ecu question: what would happen if?
06-05-2008, 12:27 AM
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ecu question: what would happen if?
I have a question.
I have a 95 cx. GSR swapped.
I am running the stock ecu. (not sure what the name is p72 or something)
I was wondering what would happen if I ran an unchipped p28.
My friend has one for 40.
I heard that VTEC will engage lower and fully at 5000 something.
LMK thanks.
I have a 95 cx. GSR swapped.
I am running the stock ecu. (not sure what the name is p72 or something)
I was wondering what would happen if I ran an unchipped p28.
My friend has one for 40.
I heard that VTEC will engage lower and fully at 5000 something.
LMK thanks.
06-05-2008, 01:14 AM
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Re: ecu question: what would happen if? (watsvtecEK)
Yea.
So it will be bad because of the intake manifold or something?
I know it will run though I had a friend do this when his p72 went out.
I'm just wondering what will happen; motor performance wise.
So it will be bad because of the intake manifold or something?
I know it will run though I had a friend do this when his p72 went out.
I'm just wondering what will happen; motor performance wise.
06-05-2008, 03:15 AM
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Yes it would be bad because the GSR uses secondary butterfly valves in the intake manifold. If you want to lower the vtec engagement I would buy another motor. Leave the GSR where it is, Honda made it that way for a reason. Just my .02 but running the wrong ecu unchipped is a bad idea.
06-05-2008, 11:31 PM
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Re: (fortymcpants)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by aquabob89 »</TD></TR><TR><TD CLASS="quote">Yea.
I'm just wondering what will happen; motor performance wise.</TD></TR></TABLE>
It will be slow, the secondarys wont open, and the fuel maps will be off and it will run lean.
I'm just wondering what will happen; motor performance wise.</TD></TR></TABLE>
It will be slow, the secondarys wont open, and the fuel maps will be off and it will run lean.
06-06-2008, 03:25 AM
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Re: ecu question: what would happen if? (gibsanez)
No offense but honda doesn't necessarily set vtec to engage at the best spot performance wise. There are ways to change your vtec engagement point and tune it to perform better but you have to do it on the dyno.
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06-06-2008, 04:05 AM
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Re: ecu question: what would happen if? (em1me2)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by em1me2 »</TD></TR><TR><TD CLASS="quote">No offense but honda doesn't necessarily set vtec to engage at the best spot performance wise. There are ways to change your vtec engagement point and tune it to perform better but you have to do it on the dyno.</TD></TR></TABLE>
The stock engagement will usually be the smoothest on a stock cam. But this kid isn't even considering a dyno tune, he just wants to put a different ecu in his car for reasons unknown to him.
OP, just leave the stock ECU in the car.
The stock engagement will usually be the smoothest on a stock cam. But this kid isn't even considering a dyno tune, he just wants to put a different ecu in his car for reasons unknown to him.
OP, just leave the stock ECU in the car.
06-06-2008, 05:09 AM
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Re: ecu question: what would happen if? (gibsanez)
Why hasn't anyone pointed out that the stock GS-R P72 VTEC engagement is already lower than the P28?
Look it up - P72/B18C1 VTEC engages at 4500rpm, with secondary butterflies opening up at 5800-6200rpm depending on throttle position.
Besides this obvious fact as others have stated the P28 will run a B18C1 lean, it will also have a lower rev limit, wrong timing maps, etc.
It's a bad, bad idea.
Look it up - P72/B18C1 VTEC engages at 4500rpm, with secondary butterflies opening up at 5800-6200rpm depending on throttle position.
Besides this obvious fact as others have stated the P28 will run a B18C1 lean, it will also have a lower rev limit, wrong timing maps, etc.
It's a bad, bad idea.
06-06-2008, 05:15 AM
#10
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Re: ecu question: what would happen if? (B18C5-EH2)
BTW:
The already crazy low VTEC engagement is designed with the stock GS-R dual butterfly manifold in mind. Honda knew what they were doing when they designed this.
]Stock vs. stock a B18C1 has better pull in the low/midrange than an ITR engine because of the clever intake manifold and ECU programming from Honda. After 6500rpm it's game over because of the high rpm output of the ITR engine, but around town the GS-R is great, especially when bumping around at less than 6000rpm or so.
This is EXACTLY why when people toss a Skunk2 manifold on an otherwise stock B18C1 and leave the P72 ECU it runs like crap and is slower than if it had the stock GS-R manifold. The VTEc point being at 4500rpm is way too low for the high rpm style intake manifold. Honda knew that, so that's why the stock VTEc cross over for an ITR is over 1500rpm higher than the GS-R's 4500rpm.
