High Performance Big Block Cadillacs
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Author Topic: exhaust diameter  (Read 17641 times)
dave brode
C5
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Posts: 1074


Best of 11.66, 113.96, 1.59 sixty


« Reply #30 on: February 02, 2008, 09:19:32 PM »



When I suggested the 45* turn down, I should add the cut is parallel to and at the same level as the bottom of the tail pipe,  no downward dimension.



That's what I was trying to say in my earlier post. Although, for a tighter bend, a 90 can be sliced.

Dave
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3960 lb '71 C-10. 11.7-1 CR 514". PEP I beam rods floating MTS 18cc dish Probes, Elgin solid cam, home ported heads, MTS 2.19/1.84", Potter/Probe shaft rockers, edel 2115, 4781 850. Switch-pitch TH400, 12" 1800/3200 Tri-Shield convertor, 4.30 gears. Best so far of 11.66, 114.8 mph and 1.59 sixty
caddycarlo
Guest
« Reply #31 on: February 03, 2008, 11:15:48 AM »

here are some pictures of the ex on the truck I know they are not great but you will get the idea ........... also the engine is 488 cid the pipes of the manifold is 2 1/4 inch on each side and the tail is 3 inch ........ mufflers and x pipe and all is 2 1/4 inch if you do the math two 2 1/4 inch pipes are close to one 3 inch pipe ....... also the engine is basicly stock but this ex helped a lot at wot and has no drone like it did with duels


* truch ex 001.JPG (37.17 KB, 800x275 - viewed 262 times.)

* truch ex 002.JPG (26.01 KB, 800x151 - viewed 254 times.)

* truch ex 003.JPG (25.65 KB, 800x170 - viewed 258 times.)
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caddycarlo
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« Reply #32 on: February 03, 2008, 11:16:28 AM »

more


* truch ex 004.JPG (31.2 KB, 800x221 - viewed 247 times.)

* truch ex 005.JPG (46.85 KB, 800x536 - viewed 250 times.)

* truch ex 006.JPG (50.51 KB, 672x800 - viewed 248 times.)
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sMiles
C4
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Posts: 321


« Reply #33 on: February 03, 2008, 10:33:31 PM »


Thanks for the pics, the same side installation is interesting .. wouldn't work for my deal but it sure would simplify pipe routing issues .. I ran the math and it is a bit shy at the 3" about 11% ,  no biggie for the truck.

Did the previous duals have an X or an H style ? Same mufflers ?
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caddycarlo
Guest
« Reply #34 on: February 03, 2008, 11:34:09 PM »

the gas tank is on the other side so I had not chouse on where to put it .......... stock system was a 35 gal drum of a muffler and the cats with this tail ...... other then being very quiet its flow was very bad .. It felt like I was draging an anchor at wot ........

To fix this I pulled the cats and replaced them with stright pipe and replaced the mufflers with the edebrock then duel turndowns ....... no h pipe or x pipe ........ though it ran better it was droney and loud so after a whie I took it off and went back to stock ........

Then after reading some stuff about ex systems I desided to try again so I started by pulling the cats and everything to the rear of them ..... I then went for a quick drive open ....And boy did it run well but it sounded like a farm tractor ........ so I then took what I had ....... and got an x pipe and y pipe and made it all fit .......

And I now have the best of both worlds ......
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sMiles
C4
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Posts: 321


« Reply #35 on: February 04, 2008, 08:41:19 AM »



Thanks for the info, CC.  Its nice to know my intended design is likely to meet the goals.

Ruby, the car,  is still a driver till I finish the engine and start the installation. 
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Stiney
C3
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Posts: 114



« Reply #36 on: February 04, 2008, 09:11:02 AM »

sMILES, you wanted to know where I found that quote?

Here's the link, it was in there or on another link in that thread.

http://forums.hybridz.org/showthread.php?t=98786&page=2

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caddycarlo
Guest
« Reply #37 on: February 05, 2008, 07:42:04 AM »

Quote
Mufflers: Other than noise reduction, get a high enough flowing muffler to handle the HP. Don't use a muffler that flows less than the correctly sized secondary piping. For each peak HP, have the total muffler flow be 2.2cfm. He gives a graph of percentage of maximum power retained with a muffler on versus cfm per open pipe horse power to show that at 1.5cfm/hp, you lose about 17% of your peak hp, 5% loss at 1.75cfm/hp, and 2% loss at 2.00cfm/hp. At 2.25cfm/hp and beyond, the loss is less than 1%! On the same graph is a curve for backpressure versus cfm per open pipe horsepower:

1.50cfm/hp gives 2.0psi backpressure
1.75cfm/hp gives 1.1psi
2.00cfm/hp gives 0.3psi
2.25cfm/hp gives 0.1psi


In reading at the provided link I found the thing about vissard and flow   ............... I hate when they do not list test pressure ......... but if I assume a 28 " test then you get 146 cfm per square inch in plan pipe..........so duel 2.5 inch pipe would mean that you would have 4.908 sq in per pipe or 9.818 per system or 1433.355 cfm for the system which means it would support 637 hp ......... I am not sure I agree with that ......... I have seen sbc engines that are high hp that do better with 3 inch ex over 2.5 ......... also is this just testing the mufffler on the end of a headder on a dyno or the whole ex system to the bumper .......... becouse I think that the longer the pipe the bigger it should be ...........
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sMiles
C4
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Posts: 321


« Reply #38 on: February 13, 2008, 03:29:53 PM »


Stiney .. thanks for the link .

After reading the entirety of that thread I better appreciate Speedtalk.com.
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