[Formulajones]

Originally Posted by tom s

I dont believe anyone could feel 10 HP on a 500HP pontiac in the ass dyno!Tom

Especially since they are so good at making torque anyway, which the manifolds seem to do a good job of maintaining vs headers.

[Formulajones]

Originally Posted by PAUL K

Correct me if I'm wrong, I didn't have a bunch of time to read these comments or the article. But it looks like most folks feel the headers aren't worth the bother over the RA manifolds. But there is a bigger gain with the headers compared to RA manifolds than there is with the RA manifolds compared to the logs.

Why are the RA manifolds worth the cost, two year wait time when you could lose less (than the difference between headers and RA manifolds) using log manifolds which usually can be had for free.

I know it may sound like I'm pushing manifolds. Honestly I'm a header guy at heart and believe any performance oriented engine worth anything should have a set of headers. The only reason I run manifolds is for a couple reasons. Looking for a stock appearance and/or the racing class requires it. Otherwise my stuff will have headers every time. I just simply don't have leak problems or ground clearance problems or any of the other stuff people complain about.

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

[PAUL K]

Originally Posted by tom s

I dont believe anyone could feel 10 HP on a 500HP pontiac in the ass dyno!Tom

You know 10 here, five there and seven over there and the next thing you know your Pontiac runs like a well tuned Chevrolet.

[jhein]

Originally Posted by Verdoro 68

Your engine is probably the closest to mine in terms of configuration, although your aluminum heads flow more than my cast iron ones. I'm totally comfortable giving up 10hp. For headers to be compelling I'd probably want to see a 20+hp gain.

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.

[jhein]

Originally Posted by PAUL K

Correct me if I'm wrong, I didn't have a bunch of time to read these comments or the article. But it looks like most folks feel the headers aren't worth the bother over the RA manifolds. But there is a bigger gain with the headers compared to RA manifolds than there is with the RA manifolds compared to the logs.

Why are the RA manifolds worth the cost, two year wait time when you could lose less (than the difference between headers and RA manifolds) using log manifolds which usually can be had for free.

Ah, now that's a different issue. Opening my hood and revealing logs would have a significant impact on my self-esteem dyno.

[PAUL K]

Originally Posted by Formulajones

The only reason I run manifolds is for a couple reasons.

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.

[nas t eh]

Originally Posted by PAUL K

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.

I agree, and would add that I think a lot of RamAir manifolds got replaced with headers too, but the temptation to do that on a mostly original car today is far less appealing.

[grandam1979]

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.

[Verdoro 68]

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.

[scott70]

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.

[Sirrotica]

Originally Posted by PAUL K

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.

Since I lived the time where I saw many day 2 cars, on day 2, the cars with RA manifolds were few and far between. I would say if I was to recollect how many left the manifolds on their cars, it would be about 50/50. Remember we didn't have any dyno tests to refer to, so if you wanted to win the stop light Grand Prix at the local cruise spot, you went with headers. As soon as Pontiac made the RA manifolds available, 5 header manufacturers were making headers to replace them. Case in point, I had a customer that bought a 73 SD T/A, he wasted no time in removing the Q jet, adding a holley spread bore replacement, and ditching the RA manifolds, and replacing them with Hooker headers.

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..........

[JUDGE3]

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?

[SD455DJ]

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

[PAUL K]

Originally Posted by nas t eh

I agree, and would add that I think a lot of RamAir manifolds got replaced with headers too, but the temptation to do that on a mostly original car today is far less appealing.

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.

[PAUL K]

Originally Posted by SD455DJ

Appliance headers (white…remember those?)


Sorry about the long-winded story.

Dennis

Great story, thanks for sharing.

Weren't those the four tube headers that came with the square four bolt collectors for the "street hook-ups"?

[Dragncar]

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.

[SD455DJ]

Originally Posted by PAUL K

Great story, thanks for sharing.

Weren't those the four tube headers that came with the square four bolt collectors for the "street hook-ups"?

Yes, they had the square collector flanges. I recall them being advertised with heavier gauge tubes and flanges. It took me a good weekend to get those buggers in from beneath in our parent's garage. I sure messed up the white paint when I was done...lol! But they did fit well and I didn't need to massage any of the tubes once I lifted the engine a few inches (one side at a time). I wish I had pictures of that car.

Dennis

[OCMDGTO]

Originally Posted by scott70

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.

I picked up 2/10s in the 1/4 mile going from 2.5" to 3" headpipes, can't remember mph

[scott70]

Originally Posted by OCMDGTO

I picked up 2/10s in the 1/4 mile going from 2.5" to 3" headpipes, can't remember mph

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.

[JLBIII]

Originally Posted by SD455DJ

Yes, they had the square collector flanges. I recall them being advertised with heavier gauge tubes and flanges. It took me a good weekend to get those buggers in from beneath in our parent's garage. I sure messed up the white paint when I was done...lol! But they did fit well and I didn't need to massage any of the tubes once I lifted the engine a few inches (one side at a time). I wish I had pictures of that car.

Dennis

I remember those with 4 bolt flanges, heavier steel and white paint that would flake off. I got a set back around 73 for my 65 Mustang. IIRC they were a fairly easy install even with the Z bar. Good times!