Do i need to run baffles

I have some 2" show pipes on my car I want to run them straight off my headers, I've heard I need to run baffles so cold air don't run back up the pipes and may mess up my motor. Is anyone out there running the pipes on there car? or do you have any input. the pipes I have are 60" long

 

No baffles are needed

 

I know for a fact that this myth goes back into the early 60s when I first heard it and actually believed it for a while until I saw several engines run on the floor with no exhaust what so ever. Not even a manifold. At that time everyone new more about cars than me.

It sounded logical. It's a hard myth to kill but it is indeed a myth.

 

Yep, it's a myth started by the next door neighbors.
Larry T

 

Running straight pipes or without and baffles is fine, but it should be mentioned that running without any exhaust manifold at all will burn your exhaust valves.

 

That's right up there with a battery on cement.

 

How much hearing loss do you want to have?

 

^huh?

 

Yeah that is what they said but it never did on any of the engines that we started on the floor. I've had customers drive to my shop with no manifolds for us to install headers and the rest of the exhaust. I don't recommend it but it did happen with no ill affects.

 

Looks like the myth is alive and well, although I don't think I've ever heard the myth ***ociated with burning valves. The risk, IF ANY, is warping of the exhaust valves due to uneven, rapid cooling after the engine is shut off, and would likely only be a risk if the engine is run without exhaust manifolds.

I guess if you extend the timeframe, the result of continued running of the engine with warped valves would eventually be burned valves.

 

Now, don't be driving to the carwash to pressure wash your engine though. The heads make some pretty weird noises when the cold water hits them. That is not a good thing.

 

Actually it will but it has to be real cold air.

Now lets kill another myth, flying at 30,000 feet cold air will not hurt your valves. It is when you park it after the flight. When they parked the bombers and fighters in WWII in frigid cold weather they capped the pipes.

Just to make it perfectly clear short pipes to no pipes in frigid cold weather will or can warp a valve after you shut down when you have been running it hot. I saw it happen at the ice races up in Saskatchewan in the '70s.

Just because you have not seen it happen at the drag strip in good weather doesn't mean that it cannot or will not happen in extreme situations.

Getting back to the original question I do not know what show pipes are but you will be alright running them straight unless you are dealing with below zero temps and the pipes are real short like in just a few inches past the ends of your ports.

 

The old battery on cement myth. Haven't thought about that one for a while. I worked for Duesenberg Motors (car manufacturer) for years. My old boss, a guy that should have known better, perpetuated that myth. He raised holy hell if he saw a battery on the floor without a piece of wood under it. I tried to convince him that it wasn't true, but he was having none of it. LOL!
Tom

 

These pipes have baffles. When I got the car, it sounded cool. Then I went to a cruise down the freeway, 35 miles one way. The next day I put a full exhaust under her. Guess I'm getting old and I want to keep what hearing I have left.....

 

a bit of back pressue is a good thing..especially for low end torque..

why rob yourself of it?
as far as the myth..im still playing with old wifes tails

 

This. Straight pipes may not hurt your engine, but it does effect performance.

 

What about that old myth that reving your engine as you shut off the ignition makes it easier to start later on. The only things that SOMETIMES worked on was old motorcycles with the manual timing advance on the handlebars. My Dad had a 29 Harley-Davidson JD and once in a while you could turn the key on, twist the advance grip and it would fire a cylinder and start, if it was in the perfect spot on the power stroke. You wouldn't have to kick it. On cars, all it seems to do is foul plugs, wash down cylinders, or set the carb on fire. Fuel injection has curtailed it on newer cars but, I still hear some with carbs do it at criuse-ins and shows. That myth just won't die.

 

Nice. Now I can make that cement battery tray I've been wanting to build!

 

That one has been around since the 50's when I first heard it from one of my dads
friends at a gas station concerning a local dirt track car. It went something like those short exhaust pipes will ruin the valves when the engine is shut off and the cold air is ****ed up the pipes. But those guys were all WWII vets and he may have been around planes way up north.

I still set my batteries on a wood block up off the concrete floor even though they don't have rubber cases anymore. Myth, truth or force of habit I do it.

 

You got to tune one to run straight pipes it isn't just a matter of bolting them on and going. hearing is a good thing also. Loud is OK and does sound cool if you have enough compression but mello is better on a stock engine. Mallo also helps you when you have to drive in traffic and hearing is one of the senses that you should be using to avoid an accident.

At Daytona the other fellas really don't want to crash any more than you do but in traffic you have to deal with the yackers, texters and day dreaming soccer moms.

 

Not trying to be a smart ***, but how could one tune a car to run on straight pipes?

I'm an exhaust noob, but I was under the impression that the point was to push the exhaust out of the engine. Since exhaust travels in waves, and that the waves do not exit most efficiently with no back pressure, straight pipes are not as good as a system with some sortbof muffler/resonator/baffle.

