FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#1
|
||||
|
||||
Exhaust Diameter
Looking for some opinions..
My current setup: 492 CI 650ish HP Car runs 10.28 - 10.35 @ 129 consistently through the mufflers Shift RPM 6300 2" primary / 3.5" collector Mad Dogs 3" ID exhaust with Flowmaster Super 40s Car does see street time My question is, would bumping up to a 3.5" ID exhaust be worth the change? And also, are there better muffler choices like a Pypes product? Thanks for any insight. -joe
__________________
"2015 Pontiac Nationals "Chief of the Pontiacs" Champion 2009 HPP Magazine P2 Class Winner Englishtown, NJ 69' Firebird 492 CI E-Heads, 3.73's Street driven Best - 10.21 @ 128.98 |
#2
|
||||
|
||||
Not sure about the exh. diameter; I think you are on the edge of maybe 'needing' 3&1/2 inch and I am sure some will say there would be some improvement. As to the mufflers I really like the Dynomax Ultra Flows. Not too loud at cruise but wide awake at wot!
__________________
69 Bird w/1970 400 block(409 cubes), #64 heads, hyd. roller, Q-jet by Jeff E., original interior, ps, pdb, th350, and 3.73 gears. Pump gas, street driven muscle. 3800 lbs. race weight. Best, 11.39 @118, my son's car. 79 T/A w/463, Scat crank, Eagle rods, Icon pistons, Lunati solid roller, 262/270, KRE 325 heads,Northwind intake, QF950 carb, full interior, ps, pdb, th350, and 3.73 gears. Pump gas, 3650 lbs. race weight. 10.72 @ 126 so far... no tuning yet. |
#3
|
||||
|
||||
Quote:
__________________
"2015 Pontiac Nationals "Chief of the Pontiacs" Champion 2009 HPP Magazine P2 Class Winner Englishtown, NJ 69' Firebird 492 CI E-Heads, 3.73's Street driven Best - 10.21 @ 128.98 |
#4
|
||||
|
||||
I run 3.5 Dynomax Round Welded Ultraflo's, with a 3.5 mandrel bent with an X pipe on my 66. Car runs the same with open headers as it does with exhaust on it. Car is pretty quiet considering.
I think the 3.5" would help.
__________________
66 GTO Nostalgia Super Stock/Street Legal Car 421 CID, stock block, Wenzler Intake, 2- Carter 750 AFB's, 3.90 Gears, Full Factory Interior, Full Exhaust, Stock Suspension 3750LBS 9.77@136.99 Multiple NSCA/NMCA World Champion 66 GTO 389 3x2, 4 speed, 4.33 gear, Montero Red 33K original Miles 67 GTO 2dr Post, 428, Tri Power, 3.55 Gears 80 Trans Am Black SE Y84 W72 WS6 |
#5
|
||||
|
||||
I've been wondering this as well. I have been planning to go 3-1/2" to the mufflers and stay with the 3" tail pipes. Thinking it was hard to get mandrel bent 3" over the rear.
|
#6
|
||||
|
||||
I run about 4' of 3 1/2" pipe to 3 1/2" Pypes Race Pros with turn downs before the axle. No crossover or X pipe. It runs .06-.08 slower ETs in the 1/4 with the mufflers on. I have it set up to drop the mufflers quickly. When I drop the mufflers, it leaves 24" of pipe as collector extensions. Previous exhaust was 2 1/2" Flowmaster system and it killed the ET and MPH! Have you ran yours with the exhaust open?
__________________
'68 Firebird 463/pump gas/SD 325 E-heads/266-272 SR cam/1050 Dominator/3.73/ET Street Radials/1.37 60'/6.30@108.80/9.93@135.14 Hot Rod Drag Week finishing averages: 2014 - 11.12 @ 118.56 2015 - 10.84 @ 124.97 2016 - 10.56 @ 127.88 2017 - 10.29 @ 130.74 2018 - 10.29 @ 130.53 2019 - 10.16 @ 132.34 2021 - 10.09 @ 132.69 2022 - 10.13 @ 133.07 9.93 run - https://youtu.be/hII0_UlYM4U |
#7
|
||||
|
||||
|
#8
|
||||
|
||||
Quote:
So, if increasing the pipe diameter to 3.5" and find the best flowing muffler helps me, that is the path I'd like to go down. According to the Dynomax chart that ponjohn posted here, looks like I should be running 3.5". Thanks guys. Hoping to see a few other opinions on actual change of muffler manufacturers also.
