Lowering VTEC
05-11-2013 | 08:15 AM
#41
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Joined: Oct 2012
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I have a stock '02 ap1 (except gutted airbox) as far as power mods goes. And my current goal is to lower vtec a little and smooth out the power band. Im working off what i understand to be the cheapest and least mod intensive way to do this. I am buying a 70mm berk HFC from another s2ki member who lives close to me. Next i will order an afc neo (if anyone has a used one with PnP harness please pm me). I will then get these dyno tuned and hopefully post dyno charts of stock baseline and berk HFC pre and post tune.
If Im missing something please offer some guidence, this is my first post on s2ki so please dont flame me. Thanks for the info so far
If Im missing something please offer some guidence, this is my first post on s2ki so please dont flame me. Thanks for the info so far
05-11-2013 | 06:50 PM
#42
Joined: Dec 2007
Posts: 4,289
Likes: 12
Also depending on the year of the car (+02 and especially 04+) if you got some good bolt ons which provide a worthwhile increase in flow, the stock ecu will not accommodate the added fuel needed to support this. A TP is about it, beyond that you should plan on incorporating some measure of additional fuel, either from as simple as an adjustable fpr to turn up fuel pressure, to a full ems. Beyond about 13-13.5 afr you will be past lean best, run dangerously hot combustion temps and will start losing power. The factory ecu with cat puts the car in the 12's on years mentioned, a TP runs you near a full point leaner. You need a tune beyond that not just to maximize your gains, but to run safe.
I'd have to disagree with this. I have an 03, and even in the winter where AFRs would be the leanest, on the stock ecu, my wideband doesn't show any scary lean AFRs. It will jump to high 13s right at vtec but then will go down to where it's supposed to.
Another example of the stock ecu being fine for simple bolt ons is that a lot of people will do bolt ons and then tune it with a VAFC, which can ONLY lean out the fuel mixture. While obviously this solution isn't ideal, as a lot of the gains from lowering vtec is advancing the timing in the area where you are now on the high cam instead of the low cam, and some areas may need more fuel for a flat AFR curve, and the VAFC can't alter timing or add fuel, I don't consider this to be dangerous option, just not the best tuning solution.
I have yet to see a thread on here where someone stated they blew their engine because they didn't tune their N/A bolt on S2k. I have been running full bolt ons on stock ecu for years with no problems. I recently got tuned on an AEM EMS and went from 190whp/130wtq to 221whp/146wtq with 20-25whp gains in the mid range, but Im currently back on the stock ecu, and AFRs on my wideband are still safe.
05-11-2013 | 07:06 PM
#43
Joined: Sep 2012
Posts: 3,220
Likes: 145
From: Greenwood, AR
Lowering vtec switchover point without dyno test is really not good. In the stock version of s2000 the vtec should not be lowered more than 5500 rpm otherwise you will lose power
When you have modification lowering more is most of the time good but dynotest is a necessity
When you have modification lowering more is most of the time good but dynotest is a necessity
Road tune and data logging; problem solved.
05-14-2013 | 11:51 AM
#44
Community Organizer
Joined: Jun 2007
Posts: 31,059
Likes: 555
Originally Posted by s2000Junky' timestamp='1368246925' post='22534940
Also depending on the year of the car (+02 and especially 04+) if you got some good bolt ons which provide a worthwhile increase in flow, the stock ecu will not accommodate the added fuel needed to support this. A TP is about it, beyond that you should plan on incorporating some measure of additional fuel, either from as simple as an adjustable fpr to turn up fuel pressure, to a full ems. Beyond about 13-13.5 afr you will be past lean best, run dangerously hot combustion temps and will start losing power. The factory ecu with cat puts the car in the 12's on years mentioned, a TP runs you near a full point leaner. You need a tune beyond that not just to maximize your gains, but to run safe.
I'd have to disagree with this. I have an 03, and even in the winter where AFRs would be the leanest, on the stock ecu, my wideband doesn't show any scary lean AFRs. It will jump to high 13s right at vtec but then will go down to where it's supposed to.
