Exhaust Manifolds

[Daddys409Belair]

Decisions, decisions....

Does anyone know what kind of horsepower difference we're talking about using the hi performance cast manifolds (GM #'s 3822925 & 3822926) say compared to a set of block huggers or a standard set of headers? When I ran a set of standard headers on my 350 I COOKED the starter repeatedly.

Has anyone ever bought a set of these exhaust manifolds from Showcars? I always get warned about the items they sell. While the are extremely expensive ($899 for the pair!!!!), I would gladly pay it so I don't have to constantly change out the starter on my '09. :cuss But I do want decent breathability (is that a word?)

Thanx

[walkerheaders]

If you r not looking for every last ounce of power use the manifolds.
if your all out racing your 409, or want it all, one of our members, SS425HP may be able to get you a set of the best big tube 4 into 1 headers we have seen yet.
for anything other than pro drag racing, i like the tri-y setup. there are tri-y headers available that fit good and dont hurt starters.
the manifolds are a one time purchase and are tri-y design. they breath fair enough to have been standard on the 400, 425 and Z11 cars.

any kind of headers you can dream of are available to me.......so, i went with manifolds! and my car will rev to 6500 easy.

[Ronnie Russell]

For what its worth, I agree with Bob 100% The manifolds are the best choice. I have used the tri-y headers with good sucess also and no starter problems, but I would doubt the hp gain would be much at all over the hipo manifolds. I cannot comment on the quality of the reproduced manifolds but surely we have members who have used them.

[jim_ss409]

I've got very little real world experience with this but I've always found header design an interesting subject. So, I've read every magazine header comparison test I could find and the simple answer is... Long tube headers and tri-Y's always make more power than cast exhaust manifolds or shorty blockhuggers. How much more seems to be dictated by how bad the factory manifolds were and how much cam the engine has. The high perf. 409 manifolds look like a really good free flowing design so I'd bet they'd work really well on a relatively stock 409. But if you throw in a cam with lots of overlap headers really start to look good. I hope that someone that has changed from high perf. manifolds to headers on a 409 will chime in here. :scratch My guess is that a good set of long tube headers or tri-Y's would add about 20hp at higher rpms and bump up the midrange torque by about 35 lbs on a stock 425hp 409. So if I'm close on this you've got to decide if it's worth the hassle of running headers in your particular application. For me, I needed the power! :D :beerbang

[Bungy]

Here's some nice pictures for ya.
http://cgi.ebay.com/ebaymotors/CHEVROLET-CHEVY-409-EXHAUST-MANIFOLDS-3822925-3822926_W0QQcmdZViewItemQQcategoryZ46096QQitemZ795 4964456

[rogersimpala]

I would have to agree with bob go with the manifolds
I have a 409 425 hp in my 61 impala, with a set of block huggers
I seem to get a lot of heat inside the car from the headers, so crusing around sometimes isnt a lot of fun hear in the texas heat
I plan on changing mine over to exhaust manifolds, when ever I can find a set that I can afford
I dont think I will loose that much hp in realiation to what I would gain by being a little more comfortable when out crusing
However I do not race the car, but do stick my foot in it every once in a while :love :love

just thought I would stick my 2 cents in for whatever its worth :rofl :rofl
61 impala
409 425 hp
4 speed

[BC409]

i have also wondered this. everyone seems to be in general agreement but i would really love to see some real test numbers.if not dyno numbers how about e.t. and mph before and after.ive looked for this info for years with no luck.
i know there has to be someone in this group that can give us some firsthand experience on this. thanx guys
BC409

[Ronnie Russell]

BC, dont think you will find the numbers you are looking for. As stated earlier, you can expect 20 to maybe 30 hp with top quality long 4 tube headers over the manifolds. In the real world you could expect 5 to 8 hundredths improvement in e.t.s. Takes a lot of hp to gain a full tenth. Unless you are trying to drag every hp out of your motor, the manifolds still seem to be best. Headers are usually a nightmare to deal with, but worth it if you are racing only. I still believe the hipo manifolds are best for dual purpose car.

[Tom Kochtanek]

I wish I had a set of those swept back rear dumpcast iron exhaust manifolds, but alas I only have sets of the earlier 682/683 units with the center dump. My application is for "dual" driving, with an emphasis on streetability. The engine is stroked, and I realize that headers would be an improvement, but we're starting off with stock components.

I wonder how different the earlier 2.5" manifolds are from the later rear dump units (925/6)?

Best,
TomK

[Ronnie Russell]

Tom, I am unfamiliar with part nos. ( if I werent so lazy, I could look them up) but I assume the manifolds you refer to are the smaller 340 manifolds. There is a huge differance between them and the hipo manifolds. With a stroker I think you would need at the very least, the hipo version. If this is cost prohibited, the tri-y header would be the next step up. The high quality 4 tube headers are an option, but you should check with someone who has installed a set of Hookers on a car first. This is not a "walk in the park" installation. Anyway, since you are a Real Estate Magnate, you can afford the good manifolds.

[TomO]

Tom K is a "W" magnet.

