Well hopefully my last question as it pertains to exhaust.  I am going to have new exhaust bent up and new mufflers, Magnaflow, installed and have a question about diameter of pipe.  Will I see any difference in performance with my 390 going from 2.5" to 3"  Is there any significant cost increase.  Because if the answer is no then I will just go with 3".  As you can see in my signature block a mild 390 never going to be a drag car but I like the lope and want it to sounf a little healthier.

Thanks as always Gurus of the FE world

Also thought I would show you my Moterey

1226540918.JPG

Tim

Tim Krause 1967 red Convertible Monterey.
390 with edelbrock rpm heads intake and cam. MSD Dist 6 Plus controller electric water pump and fan and headers

I would say 1) no signficant performance increase unless the 390 is putting out around 450+ HP and 2) yes, 3" pipe costs more than 2 1/2" pipe. How much depends on the shop and how they price their materials.

1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

Fine looking '67 Mercury you have there, Tim. Should have my '67 Park Lane finished by summer!

n/m



1964 Galaxie 500XL 458cid,med riser dual quad,mech roller cam,C-6 3500stall
1994 Mazda B4000
2004 Audi A6 Quattro S-Line
2003 VW GTI 1.8T
2003 Ford Excursion 4x4 enhanced 6.0 Powerstroke Diesel

Tim,
I had to guess at the following, see how close I was:
C-6, stock~2000 stall, 3.25 traclock
10.0cr
735 Holley
Curb 4350 lb

Gross numbers for your engine, even with the "newer" Edel heads that don't quite seem to flow what they did out of the box in the 1990s, came out with a properly tuned carb and timing to:
Torq 455 at 4000
Power 440 at 5500
Not all that mild I'd say.

Complete with that electric fan you mentioned, down the track Gonkulated to:
2.5" Magnaflows
2.31
9.41 at 78.2
14.38 at 98.2

3.0" pipes
2.31
9.37 at 78.8
14.30 at 98.9

So in comparing 2.5" vs 3.0" I think there would be an improvement, but it might be hard to measure or even feel 0.08 sec and 0.8mph, if you swapped pipes and went back to the track the next weekend, the weather and even wind could make more difference than that. So it kinda comes down to how much $$$ you think 0.08 sec is worth when comparing the price of 2.5" vs 3.0".

That 67 Merc sure brings back a lot of memories.
I hope you can get a chance to weigh the big ragtop if you haven't already?

wow thanks I need to weight it feels quick but I would love low 14's. I have a 3.5 Detroit locker and. 750. Carb. Thanks again makes me feel pretty good about my efforts right now I have 2" with an H pipe madrel bent. I am heading out to upgrade before I put it up for the winter thanks again

Tim Krause 1967 red Convertible Monterey.
390 with edelbrock rpm heads intake and cam. MSD Dist 6 Plus controller electric water pump and fan and headers

I think 2-1/2" would be fine and would help keep the noise factor reasonable. The 2 1/2 will also make it a little easier in some of the tight spots toward the back if your going full length. Full radius bends and an X or H pipe will help with power. This is the set we welded up out of 409 stainles for Evan's 67 Gal. Mike

where did you get the bends? if you have any details about how many of each type bend it took that info would be much appreciated. I have a '65 galaxie that I am thinking of making my own exhaust for and it has pretty much the same frame, etc.

http://www.supermotors.net/vehicles/registry/9026

I used mandrel bent U bends and sectioned them to fit my needs. If memory serves the last ones I bought were from Dyno Max on line. I believe I used four of them on that build. The first time I bought them I got them through NAPA. Mike