Are the stock exhaust manifolds more restrictive than the stock L98 heads and TPI? What I really want to know is, are my exhaust manifolds restricting my 383 strokers power even though I have stock heads and TPI? How much power do you think I would get by using 1 3/4" headers and gutting my cats (I have a 2.5" true dual exhaust)? Would this give me more upper RPM power?

 

ever sucked a golf ball through a garden hose?.. didnt think so...

 

man you definitely need headers. those 1 3/4 would work great too. run a pipe through those cats or get some hi flo's.

 

Well...

I'll post this reply just to play the "Devil's Advocate" a little.

If you go to this big thread regarding a Vortec 383 LTR set-up:

https://www.thirdgen.org/techbb2/showthread.php?s=&threadid=84340

You can see that Mike has an awesome running 383 LTR car (12.5s @ 107) with a list of mods much greater than yours (heads, runners, base, TB, and 1 3/4 SLP headers). You can also see that he's getting about 35 RWHP and 40 RWTQ more than you. What percentage of the differences in dyno numbers are due to the headers? Good question. Is the contribution worth the $500 for the headers? Another good question. It would be interesting to see what kind of rear wheel numbers you would get with the addition of the headers only (or what kind of #s he could make with the manifolds back on).

 

I think your math is off.

I count approx.

25hp
35tq

as the difference, but thats just me

 

Momar,

I was using the dyno numbers he got last weekend with his new runners...

 

Sorry, I was just looking at the ones he had posted at the top.

Ben