which 3'' exhaust do i want?

-
1

11.2

Well-Known Member
Joined
May 31, 2007
Messages
354
Reaction score
10
i have a 75 dart sport and will be installing a set of tti's this winter. i also want 3'' x pipe with cutouts, looking at my exsisting 2.5 i'm going to say that 3'' will be as tighter then a bulls *** in bug season.
who makes the best fitting system with tailpipes?
 
11.2 said:
.... tighter then a bulls *** in bug season.
Click to expand...


And I thought tighter than a crab's *** was a funny one! (BTW: It's so tight, it's WATER tight)

I haven't installed mine yet, but TTI is universally acknowledged as being the only QUALITY exhaust systems for our cars. I hear that scattersheilds touch, and sometimes the valve covers come close to pipes, but they are beautifully made. Oh, and BTW: Unless your making some stupid horsepower, the 3" system might actually HURT your performance. I went with the 2.5" X pipe system myself.

But man-o-man, they ARE sexy!
 
ive had this ''to big of exhaust'' discusion before and don't get it. the first thing everyone does at the track is run open headers ''less restriction/ backpressure]. nobody has came up with a good enough theory to convince me, maybe i'll get some enlightenment here since there is alot of experiance on these forums.
 
11.2 said:
Ive had this ''to big of exhaust'' discussion before and don't get it. the first thing everyone does at the track is run open headers ''less restriction/ back pressure]. nobody has came up with a good enough theory to convince me, maybe i'll get some enlightenment here since there is a lot of experience on these forums.
Click to expand...

I had a hard time with it too. Everyone thinks bigger MUST be better. The way you can over-carb an engine, you can have too little back pressure too. That's why professional engine builders tune an engine to primary tube length and diameter. There's some science involved relating to creating pressure pulses and scavenging. All I know is it's going to hurt performance unless your moving a HUGE amount of air through the engine going with 3".

I came *THIS CLOSE* to putting a 3" system in my car, but was told that with my cam, compression, heads, carbs... I'd be better off with 2.5".

Hope this helps.
 
You do have to make a lot of hp (500+) to warrant a 3" system. Most exhaust systems are stepped down throughout the system in order to keep the exhaust gases hot and moving. Cool exhaust gas will not flow as well and without some back pressure will affect your low end torque. If you`re running open headers, you`re probably racing and should tune your engine accordingly. With open headers the idea is to get rid of the exhaust gas as fast as you can because you`re running nothing but wide open throttle. In a street application you`ll want to maintain a high exhaust gas temperature so the system will flow. If you make a lot of hp and need the 3" system ,then go for it, but try to maintain high exhaust temperature by stepping down the pipe at the muffler to a 2.5 or use another method to create back pressure and thus higher exhaust gas temperatures.
 
i'm not convinced. i ran a 68 firebird several years ago, jetted to 2.5 exhaust and a buddy convinced me to open up the headers, after some rejetting, times went up by 3 tenths and 1 tenth of it was in the 60ft mark with stock stall.
 
I would have to say what ever size you decide on, TTI makes the best system, but it's pricey. JEGS offers an in-expensive system that's been said to fit well. Which ever brand you go with, the 3" will be a tight fit, but it can be done.

I'd go with TTI.
 
i had the locak exhaust shop do my 3" exhaust on my dart....


my car runs just as fast through the 3" X-Pipe exhaustas it oes open headders... run the 3" you'll be fine.
 
It's not a theory it is fact that to large an exhaust system can lower torgue and HP except in a forced induction setup, then there is no such thing as too large an exhaust system. A N/A motor uses heat and exhaust tubing size to help scavange the cylinders. For example I am using 2" primary tube headers on my Valiant and I know I am loosing some low rpm torgue and should use a smaller tube header because they are too large but I got a great deal on then so I used them. They would be fine if my car was lighter or had more gear but never the less with the package I have they are two large.

Your example about the Firechicken means nothing, that was a complete different package than you are talking about now and different packages respond differently with different changes. Your Dart may actually run better with a bigger exhaust system but just because it is bigger doesn't automatically mean it will run better. I have a buddy with a '70 Chevelle 396 and he used to run it uncorked. After some test and tune sessions it turned out that the car would ET better with the exhaust corked. It would 60' better which translated in a quicker ET. His MPH did not change which meant he really didn't loose any HP but did gain torque because it ran a better ET. I not saying don't put on the larger exhaust I am saying it is very possible that you can receive no gain in power and can actually loose power depending on the package you have.


