Exhaust Setup for Torque...
 

While I've known for quite some time that larger diameter exhaust helps out more in the upper rpm range due to higher exhaust volume, and smaller diameter exahust is better for low end power due to increased exhaust velocity, I wasn't exactly sure how true dual exhaust compared to the stock, single exhaust setup. I figured that true duals would be superior in every way to a single exhaust setup (except cost). However, I was talking to someone who owns an '03 SD PSD and he told me that single exhaust is better for low end torque-- that's why the diesels come stock with single exhaust. He went on to say that true duals is for top end power, as are long tube headers and that if I want to maximize my low end power, I should stick with my shorty headers. This is contrary to what I've heard. I was just curious if anyone has any comments or experience with both exhaust setups and would like to offer their insight. It would be much appreciated since I really want to increase my off-idle power and since I do most of my driving in the 1500-3000 rpm range, it would make sense to build up power in that range as opposed to the over 4000 range. Thanks!

Like most Diesels, that guy was blowing smoke.

In general, the longer the header tubes, the lower the RPM for which they are maximized. Shorties do not have any tunung effect per se, but they do give very similar peak HP numbers to long tubes since peak HP occurs at revs where the long tubes generally are not optimized.

There are some differences between single and dual exhausts in terms of RPM range, etc. But on a V engine you always want duals since it is nearly impossible to make both sides equal length if they're feeding into a single. With a V-8 you need an H or X pipe to balance the uneven exhaust pulses, with a V-6 it's unnecessary. If you want to know about single vs. dual on an inline, I'll have to get back to you with an answer after I do some re-reading.

TF I can tell you what I know. When I added my long tubes...my 60' times dropped from mid 2.3s to low 2.2s. And in the 1/4 about a 2mph gain. SO I'd say they give more low end. Diesels come with single exhaust because they run 1 turbo so it has 1 exhaust poer there going duals after the downpipe would do nothing. I went with Dynomax ceramic coated long tubes, magnaflow x-pipe and dual magnaflow mufflers all 2.25" piping and I would never want anythign else.

For torque i would choose small tube headers. Duel exhaust is fine just make sure you don't go too big with the pipes. I think 2.5" would work good for a duel setup on a small block.

-Jon

Thanks guys. This all makes much more sense than what that guy was saying. :thumbsup:

1.5" primary tubes on full length headers. Hookers (what I have), Dynomax, etc. 2.5" collectors.

351W? Go with 2.5" pipes to a single 3"

302? Go with 2.25"pipes to a single 3"

I have 2.5" pipes to a 3" as I wanted a bit more top end pull with my lil 302.

Hope that helps. :)

Thanks. I'll see what the smog refs will let me get away with. But I will definitely keep this in mind.