Exhausted......

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Re: Exhausted......

Post by Bugman114 on Tue Jan 04, 2011 8:11 pm

run it without the stinger, lol. just kidding. i did that for a while, but it was so loud, it would give me headaches after long drives lol!
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Re: Exhausted......

Post by vwovalchild on Tue Jan 04, 2011 11:17 pm

Not good to do that. You have to have some back pressure. Could also cause valve trouble. Josh weld that muffler you had there from that bike on it. You would be the only one with one like that.
LOL
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Re: Exhausted......

Post by Bugman114 on Tue Jan 04, 2011 11:53 pm

actually no, you don't need backpressure, you need air speed. a stinger pipe doesn't provide any significant backpressure anyway, but it does contribute to the velocity of the air, as each cylinder forces air thru the collector, it creates a vacuum in the other pipes, thus creating a scavenging effect. on a small motor you still want to get as close to zero backpressure as possible. you want to have small enough pipes to have good exhaust velocity, but big enough so its not a restriction. the bigger the pipes the slower air speed, which is better for the top end, but the low end will suffer. the smaller the pipes, the faster the air speed, which is better for the bottom end, but the top end will suffer.

a good example of this is on my 2074cc. the PO installed some huge j-pipes and header (i believe they were about 1.5 inches in diameter). it ran pretty good, but the bottom end seemed a bit weak. i switched to stock factory heaterboxes and a smaller header (i believe the pipe diemater was around 1-1/4'', definately a lot smaller then what i had before), and the bottom end was MUCH better. It pulls like a tractor now, but the problem is after about 5K RPM it falls on its face, which before with the bigger pipes, it would pull hard starting at 4K all the way up to 6K. so the smaller exhaust basically moved my power band from 4-6K to around 2-4K. Most would prolly complain about this, but for me i prefer this, as i don't like to wind it up that high anyway. Very Happy


and the valve warping idea is just a myth. think about it, if valves were that sensitive to temperature change, as soon as you start up your motor, the valve would warp, as they go from whatever temperature it is outside (lets say 40 degrees), to over 200 degrees in seconds. I ran my 74 super for over a year with an open header, and a few months back i did a compression test, and i was around 130 PSI on all cylinders, no warped valves.
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Re: Exhausted......

Post by camch on Wed Jan 05, 2011 12:57 pm

I have a small one I think.I will look when I get home..if that is a myth run yours with no exhaust and let us no how it works in a week or so, pratice what you preach not what you have read somewhere
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Re: Exhausted......

Post by Bugman114 on Wed Jan 05, 2011 1:23 pm

camch wrote:.......if that is a myth run yours with no exhaust and let us no how it works in a week or so, pratice what you preach not what you have read somewhere


Quote from my post yesterday
Bugman114 wrote:...... I ran my 74 super for over a year with an open header, and a few months back i did a compression test, and i was around 130 PSI on all cylinders, no warped valves.

I'm done, sorry for the thread hijack.
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Re: Exhausted......

Post by camch on Wed Jan 05, 2011 6:06 pm

Bugman114 wrote:
camch wrote:.......if that is a myth run yours with no exhaust and let us no how it works in a week or so, pratice what you preach not what you have read somewhere


Quote from my post yesterday
Bugman114 wrote:...... I ran my 74 super for over a year with an open header, and a few months back i did a compression test, and i was around 130 PSI on all cylinders, no warped valves.

I'm done, sorry for the thread hijack.


like I said run your car with NO exhaust and let us know your results on the valve issue, "not an exhaust with no stinger"
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Exhausted......

Post by Bugman114 on Wed Jan 05, 2011 7:05 pm

When did i say NO exhaust won't bend valves? i said an open header won't bend valves. i got the heads off that motor right now, ya wanna come over and inspect the valves for yourself? i just lapped them too, the mating surface came out nice and even. at 130 PSI per cylinder (before i lapped them), i'd say the valves are just fine. lemme ask you this, have you ever ran an engine with an open header, and warped a valve? If not then take your own advice and quit preaching what you've read Wink . I guess the guys who have dragsters, or old 30's model rat rods with one foot long exhaust pipes on each cylinder must all have warped valves Laughing

not tryin to be an ass, just sharing my own experiences. If you don't believe me, then fine, i'm not mad at ya. and i'm not pretending to be an expert or anything. i'm just going from what i've personally experienced. hell, I'd invite you over for a cold one on me and talk about it if ya want Wink
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Re: Exhausted......

Post by camch on Wed Jan 05, 2011 7:37 pm

here it is "and the valve warping idea is just a myth. think about it, if valves were that sensitive to temperature change, as soon as you start up your motor"
as far as me practicing what i preach i fix peoples mistakes like this every day.,if you think about it ,the cold air {with no exhaust} would be sucked to the chamber when hot which is not good,cold to cold not going to hurt ,cold air to a hot chamber is bad, another example is a windsheild take a frozen windshield and poor hot water onto it and see what happens ,and yes i have seen people have cracked exhaust with valves that are bent more than once
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Re: Exhausted......

