FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#41
|
|||
|
|||
Well, the '72 stock style exhaust double chrome splitter on the end only fits 2 1/4". The one side dual exhaust that came with the car was 2 1/4". Maybe the exhaust on a 350 was 2".
|
The Following User Says Thank You to tjs72lemans For This Useful Post: | ||
#42
|
||||
|
||||
Tracked down the info .. 68 was a whacky year. Standard 400 (4 bbl) manual got a 2" headpipe, 2 1/4" tail pipe. Autos got a 2" headpipe and the funky resonator with a 2" tailpipe.
__________________
I'm World's Best Hyperbolist !! |
#43
|
||||
|
||||
Quote:
While I would frown on that at tech at a pure stock race, it's worth mentioning in this case if the OP wants to test something since we aren't playing by the rules. It's pretty easy at the track to remove the 16" lid and replace with a 14" lid to see how that affects the car. That might give you an idea of a direction to go. |
#44
|
|||
|
|||
Dataway, that's interesting, since the 68 models were supposed to be more hp than the 72.
|
#45
|
||||
|
||||
A lot of the big HP muscle cars of the 60's had similar small exhaust.
The OEM system on our Z is just 2 1/4" head pipes, intermediate pipes, and the tail pipes are 2" That same system is what was used on the COPO camaro 427's and even the ZL1 camaros. Even if you opted for the Chamber exhaust the sizes were the same. Firebirds of that era would have been very similar. In fact I'm restoring a 68 400 Firebird now and it still has it's original system intact, and it's pretty small by the naked eye. It sounds nice and mellow, but I just cringe looking at it thinking of the HP that's soaking up LOL Dad's GTO had small exhaust very similar, with little 2" resonators at the end of it. There's a reason why these cars pick up so much with just the addition of a nice 2 1/2" mandrel bend system and some free flowing mufflers. |
The Following User Says Thank You to Formulajones For This Useful Post: | ||
#46
|
||||
|
||||
Quote:
One was definitely for the Ram Air manifolds which I excluded for now. Is this site below, showing the downpipes to use for the log manifolds? https://www.pypesexhaust.com/product...-409-stainless Thanks for your help.
__________________
"No replacement for displacement!" GTOAA--https://www.gtoaa.org/ |
#47
|
||||
|
||||
Quote:
Those are the ones I have on my own car using the standard log exhaust manifolds. Probably getting them from Summit would be cheaper considering the shipping cost.
__________________
1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
The Following User Says Thank You to b-man For This Useful Post: | ||
#48
|
|||
|
|||
Thanks.
|
#49
|
|||
|
|||
Quote:
Learn What Makes Them Really Run Mark Weymouth writerDan Jensen photographer Aug 1, 2008 "ExhaustThe exhaust system is your last drivetrain issue to address. How important is the exhaust? Very! The Ram Air IV Judge in the lead shot of the last installment is a good example. The previous owner used it as a show car and we were going to use it as a race car. Its NOS exhaust system and factory-spec engine only allowed 13.90s at 105 mph. With a change to an X-type pipe system, the car went 13.13 at 111.8 mph. To achieve the best results, you'll need to start with an all mandrel-bent 2.5-inch exhaust. Next, you need to decide whether to use an H-style pipe or an X-type pipe. Each has its own merit. Most racers have adopted the X-type pipe system. It provides excellent scavenging in the low to upper midrange. At very high rpm, it's not as effective. Most PS cars run completely in the rpm range, where it does its best work. The one exception is the Ram Air IV, but even this motor, overall, is well served by the X-type, as it provides additional bottom end and midrange that the engine lacks on its own." |
#50
|
||||
|
||||
Quote:
I've since tuned and tweaked some more to run a best 13.10 @ 106 uncorrected in a bone stock RAIII. I contribute a big part of getting there in just the exhaust system alone. |
The Following User Says Thank You to Formulajones For This Useful Post: | ||
#51
|
|||
|
|||
Quote:
Looking to go to a mandrel pypes system. What would the ram air manifolds bring for improvement? Worth the effort if I can find them? |
#52
|
||||
|
||||
Quote:
From the dyno stuff I've seen these guys post like Dennis, I don't recall a huge difference between logs and RA manifolds as surprising as that may sound. I think the HP differences were in the single digits if I remember correctly. |
The Following User Says Thank You to Formulajones For This Useful Post: | ||
#53
|
||||
|
||||
From what I’ve read the RA manifolds are good for around 8 to 10 horsepower at the most over the logs on near stock applications.
Not much bang for the buck when you consider the cost to do the changeover. The biggest gain is from freeing up the exhaust by going to the 2-1/2” mandrel bent system and good mufflers, probably gaining 25 hp over the restrictive 2-1/4” crush bent exhaust.
__________________
1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
The Following User Says Thank You to b-man For This Useful Post: | ||
#54
|
|||
|
|||
My 71 Olds 442 came from the factory with 2 1/4 headpipes and 2 inch tailpipes.I had changed the cam in the motor with a Kenne-Bell Mark 2. The best I could get out of the car with stock exhaust was 13.9 at 103 mph. I took a long extension with a 9/16 socket and loosened the headpipes off the exhaust manifolds about 1/4 inch to relieve some backpressure and ran it down the 1/4 mile. The car went 13.4 at 107 mph, backfiring out of the carb at higher rpm from being too lean. If I would have had richer secondary rods for the Q-Jet to put in, I'm sure it would have improved even more.
|
#55
|
||||
|
||||
This what I run. I use a common 14" lid with a wix 46926R "racing" filter. Stock filter measures about 2 7/8" high and the wix is 3 3/16" so I get a little more height and gets the lid a little further from the carb.
__________________
72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007 (cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD 1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86' |
#56
|
||||
|
||||
Quote:
But it works |
#57
|
|||
|
|||
Thanks for the info. I sold about three after market chrome (not great) air cleaners at my garage sale last year, as I was clearing stuff out I thought I'd never use. Now I wish I had one of those back. I used them on Chevies!
|
#58
|
||||
|
||||
.. and the same thing I stated in Post #9 but I guess I'm not the authority the rest of you all seem to be.
__________________
Triple Black 1971 GTO |
#59
|
||||
|
||||
Just showing what I've used for many years now.
__________________
72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007 (cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD 1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86' |
#60
|
|||
|
|||
I read post 9 and took note of it, interesting. Thanks
|
Reply |
Thread Tools | |
Display Modes | |
|
|