hotside dump tube how much power

[RNR_MOTORS]

how much horsepower do u get by adding the hotside dump tube also what are the pros and cons

also do i need to retune after adding a dump tube and a co2 ring?? i need to know thanxs everyone

 

[andy4g63]

Just to mention:
3" exhaust is kind of rated around 500 HP. Over here almost anyone runs 3", BUT MOST OF THE CARS ARE BELOW THAT LEVEL and have to be some what street legal...

 

[91stocker]

no i believe your info is incorrect andy

okay, I found the article by David Vizard, and it was actually in Super Chevy magazine. It's a long article, so I'll supply you with his exhaust math below:

according to Mr. Vizard (who's theories I happen to value) you need to flow 2.2 CFM (cubic feet per minute) of exhaust per 1 HP. Therefore you first need to know what your flywheel HP is, and multiply it by 2.2

So for an example if your engine produces 500 HP at the crankshaft, then that's 500x2.2=1,100CFM. Now remember that because you're using dual exhaust and therefore will have two exhaust pipes (left and right) then you need to divide this total CFM figure by2. So that's 1,100 CFM cut in half.... or 1,100 divided by 2=550 CFM. So you'll need an exhaust pipe diameter that will flow 550 CFM. with that in mind here are the pipe diameters and their flow rates (according to Mr. Vizard)...

2.5" diameter=560CFM

3" diameter=672CFM

3.5" diameter=784CFM

4" diameter=896CFM

so just do the math above using your engine's HP and you'll be able to determine how big of an exhaust pipe diameter you'll need. I hope this helps you.

or

In general 1 inch Hg backpressure = 1 HP lost

For reference, we have the following conversions factors:

1 ATM = 14.7 PSI = 76 cm of Hg = 29.921 inches of Hg = 1.013 bar


So do a little more math and and it wouldn't be too far off to say that a 500 hp engine could see as much as 20% power loss from a single 3" exhaust.

 

[mindset]

Seems to be that's for a v8 only.

On a I4 running 350hp @ the flywheel.

350 x 2.2 = 770 cfms

Divided by 1, for one straight exhaust to get the original 770 cfms.

This results in a 3.5" exhaust? I always thought the only negative thing to running a 3" at a lower HP on our cars results in boost creep.

 

[91stocker]

Well yea thats what i mean, 350hp seems to be when a single 3" exhaust starts to choke out, the guy with the shiny engine is another talking out his arse.

 

[habitatguy187]

Thanks for the info 91stocker!


I really do believe there is more to be had even for a lot of 16g setups in running a 3.5" exhaust, but since no one makes one for our cars, we all just assume that 3" is all that's needed.

 

[RNR_MOTORS]

And, yes, this is a forum that is meant to help people... so why is it that you told me the other day that I need to "go do some reading"? Lol... cracked me up man. I think if someone asks a question it should ALWAYS get an answer whether it's been asked before and documented or not. You will catch a lot more kudos helping someone out rather than sending them off on the witch hunt for search results.

thanks for typing this FACTORY CHROME
im getting sick of the ones who already know what some people are trying to learn and act like its common sense

for those with that attitude WHY WOULD JOIN A FORUM in the first place


also i finished the dump tube upgrade really doesnt feel like more power sounds normal at ) lbs of boost so for the ones who drive normal u cant even hear until u hit boost levels sounds really good and looks good under the hood so dump tube get my vote

 

[JusMX141]

I really do believe there is more to be had even for a lot of 16g setups in running a 3.5" exhaust....

Yeah, like INSANE BOOST CREEP.


We have enough threads from guys having creep issues with 3"...could you imagine 3.5"?

 

[habitatguy187]

, peepers mod?

 

[JusMX141]

^ ^

That concept was abandoned after this happened:

http://www.dsmtuners.com/forums/blogs/mr-peepers/455-boost-creep.html