Another example of the stock ecu being fine for simple bolt ons is that a lot of people will do bolt ons and then tune it with a VAFC, which can ONLY lean out the fuel mixture. While obviously this solution isn't ideal, as a lot of the gains from lowering vtec is advancing the timing in the area where you are now on the high cam instead of the low cam, and some areas may need more fuel for a flat AFR curve, and the VAFC can't alter timing or add fuel, I don't consider this to be dangerous option, just not the best tuning solution.
I have yet to see a thread on here where someone stated they blew their engine because they didn't tune their N/A bolt on S2k. I have been running full bolt ons on stock ecu for years with no problems. I recently got tuned on an AEM EMS and went from 190whp/130wtq to 221whp/146wtq with 20-25whp gains in the mid range, but Im currently back on the stock ecu, and AFRs on my wideband are still safe.
05-14-2013 | 07:59 PM
#46
Community Organizer
Joined: Jun 2007
Posts: 31,059
Likes: 555
Test Pipe and E-manage. Best bang for the buck.
If you don't have any E-manage support available to you, a simple adjustable rate fpr and vafc will give you about 75% of the overall power potential you would with an E-manage or full stand alone. One compromise I want to mention with the vafc though is that vtec is all rpm based, rather then throttle percentage or load such stock or other EMS, so if you want to see vtec as low as possible in the 3500-4000rpm range, you may find yourself there a lot when you don't want to be, like in-between each shift or cruising on freeway. Its not a harmful thing, except for your mpg. Setting it higher in the 4500-5000 range helps that, but then your not getting the full benefit of lower rpm power improvement.
If you don't have any E-manage support available to you, a simple adjustable rate fpr and vafc will give you about 75% of the overall power potential you would with an E-manage or full stand alone. One compromise I want to mention with the vafc though is that vtec is all rpm based, rather then throttle percentage or load such stock or other EMS, so if you want to see vtec as low as possible in the 3500-4000rpm range, you may find yourself there a lot when you don't want to be, like in-between each shift or cruising on freeway. Its not a harmful thing, except for your mpg. Setting it higher in the 4500-5000 range helps that, but then your not getting the full benefit of lower rpm power improvement.
05-15-2013 | 03:06 PM
#47
Joined: Dec 2007
Posts: 4,289
Likes: 12
Originally Posted by liquid_helix136' timestamp='1368327002' post='22536393
[quote name='s2000Junky' timestamp='1368246925' post='22534940']
Also depending on the year of the car (+02 and especially 04+) if you got some good bolt ons which provide a worthwhile increase in flow, the stock ecu will not accommodate the added fuel needed to support this. A TP is about it, beyond that you should plan on incorporating some measure of additional fuel, either from as simple as an adjustable fpr to turn up fuel pressure, to a full ems. Beyond about 13-13.5 afr you will be past lean best, run dangerously hot combustion temps and will start losing power. The factory ecu with cat puts the car in the 12's on years mentioned, a TP runs you near a full point leaner. You need a tune beyond that not just to maximize your gains, but to run safe.
Also depending on the year of the car (+02 and especially 04+) if you got some good bolt ons which provide a worthwhile increase in flow, the stock ecu will not accommodate the added fuel needed to support this. A TP is about it, beyond that you should plan on incorporating some measure of additional fuel, either from as simple as an adjustable fpr to turn up fuel pressure, to a full ems. Beyond about 13-13.5 afr you will be past lean best, run dangerously hot combustion temps and will start losing power. The factory ecu with cat puts the car in the 12's on years mentioned, a TP runs you near a full point leaner. You need a tune beyond that not just to maximize your gains, but to run safe.
I'd have to disagree with this. I have an 03, and even in the winter where AFRs would be the leanest, on the stock ecu, my wideband doesn't show any scary lean AFRs. It will jump to high 13s right at vtec but then will go down to where it's supposed to.
Another example of the stock ecu being fine for simple bolt ons is that a lot of people will do bolt ons and then tune it with a VAFC, which can ONLY lean out the fuel mixture. While obviously this solution isn't ideal, as a lot of the gains from lowering vtec is advancing the timing in the area where you are now on the high cam instead of the low cam, and some areas may need more fuel for a flat AFR curve, and the VAFC can't alter timing or add fuel, I don't consider this to be dangerous option, just not the best tuning solution.
