Interesting 2.5 inch Exhaust Review

[srad2drag]

As usual I'm thinking of ways to get more hp out of my Escort.
I usually surf to the jbody.org website since I used to own a 99 Z24.
Pretty good car dynoed out at 142.hp with a Aem intake Pacesetter headers and catback, underdrive pulleys.

But anyway I was considering going to a 2.5 inch exhaust. After reading this article I am definitley going to try to get one.

This test was done on a Z24. I know its a 2.4 liter but it still a 4 cylinder engine and the results should be similar to any other comparable vehicle.

http://www.i-performance.biz/dyno/exhaust01.html

[TitaniumGT]

even though its also a 4 cylinder engine, you still need to consider displacment. youre talking about over half a liter of engine size.

thats like saying a 305 v8 needs the same exhaust as a 350cid v8.. which isnt true. more air in, more air out.

i really like 2.25" on a modded 1.8 BP. maybe because you have the gude head package you may see a benefit from the 2.5"/

[95ProLeila]

IMO 2.5 is too big unless you're boosting, you'll kill your exhaust velocity and loose low end.

edit: and if anybody dare say "you need backpressure" you will be smacked

[BuGS]

Um I would go with 2" because you need backpressure... oh wait .

There was a guy with an MX-3 running 2.5" for awhile. He was planning on boosting but decided to go all motor so he switched to 2.25" to get better performance. THat extra 1/4 is just too much for the low end. It did help on the top end thou so I guess it matters on how you want to do stuff...

[srad2drag]

Yet again, our testing has shown that 2 1/2 inch is the proper size for any naturally aspirated four cylinder engines and 2 1/4 inch is too small.
*We have demonstrated once more, that there is no loss of mid or low range torque or horsepower when comparing 2 1/4 inch exhaust systems to 2 1/2 inch exhaust systems

I agree with this to a certain point. I mean I wouldn't go out and put a exhaust this size on a 1.5 or 1.6 motor.But in a 1.8 DOHC motor I think the pros out weigh the cons.

I think Gen1Gt has a 2.5 inch exhaust on his car and his motor isn't too far from stock(cams and sprockets) and he still has the stock exhaust manifold.
He is putting out 125 hp so I think the exhaust has definitely helped him out.

[95ProLeila]

^that's nice^ I disagree. The bottom line is you need to put up some sheets to back up your statement. Josh is going for top end, for the drag strip. I don't even think he drives his racer on the street now that he has his second car. The 125 whp came from massive amounts of tuning, not just mods.

[srad2drag]

For the record tuning and modding go hand in hand.Most people know when you add performance enhancing parts to their vehicle they are not going to reap the benefits until the part or parts are properly tuned.

I used Gen1 as a reference because he is the only one I've seen using a 2.5 inch exhaust to his benefit. Also I was going by the list of mods in his signature,I do not know every intricate detail of his engine or his life story such as you.


Just stating some information that I came across.......
As soon as I find a manufacture who can make a 2.5 mandrel bend exhaust. I will post a dyno sheet of the before and after of the "MOD" with tuning also.