hurley209 Show full post »
staticattic
Dual quiet packs will sport a dual look, although the spread is larger than the original pea shooters. Not a big fan. I had dual quiet packs for awhile, but they broke in half. One of the hangers had come loose, so one side was unsupported. Plus, they didn't match up properly to the mount, so one side was about 2 inches higher than the other.

IRT backpressure, here is something I found on the web. It appears to be an answer to a question concerning cars with computers that automatically adjust themselves, so it may not all apply to us. I would assume if the carbs are setup for no backpressure or even very little backpressure, everything should be ok.  

Collected from http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm


Destroying a myth.


Some say that "an engine needs backpressure to work correctly." Is this true?

No. It would be more correct to say, "a perfectly stock engine that cannot adjust its fuel delivery needs backpressure to work correctly." This idea is a myth. As with all myths, however, there is a hint of fact with this one. Particularly, some people equate backpressure with torque, and others fear that too little backpressure will lead to valve burning.

The first reason why people say "backpressure is good" is because they believe that increased backpressure by itself will increase torque, particularly with a stock exhaust manifold. Granted, some stock manifolds act somewhat like performance headers at low RPM, but these manifolds will exhibit poor performance at higher RPM. This, however does not automatically lead to the conclusion that backpressure produces more torque. The increase in torque is not due to backpressure, but to the effects of changes in fuel/air mixture, which will be described in more detail below.

The other reason why people say "backpressure is good" is because they hear that cars (or motorcycles) that have had performance exhaust work done to them would then go on to burn exhaust valves. Now, it is true that such valve burning has occurred as a result of the exhaust mods, but it isn't due merely to a lack of backpressure.

The internal combustion engine is a complex, dynamic collection of different systems working together to convert the stored power in gasoline into mechanical energy to push a car down the road. Anytime one of these systems are modified, that mod will also indirectly affect the other systems, as well.

Now, valve burning occurs as a result of a very lean-burning engine. In order to achieve a theoretical optimal combustion, an engine needs 14.7 parts of oxygen by mass to 1 part of gasoline (again, by mass). This is referred to as a stochiometric (chemically correct) mixture, and is commonly referred to as a 14.7:1 mix. If an engine burns with less oxygen present (13:1, 12:1, etc...), it is said to run rich. Conversely, if the engine runs with more oxygen present (16:1, 17:1, etc...), it is said to run lean. Today's engines are designed to run at 14.7:1 for normally cruising, with rich mixtures on acceleration or warm-up, and lean mixtures while decelerating.

Getting back to the discussion, the reason that exhaust valves burn is because the engine is burning lean. Normal engines will tolerate lean burning for a little bit, but not for sustained periods of time. The reason why the engine is burning lean to begin with is that the reduction in backpressure is causing more air to be drawn into the combustion chamber than before. Earlier cars (and motorcycles) with carburetion often could not adjust because of the way that backpressure caused air to flow backwards through the carburetor after the air already got loaded down with fuel, and caused the air to receive a second load of fuel. While a bad design, it was nonetheless used in a lot of vehicles. Once these vehicles received performance mods that reduced backpressure, they no longer had that double-loading effect, and then tended to burn valves because of the resulting over-lean condition. This, incidentally, also provides a basis for the "torque increase" seen if backpressure is maintained. As the fuel/air mixture becomes leaner, the resultant combustion will produce progressively less and less of the force needed to produce torque.

Jeff
72 Super Beetle
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hurley209

ok, so what i understand is that no backpressure will make my engine run lean, which will then in turn result in burned exhaust valves...well tleast thats what i got from the last paragraph concerning carb'd cars....

im still kinda confused... lol..

does it mean i have to compensate by putting in bigger jets in my carbs?

cant i just stick the baffle into the stinger and solve the problem? i mean it adds a bit of backpressure right/....
 

