How much HP is a single 3'' exaust good for?

markislive78 · 01-11-2005, 12:55 PM

Hey Guys,

Anyone know how many horses a single 3'' is good for? According to Horsepower TV a single 3'' can flow about as much as (2)2.25'' pipes. Anyone know what the cap is on that....i mean if i have a supercharger on my titan @ approx 475-490 horse will a single 3'' be sufficient?

GETSOMZ28 · 01-11-2005, 01:29 PM

Yes, 3" is more than enough for those power levels.

HavockWK · 01-11-2005, 01:58 PM

Flowmaster recommends bigger: http://www.flowmastermufflers.com/cg...r/muffsys.html

Magnaflow says 3" - 4":http://www.magnaflow.com/07techtips/faq/question10.asp

And if I remember correctly, to get the same volume as a dual 2.5" pipes, you would have to go with a 3.5" single. This is of course based on the actual calculation for the volume of the pipe. Part of the reason why they say you can still run dual 2.5"s but you need a 3.5" - 4" single for the kind of numbers you are shooting for.

markislive78 · 01-11-2005, 02:04 PM

Quote:

Originally Posted by HavockWK

Flowmaster recommends bigger: http://www.flowmastermufflers.com/cg...r/muffsys.html

Magnaflow says 3" - 4":http://www.magnaflow.com/07techtips/faq/question10.asp

And if I remember correctly, to get the same volume as a dual 2.5" pipes, you would have to go with a 3.5" single. This is of course based on the actual calculation for the volume of the pipe. Part of the reason why they say you can still run dual 2.5"s but you need a 3.5" - 4" single for the kind of numbers you are shooting for.

So what i am gathering from those links is that dual 3 inchers would not be over kill. Shoot i wish i would have thought about this before spending all of that money on my banks...

**gr8titan** · 01-11-2005, 06:36 PM

This info may help on exhaust pipe sizes. www.bobsmuffler.com/sugpipe.htm
Hope this helps a bit PEACE

RockyMtnTitan · 01-11-2005, 08:32 PM

I've got a pretty good book on superchargers by Corky Bell. He basically says to design your system for minimal backpressure. He recommends only 1 psi, which is impossible w/ cats, etc. So realistically he recommends that you shoot for less than 5 psi total back pressure, as measured before your cats at full boost, WOT and redline rpm's. I have another book by Dave Vizard that concurs with this. I don't want to start the whole "must have BP for low torque" debate, but it is true that minimal BP is best for making more power, but ONLY if your fuel system can keep you in the proper a/f ratio range across the board at WOT, say 12.5-13:1. Tough to say if these modern ECM controlled injection systems like ours could keep up or not. SC kits will probably include upsized injectors, anyway.

I've been thinking for a while now about checking my BP after my cats at the y-pipe to see what kind of pressure I'm running there. Wouldn't give me total BP, but I have to leave the cats in anyway, so I'm not worried about it right now. Then I was thinking about adding a couple other taps downstream to check press drop across my reso and muffler just for grins, since this is an area I can have some control over.

Your cats are gonna be the most restrictive component anyway, so I doubt you'd gain much by going larger than single 3", dual 2.25" pipe. Maybe with headers and no cats!

I would just keep the Banks until you get the SC, and then measure your BP and see where you're at....may surprise ya.

Corky states in his book that you gain between 1.25- 1.5% hp for every 1 psi reduction it BP. He is the Master.....I am not worthy! Good Luck.

TexasTitan04 · 01-11-2005, 08:50 PM

I agree, a 3" will more than do.....just ask the guys at turbobuick.com they'll tell you the same, as I'm sure that Jay Carter on this board will too.

John C.

FLA-Titan · 01-12-2005, 12:05 PM

Here is an article by Sport Truck on installing a Gibson Single. It was good for 12 HP/ 13 LB-FT gain.

http://www.gibsonperformance.com/pdf...port_Truck.pdf

Turbodog · 01-17-2005, 09:09 PM

I will say from people's experience in 300ZXs, having 3" "test pipes" as opposed to 2.5" test pipes provided little or no extra powere, however there was quite a bit more interior noise with the 3" pipes. More resonance. I personally run a dual 2.5" system on my Z and it's great. I'm going to do the same with the Titan when the time comes.