70mm exhaust on a N/A
12-05-2016, 10:32 AM
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70mm exhaust on a N/A
i was reading some information on exhausts and saw someone say that a 70mm exhaust on a n/a s2000 loses power in the lower end of the power band? is that true? i ordered a 70mm hks hi power single recently. yet to be delivered but should be soon. other mods i have are the 63mm high flow cat which will be upgraded to a 70mm test pipe, i have a takeda afe intake, and ingalls ETD.
Last edited by 06s2kid; 12-05-2016 at 10:39 AM.
12-05-2016, 04:02 PM
#2
Lots of research over the years confirms the best performance keeps the exhaust diameter constant and avoids large changes which disrupt the exhaust flow. Going from a 57mm header to a 70mm cat or cat-delete disrupts the exhaust pulses.
I read enough here to go with a 63.5mm Berk high flow cat and a 60mm Tanabe Medalion Touring exhaust. 221 bhp on a Mustang dyno (these are reputed to read low).
You have a 2006? Get a Hondata FlashPro and Gernby road tune. This will lower VTEC to 3600 rpm and greatly improve mid-range power.
-- Chuck
I read enough here to go with a 63.5mm Berk high flow cat and a 60mm Tanabe Medalion Touring exhaust. 221 bhp on a Mustang dyno (these are reputed to read low).
You have a 2006? Get a Hondata FlashPro and Gernby road tune. This will lower VTEC to 3600 rpm and greatly improve mid-range power.
-- Chuck
12-05-2016, 04:15 PM
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Yes i have flashpro too, i had his tune for a while but then i got a intake, so im back on the basemap. so you think id lose power going to a 70mm test pipe and 70mm exhaust? i heard that the hks single makes power
12-06-2016, 02:26 AM
#5
Without a dyno you'll not be able to determine power loss/gain. I'm convinced there is no power gain going to 70mm but I'm probably not the majority opinion, nor do I have access to a dyno for dozens of tests. The HKS is well regarded but the cosmetics of a single exhaust put me off.
I'd expect the ECU can adjust itself for a different intake without a major retune. The increase in mid-range power with the Gernby tune caused me to fit a red line alarm as I was bumping the rev limiter too often in the lower gears. With a 3600 VTEC it's seldom necessary to downshift to pass and rarely do I need to drop two gears: VTEC is right under my right foot.
Chasing horsepower just to compare dyno sheets can get expensive and have no practical gain. My buddy's AP1 is lighter and was faster than mine before the Gernby tune. He's still working the bugs out of his supercharger so I'll be behind him by next summer.
-- Chuck
I'd expect the ECU can adjust itself for a different intake without a major retune. The increase in mid-range power with the Gernby tune caused me to fit a red line alarm as I was bumping the rev limiter too often in the lower gears. With a 3600 VTEC it's seldom necessary to downshift to pass and rarely do I need to drop two gears: VTEC is right under my right foot.
Chasing horsepower just to compare dyno sheets can get expensive and have no practical gain. My buddy's AP1 is lighter and was faster than mine before the Gernby tune. He's still working the bugs out of his supercharger so I'll be behind him by next summer.
-- Chuck
12-06-2016, 08:01 AM
#7
You have a powerful logging tool in the flashpro.
Find a suitable road where you can do a few third gear pulls from ~2krpm to redline, save the logs and import them to Virtual Dyno for example.
Then go ahead and change your exhaust and make new pulls and share your results here
You can get very accurate results if you are consistent with the pulls.
Find a suitable road where you can do a few third gear pulls from ~2krpm to redline, save the logs and import them to Virtual Dyno for example.
Then go ahead and change your exhaust and make new pulls and share your results here
You can get very accurate results if you are consistent with the pulls.
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12-06-2016, 04:09 PM
#10
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Without a dyno you'll not be able to determine power loss/gain. I'm convinced there is no power gain going to 70mm but I'm probably not the majority opinion, nor do I have access to a dyno for dozens of tests. The HKS is well regarded but the cosmetics of a single exhaust put me off.
I'd expect the ECU can adjust itself for a different intake without a major retune. The increase in mid-range power with the Gernby tune caused me to fit a red line alarm as I was bumping the rev limiter too often in the lower gears. With a 3600 VTEC it's seldom necessary to downshift to pass and rarely do I need to drop two gears: VTEC is right under my right foot.
Chasing horsepower just to compare dyno sheets can get expensive and have no practical gain. My buddy's AP1 is lighter and was faster than mine before the Gernby tune. He's still working the bugs out of his supercharger so I'll be behind him by next summer.
-- Chuck
I'd expect the ECU can adjust itself for a different intake without a major retune. The increase in mid-range power with the Gernby tune caused me to fit a red line alarm as I was bumping the rev limiter too often in the lower gears. With a 3600 VTEC it's seldom necessary to downshift to pass and rarely do I need to drop two gears: VTEC is right under my right foot.
Chasing horsepower just to compare dyno sheets can get expensive and have no practical gain. My buddy's AP1 is lighter and was faster than mine before the Gernby tune. He's still working the bugs out of his supercharger so I'll be behind him by next summer.
-- Chuck