2.5" vs 3" exhaust
11-13-2007, 09:52 PM
#1
Three Wheelin'
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2.5" vs 3" exhaust
Hybrid is together finally. Starting the exhuast now. Coming off MSDS headers. ID of collector is about 2.85". Will I really see a huge difference going 3" ID all the way back? Funny thing is the company that I got my 3" X-pipe from sent me a 2.5" by mistake as well. Shipping it back cost more than it's worth to them so I was allowed to keep both.
Cross section of the 2.5" is 19.63sqin vs 28.26sqin for the 3". Obviously the 3" will flow much better, but is it overkill at the cost of torque or power elsewhere on the RPM band? Although I may track the car in the next couple years, for the short term it is my daily rice killer, light to light and some highway driving. Also 3" in/out mufflers are hard to find locally, and usualy bigger as well. With two mufflers to tuck in next to the tranny, I want to keep them lower profile. 2.5" may give me more options, though I think I will be staying with the Flowmaster models. I already have one 3" Flowmaster, so I'd save 100 beans re-using it. But it is pretty large and it has dual 2.5" outs so I'd have 2 tips on each side...
Either way I may have an extra X-pipe to anyone who pays shipping.
Cross section of the 2.5" is 19.63sqin vs 28.26sqin for the 3". Obviously the 3" will flow much better, but is it overkill at the cost of torque or power elsewhere on the RPM band? Although I may track the car in the next couple years, for the short term it is my daily rice killer, light to light and some highway driving. Also 3" in/out mufflers are hard to find locally, and usualy bigger as well. With two mufflers to tuck in next to the tranny, I want to keep them lower profile. 2.5" may give me more options, though I think I will be staying with the Flowmaster models. I already have one 3" Flowmaster, so I'd save 100 beans re-using it. But it is pretty large and it has dual 2.5" outs so I'd have 2 tips on each side...
Either way I may have an extra X-pipe to anyone who pays shipping.
11-13-2007, 10:08 PM
#3
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I plan to post as I go. So far just MSDS headers sticking out below.
Old system was a Y-Pipe off 85 manifolds straight into the Delta 50 muffler and twin outs in front of the rear tires. Muffler tucked up into cat space. With two mufflers it will be more difficult and have to be farther back.
Add to that I haven't welded since I got out of the Navy in '92... might be a little ugly.
I love what TASS 928 did with his. He has much more skill than I. Check out his work here.
Kick *** Exhuast Thread
Old system was a Y-Pipe off 85 manifolds straight into the Delta 50 muffler and twin outs in front of the rear tires. Muffler tucked up into cat space. With two mufflers it will be more difficult and have to be farther back.
Add to that I haven't welded since I got out of the Navy in '92... might be a little ugly.
I love what TASS 928 did with his. He has much more skill than I. Check out his work here.
Kick *** Exhuast Thread
11-13-2007, 10:16 PM
#5
Instructor
I just finished my 84. Mandrel bent 2.25" into a MagnaFlow Y pipe and 2.5" to the original rear box. No cats or resonators. Sounds sick too, Im going to put a Magnaflow resonator in to quiet it down a bit. I posted some pics last week...Look forward to seeing what you come up with..
11-13-2007, 10:16 PM
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first:
the low rpm power you think will be lost by going to 3 inch pipe is not the case. the loss or gain of low rpm power has to do with the primary and collector sizes, both length and diameters come into play.
the longer the primary or collector, and the smaller the diameter pipe, the more bottom end power you will have.
the shorter the primary or collector, and the bigger diameter pipe, the less bottom end power you will have.
your MSDS headers should have a 2.75 primary and a 3 inch collector, which is fine for any 928.
As for anything rearward of the headers, the bigger you go--the better it breathes. 3 inch is just fine, in conjunction with your x-pipe. 3 inch is probably the biggest you can fit under a 928, particularly if you are putting in a true dual system.
I recommend the 3 inch pipes with 3inch FlowMaster 40 or 50 series mufflers. You can get them from Jeg's or Summit Racing on-line.
If you need 3 inch CATS, they can be bought as well.........
But then again-----I prefer my header sidepipes (4 inch collectors)!!!!!
--Russ
the low rpm power you think will be lost by going to 3 inch pipe is not the case. the loss or gain of low rpm power has to do with the primary and collector sizes, both length and diameters come into play.
the longer the primary or collector, and the smaller the diameter pipe, the more bottom end power you will have.
the shorter the primary or collector, and the bigger diameter pipe, the less bottom end power you will have.
your MSDS headers should have a 2.75 primary and a 3 inch collector, which is fine for any 928.
