TP and Exhaust diameter question
07-08-2016, 12:22 PM
#1
TP and Exhaust diameter question
Ok so I have MY04 AP2 and in getting ready to install:
Haltech Pro Plug In ECU
AEM V2 CAI
Toda Spec C Cams
Toda Valve Springs
Toda Cam Gears
Toda Torquie-Kun Header (60mm collector)
60mm TP
60mm Catback
Will it be worth while for me to go from a 60mm header, 60mm TP and 60mm exhaust to a
60mm to 70mm transitioning TP and 70mm exhaust when my headers collector is only 60mm?
Haltech Pro Plug In ECU
AEM V2 CAI
Toda Spec C Cams
Toda Valve Springs
Toda Cam Gears
Toda Torquie-Kun Header (60mm collector)
60mm TP
60mm Catback
Will it be worth while for me to go from a 60mm header, 60mm TP and 60mm exhaust to a
60mm to 70mm transitioning TP and 70mm exhaust when my headers collector is only 60mm?
07-08-2016, 02:15 PM
#2
A specialty Honda S2000 tuner is the guy to ask, preferably the same one who's gonna tune your car. Lots of fluid dynamics here that few of us do more than think we understand some of it. 
A lot of money for an additional 10-15bhp at the rear wheels.
-- Chuck
A lot of money for an additional 10-15bhp at the rear wheels.
-- Chuck
07-15-2016, 03:18 PM
#3
Being that you're going to be getting tuned, I'd go with a 70mm TP and exhaust in order to get the most out of your upgraded valvetrain.
60mm I feel is personally better for an s2000 that's staying internally stock, untuned, or both.
60mm I feel is personally better for an s2000 that's staying internally stock, untuned, or both.
07-30-2016, 03:15 PM
#4
I should have been more specific... Wild it be better for me to go to A TRANSITIONING TP like this Toda shown below that is 60mm on one end and 70mm on the other or just a plain old 70mm TP
07-30-2016, 05:03 PM
#5
The header is ~57mm ID where it joins the cat so they're all that diameter on that end (where the two holes for the spring bolts are).
The one in the photo is 3 sections of pipe.
I measured the ID of the OEM cat off my '06 car and it's a nominal 60mm exit and maybe closer to 57mm at the entrance -- my calipers don't reach quite that far. OEM exhaust inlet (right after the cat) is the same 60mm.
Makes no sense to dump exhaust gas from a 57mm header into 70mm pipe and then back in to 60mm piping and expect the exhaust to flow well. You'll get less restriction but gas flow disruption may negate any gain. 70mm high flow cat/test pipe only makes sense if you're fitting a 70mm cat-back exhaust.
-- Chuck
The one in the photo is 3 sections of pipe.
I measured the ID of the OEM cat off my '06 car and it's a nominal 60mm exit and maybe closer to 57mm at the entrance -- my calipers don't reach quite that far. OEM exhaust inlet (right after the cat) is the same 60mm.
Makes no sense to dump exhaust gas from a 57mm header into 70mm pipe and then back in to 60mm piping and expect the exhaust to flow well. You'll get less restriction but gas flow disruption may negate any gain. 70mm high flow cat/test pipe only makes sense if you're fitting a 70mm cat-back exhaust.
-- Chuck
07-30-2016, 05:36 PM
#6
The header is ~57mm ID where it joins the cat so they're all that diameter on that end (where the two holes for the spring bolts are).
The one in the photo is 3 sections of pipe.
I measured the ID of the OEM cat off my '06 car and it's a nominal 60mm exit and maybe closer to 57mm at the entrance -- my calipers don't reach quite that far. OEM exhaust inlet (right after the cat) is the same 60mm.
Makes no sense to dump exhaust gas from a 57mm header into 70mm pipe and then back in to 60mm piping and expect the exhaust to flow well. You'll get less restriction but gas flow disruption may negate any gain. 70mm high flow cat/test pipe only makes sense if you're fitting a 70mm cat-back exhaust.
-- Chuck
The one in the photo is 3 sections of pipe.
I measured the ID of the OEM cat off my '06 car and it's a nominal 60mm exit and maybe closer to 57mm at the entrance -- my calipers don't reach quite that far. OEM exhaust inlet (right after the cat) is the same 60mm.
Makes no sense to dump exhaust gas from a 57mm header into 70mm pipe and then back in to 60mm piping and expect the exhaust to flow well. You'll get less restriction but gas flow disruption may negate any gain. 70mm high flow cat/test pipe only makes sense if you're fitting a 70mm cat-back exhaust.
-- Chuck
07-31-2016, 03:25 AM
#7
You're describing the pictured test pipe which steps the diameter up from ~60mm to 70mm which is the way to do it but only if you're installing a 70mm exhaust. It should be better than a "plain old 70mm test pipe but putting this in the middle of the stock system where the pipe diameter drops back to 60mm may decrease performance due to exhaust turbulence. (Which was what my poorly written note described.)
Use a 60mm (ish) high flow cat/test pipe with a 60mm exhaust.
-- Chuck
Use a 60mm (ish) high flow cat/test pipe with a 60mm exhaust.
-- Chuck
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07-31-2016, 09:01 PM
#8
You're describing the pictured test pipe which steps the diameter up from ~60mm to 70mm which is the way to do it but only if you're installing a 70mm exhaust. It should be better than a "plain old 70mm test pipe but putting this in the middle of the stock system where the pipe diameter drops back to 60mm may decrease performance due to exhaust turbulence. (Which was what my poorly written note described.)
Use a 60mm (ish) high flow cat/test pipe with a 60mm exhaust.
-- Chuck
Use a 60mm (ish) high flow cat/test pipe with a 60mm exhaust.
-- Chuck
08-01-2016, 03:17 AM
#10
Yep. But since lots of folks read these I noted just putting a large pipe in place of the cat ain't gonna help with smaller tube after it. Nothing magic about a large diameter pipe. 57mm IN to 70mm OUT works best in tapered arrangement.
-- Chuck
-- Chuck