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staticattic

It confuses me too bro. Do a search for backpressure or stingers and you will see my name come up quite often. I thought maybe there was a math formula to figure out exactly the amount of needed backpressure, but it seems it is more trial and error. What kind of carbs are you running? I have a 1776 with dual 44 Weber's. The only thing I can think of would be to set your car up how you want it, run an unbaffled exhaust for about a week, then pull the plugs for 2 and 4. That will tell you right away if your car is running too rich or too lean. My personal opinion, the louder the better.  My car originally had a 1600 with a stock carb and an unbaffled stinger and I ran the hell out of that engine. No valve problems, carb problems, no popping or backfiring, just pure engine rumble. That was why when I put in my new 1776 and started having problems with a popping stinger, it drove me nuts trying to figure out why it popped on the 1776, but never did on the 1600. This weekend, I did find an exhaust leak so I fixed that and now I am back to the unbaffled stinger.

Jeff
72 Super Beetle
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hurley209
psshhh, i dont blame you for doin the research dude, there are so many factors involved in everything, its good to understand cause and effect..
i just wish itd be easier..lol...
but seeing as how youve mentioned youve ran one with no problems is a good motivation for me to try it out.. :-)

alot of times trying it for yourself is better than what the books tell you, so if yours has ran fine, thats good enough for me..
so what should i look for when pullin 2 & 4 plugs?
smoked surface?
if so does that mean stick a baffle in there?

it seems the things that seem the simplest, like for example, bolting on a new exhaust, turn out to be friggin confusing man.. 


so would you reccomend the exhaust? i cant decide between a stinger or gt...
i want good performance, which i know wont make too much of a differnce unless i am running a crazy rad performance engine, but still, i want it to be a good beneficial investment u know?...


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staticattic
If the plugs are burnt looking, the engine is running lean. If they are sooty, the engine is running rich. Mine always seems to run rich.

I bought the ceramic coated merged headers and stinger from MidAmerica Motorworks. Here is the link: http://www.mamotorworks.com/acvw-merged-volkswagen-headers-1-18-6486.html. As you can see, the ceramic coated setup is $100.00 more than the black setup. Worth the price difference? Not really. Like I said, I bought a lot of stuff without really doing my homework. Shelled out way more money than I needed to.

As far as what choice you make, it really is going to boil down to your personal preference. I like the merged headers because I can change my exhaust pipe fairly easily from several different styles, like dual quiet packs, hide out mufflers, mondo mufflers, or stingers. Never really looked how a GT exhaust connects, might be easy to swap out, might not be.

Jeff
72 Super Beetle
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staticattic
Something else to think about, having an exhaust that protrudes past your bumper might be illegal where you are. I think they are illegal here, but I have never been stopped for it, yet. Knock on wood. Been stopped for window tint, but not the stinger. However, my neighbors have come over to my house to complain about my loud car. I just tell them it is part of my ion propulsion system, so I can't take it off... 
Jeff
72 Super Beetle
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hurley209
well to rich is better than to lean i suppose right??

i dont have any bumpers, haha, :-)
but i dont think the cops will give me any trouble, theyre pretty laid back around my area.. although i did get a ticket for tinted windows also though, but that was up on the highway in a lil sports car i used to have, the cop went off on me man, had his hand on his gun and everything, all just cuz i was goin a little over the speed limit.. i was even as polite as i could be. but ya, my mom and aunt were in the car, he freaked them out.. that jerk.. but ya thats another story haha....

i dont think theyl care bout the stinger though, ive come to notice many get caught up in the whole " o look at that cool classic car" thing, and dont seem to pay attn..lol..


i think im goin with the stinger, i had never stopped to notice all the options you can have with them, thanks for showin me though..
plus, itl be funny to watch those little hondas get showed up by a bug when they start reving up.. haha...im already a lil louder but im sure the stinger will put them to shame....
i bet u know what im talkin bout right??..lol
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68autobug
Wow,
some high tech reading matter there...   lol
I always run My engine rich so the exhausts are always sooty black...
and i'm running no back pressure in My muffler as I have two large pipes welded on where the pea shooters normally attach to..
I did run two flaired baffled pipes on my muffler on a trip , which would have had back pressure and it didn't seem to make any difference .. only quieter inside the car...
 
A local beetle owner who has always had VWs and Has owned His current 76 beetle since new, says He likes having back pressure and says a beetle engine likes it...!!
He has had all sorts of exhausts but now has the pea shooters back on....
 
