I feel like every time I ask a question I have MORE questions after wading through all the differing opinions but here goes--if we remove the exhaust system from the roadster and just run the straight open headers, will we "burn" the valves? Will not shoving a tennis ball into the open ends when we shut it off cause cold air to enter the exhaust and warp the valves? Can we tune for open exhaust to eliminate all the popping on deceleration? Thanks!
These exhaust notions are 100% pure bullshit. Think about this: A P51 Mustang can fly at 42,500 feet, where the temperature is between -40º and -70ºF. The exhaust on a P51 is 11" long, un-baffled, and wide open. Zero history of valve warping. Zero history of valve burning.
Actually the P51 flew in extreme temps but didn't park at those temps. The theory on warped valves has to do with cooling after shut down and I have seen photos WWII war birds with plugs in the tubes. That said, the real reason that they stick plugs in the zoomies on dragsters is the same reason that they plug the injector stacks, to keep birds from building a nest in there. I don't know about the P51 I wasn't there. As for burnt valves that is an old wives tale and to this day there are people who believe it, some of them believe it enough to ask. I have been told in the past that burned exhaust valves comes from improperly adjusted valves. Perhaps the mechanic that told me that had no idea, he had only been wrenching since before the war. As for tuning, if your exhaust is popping that is usually a sign that there is an air leak. We used to actually drill a 1/8" hole before the muffler to make one pop. Dumb but what did we know we were kids. Now I am going to mention something, someone else is going to be offended and I don't give a big rats ass I am going to say it anyway. In my own personal opinion a low compression engine running out of the collector sounds like ass. But if you want your car to sound like a farm implement go for it. Edit: this is a general statement and no reflection of the OPs car at all.
seems like every day something we were taught is being questioned or dis-proved, Talk about change, and NUTHIN' stays the same, I'd like to go back and kick some of those teachers' ass. back to regular program,
so much for the old wives tale. but, beyond the attention draw factor straight pipes do not always sound better and can negatively affect performance. every engine has different needs. listen to motorcycles with tuned exhaust or, just the muffler/baffles removed.
LOL last year at the HAMB Drags one of the fellas was uncorking his exhaust. he said with a loud voice, it won't make it any faster but it'll be loud. We all laughed because he was right on both accounts. Exhaust tuning is an art just like any other type of tuning. For the most part an open tuned exhaust is peaky. For a street car or bike it is just a different noise then a muffled exhaust system, and with todays technology sometimes you can actually make more zot with a muffled exhaust. The sound itself and the like or dislike is subjective, we all have different likes and dislikes. I don't particularly care for a 6 with splits for example, a lot of guys do, I certainly don't care for a stock wheezer engine with straights, but some guys think it is music. I can't say about the W motor in question I haven't heard it, and if things don't change unless I hear it soon I may never hear it.
As Beaner Said , We capped the zoomies to keep all the gravel and other crap out that's on the return road and the pits, Plus the birds and mice at home Tim Jones
What, the burnt valve tale is false?...wow Next you're going to tell me that when I turn the engine off at a red light and start it when it's green that it doesn't use twice as much gas as leaving it running.
Beaner, we use to drill the 1/8" hole in the header to tune the engine on our dirt modified cause the plugs were very hard to read when we ran methanol. I have been hearing about warped valves with open headers for over 50 years and yet to see it actually happen.....
I did see a Fiat warp some valves @ the ice races in Saskatchewan back in the '70s. They were running short zoomies to make it lay down on the bottom. and were cutting a fat hawg in the quarter finals, shut down for the night and it was poppin hot. Next morning it wouldn't pull an old sick woman off a bed pan. I kept in touch with the guy and when he tore into it at home he said he found a couple of warped exhaust valves. Was it from the cold air on the hot valves after shut down, I have no idea but it could have been. it could have been a lot of things I guess. It don't get that cold here and I don't run short zoomies so it is not an issue for me. I used to run short drag I pipes on my bikes until I found out that they ran better with 40" pipes. I have not yet had an issue in over 40 years. They sound less obnoxious with the longer pipes too. I have read about guys drilling the headers near the ports to check the mix. I guess that is an old school pyrometer.
So, your telling me that adding an electric fuel pump instead of putting the magic clothes pins on my fuel line was a smart thing to do?
JJ...You must not have ever lived in the country where your Mother hung the washing outdoors an a closeline
LOL you must be really young we hung out the wash in the city when I was growing up. First dryer I ever used was in a laundry mat after I was a grown man ( or so I thought).
Beaner if 82 is young,I guess I'm young.....young enough the have drawn water from a well and heated in the big old Iron pot in the backyard in order to do the washing...
Nope that's older than I intend to get. I did buy my mom a gas powered washing machine once, she broke it too. That woman could not keep a washing machine in tact to save her soul.
I'm glad to hear that the woes of the individual pipe headers are myths. There are no over the counter headers fitting for my application...but I can get header flanges. So, as a matter of simplicity and cost of construction, I've been planning on long individual tube headers with motorcycle baffles in each tube. Other than a sound some may not appreciate, are there any problems with this kind of configuration?
Very narrow power band? Lots of the fellas run long zoomies and they were popular in the '60s. You may find that with longer pipes you don't really need baffles. I would run 'em without first and go from there.
That brings back memories. Growing up we used to spend a lot of our summer at the family cottage...water coming from a hand pump behind the grocery & bait store down the road...an ice box instead of a fridge...no electricity at all until the mid 1960s...cutting the wild grass and weeds in the neighboring field with a scythe...a bath was a bar of soap in the lake. I miss those days.
To check the proper length of the pipes run a stripe of house paint down the tubes and cut it off an inch after it burns off. Clothes pins work.....I have also pulled water from the well and heated on a wood burning stove....how else was I going to take a bath ??
LOL I used to walk to school 5 miles barefoot in the snow. Uphill both to and from. Couldn't resist my granddad was born on the Oregon Trail and used to say that and just laugh. I really miss that old man. Well now I'm going all face book on ya, sorry.
What would be the cause of the narrow power band? This application is a Bobtail T. The individual pipes would be 8" or so radius 90 bends coming off the flanges, then extending back to the leading edge of the doors.
I'm pretty much going to be limited to whatever length reaches the door openings. Because of my mobility issues, I'm going to be doing funky things with the doors, so they are the dead-end for the pipes.
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