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11-15-2011, 03:43 PM

#21

Comanche3Six

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Quote:

Originally Posted by ApachePete

Sttellings to start, then CMI Big Tube's

Just got off the phone with Daviid at CMI & he said "Not exactly EL, but very, very close" for the Big Tubes.

Stellings states they are not EL.

Last edited by Comanche3Six; 11-15-2011 at 03:49 PM.

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I'CE (01-20-2023)

08-09-2014, 02:03 PM

#22

delsol

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TTT -- Bringing up an old thread I found through searching Y pipes

Apache Pete -- How much of a difference did you see by going to the 4 individual tails versus the Y pipes? I am thinking of going 4.5 " tails into one 6" Y pipe and out the transom on a staggered configuration.
But after seeing that both AV and Warhawk have upgraded to 4 tails I'm curious as to the pros and cons...?

Thanks, Dave

08-10-2014, 12:42 PM

#23

ApachePete

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Quote:

Originally Posted by delsol

Can't really tell, as I made several changes at the same time: motors, drive heights.

Didn't do a scientific evaluation.

Early in the game, I did change from 4" to 6" Y tailpipes, and saw no difference.

The reason I got rid of the Y-pipes was strictly because the headers (Stelling's) were leaking, and could no longer be repaired (had re-welded them several times) So I changed to CMI Big Tubes.

Last edited by ApachePete; 08-11-2014 at 10:01 AM.

08-10-2014, 01:24 PM

#24

MikeyFIN

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Makes me think, time schedule or what made you get rid of the Y pipes while getting the even more EL Big Tubes, or no real world diff on the boat (like 20hp tops together). They just sound wicked on top of everything.

Last edited by MikeyFIN; 08-10-2014 at 01:26 PM.

08-10-2014, 01:39 PM

#25

MikeyFIN

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Quote:

Originally Posted by Comanche3Six

Just got off the phone with Daviid at CMI & he said "Not exactly EL, but very, very close" for the Big Tubes.

Stellings states they are not EL.

Hmmm how much is very close, those ELs I have mocked up on racecars and even my own daily driver one inch was too much in my book.

08-10-2014, 03:31 PM

#26

Comanche3Six

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Quote:

Originally Posted by MikeyFIN

Hmmm how much is very close, those ELs I have mocked up on racecars and even my own daily driver one inch was too much in my book.

I have no answer for that question. I agree el is el, and anything else is an exhaust pulse collision of some sort.

08-10-2014, 03:39 PM

#27

MikeyFIN

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Quote:

Originally Posted by Comanche3Six

I have no answer for that question. I agree el is el, and anything else is an exhaust pulse collision of some sort.

No collision to speak of if the pulses are 180 apart...thats why I'm all for 8-4-2-1's.

08-10-2014, 08:44 PM

#28

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Correct length is more important than equal length. If the length suks (ie: is way off) for your app, who cares equal length or not.

Collector ID and length seems way more important for exhaust tuning than primary length. Assuming Primary ID is correct of course.

The wrong collector length can kick your azz big time. On the same theme, a correct collector length cam make your engine seem to over achieve.

For NA engines, there are multiple correct lengths and multiple 'wrong ' lengths for each engine build. This is because of wave tuning.

I suggest Pipemax for anyone that takes engine's seriously.

08-10-2014, 09:00 PM

#29

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Here's one I ran on a certain 502.

BTW: The program givea much, much more info than I have posted below. But it will give you a good idea on things.

Remember, the 'collector' is not just the headers collector. If risers and tails are same ID, which most re, then they too are part of the collector.

Quote:

Pipemax

--- Single Primary Pipe Specs --- for 502.176 CID from 3800 to 6300 RPM
Diameter= 1.899 to 2.024 Length= 33.7 to 36.7 inches long
--- 2-Step Primary Pipe Specs ---
1st Dia. inches= 1.899 Length= 16.9 to 18.4
2nd Dia. inches= 2.024 Length= 16.9 to 18.4
--- 3-Step Primary Pipe Specs ---
1st Dia. inches= 1.899 Length= 16.9 to 18.4
2nd Dia. inches= 2.024 Length= 8.4 to 9.2
3rd Dia. inches= 2.149 Length= 8.4 to 9.2

--- Header Collector Specs (Conventional Straight Tube) ---
Diameter= 3.466 to 3.716 Tuned Lengths= 19.4 best and also 9.7 or 38.8

--- Header Collector Specs (Megaphone or Diffuser Cone Shape) ---
Diameter= 2.966 taper to 3.966 Megaphone/Diffuser Length= 19.4 inches

Best HP/TQ Tuned Collector Lengths= 19.4 , 38.8 , 77.6 , 155.2 inches long

Worst HP/TQ Loss Collector Lengths= 29.1 , 58.2 , 116.4 , 232.8 inches long

Note-> all Pipe Diameters are OD and based-off .0625 inch Pipe thickness

---- Primary Pipe's Harmonics ----
1st Harmonic = 149.4 inches long ... typically never used
2nd Harmonic = 56.5 inches long ... longest recommended
3rd Harmonic = 33.7 inches long ... highly recommended , best Torque Curve
4th Harmonic = 23.4 inches long ... shortest recommended
5th Harmonic = 17.5 inches long ... typically never used
6th Harmonic = 13.8 inches long ... typically never used
7th Harmonic = 11.1 inches long ... typically never used
8th Harmonic = 9.2 inches long ... typically never used

---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ----
1st Harmonic = 155.2 inches long ... longest with Mufflers and TailPipes
Note: Worst = 116.4 inches long for HP/TQ Loss
2nd Harmonic = 77.6 inches long ... longest recommended with Mufflers
Note: Worst = 58.2 inches long for HP/TQ Loss
3rd Harmonic = 38.8 inches long ... more bottom-end Torque
Note: Worst = 29.1 inches long for HP/TQ Loss
4th Harmonic = 19.4 inches long ... highly recommended , best Torque Curve
5th Harmonic = 9.7 inches long ... reduced Torque , more top-end HP sometimes
6th Harmonic = 4.9 inches long ... reduced Torque , not recommended

Last edited by SB; 08-10-2014 at 09:03 PM.

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I'CE (01-20-2023)

08-11-2014, 07:56 AM

#30

delsol

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Quote:

Originally Posted by ApachePete

Early in the game, IU did change from 4" to 6" Y tailpipes, and saw no difference.

.

That's pretty interesting right there -- would have thought that the 4" tail would have choked it somewhat. Do you have any pics of it when you had the Y pipes on it?