I like a free flowing exhaust and a rich engine...
 
cheers
 
Lee
 
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68autobug
 
nice looking custom exhaust in the photo...
 
I don't think it would cost all that much, depending on how many tries they had to get it perfect...
If the maker is clued in and makes many custom exhausts then it should take all that long...
 
Every beetle in australia with a turbo exhaust or a different engine in the car has a custom [one off] exhaust system..
 
I remember seeing one setup where there was a large cutout in the muffler for a pipe to go thru...
 
ceramic coated exhausts look great and should last a very long time.. but I'll never be able to afford one... lol
My Son has ceramic coated extractors on His beetle..
 
interesting about cars being pulled up for tinted windows ??
what was the problem there??
 
 
Lee
 
 
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fatalifeaten
Lee, it's the manufacturer that determines the cost there. A1 makes very high end performance VW exhausts, and a typical setup from them will run you 550.00 US and up. 900.00 may be on the high side, but they do have setups similar to that in that price range.

As for tint, it varies from state to state, but most states have laws about how dark you can go on the tint. For instance, in Arizona, you can only go 35% darker than the factory tint on front windows. Back windows can be as dark as you like. I think it stemmed from  several incidents where law enforcement personnel were shot by people in cars with heavily tinted windows because they couldn't see that the people inside were packing heat.

I know AZ is less restrictive than CA is on it. the California Highway Patrolmen used to carry little pneumatic punches and they'd smash out your windows if they were tinted too dark, AND give you a ticket. That didn't last too long, but they're still very anal about it. I've been pulled over before with just the stock tinting in my car and hassled about it.

It's a BS kind of enforcement stop, usually because the cop's bored and you happened to drive by.

Daily Driven Dubz Phoenix AZ Family


'66 Deluxe
'63 Deluxe ragtop
'61 Deluxe
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hurley209
i guess i could also just buy the header, and make my own pipes huh??
and yes cops get bored.lol.....
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68autobug
Hi
 
We do have restrictions over here on tinted glass
I'm not sure what they are nowadays...
 
years ago I had a vehicle that was tinted and loved it
so the next car I bought I went and had tinted and there were all these different colors and shades..
some legal and some illegal...
I did get a shade too illegal but it was never tested and I had that car for many years..
nowadays most tinters only have one tint they use all the time.. its probably the one closest to the illegal side...
 
I tinted My windows in My beetle but the rear window ended up costing Me $100 to have done, after My two tries..  thats with the window out too....lol
 
If You can see the driver - then its not too dark...lol
 
I suppose that exhaust was tuned etc.. as it was built..
and it is a work of art... and ALL welded together too...
 
Years ago, I had a 1971 1302S that had extractors and the muffler was sitting over the top of the RHS rear axle..
and the exhaust came out under the RHS rear fender..
 
My exhaust pipes were very long at first, way past the rear bumper, so I cut a few inches off, then I cut another few inches off...
I just hope no one ever burns their leg on it...  lol
 
Lee
 
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hurley209
lol, i tried tinting my bugs widows with my friend, we did both the left and right sides, then during out one one with the rear window, we called it quits..lol... so i have no tint on the back, you cant really tell though, it seems to blend in cuz of the rest of the glass, but ya, im goin to eventualy get it professionaly done.....lol

so what do you think? a merged header, and instead of a stinger tip, i fabricate a pipe that splits into two and comes out of the cut outs on the apron where the stock ones came out?
or should i just go with a unbaffled stinger like Jeff's? and keep a baffle around for when im not in the mood for noise?

or, should i just got with the two tip gt exhaust from empi? i have the four tip version on the car now, but i hate how it looks, and the header is rusted..so ya.. it needs replacing..lol
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68autobug
 
I don't mind the merged headers but the two cutouts need to be taken off....
 
I have seen some large exhausts over here where the pipe comes out of one of the cutouts...
then a dummy pipe sticks out of the other cutout.... lol
 
one of the locals here did make up an extractor exhaust system where two outlets came out the two cutouts...
but He is a fitter/machinist and can do anything...
 
Not like Me...  lol
 
Lee
 

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