I have yet to see a thread on here where someone stated they blew their engine because they didn't tune their N/A bolt on S2k. I have been running full bolt ons on stock ecu for years with no problems. I recently got tuned on an AEM EMS and went from 190whp/130wtq to 221whp/146wtq with 20-25whp gains in the mid range, but Im currently back on the stock ecu, and AFRs on my wideband are still safe.
[/quote]
I'll agree that there is a lot of hype around particular mods and a lot of people doing them without actually knowing what effect they are having towards an engine. I definitely agree with at least getting a wideband if you plan on modding your car beyond some of the very basic things (just a catback, or just an intake etc.) I don't think I'll ever own another performance car again without hooking up a wideband to it. So much information can be gathered about whats going on with your car just by knowing the AFRs at that point. Especially when troubleshooting issues.
05-15-2013 | 06:00 PM
#48
Community Organizer
Joined: Jun 2007
Posts: 31,059
Likes: 555
Originally Posted by s2000Junky' timestamp='1368561071' post='22542129
[quote name='liquid_helix136' timestamp='1368327002' post='22536393']
[quote name='s2000Junky' timestamp='1368246925' post='22534940']
Also depending on the year of the car (+02 and especially 04+) if you got some good bolt ons which provide a worthwhile increase in flow, the stock ecu will not accommodate the added fuel needed to support this. A TP is about it, beyond that you should plan on incorporating some measure of additional fuel, either from as simple as an adjustable fpr to turn up fuel pressure, to a full ems. Beyond about 13-13.5 afr you will be past lean best, run dangerously hot combustion temps and will start losing power. The factory ecu with cat puts the car in the 12's on years mentioned, a TP runs you near a full point leaner. You need a tune beyond that not just to maximize your gains, but to run safe.
[quote name='s2000Junky' timestamp='1368246925' post='22534940']
Also depending on the year of the car (+02 and especially 04+) if you got some good bolt ons which provide a worthwhile increase in flow, the stock ecu will not accommodate the added fuel needed to support this. A TP is about it, beyond that you should plan on incorporating some measure of additional fuel, either from as simple as an adjustable fpr to turn up fuel pressure, to a full ems. Beyond about 13-13.5 afr you will be past lean best, run dangerously hot combustion temps and will start losing power. The factory ecu with cat puts the car in the 12's on years mentioned, a TP runs you near a full point leaner. You need a tune beyond that not just to maximize your gains, but to run safe.
I'd have to disagree with this. I have an 03, and even in the winter where AFRs would be the leanest, on the stock ecu, my wideband doesn't show any scary lean AFRs. It will jump to high 13s right at vtec but then will go down to where it's supposed to.
Another example of the stock ecu being fine for simple bolt ons is that a lot of people will do bolt ons and then tune it with a VAFC, which can ONLY lean out the fuel mixture. While obviously this solution isn't ideal, as a lot of the gains from lowering vtec is advancing the timing in the area where you are now on the high cam instead of the low cam, and some areas may need more fuel for a flat AFR curve, and the VAFC can't alter timing or add fuel, I don't consider this to be dangerous option, just not the best tuning solution.
I have yet to see a thread on here where someone stated they blew their engine because they didn't tune their N/A bolt on S2k. I have been running full bolt ons on stock ecu for years with no problems. I recently got tuned on an AEM EMS and went from 190whp/130wtq to 221whp/146wtq with 20-25whp gains in the mid range, but Im currently back on the stock ecu, and AFRs on my wideband are still safe.
[/quote]
I'll agree that there is a lot of hype around particular mods and a lot of people doing them without actually knowing what effect they are having towards an engine. I definitely agree with at least getting a wideband if you plan on modding your car beyond some of the very basic things (just a catback, or just an intake etc.) I don't think I'll ever own another performance car again without hooking up a wideband to it. So much information can be gathered about whats going on with your car just by knowing the AFRs at that point. Especially when troubleshooting issues.
[/quote]
Yes sir
