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  #1  
Old 05-25-2002, 07:07 AM
ap6valiant ap6valiant is offline
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Default block hugger vers full pipes

guys given i have an a body car and clearance for headers on my 360 is minimal can anyone tell me the actual performance diff between block hugger style verses full headers say 32 to 36 inch long is the diff that big to warrant hassle to build full exhaust as off the shelf stuff here is hard to get good quality fit etc
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  #2  
Old 05-25-2002, 09:46 AM
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rumblefish360 rumblefish360 is offline
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Longer the tube, the higher the rpm band. Block hugger type headers save headaches with space and clearance and ease of installlation. The performance diff is not alot. Power should fall off in the upper rpm levels. The more built the engine, the more power loss diff. they'll be.
The other solution;
To sit down and create your own headers. It is a royal pain in the rear. However, the payoff is great.
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  #3  
Old 05-25-2002, 10:01 AM
beepbeep2k1 beepbeep2k1 is offline
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Rumble,
the long tube headers raise the rpm range,
what is the rpm range limit the block huggers produce.?
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  #4  
Old 05-25-2002, 10:18 AM
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rumblefish360 rumblefish360 is offline
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Default A little long,

Ooops, I got it backwards there. Ya got me.
Lets look at, say hooker headers.
The standard headers @ 1 5/8 tube (sb) are set up for general power. Right. Now look at the super comp. headers. Tube size will increase to 1 3/4. But length shortens a little.
The increase of tube size is for extra volume as so not to restict the engines breathing. The shorter length is for a tuned rpm. When racing, your more likely to stay in a particular rpm range.
Block headers are space savers. I have not ever seen a rpm range given to these type of headers. Tube sizes are small on these type of headers. Keeping them in a street cruising range.
If you were to increase the size of the tube, useable rpm range would drop.
EX;
Dragster/Funny car headers. Big fat tubes, really short.
Of course thats a drastic change, but a perfect example how things work.

When selecting headers, be realistic on your choice. Street headers go far in making power. If your heading for the strip, Super comps are worth the price diff. But not really worth it for the street. Unless you really want it.
The increase in tube size and shorter length take away the bottom end needed for regular street use. (Lack of low end torque.)
Block hugger headers really don't lose the low end torque due to the small tube coming together quickly into a normal type of exhaust.
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  #5  
Old 05-25-2002, 10:25 AM
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rumblefish360 rumblefish360 is offline
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Default quick note

In my sig. you'll notice that I have super comps on the car. The car is sluggish down low. At 3000 rpm the car wakes up. by 4500 the car is cookin. I'll take her up to about 6000-6500 rpms.
"From 4500 to 6500, the car is, ALIVE!"
In this rpm range, the super comps will produce more power than standard headers.
It's all part of the package deal. A more streetable package would be a smaller cam, smaller headers, smaller carb. Though the small cam is a bigger factor in where the cars rpm range is, smaller headers will suit the smaller cam better giving more usable torque for the street.
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Old 05-25-2002, 10:26 AM
Tarrbabe Tarrbabe is offline
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I was taught that the longer the tube, the lower the power band moved as this adds restriction. This can be offset by increasing the tube size to balance the torque and horsepower. That is why the zoomies on f/c's and rails are short and large to keep the power high in the rpm. Block huggers do breath better than manifolds but not as well as full length headers. But huggers and 2.5" or larger plumbing can make serious power without cutting the fender-wells out.
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  #7  
Old 05-25-2002, 10:32 AM
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rumblefish360 rumblefish360 is offline
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Tarrbabe;
Correct.

So, now on headers, with shortys involed, vs. a header you would preferre to race with. The Hooker or a tti would be better. No?

I wonder, a small tube street header vs. a shorty like you said with a larger tube exhaust pipe than the headers. How would win?
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  #8  
Old 05-25-2002, 11:10 AM
beepbeep2k1 beepbeep2k1 is offline
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Thumbs up 1 5/8 vrs 1 7/8 +

Rumble,
that was very good proof on the header size running larger for higher rpms and large bores. Jerry Jardine talkes about the 1 5/8 for low rpm power street machines and larger for the racers in the high rmp ranges. I'm keeping mine under the 5500 range and prefer the long tubes but have an interest in the block huggers, just not much info on it. definate improvement over the stock manifold anyway. Block Huggers should fit my needs just fine..
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  #9  
Old 05-25-2002, 10:38 PM
speedfreak speedfreak is offline
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cool,,i thought about block huggers my self,and for my 4/318,,73 dart sport block hugger should be fine,,,speedfreak.
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  #10  
Old 05-26-2002, 03:47 AM
72Challenger 72Challenger is offline
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If anyone's interested in why changing the size of a header tube tunes for a specific RPM range, I will try to give some more detail.