As for anything rearward of the headers, the bigger you go--the better it breathes. 3 inch is just fine, in conjunction with your x-pipe. 3 inch is probably the biggest you can fit under a 928, particularly if you are putting in a true dual system.
I recommend the 3 inch pipes with 3inch FlowMaster 40 or 50 series mufflers. You can get them from Jeg's or Summit Racing on-line.
If you need 3 inch CATS, they can be bought as well.........
But then again-----I prefer my header sidepipes (4 inch collectors)!!!!!
--Russ
11-13-2007, 10:16 PM
#7
Three Wheelin'
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You got it as soon as I decide on what size to go with. PM me so I can remember.
I just don't want to loose low end punch in favor of top end power. Top speed mean nothing to me right now.
I just don't want to loose low end punch in favor of top end power. Top speed mean nothing to me right now.
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11-13-2007, 10:24 PM
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11-13-2007, 10:35 PM
#10
Three Wheelin'
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first:
the low rpm power you think will be lost by going to 3 inch pipe is not the case. the loss or gain of low rpm power has to do with the primary and collector sizes, both length and diameters come into play.
the longer the primary or collector, and the smaller the diameter pipe, the more bottom end power you will have.
the shorter the primary or collector, and the bigger diameter pipe, the less bottom end power you will have.
your MSDS headers should have a 2.75 primary and a 3 inch collector, which is fine for any 928.
As for anything rearward of the headers, the bigger you go--the better it breathes. 3 inch is just fine, in conjunction with your x-pipe. 3 inch is probably the biggest you can fit under a 928, particularly if you are putting in a true dual system.
I recommend the 3 inch pipes with 3inch FlowMaster 40 or 50 series mufflers. You can get them from Jeg's or Summit Racing on-line.
If you need 3 inch CATS, they can be bought as well.........
But then again-----I prefer my header sidepipes (4 inch collectors)!!!!!
--Russ
the low rpm power you think will be lost by going to 3 inch pipe is not the case. the loss or gain of low rpm power has to do with the primary and collector sizes, both length and diameters come into play.
the longer the primary or collector, and the smaller the diameter pipe, the more bottom end power you will have.
the shorter the primary or collector, and the bigger diameter pipe, the less bottom end power you will have.
your MSDS headers should have a 2.75 primary and a 3 inch collector, which is fine for any 928.
As for anything rearward of the headers, the bigger you go--the better it breathes. 3 inch is just fine, in conjunction with your x-pipe. 3 inch is probably the biggest you can fit under a 928, particularly if you are putting in a true dual system.
I recommend the 3 inch pipes with 3inch FlowMaster 40 or 50 series mufflers. You can get them from Jeg's or Summit Racing on-line.
If you need 3 inch CATS, they can be bought as well.........
But then again-----I prefer my header sidepipes (4 inch collectors)!!!!!
--Russ
I may one of the few who likes your side pipes!
Sounds like 3" is the way to go. I'm going to use aluminized steel pipe, as SS it above my price range right now. The Delta50 I had on with the Y-Pipe sounded SICK, may just add another if I can get it to fit. Lots of compliments. Biggest compliment I get is pulling up to the ricers and have them glance my way and then proceed to pretend they don't see me. You know, the look away, roll up the window, pull off slowly act. Of course side facing exhaust makes you sound 10x meaner to the car right beside you.
Giovanni, if he backs out, you're next. Nothing to get too excited about, it's the generic X pictured above. Think it cost about $43 on ebay, which means their cost was less than that. $20 to ship...not worth it.
11-13-2007, 10:50 PM
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before I put the side pipes on, I had twin 2.5 from the Euro resonator muff to the back with twin 3.5 s/s tips (12" long) exiting the stock left rear location.
every riceburner in Houston was trying to bait me into racing them......
now, with the sidepipes, they automatically know it's a V8 and not so much aggravation from the 4-banger crowd......
it's been argued that a $20K Scion and your next door teenager could out run an early 928, but it still pisses me off to see them try to bait me.....until they try to keep up with me turning a corner---then it's all over for them.
---Russ
every riceburner in Houston was trying to bait me into racing them......
now, with the sidepipes, they automatically know it's a V8 and not so much aggravation from the 4-banger crowd......
it's been argued that a $20K Scion and your next door teenager could out run an early 928, but it still pisses me off to see them try to bait me.....until they try to keep up with me turning a corner---then it's all over for them.
---Russ
11-13-2007, 10:55 PM
#12
Thank you. I bought the $79.95 off ebay and had it on my ex '88 and it made a good improvement. It should be the same for the generic brand.
11-13-2007, 11:04 PM
#14