This is topic 393w exhaust 2.5 or 3"? in forum Tech Talk at Northern California Ford Owners  .


To visit this topic, use this URL:
https://californiafords.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=6;t=028242
Posted by 4MY8TERS (Member # 7840) on :
 
I know 3" would be best since I'm going blown, but how about the clearance issues over the rear end?
 
Posted by racsirx (Member # 1710) on :
 
Yes 3" would the best, I got my 3" catback from Flowmaster
 
Posted by Secnd2nun64 (Member # 1431) on :
 
2.5 will be fine if that's what you already got. I wouldn't go out and buy new exhaust to just to go to 3", not worth the investment.
 
Posted by racsirx (Member # 1710) on :
 
quote:
Originally posted by Secnd2nun64:
2.5 will be fine if that's what you already got. I wouldn't go out and buy new exhaust to just to go to 3", not worth the investment.
A blown 393 needs to breathe, 2.5" will hold it back.
 
Posted by Secnd2nun64 (Member # 1431) on :
 
quote:
Originally posted by racsirx:
quote:
Originally posted by Secnd2nun64:
2.5 will be fine if that's what you already got. I wouldn't go out and buy new exhaust to just to go to 3", not worth the investment.
A blown 393 needs to breathe, 2.5" will hold it back.
Not saying that it wouldn't. I'm saying the gain is not worth the investment if you already have 2.5 pipes. The 2.5 can handle 500hp. Going to 3" may pick up 15-20 hp. It really depends on if the builder is looking to get every little bit out of the combo, but if so why not do a 427w?
 
Posted by racsirx (Member # 1710) on :
 
I have seen bigger gains with a 302 HCI with a S-trim when switching over to 3"
 
Posted by turbo50 (Member # 6700) on :
 
We seen gains on the naturally aspirated 393 when going back to smaller header 1 5/8 and 3 inch exhaust versus larger 1 3/4 header and 3 inch exhaust. Never got to test it with 2.5 but maybe the new owner will.
 
Posted by Boss 327 (Member # 9143) on :
 
quote:
Originally posted by turbo50:
We seen gains on the naturally aspirated 393 when going back to smaller header 1 5/8 and 3 inch exhaust versus larger 1 3/4 header and 3 inch exhaust. Never got to test it with 2.5 but maybe the new owner will.
Why do you think that is?
 
Posted by Notch1320 (Member # 2647) on :
 
The header is key on a max effort deal. There is a reason good headers cost so much! Finding the right stepped header/ collector combo for my car made some good gains. I would go 3" on your car though for the exhaust.
 
Posted by warhorse58gt (Member # 7702) on :
 
Go 3" I have went 9.76 on shorties and 2 1/2 exhaust. I added 135lbs, when I added the long tubes & 3" exhaust. Car still picked up a full .10 and 2 mph. So it was worth at least .2 & 2mph with the extra weight. To me that is worth the money to do.
 
Posted by Secnd2nun64 (Member # 1431) on :
 
quote:
Originally posted by warhorse58gt:
Go 3" I have went 9.76 on shorties and 2 1/2 exhaust. I added 135lbs, when I added the long tubes & 3" exhaust. Car still picked up a full .10 and 2 mph. So it was worth at least .2 & 2mph with the extra weight. To me that is worth the money to do.
Did you change mufflers too? I asked a lot of people and researched when I had my exhaust redone for my 393w and was told to keep the 2.5. Got me wondering if I should change mine out now. lol
 
Posted by racsirx (Member # 1710) on :
 
I can't remember exact numbers but Forced331 saw a difference

http://californiafords.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=052358
 
Posted by warhorse58gt (Member # 7702) on :
 
quote:
Originally posted by Secnd2nun64:
quote:
Originally posted by warhorse58gt:
Go 3" I have went 9.76 on shorties and 2 1/2 exhaust. I added 135lbs, when I added the long tubes & 3" exhaust. Car still picked up a full .10 and 2 mph. So it was worth at least .2 & 2mph with the extra weight. To me that is worth the money to do.
Did you change mufflers too? I asked a lot of people and researched when I had my exhaust redone for my 393w and was told to keep the 2.5. Got me wondering if I should change mine out now. lol
I had the shorties then a x-pipe, with 12" race bullets. With the long tubes I have 1 7/8 kooks header with a 3" collector to x-pipe, Then in to borla xs 2 mufflers. I got them dumped after the mufflers. I would like to have it all the way out to the back of the car. But I ave a weld in sway bar, that keeps me for being able to do that. [Frown]

[ 2013-07-18, 09:34 PM: Message edited by: warhorse58gt ]
 




Fueled by Ford Mustang Owners
on CaliforniaFords.com