TomO

[SS425HP]

If you would be interested in 4 tube headers, I know I have one set left, from the run Dean and I did. They are $875.00 plus shipping. If there would be more interest, I have talked to the guy that bought Dean's shop, and he is willing to build headers from our jig. If that doesn't work out, I have another fellow that will take the jigs and build from them, too. I'm working on pricing for more headers at the present. These are 4 tube, 1 7/8" tubing, with 3" collector, and the collector ends where you can turn back to go to stock exhaust system. They fit tight, but there is no over the frame pipes, no a frame bolts to be cut. Must use a smaller spin on filter and late model GM starter. It is smaller, too. Also, these are ceramic coated.
No dyno runs, as Dean got sick before we could go that far. I'm using them on my car and racing it. They sound good. Can't compare performance, as I put them on and then went racing.

Fred

[Daddys409Belair]

I kind of figured that the hipo manifolds were better than the earlier manifolds. I read that they were not only less restrictive, they also had less 'interference' between cylinders (especially cylinders 5 & 7!)

Would someone please answer my question about the quality of show cars parts before I drop $900 down? I'd really hate to look like this guy :cuss

Thanks

[W Head]

I kind of figured that the hipo manifolds were better than the earlier manifolds. I read that they were not only less restrictive, they also had less 'interference' between cylinders (especially cylinders 5 & 7!)

Would someone please answer my question about the quality of show cars parts before I drop $900 down? I'd really hate to look like this guy :cuss

Thanks

I was informed that the exhaust manifolds sold by Show Cars is are the same as the exhaust sold by Late Great Chevys in Florida. $899.00 Only one foundry is casting these. I was also told that very little of these are kept in stock and it is abour a 3 month wait if the manifolds are out of stock. There is a couple of other places that sale these, they are all the same and all cost about $900.00 I almost purchase a set of these about a year ago and did a lot of checking around. Was forced to take early retirement about that time and my cash flow went down a bunch :bang, so I didnot buy.

W Head

59 El Camino 348-3,2s
59 Impala 409-2,4s

[SS425HP]

I'd almost swear that I saw the molds for these headers being sold on E-Bay about a year ago. Don't know if there is a way to check, but I'm pretty sure I saw it. I just wonder, if they have the GM number cast into them. That could get risky. GM looks pretty hard at that stuff. Just wondering.

Fred

[Tom Kochtanek]

Fred, you are correct that about a year ago a set of "private" molds was put up for sale. Story had it that the guy could not locate a pair of swept back manifolds, so he commissioned these molds to be made. They did have casting numbers as I recall. The auction was for a set of heads (made from that particular mold, needing to be cleaned up) and the molds themselves. I think they went for something like $1800. I remember bidding on them, not sure what I was thinking :).

I suspect the molds would have needed a lot of work to make them work well, and that whoever did the castings had to be quite skilled in the art and science of metallurgy :).

Anyone else remember that sale? Not sure who got them, or whether SC or some other subcontractor purchased them and made a run...

regards,
TomK

[jim_ss409]

After seeing Freds headers I can honestly say that they are by far the nicest looking headers I've seen.

[CDNpontiac409guy]

An exhaust manifold / header debate ?

Just my 2 cents :dunno

Headers.... always.... everywhere :deal ( except maybe a luxury car or number matching restoration )

When we dyno tested the engine, I first used the Belanger 1 7/8" tube, 36" length, 3" collector. Then changed to my headers.
Picked up over 20+ ft lb torq & 26 HP.

An update on my headers that I built last year for my Stocker...
2" stepped to 2 1/8" tube, into 3 1/2" collector ( about 14" long )
I just shortened the primary tubing to 32"-36" ( took out about 6" )
Upper RPM ( torque curve ) power is up.

Yes, with my headers, I had to cut both front upper control arm bolts. To get around them with a @" tube would require practically flattening the tube ( not acceptable ). As it is, I still needed a little dimple on each side ( rubber engine mounts dictated that ).
They are completely in chassis, clear the factory starter ( I have an aluminum one on the car though ), clear the factory canister oil filter, and of course all clutch linkage and scattershield. :deal

Until I can afford the money and time to get them coated, here they are with paint on them ( I clean up the welds before coating.... at the moment, I just wanna GO FAST :deal :p )

[Ronnie Russell]

Aubrey, This aint no exhaust manifold / header debate!!!!!! Daddys just wants some "breatheabilty" We are not arguing or debating which makes the most horsepower. We all know that, Aubrey, but if I were looking for headers for a race car, I sure would like to sneak off with yours. Before I do that though, could you re-do the front tubes,, I dont like the dimples.

[CHEV601234]

Aubrey,
7&8 sure do look snaky. Have you gotten some plug readings yet?

[CDNpontiac409guy]

but if I were looking for headers for a race car, I sure would like to sneak off with yours. Before I do that though, could you re-do the front tubes,, I dont like the dimples.

:evil .......... ;)
:rofl

Well CHEV60.... as a matter of fact :deal

Here are the plugs from the engine.
NGK. Have about 10 hours running time on them... probably 20 passes.
The last few minutes running was on a warm engine, backing the car into the shop.

The plugs are numbered on the box