Hey guys just trying to get your thoughts on the header tube diameter.
The motor is a 496 with 11:1 compression, angle milled AFR 305 heads with CNC chambers, UDHarold custom solid roller cam with .725 lift and Isky Red Zone lifters, Victor Jr intake, QuickFuel 950 carb, and Mallory ignition.

What size headers should I run 1 3/4", 2", or 2 1/8"?

I have had good luck with Dynomax on small blocks and have heard good things about the Summit headers but both are only available in 1 3/4" which sounds to small

Hedman has a 2" along with Hooker in there Competition series. I had clearance issues with the headers on the 400 small block in there now and think they are Hedmans so not sure how the big block headers fit the chassis.

I know Hooker also has the Super Competition series in the 2 1/2" but are they worth that much more in power quality and fit to justify the extra cost?

Thanks

LMAO at the 1.75's. Get the 1 1/8 if they'll fit.

AFRs require at least a 2" primary tube just to seal up against the monster exhaust ports. I am using the Hooker Super Comps (2" primaries) on the AFR-headed 454 that's going in my truck.

i aggree,, something like at least 2" if you have narrow lobe centers. can be even a little bit bigger for very narrow lobe centers,, smaller for wider centers. general rule of thumb. andy

If it is a mild 496, the smaller 1.75" and 1.875" headers are best b/c they create alotta midrange T!! I have 1.75" on mine.

A more hopped up 496 can of course use bigger headers, BUT don't get into the "BIB" thing here b/c it's been proven, big headers can cost you midrange T!!

Kinda like the rect heads vs large ovals here is all until you really get to rpm'ming a BIG engine!...

As always, jmho..

pdq67

sounds like with .725 lift,, that this cam is in the 270's @ .050 range. gonna be a monster setup for sure.
pdq has some good points.

Go 2" if you want a torque monster.

If its a racecar/pro street I say go 2 1/8" like I did,the small amount you may give up in the low/mid range,you'll make up in the high power band...if it can rev faster,it'll get there faster.

Put the 1 3/4 on if you're going to put it in a dump truck ;)

Go 2" if you want a torque monster.

If its a racecar/pro street I say go 2 1/8" like I did,the small amount you may give up in the low/mid range,you'll make up in the high power band...if it can rev faster,it'll get there faster.
^^^^+1
IMHO A 496 with as much cam as that will need at least 2".

Steve.

Depends on where you built it to shift. 6 grand will want about 1 7/8", 6500 will probably make best peak power with 2", and if you plan to beat on it and let 'er eat, run 2 1/8" pipes. My .02

I did, I call my about 550hp at 5500 rpm and 580 t at 4500 rpm, my great big "tow-truck" engine!!

1.75" jobbers for my 496 for me!!

pdq67

PS., funny tho, running my D2k power curves through DRAG, it should run like 10.5 at 130 mph if it hook's and doesn't break anything!!

I know, both D2k and DRAG are sim. programs so I will be tickled pink for a low 11!!

Thanks for the replys.
I just bought a set of 2" Hooker Comps from a guy on Ebay for $77

The motor combo is a 4.310 bore with tops chamfered, 4.25 stroke Scat crank, SRP forged pistons, zero gap 2nd ring set, AFR 305 cc heads with CNC chambers and angle milled to raise compression to 11:1, Crane Gold Race roller rockers, Edelbrock Victor Jr intake, QuickFuel 950 carb

Cam is a UDHarold assymetrical solid roller design with .725 lift, 257 intake 265 exhaust duration @ .050 on a 110 centerline with a 4/7 swap on the firing order.

What do you guys think?

I hope this thing is a monster when done.
Only time will tell though.

I think you did fine. Like I said in my previous post, you need at least 2" just to fit over the monster exhaust port of the AFR heads.

Imho, your compression is a tad low is all!!

But the sucker outta haul as- fine, imho, regardless!!

He, He!!

pdq67

I personally use the 2.125 hooker super comp on my 454. I have the AFR 315 CNC heads. It was a tight fit, but it was worth all the power. I think you will like this setup.

Jack

I have the Hooker Comp 2455 2" primaries on my yet to be started 509. AFR 315, UDHarold Custom SR 260/266 .730/.730 net lift. I needed to grind the header flanges to keep them out of the exhaust port roof. Otherwise a good choice for a street / strip 496.

John