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Jdlee View Drop Down
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    Posted: 14 Feb. 2014 at 10:32pm
I was curious as to which way to go with the exhaust on my 2a. I'm keeping the l134 engine but I'm looking for a way to make it breath better, so I wanted to ask opinions. Should I use the stock manifold and port/polish it, an f head manifold ported/polished, or a header? I'm interested in the feedback.
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You need to have some back pressure in the exhaust system  Even headers need a muffler to have back pressure. 
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I understand the back pressure part with the muffler, but with the engine ported polished and balanced with a custom ground cam I need to have the exhaust flow as well. I will be opening up the exhaust pipes and adding a different muffler
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Back pressure, is a VERY incorrect term. Just think about it for a minute. PRESSURE? In the EXHAUST system? That's like saying, that you should be constipated, so you could preform better!!! Like I said, think about it. Or just shove a potato in the exhaust pipe. That will produce some back pressure...
 
Velocity, is what you are looking for. The CFM of the exhaust, being PUSHED through the system, CAN be manipulated by, a SLIGHT reduction in the size of the manifold and/or pipes. think about the old saying "Still waters, run deep". Why? because of the large area, that the water moves through.
 
A large exhaust system will produce little, if any, velocity. You want an exhaust system that will create a vacuum, through velocity, to evacuate the cylinders. Small tubes, will create a higher velocity. BUT, as RPMs and pressure increase, a larger tube will be required.
 
A flow bench, or LOTS of testing, will provide/produce the results that you are looking for. But ANYBODY who says, that "backpressure' is needed, should think about being constipated...
 
Port & polish, GOOD. Back pressure, Bad, VERY VERY BAD!!!
 
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Originally posted by Thunder Thunder wrote:

Back pressure, is a VERY incorrect term. Just think about it for a minute. PRESSURE? In the EXHAUST system? That's like saying, that you should be constipated, so you could preform better!!! Like I said, think about it. Or just shove a potato in the exhaust pipe. That will produce some back pressure...
 
Velocity, is what you are looking for. The CFM of the exhaust, being PUSHED through the system, CAN be manipulated by, a SLIGHT reduction in the size of the manifold and/or pipes. think about the old saying "Still waters, run deep". Why? because of the large area, that the water moves through.
 
A large exhaust system will produce little, if any, velocity. You want an exhaust system that will create a vacuum, through velocity, to evacuate the cylinders. Small tubes, will create a higher velocity. BUT, as RPMs and pressure increase, a larger tube will be required.
 
A flow bench, or LOTS of testing, will provide/produce the results that you are looking for. But ANYBODY who says, that "backpressure' is needed, should think about being constipated...
 
Port & polish, GOOD. Back pressure, Bad, VERY VERY BAD!!! 


I like your terminology.  Throw two-strokes in the mix and you have a whole new story.
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I don't think your going to get much improvement with the L134 by porting and polishing. This is a low rpm four cylinder long stroke under square engine that is designed for low end torque. To port and polish only works at mid to high rpm's and since the L134 is a 4000 rpm engine and should only be driven about 50 mph what is the point. 

Since the engine is a long stroke you can't go over 5000 rpm safely.  
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Breathing has two components, breathing IN and breathing OUT.

The 'in' part is parting addressed by porting the intakes, but this would be better...


Add some compression (shaving the head) and free flowing exhaust...


Probably good for 10 to 15 HP.
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Originally posted by zooke581 zooke581 wrote:

[/QUOTE]


I like your terminology.  Throw two-strokes in the mix and you have a whole new story.
[/QUOTE]
 
I'm glad that you mentioned that. Here's my "Monster". Detroit 8V92. That a Turbo AND a supercharger, on top of a two stroke... Please take notice of the "Single" 5" exhaust... At 5000# heavier, than the rig owned by my ex, all she ever saw of this unit, was taillights...
 
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Thanks mike. I was planing to do a shaved head and aluminum intake with the dual carbs but the one I picked up on ebay that the seller said was a willys head and intake turned out to be a roof Anderson head and intake for I don't know what.so it's back to the drawing board for the head, but I will be tiging up a dual carb intake when I get the chance
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Originally posted by Jdlee Jdlee wrote:

Thanks mike. I was planing to do a shaved head and aluminum intake with the dual carbs but the one I picked up on ebay that the seller said was a willys head and intake turned out to be a roof Anderson head and intake for I don't know what.so it's back to the drawing board for the head, but I will be tiging up a dual carb intake when I get the chance

There is a Kaiser Supersonic head on eBay right now - but about to end. 


I'd be interested to see what you come up with for an intake manifold... 


Edited by Mike S - 15 Feb. 2014 at 7:23pm
'47 CJ2A -- #114542
Warn FF D41 rear
Lock-Right locker
11" drum brakes
Dual master cylinder
T90C Transmission
16 X 6 Jeep truck wheels
Cooper STT Pro tires
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Lee MN View Drop Down
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Not to pirate the thread, but $175 for an unchecked head, WOW, someone is brave

Lee
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Lee, I am NOT one of the bidders. I have an extra ribbed head and ASIICT there is no substantive difference. I can shave my head to get the CR I want in my gear drive engine.
'47 CJ2A -- #114542
Warn FF D41 rear
Lock-Right locker
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Dual master cylinder
T90C Transmission
16 X 6 Jeep truck wheels
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Yeah I would have rather paid the 175 instead of the huge chunk I spent on a head that was never finished to begin with.
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Lee MN View Drop Down
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Originally posted by Mike S Mike S wrote:

Lee, I am NOT one of the bidders. I have an extra ribbed head and ASIICT there is no substantive difference. I can shave my head to get the CR I want in my gear drive engine.


Very true!

jdlee, sorry for your bad deal, I have been messing with jeeps for years, I made the comment because so many heads I find are cracked, I hate to see anyone wast hard earned dollars on a classic head, only to find out it is cracked, or unuseable, IMHO the seller would have been more fair to have the head checked by an automotive machinist, that way the e-bay buyer well knows what he is bidding on will be serviceable. Best of luck to you on your mods, very interesting .

Lee
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I picked mine up for $35.  I hope to get it installed with a copper gasket in the Fall. I may plane it to 7.5:1.
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Heck of a deal!
'47 CJ2A -- #114542
Warn FF D41 rear
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T90C Transmission
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I know, I couldn't pass it up.  I also got an intake for $20 to experiment with.  Got the parts from Quarter Ton Parts in GA.  Matt is a great parts guy. 
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Wow, that's a smoking deal on a supersonic head, good for you!. Pay very close attention to the #3 combustion chamber, that's where they like to crack for some reason.

MHO, Lee
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