4" or 5"?

[Darel]

How much of a difference will a good exhaust make in my average EGTs and fuel economy? Will a 5" make much more of a difference for the added cost?

Darel

 

[Cooker]

Unless you were way up there in HP (500 Horse?) I wouldn't imagine there to be any performance benefits of the 5" over the 4"



JMHO,

Ryan

 

[cumminsgetme]

I didn't see much of a difference going from 3" to 5" (I went to 5" around the 420hp mark). I like the sound of my 5" better and it may have helped egt's a little, but not enough to be excited. You may want to consider building your own exhaust system. I was able to build my 5" system for about $150.

-Cord

 

[John_P]

Darel:



I noticed about a 75 degree drop in my EGT temps AFTER

installing my 4" exhaust system. The most noticeable

thing on my truck was that the temperatures did not

climb as fast on my truck under hard acceleration.

The truck also idles better and seems to cool down

faster under all conditions.



As "Cooker" said, I don't think a 5" would make much

difference unless you are WAY UP in the H. P. dept.

Joe Donnelly did alot of research on the aftermarket

exhaust systems and found that they don't add much

H. P. either. But like you, I need all the help I can get

on EGT's!!



--------

John_P

 

[Mark_Kendrick]

A 5" dump infront of the rear wheels would look way



I was talking to KwikKurt yesterday and he seemed to think the way to go would be to run 4" back to the muffler then 3 after.



Says it scavenges better and the velocity up. the gasses cool as they get back there so there's less need for big pipe at the back. I've seen it done on hot rods w/good sucess.

 

[Joseph Donnelly]

Sickly runs 4".

Lowering egt's: (in order of escalating cost or when in the sequence to do the upgrade)

16 cm2 housing on HX35

low restriction muffler (make sure cat is not plugged too) on 3"

HX40/4" exhaust

ported head, ATS manifold

custom camshaft developed by DD and me

bigger turbo like H2E or HX55 (before or after cam)



with the above, you can add about 200 hp over just the 16 housing and keep the egts down the same amount. For example, the #10 plate/16 housing gives 1300-1500 deg with low restriction 3" exhaust. Doing all the above allows 565 hp with about 1400 deg. egt.