edcmat-l1

iTrader: (10)

Do you have graphs? How much power did you loose? Where, and for how long RPM wise?
I'll tell ya, I've not seen any real loss of power, engine for engine, 1 3/4 vs 1 7/8. This was just a good comparison, worthy of posting.

edcmat-l1

iTrader: (10)

I absolutely disagree, and would go with the 1 7/8ths. I don't think you'll loose a bit, and most likely you'll gain up top.

the_merv

iTrader: (88)

I'm wondering what I would gain by opening up the Exhaust on the L92's a little bit, I see room for improvement based on what they can flow already, and what is there to work with.

Louis

iTrader: (7)

Usually 1 3/4 picks up down low. I just did a back to back, and while the 1 7/8 gained up top, the 1 3/4 gained down low, like it should.

fbodyman1026

iTrader: (11)

so the blue graph line(car you tested 3 months ago) picked up 9rwhp/17rwtq more than the red graph line(car tested recently). I would say that the blue graph car must have had the 1 7/8 headers to make such a difference.

edcmat-l1

iTrader: (10)

I would be very interested in seeing the results.

mondojackal

you took the approach i was thinking of. both cars ended up the same, but the one that started out with the lower power is the one that gained more (obviously) so that car will have the better-sized header for that particular application.

MeentSS02

iTrader: (11)

What color were both cars? That might have made the difference...

Everyone knows black cars are the fastest and put down the best numbers.

red fury

iTrader: (1)

I just searched 383 strokers. There was one thread that a guy compared 1 3/4 vs 1 7/8 headers on his 383ci with no other changes.... the 1 7/8 gave an extra 5rwhp peak but they were down 10rwtq peak compared to the 1 3/4.

I guess it all comes down to how many cubic inches and what head you put on those cubic inches. For example... a 1 3/4 probley wouldn't hurt you much if you are running a 402 with heads that flow 300cfm compared to running a MTI LS7 head that flows 420cfm.

slow trap

iTrader: (22)

i've still got qtp 1 3/4 tubes on my junk. i have been debating on spending/wasting a grand on switching over to an 1 7/8 tube and am still not convinced/persuaded they are worth much. i don't really see my car picking up 10 rw or more . on spray the 1 7/8 would be alot better.
you have done a good test. now everyone will be waiting on those 2 cars to start modding to see the comparison difference haha. i'll be first. hit them both with a 150 shot and let's see the results.

Gh0st

iTrader: (3)

Ed,

"Lose"

Thanks,
Management

WKMCD

iTrader: (2)

Louis,

Curious, were the primary lengths and collector the same both tests?

BTW: Happy Holidays

Kevin

WKMCD

iTrader: (2)

The low end on my L92 build sucks with 1 7/8 LT's.

You're talking about below 600RPM -right?

edcmat-l1

iTrader: (10)

It's the Timberlake grind. Gets it up quick, and keeps it up.

edcmat-l1

iTrader: (10)

Ah, we thought of that. So, in effort to keep the test as fair as possible, each car was spray bombed primer gray before hand!!

edcmat-l1

iTrader: (10)

allngn_c5

iTrader: (3)

Very interesting Ed. Glad to see you post such surprising set of graphs. Looked to me that when everything was tuned it was just about equal. Not a big enough gain/loss on either side to justify one size or the other.

Like everyone said until you go bigger cubes (427 or above) or (FI on a smaller ci) it seems to be a personal choice 1 3/4 or 1 7/8. Now with that being said if I was running a big cam 346 with a healthy shot of spray I'd like to take advantage of the 1 7/8 header to maximize my power while spraying.

Slowhawk

iTrader: (12)

Nice to see the test. I was lucky enough to test 3 different headers on the same car and tune them to max performance on a 03 Z06. My test showed the 1 7/8 making more hp everywhere. The other 2 were 1 3/4 size headers and there was a big difference between the 2 in the low end area.
Haven't done any back/back on the 05+ Vette's.

edcmat-l1

iTrader: (10)

Thanks Don. That again reaffirms what I've seen over a very long period of time. And that is THERE IS NO SIGNIFICANT LOSS OF LOW END AND MIDRANGE TORQUE WITH THE BIGGER PRIMARIES.

We should be doing a single vehicle, 1 3/4 to 1 7/8 test in the next few weeks.

the_merv

iTrader: (88)

I didn't pay attention quick enough to see what kind of cars they were, and I was finally able to see the graphs(photobucket is blocked here..)

I definately think I would see a gain seeing as how I have the same Heads, and I have a Cam in it with a few more cubes.