When the exhaust valve first opens, there is a pressure pulse that sends a wave traveling through the gas in the tube. This is not the exhaust gas itself, it's a sine wave just like the way sound travels through air. When the wave reaches the end of the tube (the beginning of the collector for regular headers, or the open air for zoomies) it is reflected back up the tube. When it gets to the port it is reflected back down the tube again. This reflection at the port actually causes a pressure reduction which helps to scavenge exhaust gas from the port, as long as the valve is still open. If the valve has already closed by the time this pulse reaches the port, then the tube is too long for that RPM.

Another factor that comes into play is exhaust gas momentum. Like any other moving object, once in motion the gas tries to keep moving. This is the reason an exhaust valve will stay open past top dead center. The momentum of the moving exhaust will continue to empty the cylinder even when the piston has started moving back down. But the larger the header tube diameter, the slower the exhaust is moving, and the less momentum it has. That's why rumblefish can't get "on the pipe" until 4500 RPM. At that speed he's producing enough exhaust gas to have good momentum and at the same time the reflected pulse is getting to his ports while the valve is still open. The result is excellent cylinder scaveging, which not only makes room for a good clean intake charge, but also helps to draw that charge into the cylinder.

In fact, this tuning is why some engines can achieve a volumetric efficiency higher than 100%. The cylinder scaveging caused by the tuned exhaust is actually pulling more air into the cylinders than they would be able to hold at normal atmospheric pressure.

This also explains why a big block wants a larger diameter header than a small block, but the tubes will still be the same length. It also explains the effectiveness of step headers, which actually generate two reflected pulses, one at the step and one at the collector.

(Hope I haven't bored anyone)
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  #11  
Old 05-26-2002, 01:52 PM
Tarrbabe Tarrbabe is offline
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Rumblefish360, I've never used the tti's but everyone says they are really good street headers. Not heard anything about using them on the track though. I have used Hookers and even a set of cheaper headers once. I have had several sets of hookers and have always been satisfied with them. I know other people make good headers but I believe in sticking with what works for you.
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  #12  
Old 05-26-2002, 10:27 PM
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rumblefish360 rumblefish360 is offline
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Tarrbabe

I think that sticking with what works is the best and sometimes cheapest soulition. Fooling around takes big bucks. I had big bucks once, I was I kid then. I lost my big bucks after I got married.

72Challenger

Good post. Well writin. "On the pipe?" never! Just kiddin. I know what you ment. True though. The car is geared on a street/strip level. When the magic RPM is in, who-ha the car gets up and go's.
This car was bulit with that in mind. The larger tube was a known evil. A compromise is what it was.

beepbeep2k1 Thanks bud.
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  #13  
Old 05-27-2002, 05:44 AM
ap6valiant ap6valiant is offline
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Default block hugger

thanks guys looks like i might as well just build a good set of huggers with ceramic coating so what is the optimum for a 360 headed engine with 0.444 lift 340 cam size of pipe to collector then on
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  #14  
Old 05-27-2002, 11:17 AM
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rumblefish360 rumblefish360 is offline
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There is a mathmatical equastion for this. But, I don't know it.
I personally would use 1 5/8 outside dia. pipe. Try to get the lengths of the pipe the same & as long as posible. I would use a tri Y design. (Don't tie in the 5 & 7 pipes together.)
I would bring the 4 pipes as far down as posible and join them into 2 at the bottom of the K frame. Run the 2 pipes under & level with the floor into a collector that ends at the floor pan.
This way you'll maxiamize torque and ground clearance.
Of the top of my head, I can't remember the tricks of collector length.
Perhaps 72Challenger or somebody else might remember this.
Exhaust pipe size; I would do a set of dual's @ 2 1/4.
"H" or "X" pipe recomended.
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  #15  
Old 05-27-2002, 02:24 PM
beepbeep2k1 beepbeep2k1 is offline
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Thumbs up blockhuggers

I have located 2 mfgs' of the blockhuggers for mine. PAW has the thinnest collector of the 2... 3" compaired to 4.5" collector. using 2" primary tubes and 2.5" starter tube. $300. for the set. put the flowmasters at the rear and hear the music...
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  #16  
Old 05-27-2002, 04:21 PM
Tarrbabe Tarrbabe is offline
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Lightbulb Thinking out loud again

Exhaust for street and "mild" performance is an exorcise in managing the flow to reduce restriction and maintain some bit of quietness. This becomes just an effort to minimize sharp bends and any obstructions to good flow. In keeping with this idea for street, you can use shorty headers, tri y's or full length headers to acheive the front end of the settup. But for street, the rest of the plumbing is just as, if not more important.
When you start talking of a more serious effort, you are starting to talk about designing a system. Race cars (Professional Level) spend many hours designing and building headers that control the pulse length and strength to blend for maximum scavaging and balance between the tubes to blend the pulses for best horsepower AND torque. True race stuff is really hard to design and build and in truth is so complex that it is wasted on a street/strip engine. I think you use your head, like understanding that you don't use tubes too small for the size of the motor is very important. Larger tubes are good for horsepower and longer length is good for torque. 1 5/8" headers can be used for small cubic inches but as you get larger, you need larger tubes. Like I said, Just thinking out loud.
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  #17  
Old 05-27-2002, 04:53 PM
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rumblefish360 rumblefish360 is offline
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beepbeep2k1; Would that be a big block?