__________________
"2015 Pontiac Nationals "Chief of the Pontiacs" Champion 2009 HPP Magazine P2 Class Winner Englishtown, NJ 69' Firebird 492 CI E-Heads, 3.73's Street driven Best - 10.21 @ 128.98 |
#9
|
||||
|
||||
That;s why I asked if you had ran the car with open exhaust. That would let you know what ET/MPH the car is capable of and if your current exhaust is hurting your performance. I bet it is, especially with Flowmaster mufflers (although they do sound great)
__________________
'68 Firebird 463/pump gas/SD 325 E-heads/266-272 SR cam/1050 Dominator/3.73/ET Street Radials/1.37 60'/6.30@108.80/9.93@135.14 Hot Rod Drag Week finishing averages: 2014 - 11.12 @ 118.56 2015 - 10.84 @ 124.97 2016 - 10.56 @ 127.88 2017 - 10.29 @ 130.74 2018 - 10.29 @ 130.53 2019 - 10.16 @ 132.34 2021 - 10.09 @ 132.69 2022 - 10.13 @ 133.07 9.93 run - https://youtu.be/hII0_UlYM4U |
#10
|
||||
|
||||
Quote:
Thanks
__________________
"2015 Pontiac Nationals "Chief of the Pontiacs" Champion 2009 HPP Magazine P2 Class Winner Englishtown, NJ 69' Firebird 492 CI E-Heads, 3.73's Street driven Best - 10.21 @ 128.98 |
#11
|
||||
|
||||
I ran open Hooker Super-Comp Headers; a Collector extension (13"? each) was mandatory for best results. 11.0 times.
You'd study your Existing Collector-headpipes for a hot zone around there. Paint line helps see the Rather than cut for open extension. Color paint , not black or white, burns the best. id suggest THAT is where you want to up-size. I went with....5" dia for 37", then into my stupid Turbo muffs and 2.5" tails. Oh but 3.5" ought be what everyone else advises. My engine Reversion has been minimized. |
#12
|
||||
|
||||
Mike any video of your car with that setup?
__________________
Darby 74 Grandville 2Dr 455 c.i 4550# 2011 1.60 60 ft,7.33@94.55-11.502@117.74 2017, 74 firebird -3600 lbs (all bests) 1.33 60 ft, 6.314@108.39 9.950@134.32 M/T 275/60 ET SS Drag Radial 2023,(Pontiac 505) 1.27 60 ft, 5.97@112.86, 9.48@139.31.... 275/60 Radial Pro's |
#13
|
||||
|
||||
Here is an 9 year old video with the old 433 CID engine. New engine (446) makes a good bit more power (around 100hp more) but same exhaust.
https://www.youtube.com/watch?v=AkwK...-UjYTQk0Q8gN-d
__________________
66 GTO Nostalgia Super Stock/Street Legal Car 421 CID, stock block, Wenzler Intake, 2- Carter 750 AFB's, 3.90 Gears, Full Factory Interior, Full Exhaust, Stock Suspension 3750LBS 9.77@136.99 Multiple NSCA/NMCA World Champion 66 GTO 389 3x2, 4 speed, 4.33 gear, Montero Red 33K original Miles 67 GTO 2dr Post, 428, Tri Power, 3.55 Gears 80 Trans Am Black SE Y84 W72 WS6 Last edited by Mike Davis; 12-27-2019 at 10:12 PM. |
#14
|
|||
|
|||
Goerlich use to make the best flowing mufflers, not sure if that's still true or not? I went with Spintech on my 3.5" oval X exhaust. My build doesn't need a 3.5" pipe system, I said I wanted a 3" system when I ordered it but the 3.5" showed up. I probably don't need a 3" system either...
|
#15
|
||||
|
||||
Quote:
__________________
1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
#16
|
||||
|
||||
Yeap. A little bit of 2-Stroke Exhaust desigh applied, to match my Converter Stall. 9.0:1 needs all the idea applied to idle and pull well off-idle.
__________________
12.24/111.6MPH/1.76 60'/28"/3.54:1/SP-TH400/469 R96A/236-244-112LC/1050&TorkerI//3850Lbs//15MPG/89oct Sold 2003: 12.00/112MPH/1.61 60'/26"x3.31:1/10"/469 #48/245-255-110LSA/Q-Jet-Torker/3650Lbs//18MPG 94oct Sold 1994: 11.00/123MPH/1.50 60'/29.5"x4.10:1/10"/469 #48/245-255-110LSA/Dual600s-Wenzler/3250Lbs//94oct |
#17
|
||||
|
||||
Quote:
Not loud at all. |
#18
|
||||
|
||||
Ok guys,
Thanks for all the info and input. Based on this thread and some reading of my own, 3.5" looks to be a worth while change. -joe
__________________
"2015 Pontiac Nationals "Chief of the Pontiacs" Champion 2009 HPP Magazine P2 Class Winner Englishtown, NJ 69' Firebird 492 CI E-Heads, 3.73's Street driven Best - 10.21 @ 128.98 |
#19
|
|||
|
|||
Quote:
the pypes race pros & dynomax untraflos are some of the better flowing mufflers & are a straight through design. summit has them for great prices... about $60ea for race pros. |
#20
|
|||
|
|||
Flow characteristics of various high-performance mufflers might be interested.
You'll need Adobe Acrobat Reader to view: http://www.exhaustsoundclips.com/cfm.pdf .
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
Reply |
Thread Tools | |
Display Modes | |
|
|