Avice please, the physics and and exhaust system

vipergts · Post by **vipergts** » Wed Dec 24, 08 1:03 pm

I would appear that a 2.5" system is goona be 2 months away but a 3" no problem.

I have hookers with 3" collectors.

I'm told that I would need at least 550 horses to be able to run the 3" system effectively.

What is the issue here....is it the lack of back pressure that a 3" system would create?

Any views + or -

Many thanks
By the way it's six pack I'm talking too who are very helpful

MilesnMiles · Post by **MilesnMiles** » Wed Dec 24, 08 1:09 pm

can't help with the physics, but I have the TTI 2.5" system. Excellent kit, but gives a lot of reasonance at around 2-2,500rpm. I imagine that this would be much amplified by the 3" version from what i have read.

A two month wait isn't so bad in deep winter if you really want 2.5"

Ivor · Post by **Ivor** » Wed Dec 24, 08 1:15 pm

I had a full three inch system on my Road Runner Paul and that was making nowhere near 550 horse power!

It went well though, drove nicely and sounded great...that was a mild steel set up with Warlock silencers.

Anonymous · Post by **Anonymous** » Wed Dec 24, 08 1:42 pm

Have a read of this debate on a Chevy forum. The guy wants to know the same, 2 1/2 or 3 inch which is better.

Lots of feed back but the last one made me smile

http://www.chevelles.com/forums/archive ... 77807.html

.

MrNorm · Post by **MrNorm** » Wed Dec 24, 08 1:44 pm

I agree with whoever advised you - 3" is not necessary, or beneficial for you at lower power. I should have about 450 and 2.5" is right for me, Bigger is not always better, the key is matching everything. Sure you could fit one and it would work fine, and sound nice (loud). Also, we are not talking major differences here. If timing or sound is a priority then get the 3", if you want to optimise then I would go with the 2.5".

AllKiller · Post by **AllKiller** » Wed Dec 24, 08 1:55 pm

Go to Pipecraft in Essex...get it done in 2.5 inch and exactly how you want it

http://homepage.ntlworld.com/susan.insole/Info.htm

vipergts · Post by **vipergts** » Wed Dec 24, 08 3:49 pm

33 Plymouth wrote:Have a read of this debate on a Chevy forum. The guy wants to know the same, 2 1/2 or 3 inch which is better.

Lots of feed back but the last one made me smile

http://www.chevelles.com/forums/archive ... 77807.html

.

Thanks Guys............The last comment is just perfect

You'd have thought it a simple enough question.

3" loses power but sounds better? Is that correct?

Do you happen to know whether Pipecraft will go out off site. The cra is at JCP and ideally I need this system sooner rather than later.

Anonymous · Post by **Anonymous** » Wed Dec 24, 08 4:00 pm

If you run the motor down the track using headers only you may pick up some if the 2 1/2" ex system is restricted , you won't lose any power with bigger exhausts , unless the boxes are restricted , which is unlikely on a 3" system , the power is made depending on the header set up , if the header primaries/colectors are not right the motor will suffer.

Tis all in the headers , H and X systems won't gain enough to set the world on fire.

vipergts · Post by **vipergts** » Wed Dec 24, 08 5:51 pm

Does a standard system have 2 or 4 silencers?

Giv en all the comments on here I wonder why Six Pack are advising me against the 3"?

My Headers should be good and Hookers are a well known and good brand.

Dave-R · Post by **Dave-R** » Wed Dec 24, 08 6:31 pm

I was always told (by people that were actually testing this sort of thing in the 80s) that the best way to maintain exhaust gas speed (and therefore cylinder scavenging) is to reduce the pipe diameter as it travels the length of the car.

Now, I have brought this up before and got all sorts of comments about pressure pulses at the speed of sound, how can the gas be moving slower at one end of the pipe compared to the other etc etc.

But as gas cools it looses pressure and also slows down. On a system that is the same diameter all the way through the pressure and speed of the gas out of the tailpipe is less than it is at the headers.

So I was always told that on cars like ours you should start at 2.5 or 3-inches to the mufflers and then reduce by a half inch from the muffler to the tailpipe.

Having said that. I have also heard it makes bugger-all difference if using headers and that a reduction in system resistance is the best way. The diameter of the pipe needs to be big enough to not add any back pressure to the header collector.

Personally. I suspect (and might have picked up somewhere in the dim past) that some small amount of back pressure is better for low rpm torque. But less back pressure is better for high rpm HP.

At the end of the day you want a system that is not annoyingly loud to drive. So that people don't look at you and think you are a prat.

I feel like a prat most of the time anyway so it is a 3" system all the way on my 440.

MilesnMiles · Post by **MilesnMiles** » Wed Dec 24, 08 10:00 pm

Dave, i've read similar about the latter part of the exhaust being slightly smaller in diameter.
As for mufflers, two is sufficient.

Anonymous · Post by **Anonymous** » Wed Dec 24, 08 10:09 pm

Hey , if in doubt fit a larger ex system , will not hurt performance in the slightest.

AllKiller · Post by **AllKiller** » Wed Dec 24, 08 10:24 pm

No mate Pipecraft only work from there shop

mopar_mark · Post by **mopar_mark** » Wed Dec 24, 08 10:54 pm

My opinion, for whats it worth....

I don't think it will make bugger all difference on a typical street installation if you went for a 3" Dia v 2 1/2" Dia.

If you were looking for 10ths @ the track, then maybe, but thats another story.

Every day driving, I would put money on it, you would not notice any "seat in the pants" difference between either dia's