Post by vwovalchild on Wed Jan 05, 2011 8:56 pm

Camch,
Thats what im saying. Just decided not to get into this any more with him. I stated what I know and my 27 years with these cars.
Keep up the good work. Would love to see your cars one day.
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Re: Exhausted......

Post by Bugman114 on Wed Jan 05, 2011 9:07 pm

lol, in the rants section now. Laughing

not really a good example there IMO. apples to oranges. Besides, we aren't talking about water, were talking about air. water conducts 25 times more heat then air. so air of the same temperature as water isn't going to cause as drastic a temperature change as water, since it doesn't conduct as much heat. if this were the case, on a cold day, with the defroster on heat hitting the windshield, the whidshield will crack, no?

But let me re-phrase my statement anyway:

A Valve will NOT warp if your running an open header. i NEVER said a valve won't warp with NO exhaust, tho i'm on the fence about that, as i've never ran a motor with out the exhaust, so i can only speculate, but as far as valves warping with an OPEN HEADER, NO, they will NOT warp. over a year running it like that, which is over 15,000 miles for me, and the valves are still as perfect as the day i installed them. the heads themselves, have over 45,000 miles of hard driving. the first year, i had a stock exhaust, the next year is when i had the open header, and the last year and a half is when i had it turbo'ed. again, i have these heads out right now. I have actually checked them, the valves are perfect, and will be reused on my 1600 turbo project (after a little porting and polishing of course Twisted Evil )

besides, will a stinger pipe actually insulate the exhaust significantly anyway? i mean its a foot long pipe about 3 inches in diameter. taking that extra foot off really isn't gonna make much of a difference. besides, that megadual exhaust that you see on dunebuggies uses even less pipe then a header anyway, and no one seems to complain of warped valves because of that exhaust. this exhaust is what i'm talking about:



and yes i understand valves crack, and bend, but was it because they ran an open header, or they had heads with a billion miles, that needed a valve job anyway? my heads were in good shape. Way before, when i first got the car about 4 years ago, i went thru the heads. guides were in good shape, i had changed the valves with brand new valves, i did a good lapping, and put everything back together. then it followed roughly 4 years of hard driving.

i even drove my 72 super with the 2074cc motor a few weeks with an open header, i took it to BAP to and from both days, that including the few weeks of driving with the open header, was over 800miles of driving, still no issues. im using 042 MOFOCO heads on this motor. compression as of a few weeks ago was still around 150PSI on all cylinders +/-3 PSI.

Again, i'm not saying that "running NO exhaust won't warp valves". I'm sorry if anyone took it like that, but thats not what i said.

But hell, if anyone here has actually RAN a car with an open header, and had a valve warp BECAUSE of the header, i'd love to hear about it. no one has actually said that they've warped a valve due to the header. And i'm not bashing anyone here, its just a friendly conversation. Very Happy .
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Re: Exhausted......

Post by Bugman114 on Wed Jan 05, 2011 9:11 pm

vwovalchild wrote:Camch,
Thats what im saying. Just decided not to get into this any more with him. I stated what I know and my 27 years with these cars.
Keep up the good work. Would love to see your cars one day.

I didn't mean to bash you or anyone, i'm just respectfully disagreeing (i'm allowed to have my own opinion, right? Laughing ). if you took it as an insult, i sincerely apologize, as that wasn't my intention. i respect you and your knowledge of VW's, as well as the awsome car's you've built Cool .
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Re: Exhausted......

Post by vwovalchild on Wed Jan 05, 2011 9:17 pm

Mike no insult here. Everyone has the right to there own opinion. Just get them on the road and drive them. :-)
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Re: Exhausted......

Post by camch on Wed Jan 05, 2011 9:21 pm

but as far as valves warping with an OPEN HEADER, NO, they will NOT warp.

tell that to the people i sell valves to becaue of cracked header ,and there are many of them.

vwovalchild thanks i guess my experience dating from 1980 is not good enough either.anytime you want to see them let me no,all 4 of them are here in the shop,and they will be @ yu buggin 2011,,would like to have you out for this event also
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Re: Exhausted......

Post by Bugman114 on Wed Jan 05, 2011 9:24 pm

amen brother. Very Happy

and by the way, that goes for mike as well. i don't mean any kind of insult. if i sounded insulting by anything i've said, please forgive me. that wasn't my intention. there are only so many laughing emoticons i can insert before the post becomes wierd, lol. Laughing .

and hell, i may be wrong. one thing i've learned on my short time on this earth, is that we never really know anything for sure. there are always going to be some kind of un-forseen variable that throws everything we've learned in to utter chaos. lol!
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Re: Exhausted......

