Getting close to finishing up my 440 based 500 stroker build. Max wedge size Trick-Flow heads, Solid cam, single plane intake. I currently have TTI 1-7/8 headers and am trying to decide if it I worth it to upgrade to TTI or Dougs 2 inch headers. I can get sell my old headers to offset some of the cost of new headers. Is it worth changing for a mainly street car?

I gonna be the first of I bet many who will say run what ya got

I tested 1 3/4 dyno headers against my normal 2 inch dyno headers last time I had my 470 on the dyno. The 1 3/4 headers cost me 10 hp on a 700 hp engine. The power difference was basically only at the higher RPM at full throttle.

On a street engine that spends most of its time at part throttle I don't think you'll see any difference. For street headers I'd be more concerned about how well they fit and how good the plug access than size.

I was told to run by Hughes TTI 2 1/8 step headers but that will depend on how much power is in the motor. My motor is around 650HP plus it has dual 3 inch exhaust with X pipe.

If the exhaust valve is 1.80 inches then I don't see much reason for a 2.125 exhaust pipe. Or at least it shouldn't be 2.125 right at the head. Maybe on a full out race engine you would start at the head with 1.875 or 2.000 and then step to 2.125 after 12 inches. On a street car I doubt that it matters much. Most street driving is at less than 3000 rpm.

You'll be fine with the 1 7/8. I always ran 2" on the race cars but I run 1 3/4 hedman's on my 500" street motor just because they were dirt cheap and I'm not concerned with ET.

for primarily street car I wouldn't bother
if looking for all the HP 2"for sure .
There was a test done in 1 of the magazines , it seemed the tipping point was 500ci and above was 2" primary .
when I went to my 505 I went to Dougs over Hooker 1 7/8 , I want everything I can get , but I also run 3 exhaust to diff". Way easier changing plugs with the Dougs

Tex

I think 1-7/8 headers will choke the thing.

1 7/8 will be fine. You might notice the difference at 6500 rpm. Don't waste your time or $.

My prediction......

For the most part, I think it would be something like this:

From around 3-400 rpm above peak TQ and below, the 1-7/8" would be better, then above that the 2" will take over.

How much difference? Not really sure....... I'd guess peak to peak maybe 20-25hp.

On a 715hp 542 it was about 40hp from my dyno headers(2-2 1/8 x4) to his 1-7/8" fenderwells.
I've done that same test before on a 670hp 493 and the results were about the same...... Close to 40hp difference.

With the 542, the big headers were on the plus side at 4500rpm, and at 6500rpm they were 55hp better.

FWIW (not much, I'm sure), I used 1-7/8" Hookers to go 11.0s w/ a RB 451. When I upgraded the heads & the cam, I also went w/ TTI 2" headers. The upgraded combination was about 1/2 sec quicker and 5 MPH faster.

It's all in the combination, but IF you want the on-track performance, I believe a 2" is better for what you've described. On the street, you'd probably never know the difference, though.

Do you have a guess at the hp level and anticipated et/mph? Maybe throw in a cam spec.

These things matter, right?

For a street car.. run the 1 7/8 header.. more
over all power

Are you at all confused by us yet? We are like a drunk and bipolar mental patient.

Do you trust a English major to get accurate information on dyno testing?
I've seen way to many errors printed in most of the popular automotive magazines like Hot Rod and Car Craft to trust every thing they print 100%
O.P., dyno testing gains don't make the car go faster at the track, trust me on that

Here's what I have:

3,950 B-body
3.54 gear
8" Dynamic
Full 3" exhaust to bumper
pump gas 505
Edel PRM heads
Indy 2D

260/268 @ 50
.585/.600
109 lsa
104-105 installed
10.96 compression

Went from Hooker 1-7/8 x 3"
to Hooker 2" x 3-1/2"

It went from 11.57-11.63 @ 115-116+
To 11.28-11.35 @ 117-118+
Weather being about the same.

Bad part is I made two changes....swap from milled tower 850 to 1000HP and going from 1-7/8" to 2" header...both Hooker

Good part is it went faster.

Broke my Dynamic 9-1/2" so I had to put my 8" Dynamic in to finish the driving season.

On the street, if anything the 8" is a more loose...hence causing more pedal to get it moving if I need to pull out of store parking lot and blend in with traffic.


The 9-1/2" is a touch tighter. I think the 9-1/2" and the 2" header would be the sweetest street/strip package for me.

About 700+ miles on the street last year

Imagine if I went to a better head the 2" header would help breathing more.

Mike

If I was you and knew what I know now I would put the 2.0 inch on it now and not wonder later if they would be better than the 1 7/8
Every test I've done on exhaust at the track and on a engine dyno on all the B/RB motors I've tested liked bigger primary pipes and bigger collectors over smaller, including a pump gas 426 C.I. M.W. 9.5 to 1 compression ratio motor I did for Boyd Coddington years ago on Pettis dyno back in the early 1990s I removed a set of 1 7/8 hooker A body fender well headers we had been using for around 15 pulls so Bob could put his new set of dyno headers he had made while we did the initial dyno testing and breaking in the new motor, his dyno headers where 2 1/4 primary x 25 inches long into a 4.0 inch collector It made better peak torque and peak HP as well as pick the averages up also
I will say that some of the things we test on the dyno don't mean that it will ALWAYS be better on the track or street

Lots of varied opinions, But pretty much what I expected. More HP on the top end, Probably won't notice it much on a street car. That being said I think I will go with the 2 inch headers, thanks for all the info.

My 400 based 511 made 750hp @7100RPM with 1 7/8"-2" stepped dyno headers and a 4150 style 1050CFM QF 1050-AN. I'm thinking it will pick up with the TTI step headers that will be used in the car.

If it ever sees the dyno again I'll put a Dominator and larger headers in the mix.