Tarrbabe; Have I told you that I like when you think out loud?
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  #18  
Old 05-27-2002, 09:51 PM
ap6valiant ap6valiant is offline
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Default merge

so what your saying is merge collectors on block huggers with standard mufflers is probably overkill lol
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  #19  
Old 05-27-2002, 10:14 PM
Tarrbabe Tarrbabe is offline
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Not sure I understood your last post, but I'll tell you what I would most likely do in your situation. You want to keep your fenderwells so the block-huggers are a good idea if they clear the stearing gear. I would then have a good muffler shop make a custom set of pipes in the range of 2.25" or 2.5". For mufflers, you have a wide choice but I always liked the stock hemi mufflers as they breath good and are pretty quiet. I'd want the pipes all the way out the back, but if theres a problem with that, you want the pipe routed to the outside so the exhaust doesn't exit under the car. Thats just my opinion. My brother had a 64 Backarudda and had a muffler shop make him a true dual exhaust. The drivers side pipe had and S in it and was a nightmare to work with. I think block huggers would be better.
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Old 05-27-2002, 10:56 PM
ap6valiant ap6valiant is offline
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sorry tarrabe it was my attempt at humour
but i think block huggers r the way to go given room etc
and it appears as though performance is not sacrificed entirely
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  #21  
Old 05-28-2002, 09:41 PM
beepbeep2k1 beepbeep2k1 is offline
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Thumbs up size does count

Rumble..
It's a small block, with an attitude.
It has 398 cu.in. 345 hp, 440 ft.lbs. torque.
The hp & tq is calculated, the known actual before
additions was lower by about 9%.
I have reused the origional intake, but it's bored out
to the max to take the Street Avenger 770 cfm holley.
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Old 05-28-2002, 10:15 PM
72Challenger 72Challenger is offline
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Okay, it took a little digging (well, actually a lot), but I found my formula for calculating ideal primary tube length.

Length (in inches) = (CID x 1900) รท (rpm x primary OD^2)

So for your 360, tuned for 5500 RPM peak with 1 5/8 headers, we get:

360 x 1900 = 684000, 5500 x 1.625 x 1.625 = 14523, 684000 / 14523 = 47 inches. I don't know of any header with tubes that long, so you see that street headers are a compromise anyway. The block hugger headers will not loose that much more over the longer tubes.

In fact, you actually get a wider power band by not tuning the headers, cam and intake to make power at the same RPM. While a race car operates at a narrow RPM range and can afford to tune for maximum power, a street maching should tune for widest powerband to maintain drivability. Of course your individual driving style will influence this as well.

There is actually a more complicated formula which also takes into account the cam opening point BBDC, but I couldn't find it and I sure the heck don't remember it
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Old 05-29-2002, 09:20 PM
beepbeep2k1 beepbeep2k1 is offline
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Thumbs down B H

I was ordering it today, and the supplier of my choice said " won't clear the K frame on B & E bodies.......... you can redesign the collector, but it's a $300 change after your done maby you won't like it ?????????
Have to find a B body with one, or more suppliers..... yes.

ap6valiant: was that a dodge charger or chrysler charger you listed.?? block hugger for the charger.??
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  #24  
Old 05-29-2002, 09:50 PM
ap6valiant ap6valiant is offline
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Default bh

beep beep
i used to own chr charger with 360 full exh no probs
new buildup is ap6valiant(australia)similar to compact dart i think it is a A body car very tight for v8 as was first production aus car to come out with v8 in 1965 (what was usa first v8 chrysler)
can see pics of my car at
http://home.iprimus.com.au/speedcar92 if interested dont worry about my silliness at site going to open new full site called www.mopars.com.au real soon regards
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Old 05-29-2002, 10:19 PM
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rumblefish360 rumblefish360 is offline
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beepbeep2k1 It's a small block, with an attitude? I bet! Sound real cool.

72Challenger; I knew somebody would come up with something.
LOL
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  #26  
Old 05-30-2002, 11:49 PM
beepbeep2k1 beepbeep2k1 is offline
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Thumbs up valiant

ap6,
your car is a match to the 65 plymouth valiant, series AV...

the 1st chrysler V8 was 1931, series CD. a whopping 80 HP...
260.8 cu.in...
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