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Lots of threads about custom exhaust on a 2.8 & 3800, anyone changed a 2.5's sound? by 2.5
Started on: 09-17-2014 04:09 PM
Replies: 7 (213 views)
Last post by: dobey on 09-18-2014 10:57 AM
2.5
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Report this Post09-17-2014 04:09 PM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
The factory duke exhaust made it pretty quiet. Anyone run a custom system with a Spintech or something on it? Maybe larger pipe for lower tone, tried different mufflers..etc?
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Report this Post09-17-2014 04:50 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post

I put a GT exhaust on my '84 duke a few years ago. Definitely improved and changed the note of the exhaust, although it still doesn't make a low revving 4-banger sound like anything other than a low revving 4-banger.

This is what it sounds like on the track (although I'm now autocrossing my '88 Formula).

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Report this Post09-18-2014 06:27 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
I put the 2.8 GT muffler and tips on my 88 4 cyl car. It sounds louder than stock, but its still a 4 cyl...
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Report this Post09-18-2014 08:50 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
You know what would be wild, a header that divides each cylinder into two so you have 8 small header tubes before the collector. If one of the tubes for the same cylinder was longer than the other, could it sound like there were more cylinders or a higher rev because of the time it takes for the exhaust to get thru the longer tube? Could even put them into two collectors and run dual from there back....Or maybe it woud just hum...?
Anybody weld?

[This message has been edited by 2.5 (edited 09-18-2014).]

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Report this Post09-18-2014 09:39 AM Click Here to See the Profile for CsjagClick Here to Email CsjagSend a Private Message to CsjagEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 2.5:

You know what would be wild, a header that divides each cylinder into two so you have 8 small header tubes before the collector. If one of the tubes for the same cylinder was longer than the other, could it sound like there were more cylinders or a higher rev because of the time it takes for the exhaust to get thru the longer tube? Could even put them into two collectors and run dual from there back....Or maybe it woud just hum...?
Anybody weld?

I like that thinking out of the box

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dobey
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Report this Post09-18-2014 10:00 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 2.5:
You know what would be wild, a header that divides each cylinder into two so you have 8 small header tubes before the collector. If one of the tubes for the same cylinder was longer than the other, could it sound like there were more cylinders or a higher rev because of the time it takes for the exhaust to get thru the longer tube? Could even put them into two collectors and run dual from there back....Or maybe it woud just hum...?
Anybody weld?



I don't think you'd get that sort of sound out of it. Rather, you will only hurt the performance (as you're greatly increasing the air volume of the pipe), damage scavenging, and probably just make it quieter.

If you want to do a true dual exhaust on the 2.5, you could do a 4-2 exhaust, and run maybe 1-7/8" or 2" pipe after the primaries for each half. Problem is that you'd then need to run dual cats, and ideally dual O2 sensors, but the ECM only supports the one.

A custom 4-2-1 header into the single cat and a single 2.5" pipe to the muffler, with dual out, like say with the Pacesetter catback exhaust for the GT, would probably sound pretty good, and louder than just the V6 exhaust.
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Report this Post09-18-2014 10:35 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:


I don't think you'd get that sort of sound out of it. Rather, you will only hurt the performance (as you're greatly increasing the air volume of the pipe), damage scavenging, and probably just make it quieter.

If you want to do a true dual exhaust on the 2.5, you could do a 4-2 exhaust, and run maybe 1-7/8" or 2" pipe after the primaries for each half. Problem is that you'd then need to run dual cats, and ideally dual O2 sensors, but the ECM only supports the one.

A custom 4-2-1 header into the single cat and a single 2.5" pipe to the muffler, with dual out, like say with the Pacesetter catback exhaust for the GT, would probably sound pretty good, and louder than just the V6 exhaust.


Well, the header tubes could be half diameter, so it wouldnt increase the volume.
I would think 1 O2 sensor like stock in the collector would work? There is none after the cat so shouldnt matter right?
Thanks for your input too. I'm just brainstorming and hoping someone posts a pic of something odd they have, or found
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Report this Post09-18-2014 10:57 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 2.5:
Well, the header tubes could be half diameter, so it wouldnt increase the volume.
I would think 1 O2 sensor like stock in the collector would work? There is none after the cat so shouldnt matter right?


Well, half diameter is not half surface area (of a flat disc), it's 1/4 of it. It needs to be closer to 2/3 diameter. if you want to split, but it will still screw with performance and scavenging, I think. Running them all back to a single collector on the header wouldn't really gain you anything either. It might make sense to do that on a DOHC head that has each exhaust valve going to its own port rather than merging them into a single port. But on most heads it would just be weird, and have no performance benefits, and probably not do anything useful for sound either.

For the O2 sensor, I was talking about a true dual setup, not a single collector for all the exhaust.
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