Do i need to run baffles

Ahh .. I gotcha
I stand corrected....maybe

 

We used to drill a 1/8" hole before the mufflers to get them to crackle and pop. An engine doesn't need or even want back pressure what it wants is for the exhaust to get along with what the engine is doing.

If you are running a real short exhaust your engine needs to run a real high RPMs as a rule. The one that kills me is all these guys that bolt zoomies or weed burners on their engines that won't turn more than 5k even on a good day.

I guess if your engine won't pull an old sick woman of a bed pan your best bet is it make it louder.

 

I thought the "short or no pipes will burn valves" was due to the fact that allowing the hot air to p*** extremely rapidly out of the combustion chamber (compared to running with exhaust that is either stock, or headers/mufflers) didn't give enough time for the piston/cylinder/head/cooling system to soak a bit of the heat from combustion, and it transferred that heat to the exhaust valve/valve stem.

That's how it was presented to me anyhow. I can see aspects to it that make sense (without the backpressure to slow the escaping g***es to speeds that the engineers were probably counting on when the cooling system and valve materials were being designed) and also wonder if the real difference in speeds of the escaping g***es is enough to make much difference.

 

I haven't run into that problem at all. The only one I have ever seen happen in the real world is warpage due to cooling too fast. It was explained to me by a fella that was a diesel mechanic up in the shield that it only happens to the valves that are not seated. I figured he probably knew but he could have been wrong I guess.

 

THANK YOU for all your reply's it looks like the pipes go on I'm going to try to get them on before GOOD GUYS if not I know I will have them on before I go to the PRIMER NATIONALS. I will give you all a up date on if they are too LOUD. Once again THANK YOU and if any of you are in the San Jose area don't forget I have a morning get together the second Sat of each month. FREE DONUTS!!!!!!!!!!!!!!!!!!!!!!!!

 

I've heard the cooling too fast from short pipes as well, but only from folks who either heard it regarding airplanes (such as your example) or from running a vehicle hard and having cool air come in and warp the valves.

NHRA drag racers probably don't spend enough time with any one set of valves (given that they seem to tear through an engine after pretty much every p***) to ever run into this issue.

The "short pipes burn valves" could be something the neighbors said to quiet my car down

 

This myth does have some historical basis. Many years ago, wooden battery cases encased a gl*** jar with the battery in it. Any moisture on the floor could cause the wood to swell and possibly fracture the gl***, causing it to leak. Later came the introduction of the "hard rubber" cases, which were somewhat porous. A current could be conducted through this container, which had a high carbon content, if the moist concrete floor permitted the current to find an electrical ground. The wise advise of the old days to "not store batteries on concrete" has apparently been p***ed down to us today, but it no longer applies.

I don't know that i ever heard that myth, but have seen plenty of fools rev the motor just before shutting it off, many killing the ignition while it is still reving. What is does do, and this is no myth is wash the oil off the cylinders, causing a dry start the next time and accelerating the cylinder wear. It seems that most of the cars i see doing it are overly rich to begin with, which only makes it worse.

 

Don when I was a kid ( probably about the time you were a kid ) some of the old timers used to say that you had to rev your engine before you shut it down to load your cylinders with fuel. I don't know that it actually did anything but it may have done something on the real old engines with updraft carbs.

I still put my batteries on a board by the way if it does anything at all it keeps them from leaking and eating up my concrete. Somethings are just ritual, I tuned for a guy once that always neeled and crossed himself (I'm sure there is a word for that but I have no idea what it would be) I always thought it had something to do with my mechanical expertise.

Batt69,
I don't think it is a problem with dragsters, not because they don't run their valves as long as a street engine but because drag races are seldom held much below 50 degrees.

The only time that I have seen it happen was in temps well below zero after a long day of heat races.

Here is something that one might try, heat up a piece of metal to about pretty hot say 1200 degrees? Now throw some ice water on it and see what it does.

 

Not about baffles, but you brought it up. The rubber cases old batteries had were not the near perfect insulators that modern plastic cases are. There was enough electrical case leakage that it could be measured with an ordinary volt meter. Of the ones I have checked, some had more case leakage than others. Apparently that means there are variations in how the case rubber was made? If a battery had anything conductive on the outside of it, like moisture or a slight film of battery acid, that helped the battery run down faster. Concrete tends to retain some moisture. An old battery sitting on moisture containing concrete would self discharge faster than one that wasn't sitting on something non-conductive. I can't tell you how much difference that would make, but it would make a difference. The biggest issue was the film of acid that old batteries vented on to the outside of the case. Although not so much of a problem today, that's were the tradition of cleaning the outside of the battery as part of a routine service came from.

 

Al that is good unfo. I never really gave it much thought. A lot of what we believe or think is a myth or both comes from the old days when things were different.

I had a shop teacher of all people once tell me that all myths are based in truth. Most of the time we don't catch the truth part of it because we live in a different world than the one that the myth came from.

 

I've had lots of Valve trouble on Fiats too.

My brother borrowed one of mine once, and brought it back running on 3 Cyls.
Said he didnt hear the difference, but he did notice it was faster in the beginning and slower on the way back...
( full exhaust and on the street )

I bent 8 of them once, because I had hogged out the ports too much so there wasnt enough material under the seats.
The spring pressure and high RPM made everything move enough to mess it all up.

I was also running a header with a straight pipe at the time, but I know that wasnt the reason.
( its been on other engines before and after that )

Another thing I learned was, you can take out all intake valves if you break a piston on a engine with siamesed intake ports...
( shrapnel will get everywhere.)

 

Mr Shapes this one was trunning like a bandit when he shut it down no miss whateoever. This guy was cleaning up.

Whatever caused the valves to become mis-shaped happened after shut down.

I do know where you are comming from with the Fiat though. I was at Cotatti once at a sports car race when a fella missed a shift comming out of an S. Over revving and almost any engine is a bad deal.

 

Racing a Fiat is kinda like living with a very difficult girlfriend...

 

I ran headers and dumped exhaust on my '82 for a couple of years. It sounded tough,
and I loved the deep tone. When I decided to sell the truck, I put the stock exhaust
back on it, and found out that it sounded like ****. It wasn't even hitting on all the
cylinders, but I could never hear it, due to roar of the exhaust.. Learned long ago,
just because it is loud doesn't mean it runs good.. (This was before ricers and their
huge exhaust tips)

 

The Ol' Man used to say that about Porsche gear boxes, they were awful. He said you didn't shift one you finessed it.

 

Winner

 

So do I?^^

 

Well is is a update, I ended up connecting my side pipes but I didn't go straight from my headers. I had Sean at Sunnyoaks Muffler in Campbell cut a hole in my frame so we could run the pipe through the frame because my car sits to low to run the pipes under my frame and there isn't enough room to go between the frame and body. So I kept my 12'' cherry bombs and ran my exhaust right into the back end of my show pipes so now it seems like my show pipes are hooked up but the show pipes only get hot at the end of the pipes which is nice and man they sound BAD ***. So if you need any exhaust work done go see Sean in Campbell at Sunnyoaks Mufffler tell him Ronnie sent you