Chuck
 
i definately agree with the header size affecting low end torque thats a given, but usually don't you gain that at the top ?

by the way guys, not that i don't want to get to the bottom of this, but the original question was who makes the best fitting kit.
 
sorry about that fastback, i guess the train fell of the track for a little bit.

is there anyone here with the jegs setup?
 
11.2 said:
i definately agree with the header size affecting low end torque thats a given, but usually don't you gain that at the top ?

by the way guys, not that i don't want to get to the bottom of this, but the original question was who makes the best fitting kit.
Click to expand...


And in killing 2 birds with one stone....heres the throw....

I have a 2-1/2 jegs/sumitt system. Well fitting and easy to assemble. A most minor issue was 1 pipe didn't want to slip into the next pipe. A tool I have from Lesile, a pipe expander. Easy fix. Though if I didn't nimd starting up the car to heat the pipe up and expand it that way and shove in a cold pipe. Once there together though, that's it.

I may not have killed the first bird, but thats my testimoney.
Richoet to the next bird.

Though you should gain top end power, this is often seen at the dyno. Actual track runs can show this as well. But when is it too big?

Exhaust will travel fastest when hot. It will travel faster in a small pipe that has no pressure. If the bigger pipe has a reduction in heat, a bennifit still may be seen through volume. Which is the catch 22 of exhaust.
There are pressure meters for exhaust pipe.

Header size can be scienced out. Tube Diameter and length are a changing item for what the need is.

On a street car, a general size for given horse power is made by the companys and they cn suggest a exhaust pipe size for a given HP. That size can change for driving the streets or track use.

Flowmaster has a chart for pipe size for given HP in both dual and single pipe.

(Hummmm, I think that might have been a second richoet)
 
http://www.headersbyed.com/

a good website for header information. i started out with this guy
in the early 70's....1 5/8 headers low/mid 13's on a stock 340 (which
was pretty good back then).

his discusion and header info still works 40 years later, check it out..
----bigger is not always better---
 
11.2 said:
i definately agree with the header size affecting low end torque thats a given, but usually don't you gain that at the top ?

by the way guys, not that i don't want to get to the bottom of this, but the original question was who makes the best fitting kit.
Click to expand...


Your absolutely right you asked who made the best setup.


Chuck
 
i got on flowmasters sight and one thing they mention to do is when going to an exhaust with less backpressure is to reduce the valve overlap.
 
i resently bought a 2 1/2" system from Jegs.
it is an all mandrel bent system and came with Imco turbo mufflers.
the bends are smooth with no kinks and heavy guage pipe.
this is a dual exhaust- no x pipe or balance pipe.
the part # is 555 30500.
it came with all clamps and hardware, header reducers.
i can't speak to the fit as i haven't installed it yet.
the total price was $202.81.
hope this helps.
 
I can't remember where or when I seen this, but I believe that there is a company that makes 3" mandrel bent systems that are oval tube instead of round for better clearance. Like I said I cant remember who has it or where I seen it, but I did see it somewhere.

May be this would help you with the tight fit problem.
 
now that you mention it, a buddy of mine was saying he saw this a while back. if anybody knows of this, a name would be greatly appreciated.
 
For reference, I added a 3" TTI X-pipe and Dynomax Ultraflo mufflers to my TTI 1 5/8"-1 3/4" step headers about 1 1/2 years ago. The exhaust ends with the mufflers just in front of the rear end housing and everythiong is coated inside & out. All indications are that it helped, especially after added tuning and removing the 60lbs that it added from elsewhere in the car to get the car back to it's original weight. It wouldn't have stayed on if I didn't think it helped. I believe the X-pipe helps scavanging/velocity. (no cut-outs)

My combo isn't very radical, but it's race-only:

* 360/904 w/2.71 low gear
* Converter flash to 5000+
* Stock heads with 1.88" intake/1.60" exhaust
* .474" lift cam (lots of duration)
* About 10.5-1 compression
* 750 Holley on a dual plane but will experiment with a single plane again soon
* 4.86 gears with 29.5" x 9" Hoosier radial slicks
* 3,530 lbs + or 3,690 lbs + depending on class
* Mid-high 11's in the 1/4 mile.

For a dual-purpose combo, it's usually better to stay a little on the conservative side - exhaust, cam, carb, compression, etc.
 
You must log in or register to reply here.
-

Back
Top