Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (http://www.hotrodders.com/forum/)
-   Hotrodding Basics (http://www.hotrodders.com/forum/hotrodding-basics/)
-   -   what size exhaust is rite ? (http://www.hotrodders.com/forum/what-size-exhaust-rite-229899.html)

macrobert68 02-23-2013 09:33 AM

what size exhaust is rite ?
 
Hello everyone .My 406 has a 3000-6800 Rough idle, upper mid-range & top end power cam
10.3 compression flat top pistons
duel welind tunnel ram with 450s
Header Style:Full-length

Header Material:Steel

Header Finish:Silver ceramic coated

Weld-Up:No

Primary Tube Diameter (in):1 5/8 in.

Collector Attachment:3-bolt flange

Collector Diameter:3.000 in.

and im looking a
pypes Stainless steel

Intermediate Pipe Diameter (in):3.000 in.

Tailpipe Diameter (in):3.000 in. Pypes Street Pro Exhaust Systems SGG13S
Is this to big and will it rob power at low speed? :confused:

DanielC 02-23-2013 09:54 AM

You are going to get a lot of theory, and ideas on this, and some of the advise may actually be true.
But with so much misinfornation existing, and being reproduced by people on the web, the only way to know is to spend lots on time on a chassis dyno, with different exhaust configurations.

macrobert68 02-23-2013 09:58 AM

Quote:

Originally Posted by DanielC (Post 1649625)
You are going to get a lot of theory, and ideas on this, and some of the advise may actually be true.
But with so much misinfornation existing, and being reproduced by people on the web, the only way to know is to spend lots on time on a chassis dyno, with different exhaust configurations.

yea i can understand that .
but i cant remember if the larger the exhaust is for top end speed or low end tork.

OneMoreTime 02-23-2013 10:49 AM

For your setup I would go with the 3 inch..I don't think you would lose that much on low end and your engine setup is for midrange and top end power..

Sam

Mr. P-Body 02-23-2013 03:21 PM

Yes, there will be a loss of low-end torque with a larger system (this engine doesn't appear to make much low-end, though). We tend to recommend, for maximum performance, and not necessarily the "sound", stay with 2 1/2" pipe until CID gets up around 500.

Particularly with smaller headers like you have, you need that "step" in the pipe to increase exit velocity. For "driving" (street use), this is important. If it's a dedicated race car that requires an exhaust system, then yes, 3".

BTW, those headers are awefully small for a 7,000 RPM 400. Just my opinion. I'd like to see 1 7/8" units on there. Upper end power would significantly increase. Regardless, this car will need some "stiff" gear to be a decent driver. What heads are they?

Jim

macrobert68 02-23-2013 03:38 PM

dart shp 72 cc

macrobert68 02-23-2013 03:43 PM

Quote:

Originally Posted by macrobert68 (Post 1649773)
dart shp 72 cc

what kind of gear would u use .i was thinking 373 0r 410:cool:

gearheadslife 02-23-2013 03:59 PM

2.5" mandrel bent pipe with x pipe..
from the x junction you have 5" for thet pulse to feed to.. more than anough for a 406

Mr. P-Body 02-23-2013 04:40 PM

Bert, what car? Approximate weight? Trans/converter? More 1/4 mile or 1/8 mile? Significant street driving?

Then I can answer that. As much "detail" as you're willing to share. What style rear axle?

X 2 on the "X" pipe. A lot of our Pontiac guys use Pypes. I've heard good and bad. The X-pipe definitely makes power, though.

Jim

vinniekq2 02-23-2013 07:33 PM

Have you ever seen a race car with mufflers go faster than a similar car with open headers? 3 inch!
also if your engine revs 6500 rpm,your headers are also too small

vinniekq2 02-23-2013 07:37 PM

The rear axle ratio needs to match the purpose of the car. I use a 3.50 gear with 27 1/2 tall tires with a standard. floor it in first or second and the tires break loose.


All times are GMT -6. The time now is 06:42 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.