1 3/4" Headers Verses 1 7/8" on a Healthy 408....Is There a Big Difference??

-
cam dynamices cam shifted at 6800, rpm. also, 1 5/8 headers had 2 1/2 "dia collectors, 1.3/4 had 3" collectors, no secrets involved , sorry.
 
Hysteric said:
My machinist tells me he built a Edelbrock headed 408 that made 579HP on the dyno with 10-1 comp a 252/260 solid cam with 1 3/4 pipes.

Edit: Should know soon what it actually makes when it runs shortly with the track opening again and competition starting again.
Click to expand...

That is pretty believable if the head work and the rest of the cam specs are up to snuff.
 
My W2 head 408 made made really close to 550HP with a single 4bbl and TTI 1 5/8-1 3/4 stepped headers.

I recently came across a set of the 1 7/8 TTI W2 headers second hand for a great price. I picked them up, but I'm now on the fence. I'm not certain the gains warrant the effort to swap. Fitment with the stepped headers is great, I hope I'm not inviting a headache if I go to the larger tubes. The collectors change from 3" to 3.5" with the larger headers.

The car is also changing from 3.23 gears to either 3.73 or 3.91 gears, now that I am installing a Gear Vendors, so perhaps the bigger headers will benefit from the gear change?

Thoughts and opinions welcomed.

Headers are in great shape, just needing a little TLC and cleanup.

@Newbomb Turk, the LSA is 106.

1714695323976390912199455640762.jpg
 
cpearce said:
My W2 head 408 made made really close to 550HP with a single 4bbl and TTI 1 5/8-1 3/4 stepped headers.

I recently came across a set of the 1 7/8 TTI W2 headers second hand for a great price. I picked them up, but I'm now on the fence. I'm not certain the gains warrant the effort to swap. Fitment with the stepped headers is great, I hope I'm not inviting a headache if I go to the larger tubes. The collectors change from 3" to 3.5" with the larger headers.

The car is also changing from 3.23 gears to either 3.73 or 3.91 gears, now that I am installing a Gear Vendors, so perhaps the bigger headers will benefit from the gear change?

Thoughts and opinions welcomed.

Headers are in great shape, just needing a little TLC and cleanup.

@Newbomb Turk, the LSA is 106.

View attachment 1716244766
Click to expand...

I recently swapped headers on my 418 stroker. Went from Doug’s 1 5/8 headers with 3 inch mufflers, to 1 3/4 to 1 7/8 step headers with same mufflers off of them.
The difference was dramatic, and at that point, that was the only change.
Based on the Et slips, difference was roughly 40 horsepower. About 10 more than what several people whose opinions I highly value suspectedI would see.
I was frankly surprised by the difference.
Think you would likely be happy with the swap.
 
B3422w5 said:
I recently swapped headers on my 418 stroker. Went from Doug’s 1 5/8 headers with 3 inch mufflers, to 1 3/4 to 1 7/8 step headers with same mufflers off of them.
The difference was dramatic, and at that point, that was the only change.
Based on the Et slips, difference was roughly 40 horsepower. About 10 more than what several people whose opinions I highly value suspectedI would see.
I was frankly surprised by the difference.
Think you would likely be happy with the swap.
Click to expand...
I'm glad to hear this, thanks very much!
 
You're going to love that GVOD. You'll wish you went with even more gear. 4.10's work great with a 28" tire and a GVOD. I used to run 4.56's, but I can't make it through the traps in 3rd gear anymore with my new engine.

Do you know your trap speed? Or an estimated trap speed?
 
I absolutely wouldn't spend the time and money to upgrade them. Even if you gained 10 HP and I really doubt that. You'll end up losing TQ in the RPM range.

FYI: I have 1-7/8" headers on a very well built 499 RB and that's all the header that engine needs.

Tom
 
I'd change them. I'm running the same 1 7/8" Hedmans on my 434 that I ran on my 408. They have 3 1/2" collectors and 3" exhaust to turn downs at the axle. My 408 didn't want for low end, 4.10 gears.
 
PROSTOCKTOM said:
I absolutely wouldn't spend the time and money to upgrade them. Even if you gained 10 HP and I really doubt that. You'll end up losing TQ in the RPM range.

FYI: I have 1-7/8" headers on a very well built 499 RB and that's all the header that engine needs.

Tom
Click to expand...

I just posted my personal results and the gains I saw on a small block stroker. Have to disagree with you, his car will love the 1 7/8 header a lot more than 10 horsepower. I saw nearly 40 horse gain with doing nothing but switching headers.
I documented it well on here with timeslips.
Those street TTI headers are a limiting factor above 550 horsepower, no doubt about it.
 
Edit..
Went through and read this old thread from the start. Stupid me, I didn’t take my own advice.
I swapped to better heads, and saw only modest gains, keeping my 1 5/8 Doug’s headers.
I later bought a set of American racing headers, because I suspected they would pick the car up quite a bit more and better take advantage of the combo.
They indeed did, they were extremely worthwhile investment.
I ended up picking up almost 4tenths after the heads and header swap, and over 7 mph. And the combo is still far from optimal with the small cam I have, it’s giving up a bunch of ET.
But at this point, if I was going to do a cam swap, it would be to an appropriate roller cam specced to what I have.
Bridge I am unlikely to cross, don’t want to get license again and upgrade cage.
 
You must log in or register to reply here.
-

Back
Top