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#21
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Especially since they are so good at making torque anyway, which the manifolds seem to do a good job of maintaining vs headers.
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#22
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What I do have is a wallet problem since a really good set of coated super comps that I need are now $1200!!! Just 2 years ago they were $700 |
#23
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You know 10 here, five there and seven over there and the next thing you know your Pontiac runs like a well tuned Chevrolet.
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The Following User Says Thank You to PAUL K For This Useful Post: | ||
#24
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Yeah, I suppose you may see some small difference at the track, but for a street car I don't think I'd feel it. Plus, I'm already traction limited anyway.
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70 TA, 467 cid IAII, Edelbrock D-port heads, 9.94:1, Butler HR 236/242 @ .050, 520/540 lift, 112 LSA, Q-jet, TKX (2.87 1st/.81 OD), 3.31 rear https://youtube.com/shorts/gG15nb4FWeo?feature=share |
#25
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70 TA, 467 cid IAII, Edelbrock D-port heads, 9.94:1, Butler HR 236/242 @ .050, 520/540 lift, 112 LSA, Q-jet, TKX (2.87 1st/.81 OD), 3.31 rear https://youtube.com/shorts/gG15nb4FWeo?feature=share |
The Following User Says Thank You to jhein For This Useful Post: | ||
#26
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The only reason is for a couple of reasons lol just teasing.
I have two words for you! ..... I like them all. Personally I don't have any issues with headers but I know some can be a real challenge. JMO I feel the build or car may dictate what I perfer. It'd be hard to put headers on a car that came with RA manifolds but if you're building a "day 2" recreation I'm doubting many guys replaced the logs with RA manifolds back in the day.... So I'd perfer headers on something like that. |
#27
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73 T/A 455, 4speed |
#28
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I think people like manifolds because they are less likely to leak much much easier to install won’t rot out in your lifetime or the next 5 years. One other thing with headers 2” round port or bigger you’re going to be moving brake lines for clearance. Most importantly they are what came on performance Pontiacs in the day.
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#29
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For a street car with round ports (e-heads or otherwise), I wonder if the difference between headers and manifolds is sometimes not that big because the passages on the factory manifolds are decently sized. Bigger than the d-port version anyway.
I'd be curious to see if r/a manifolds into a 3" down pipe then into 2.5" tail pipes do anything. I know Cliff has mentioned that before.
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Ken '68 GTO - Ram Air II 464 - 236/242 roller - 9.5” TSP converter - Moser 3.55 Truetrac (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
#30
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This summer I took off my slightly massaged 2.25" RA manifolds with a 2.5" headpipes / X pipe and replaced them with RARE oversized manifolds and their 3" headpipes. Ran new 3" X pipe back to the 2.5" mufflers. Gained only .75 mph in the 1/8th mile. That was fumbling with a 4 speed and street tires but i did run my best mph ever but not by much.
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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' |
#31
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No one knew what power each component was good for. or how much the aftermarket component gained, or lost over OEM. The belief was that OEM/bad, Aftermarket/good. Few people were testing if that latest whiz bang component actually made the car faster. If you asked the owner,how much difference it made you'd hear it gained him 50 HP, but this was total BS, street guys always said it made their car quicker, but nothing as far as timeslips etc. to back it up. As far as log manifolds, over RA manifolds, over headers. Back before R.A.R.E. was ever conceived, RA manifolds were tough to come across, because in the great scheme of things very few cars came from the factory with them, and if you priced a set from Pontiac, you could buy 3 sets of headers for what they went for over the parts counter. The first year I raced my 67 GTO dirt car (1975) I ran a 400 with log manifolds as class rules said no intake, and exhaust mnaifolds, except factory cast iron. I knew a ton of people that had Pontiac parts, and raced Pontiacs in my home town. Plus I was good friends with the parts manager, as well as the service manager, at the local Pontiac dealership where I had done my Co-op stint when I was still in high school/Vo-tech. I beat the bushes trying to come up with D port RA manifolds, and came up empty. Over the winter I bought a 1970 RA III Judge, it came with manifolds on it. The engine had been run for a long time without an air cleaner on it, and it used oil from the rings being bad. It had a P4B and of course a square bore holley. I managed to run it low for oil, and spun a rod bearing in it, but the car also came with a spare 65 389 engine because the former owner planned to swap the ailing RA III. When I swapped the engine i now had RA manifolds for my stock car, that wouldn't fit, until I hacked up the frame crossmember. After I changed the manifolds, without any other engine mods, the car was much faster, than with the logs. The main thing was it was faster at every RPM, not just at peak RPM. My take is the engine gained the ability to accelerate faster through the entire RPM range, not at just peak HP/torque speeds. The engne spends much more time accelerating from 2500-5500 RPMs than it does for tha split second you reach peak HP/torque just before you let off, and brake for the corner. The dyno figures posted in magazine articles are only looking at peak HP/torque numbers, and leave ot the gains as the engine is accelerating through the entire range. Those dyno tests all the manifold proponents always cite, only show a tiny bit of the picture. As the famous saying says, "We don't race dynos". The same thing goes for the proponents that say you can make almost the same power with RA manifolds, over headers, they're only looking at a tiny portion of the engine operation over the entire spectrum. Race cars aren't run at the maximum RPM range the entire race, so failing to look at what happens in the time the engine is accelerating is very short sighted in the overall picture. In my own cars I want the absolute best exhaust system over the entire range, not just at peak HP/torque. Breathing at lower RPM is where the engine spends most of it's time during a race, same goes for dirt track cars, road race, as well as autocross cars..........
