick up a stock LT1 exhaust from Marcho yet I have no way of transporting it, so I thought I'd take mine off, drive over and bolt his on and drive back home.
yes, I have earplugs :). Last time I drove without the exhaust on it nearly made my ears bleed. :crazy: :crazy:
The reason I am wanting to do this is to pick up a stock LT1 exhaust from Marcho yet I have no way of transporting it, so I thought I'd take mine off, drive over and bolt his on and drive back home.
yes, I have earplugs :). Last time I drove without the exhaust on it nearly made my ears bleed. :crazy: :crazy:
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Re: Driving with no cat back on... (Glock'94)
The problem isn't no back-pressure, thats just fine. The problem is when you shut it off, the cold air gets sucked right onto the valves. Hot valves don't like cold air.
I'd get some tennis ***** to shove in there when you shut it off and you'll be all set. :cheers:
I'd get some tennis ***** to shove in there when you shut it off and you'll be all set. :cheers:
Thread Starter
Team Owner
Joined: Apr 2001
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From: Dallas TX
Re: Driving with no cat back on... (NoWorries)
hmm.. ok. That makes sense. I remember when I was younger I made a stupid mistake of spraying a hot lightbulb with cold water.. that thing bursted EVERYWHERE. I guess the same kind of concept applies here.
How much air is sucked back in when you shut it off though? With the higher compression, my engine shuts off very fast. There isn't enough power to keep it rotating with 11.5:1 compression. And wouldn't the hot header warm that air up a tad?
How much air is sucked back in when you shut it off though? With the higher compression, my engine shuts off very fast. There isn't enough power to keep it rotating with 11.5:1 compression. And wouldn't the hot header warm that air up a tad?
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Re: Driving with no cat back on... (Glock'94)
I dunno any of the actual formulas and statistics, but at race tracks, you'll see tennis ***** employed all over the place. I think it is enough of a surge that you can damage things quickly.
If you really want to hear something cool, unplug a Vacuum line so your car has a vacuum leak.
Voila, instant Nitro Coupe. :lol: :smash:
[Modified by NoWorries, 2:24 AM 3/30/2002]
If you really want to hear something cool, unplug a Vacuum line so your car has a vacuum leak.
Voila, instant Nitro Coupe. :lol: :smash:
[Modified by NoWorries, 2:24 AM 3/30/2002]
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Re: Driving with no cat back on... (Glock'94)
I've driven my car open headers across town (8 miles or so) shut it off, started it back up, drove it back home because the exhaust shop couldn't do my work, shut it off again. The next day it was driven back across town and shut off again. No problems yet.
It kinda goes as a basic rule of thumb that every car we work on gets driven open headers at least once. :) We've yet to have a problem, other than one little run in with the police. Go to the race track and look at all the alcohol cars and rail cars, they have headers coming straight off the motor with nothing else, they don't seem to have any trouble. I've heard the rumor before, and I think it's just that a rumor. Now perhaps if you were to try and drive it without ANYTHING, such as no headers or manifolds, that might be a problem.
It kinda goes as a basic rule of thumb that every car we work on gets driven open headers at least once. :) We've yet to have a problem, other than one little run in with the police. Go to the race track and look at all the alcohol cars and rail cars, they have headers coming straight off the motor with nothing else, they don't seem to have any trouble. I've heard the rumor before, and I think it's just that a rumor. Now perhaps if you were to try and drive it without ANYTHING, such as no headers or manifolds, that might be a problem.
Thread Starter
Team Owner
Joined: Apr 2001
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From: Dallas TX
Re: Driving with no cat back on... (NoWorries)
If you really want to hear something cool, unplug a Vacuum line so your car has a vacuum leak.
Voila, instant Nitro Coupe. :lol: :smash:
Race Director
Joined: Oct 2000
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From: Enter Post Count Here
Re: Driving with no cat back on... (Nathan Plemons)
I wanted to point out another thing. You'll see a lot of the guys at the track, the guys with small budgets that don't have multiple motors, have those semi-truck flaps that flip open when you nail the gas, but at at idle, the pressure can't overcome gravity and they shut.
On my Honda, I have completely totally open pipes, but one has to go around three sharp bends to get to the valves, and the other has to go through five. I've been running it this way for 3K+ miles and she's still doing fine. The only thing I can attribute it to is those bends.
[Modified by NoWorries, 12:54 PM 3/30/2002]
On my Honda, I have completely totally open pipes, but one has to go around three sharp bends to get to the valves, and the other has to go through five. I've been running it this way for 3K+ miles and she's still doing fine. The only thing I can attribute it to is those bends.
[Modified by NoWorries, 12:54 PM 3/30/2002]
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Re: Driving with no cat back on... (NoWorries)
No guarantees of course, but I think as long as you have longtube headers on there you should be able to drive without hurting the engine, I think that the risk of burning valves gets much higher when people start an engine with no exhaust on the head at all or with just a short rams-horn manifold. Good luck, don't get a ticket. Post this in the engine mods or racing section and you may get more answers.
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Re: Driving with no cat back on... (Glock'94)
Drive it, you'll be fine.
Thread Starter
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From: Dallas TX
Re: Driving with no cat back on... (mackeyred96)
good news, I didn't have to torture my ears .. i forgot that my parents have a plymouth voyager van and it fit PERFECTLY in there.
Now my problem is that the car is TOO QUIET! LOL! I had no idea it would be this quiet. Some bad news is that since I have the exhaust off and can hear the engine really well, I heard some high pitched noise around 3200rpm. I'll have to try driving around without my serpentine belt to see if it goes away (i hope!).
Now my problem is that the car is TOO QUIET! LOL! I had no idea it would be this quiet. Some bad news is that since I have the exhaust off and can hear the engine really well, I heard some high pitched noise around 3200rpm. I'll have to try driving around without my serpentine belt to see if it goes away (i hope!).