Also Honda designed the slightly taller gearing of the GS-R tranny to compliment the wider powerband that the B18C1 has. For this reason when you put on a Skunk2 IM and swap the ECU for a chipped P28 that RAISES the VTEC point so it doesn't bog, the stock GS-R tranny gearing makes it come close to dropping out of VTEC even when shifting at the rev limiter.
Anyways I digress...
The already crazy low VTEC engagement is designed with the stock GS-R dual butterfly manifold in mind. Honda knew what they were doing when they designed this.
]Stock vs. stock a B18C1 has better pull in the low/midrange than an ITR engine because of the clever intake manifold and ECU programming from Honda. After 6500rpm it's game over because of the high rpm output of the ITR engine, but around town the GS-R is great, especially when bumping around at less than 6000rpm or so.
This is EXACTLY why when people toss a Skunk2 manifold on an otherwise stock B18C1 and leave the P72 ECU it runs like crap and is slower than if it had the stock GS-R manifold. The VTEc point being at 4500rpm is way too low for the high rpm style intake manifold. Honda knew that, so that's why the stock VTEc cross over for an ITR is over 1500rpm higher than the GS-R's 4500rpm.
Also Honda designed the slightly taller gearing of the GS-R tranny to compliment the wider powerband that the B18C1 has. For this reason when you put on a Skunk2 IM and swap the ECU for a chipped P28 that RAISES the VTEC point so it doesn't bog, the stock GS-R tranny gearing makes it come close to dropping out of VTEC even when shifting at the rev limiter.
Anyways I digress...
06-06-2008, 09:28 AM
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Re: ecu question: what would happen if? (B18C5-EH2)
I was just wondering.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C5-EH2 »</TD></TR><TR><TD CLASS="quote">BTW:
The already crazy low VTEC engagement is designed with the stock GS-R dual butterfly manifold in mind. Honda knew what they were doing when they designed this.
]Stock vs. stock a B18C1 has better pull in the low/midrange than an ITR engine because of the clever intake manifold and ECU programming from Honda. After 6500rpm it's game over because of the high rpm output of the ITR engine, but around town the GS-R is great, especially when bumping around at less than 6000rpm or so.
This is EXACTLY why when people toss a Skunk2 manifold on an otherwise stock B18C1 and leave the P72 ECU it runs like crap and is slower than if it had the stock GS-R manifold. The VTEc point being at 4500rpm is way too low for the high rpm style intake manifold. Honda knew that, so that's why the stock
VTEc cross over for an ITR is over 1500rpm higher than the GS-R's 4500rpm.
Also Honda designed the slightly taller gearing of the GS-R tranny to compliment the wider powerband that the B18C1 has. For this reason when you put on a Skunk2 IM and swap the ECU for a chipped P28 that RAISES the VTEC point so it doesn't bog, the stock GS-R tranny gearing makes it come close to dropping out of VTEC even when shifting at the rev limiter.
Anyways I digress...
So basically, you think intake manifolds on a stock gsr are a horrible plan for power?
</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C5-EH2 »</TD></TR><TR><TD CLASS="quote">BTW:
The already crazy low VTEC engagement is designed with the stock GS-R dual butterfly manifold in mind. Honda knew what they were doing when they designed this.
]Stock vs. stock a B18C1 has better pull in the low/midrange than an ITR engine because of the clever intake manifold and ECU programming from Honda. After 6500rpm it's game over because of the high rpm output of the ITR engine, but around town the GS-R is great, especially when bumping around at less than 6000rpm or so.
This is EXACTLY why when people toss a Skunk2 manifold on an otherwise stock B18C1 and leave the P72 ECU it runs like crap and is slower than if it had the stock GS-R manifold. The VTEc point being at 4500rpm is way too low for the high rpm style intake manifold. Honda knew that, so that's why the stock
VTEc cross over for an ITR is over 1500rpm higher than the GS-R's 4500rpm.
Also Honda designed the slightly taller gearing of the GS-R tranny to compliment the wider powerband that the B18C1 has. For this reason when you put on a Skunk2 IM and swap the ECU for a chipped P28 that RAISES the VTEC point so it doesn't bog, the stock GS-R tranny gearing makes it come close to dropping out of VTEC even when shifting at the rev limiter.
Anyways I digress...
So basically, you think intake manifolds on a stock gsr are a horrible plan for power?
</TD></TR></TABLE>
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