Post by Bugman114 on Wed Jan 05, 2011 9:36 pm

i just don't believe an open header will cause a valve to warp. now a crack in the header would be a lot closer to the valves. i've never had a header crack on me, so i have no idea personally, but i do believe you. but a good header has atleast two feet of pipe on each cylinder, no? maybe a little more. i just don't see that being an issue. especially when the stinger pipe itself is only roughly a foot long, and the shape of a funnel. i can't see that being of any good insulation anyway.
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Re: Exhausted......

Post by vwtattooed on Wed Jan 05, 2011 9:36 pm

it is not the temperature change that bends the valves, it is the air being sucked back in to the head and not allowing the valve to close. this in turn causes the exhaust valve to meet the piston and the rest is ugly. now i am no expert either but i have personally experienced this. my valve came out with half the head broken off. this occurred while i was running a merged header and fat boy muffler, that was not the problem, the problem was the blown exhaust gasket on #2 cylinder. as soon as i let off the gas air was sucked into the exhaust valve and that was that. i have also seen this on Chevy 350 valves, the guy was breaking in the cam with no headers. 15 minutes at 2500-3000 rpm, let off the gas and...POW! The valve had a nice arc to it when removed! now let's all hug and sing cumbaya jocolor
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Re: Exhausted......

Post by camch on Wed Jan 05, 2011 9:39 pm

cumbaya
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Re: Exhausted......

Post by vwovalchild on Wed Jan 05, 2011 9:41 pm

im holding my lighters up and swaying back and forth cheers
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Re: Exhausted......

Post by Bugman114 on Wed Jan 05, 2011 9:49 pm

Oh wow. see thats what i ment about how there are things that we never really know about 100% Laughing . i would have never thought of that. so if thats the case, then an open header still shouldn't be an issue, as i'm guessing the engine isn't going to suck in 2 feet of air from the roughly ~2 feet of header pipe.


camch wrote:cumbaya
Dont act like you knew that, mister "what happens if you throw hot water on a cold windshield". lol Laughing . just kidding



seriously, why didn't anyone say that before Laughing lol! lol.
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Re: Exhausted......

Post by camch on Wed Jan 05, 2011 9:59 pm

we are not just telling you stuff to hear ourselves talk,there are reasons behind what we say not fiction
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Re: Exhausted......

Post by Bugman114 on Wed Jan 05, 2011 10:31 pm

well if you don't explain why, how am i going to learn Wink . I was the kid in school who the teachers hated because everytime they said something, i would always wonder why, and ask a thousand questions as to why. I can't help it, just the way i am, lol. i like to learn how and why things happen. its annoying, i know, and sometimes i annoy myself in the process, but if i never ask why, then i'll never learn. Laughing . Like seriously, right now my favorites menu on my browser is filled with a hundred links about turbo, and megasquirt related stuff lol! .

anyhoo, so from what vwtattooed, and camch said, the problem is that if you have a leak, or crack close to the exhaust valve, this is where problems happen, right? i'm guessing the problem happens from the cold air expanding keeping the valve open, right? if so, then that means that an open header isn't a risk either then? only if there is a leak, or crack or something of that nature letting cold air in. Am i on the right track now, or am i still way off? My mind is still blown from vwtattoed's explanation, lol Laughing
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Re: Exhausted......

Post by camch on Thu Jan 06, 2011 8:21 am

I did not explain because you said there was NO WAY this could happen. You had already made your mind upthat this could not happen
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Re: Exhausted......

Post by Bugman114 on Thu Jan 06, 2011 10:21 am

ok, i was wrong, i admit it Embarassed . now i'm just trying to understand this concept, as it was completely foriegn to me. but let me ask you this, do you believe i am in any danger running an open header, or even a stinger for that matter? is there any chance that i could destroy my motor, like vwtattoed said above? Is there a difference as far as RPM's go (i.e. a race motor is more likely to suffer from this, or something)? Or is the only way this might happen is if there is an exhaust leak, or a cracked header?


what about those guys with the rat rods or dragsters with those little short exhaust pipes on each cylinder, like these guys:




Maybe its because a V8 will flow a lot more air then a 4 cylinder, so it doesn't matter as much? just a guess tho. thanks Very Happy

-Mike
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Re: Exhausted......

Post by ASBug on Thu Jan 06, 2011 10:34 am

That second photo is of a toy model.
Shadows are all wrong...
-just sayin'
KC
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Re: Exhausted......

Post by Bugman114 on Thu Jan 06, 2011 10:38 am

lol, you get the idea tho. I know we've all seen ratrods with this kind of exhaust Wink
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