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Brad Yost 1973 T/A (SOLD) 2005 GTO 1984 Grand Prix 100% Pontiacs in my driveway!!! What's in your driveway? If you don't take some of the RACETRACK home with you, Ya got cheated Last edited by Sirrotica; 10-20-2023 at 03:14 PM. |
#32
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supertuners
I appreciate the input. I call you experts "supertuners"
to explain where i'm at: posted my cam because several had stated my cam is a problem with the rare round port exhaust manifolds. specifically the 110 lobe separation. wanting to learn why? |
#33
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My only experience with headers vs. manifolds (other than a dedicated race car) happened when I had my first car, a ‘70 Formula 400 with the YS 330 hp 400, TH400 trans and the 3.07 open 12-bolt rear end. It ran low 15’s @ 90 mph (very factory stock) at the high school drags back in the day (1973). In the short time I owned it (16 months) I had the rear gears swapped to a 3.55 posi (made the biggest difference in butt-o-meter hp!), and then bought some Appliance headers (white…remember those?) to replace the logs. I added Hemi mufflers (huge!) with a couple straight section of 2 ½” that dumped out under the back seat (no tailpipes). The header flanges and mufflers scrapped and banged every little bump in the road, lol! We didn’t know about needing to richen the carb due to reduced back pressure. The following year at the high school drags it did run 14.70’s at 95 mph with open headers manually shifting the automatic at 5500 rpm, not knowing it probably would have run quicker shifting at 5000 rpm with the stock 067 cam and valve train. How much of the gain was attributable to the gears vs. the headers…who knows. I did other stupid things to that poor car like cut the snorkels off the air cleaner and cut open the scoops (did and OK cutting job on that). Not long after that I traded it in on my red ’70 Judge that had its original RA exhaust manifolds. I thought they were the coolest thing to have and loved the look of them. Like Brad said, they weren’t very common, even back then 3-5 years after these cars were on the street.
The SD455 engine, when tested with the originally planned ‘K’ cam (RAIV 041 spec), really responded well to headers (65 hp gain) and it was well known that was a must-do upgrade. It wasn’t that big of a hp gain with the stock ‘Y’ cam (744 spec), but probably 35 hp, or so. We pure stock racers are masochists tuning and racing with RA and log manifolds, but that is the challenge. The cast iron manifolds work pretty well with the soft cam timing events, but certainly will make more power with headers when tuned for them. I measured the outlets on the log manifolds, and they were only 2.0” on one side, and only 1.9” on the other! I’d like to open them up to 2 1/8” to see if there would be any power gain. That’s about as large as you can make them and still retain enough flange lip to seal to the downpipe. It would also be interesting to swap to RA manifolds, both factory and OS RARE’s, at the track to see what gains would be made. Certainly, the bigger the engine (& head flow), rpm, and cam, the more headers help…simple deduction. Sorry about the long-winded story. Dennis |
#34
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I agree... I faced that same situation with my 73 TA. I wasn't thrilled with the RA manifolds on a D-port engine and not really liking the header selection. The dilemma was solved when I came across a pair of original H-O racing tri-y's at a swap meet.
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#35
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Weren't those the four tube headers that came with the square four bolt collectors for the "street hook-ups"? |
#36
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Appliance Headers had a very cool sticker with a mean looking Buzzard sitting on a pair of headers.
It was my favorite one to ask for at local Arcata auto parts stores when I was a kid. |
#37
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Dennis |
The Following User Says Thank You to SD455DJ For This Useful Post: | ||
#38
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Chris D 69 GTO Liberty Blue/dark blue 467, 850 Holley, T2, Edelbrock Dport 310cfm w Ram Air manifolds, HFT 245/251D .561/.594L, T400, 9" w 3.50s 3905lbs 11.59@ 114, 1.57/ 60' |
#39
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Because of the drive train combo I didn't see any 60ft improvement or ET...I kinda expected that and since I was only maybe gaining 15hp . I was really relying on mph change which is all I saw. With a auto trans, decent converter and sticky tires I would be able to see more of a accurate comparison. That's a very good improvement on your car.
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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' |
#40
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