But since a straight pipe system really doesn't have any components, I really don't know what you'd tune.

My dad raced a car with a 2.0 Ford that was straight-piped for a while. We took it to an engine builder, he suggested a small muffler, due to our straight pipe system not having back pressure. The reason I bring that up is because this was a high-revving race motor, not a stocker.

I really don't know too much about all this. Anybody shed any light on the subject?

 

If this were true, wouldn't every drag car and Nascar car run some sort of muffler?

As far as tuning for straight pipes, I would think that since there is less back pressure for exhaust reversion into the cylinder to dillute the mixture, you might be able to run the carb a little richer. But that's just a guess.
Larry T

 

How does a dragster run on straight pipes.

My SBC left here for MOKAN last thurdsday with open headers. It ran fine pulled hard and ran fine the 4 hours back to where it is currently residing.

More compression is a good starting place, richer jets or at least read the plugs and jet it correctly, more lead in your timing, hotter spark, the list goes on and on.

Here's the deal if you are going to be a rodder you have to do one of two things learn to be a tuner or know a good tuner.

Not to be pissy I'm sure you won't take it that way but for the rest. there is way more to being a rodder than bolting stuff on. Stock cars are bolt together they have already been engineered to run the way that they came, rods have never been bolt together and never will be.

 

I have a bag of cement sitting in the garage on top of an old battery to keep it off the floor. Does that count as myth?

 

look at a p51 mustang to rule the myth

than at 15 to 18 thousand feet the temps would be very very cold..in the negative degrees..if cold air on a valve was an issue..they woulda had a lot of issues

those exhaust stacks on those 12 cyl RR merlins were like 5 or 6" long

http://en.wikipedia.org/wiki/File:P51-d_mustang_472216_arp.jpg

now those were tuned for those stacks, and low end torque was not a player for an aircraft with a 2 stage 2 speed supercharger

just think of how cold it is at 40, 000 feet..that was very close to that aircrafts service cieling, and they could climb to that at about 3200 feet per min

 

Its not the temp when running, but the temp of the air entering the engine after shut down. If you are shutting your airplane engine off while in the air, you have bigger issues than warped valves.

 

My two cents here. The type of exhaust is based on the rpms, engine size and torque needs at various rpms.
for instance using a ch***is dyno I found that running a certain sized and length exhaust added horsepower and torque to my engines. Short exhaust with big pipes tend to add to high rpm with major losses at low and mid rpms. On my racecars I run the exhaust all the way to the back of the car to give me good throttle response and torque off the turns.
Changes in exhaust will also change the fuel mixture too. The exhaust is what pulls fuel/air mixture into the engine. (scavenge affect). Big or short exhaust is not always better. In fact I have found that on the street an exhaust going all the way to the back of the car a plus for drivability and engine performance. Say you have a 300 hp engine, 2.5 inch more or less...not by much, 1/8"? exhaust is just fine. Your results may vary. Turbo and supercharged engines are a different monster.
Other than that the only reason not to run a engine without exhaust is you tend to catch things near the exhaust on fire....oh and hearing...you know that stuff that makes your ears ring all the dang time and you can't hear **** in a noisy room.

 

Von Fink I already posted the disclaimer for your idea on warped valves. But to reiterate it is not when the vehicle is running and blowing hot exhaust out of the stacks that is the problem it is when it is not running after being run hard that the cold air lays against hot valves that is a problem.

When the mustangs or the high al***ude bombers got parked the stacks got capped. I wasn't there but my father in law was an airplane mechanic in the second war, he kept a set of caps until he died. Some sort of a momento.

It the '70s I was tunning a triumph bonneville that was ice racing up in Canada. We were pitted near a Fiat that was just tearing it up. he was running 6" stubs from the exhaust ports.

We didn't make it to the semi the following day but the Fiat did. It got somewhere in the neighborhood of 15 below or so they said overnight. he didn't run worth a **** in the semi. We helped him try to sort it out but it just couldn't happen. I kept in touch with the guy for awhile. he told me when he pulled his heads he had a couple of warped exhaust valves.

myth or wives tale? I'll bet if he is still ice racing today he caps his exhaust before he leaves the pits for the night.

I wasn't there for WWII that is a fact but I was there to see the outcome of it in the '70s.

What everyone else is basing on conjecture here I am basing on first hand knowlege. Believe what you want its no skin off my nose.

 

It doesn't have to be a noisey room, tinnitus is a *****. I have to lay my hand on the rocker cover sometimes to tell what an engine is doing, i used to be able to just listen.

 

One of the big myths in the ghetto where my shop was located was that a small exhaust leak would cause the engine to lose power because it lowered the back pressure. Like back pressure is a good thing. I wasn't going to argue and just fixed the leaks.