why no i-vtec on s2000
07-30-2004, 12:13 AM
#51
Originally Posted by gernby,Jul 29 2004, 09:58 AM
It almost sounds like you think "potential" is all about peak numbers. The biggest complaint from performance enthusiats about the S2000 is how non-flat the power curve is ... and they're right!I agree and perfectly understand that I-VTEC produces more torque in the mid range...duh...that doesn't give it more "potential"...potential isn't the right word.
Try, driveablity, or smoother torque...
The reason the K-Series is producing more power, easier, with aftermarket parts is because Honda didn't make it producing 120hp/L out of the factory...obviously, as these dyno's show...some K-Series motors are also putting out these kind of numbers with aftermarket parts. Think 216 whp with FWD drivetrain loss, 200-205whp with RWD drivetrain loss...both 2.0L motors...both making very close numbers. But I'm sure that a S, with similar mods, would also produce slightly more...not quite as much of a jump as the K20a...but still an increase in power.
Now...what exactly do you consider "potential" to be about?
Is a flater torque curve nicer? Yes
Is it easier to drive fast? Yes
Would an S with I-VTEC...or just a flat torque curve producing the same amount of power and obviously more in the midrange, possibly beat a real S2000...most likely...and its due to a more consistant supply of torque.
Ok, ya, I'm done...I don't know why I even got invovled in this thread
I-VTEC vs. VTEC only offers better driveablity...think about it, how often, when you are racing are you below 6k? It shouldn't be much or your not driving the car right.
07-30-2004, 12:32 AM
#52
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i-VTEC is a good step to improve on technology, and I'm all for it. I don't prefer one over the other, but I do respect what the new technology offers.
I'm old school, tuning carbs, primative fuel injected systems, swapping cams on 8v and 16v 4 bangers 15 years back. If you've ever swapped a stock cam for a race type and drove around the street, you'd get incredible high end power at the cost of low end power loss. Adjustable cam gears became available where we could advance or retard the static cam timing point to move/shift the power around to our needs. If we needed more power down low, we'd advance the gear but sacrifice power on top... or if we needed more power up top, we could retard the cams at the cost of low end. Give or take was the situation back then. On dual cammed cars, we could adjust the overlap between intake and exhaust valves. We wanted a way to automatically advance the cam timing during low-rpms to gain more torque, yet have a way to retard the cam timing when the engine revs up to gain more power on top...
So, somebody made a spring-loaded mechanical cam gear with weights (similar to a mechanical distributor advance). This was ultra clunky to use and very hard to predict it's ability to provide the best setting per condition. Enter i-VTEC which allows for variable cam phasing (advancing and retarding the cam) in conjuction with switching cam profiles (to include increases in lift and duration) using various sensors and a ECU to make the best decisions for you. This is like having the ability to alter the cam timing points to advance and retard the timing as the car see's fit AND the ability to swap a street cam to a race cam at the same time. Pretty good stuff IMO.
The result/goal is to provide a very linear and broad power delivery with strong power on top where cars without this technology would simply run out of breath.
I'm old school, tuning carbs, primative fuel injected systems, swapping cams on 8v and 16v 4 bangers 15 years back. If you've ever swapped a stock cam for a race type and drove around the street, you'd get incredible high end power at the cost of low end power loss. Adjustable cam gears became available where we could advance or retard the static cam timing point to move/shift the power around to our needs. If we needed more power down low, we'd advance the gear but sacrifice power on top... or if we needed more power up top, we could retard the cams at the cost of low end. Give or take was the situation back then. On dual cammed cars, we could adjust the overlap between intake and exhaust valves. We wanted a way to automatically advance the cam timing during low-rpms to gain more torque, yet have a way to retard the cam timing when the engine revs up to gain more power on top...
So, somebody made a spring-loaded mechanical cam gear with weights (similar to a mechanical distributor advance). This was ultra clunky to use and very hard to predict it's ability to provide the best setting per condition. Enter i-VTEC which allows for variable cam phasing (advancing and retarding the cam) in conjuction with switching cam profiles (to include increases in lift and duration) using various sensors and a ECU to make the best decisions for you. This is like having the ability to alter the cam timing points to advance and retard the timing as the car see's fit AND the ability to swap a street cam to a race cam at the same time. Pretty good stuff IMO.
The result/goal is to provide a very linear and broad power delivery with strong power on top where cars without this technology would simply run out of breath.
07-30-2004, 04:58 AM
#53
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to answer the question on the TSX motor...
yes, it should have similar tuning potential as the head is almost exactly like the RSX-S. It has VTEC (a 3 rocker design) on both intake and exhaust as well as VTC on the intake cam.
the Si, RSX, Accord/element/crv basically have VTEC-E (a 2 rocker design) on the intake only and VTC on the intake cam. Some think the TSX motor is just a "tuned" Accord/CRV/Element motor...not true, it is very different.
Now, if Honda came out with an engine with VTC on both intake and exhaust, even more power could be extracted from the low/mid, and even high, rpm ranges. Perhaps the next NSX or S will have this.
yes, it should have similar tuning potential as the head is almost exactly like the RSX-S. It has VTEC (a 3 rocker design) on both intake and exhaust as well as VTC on the intake cam.
the Si, RSX, Accord/element/crv basically have VTEC-E (a 2 rocker design) on the intake only and VTC on the intake cam. Some think the TSX motor is just a "tuned" Accord/CRV/Element motor...not true, it is very different.
Now, if Honda came out with an engine with VTC on both intake and exhaust, even more power could be extracted from the low/mid, and even high, rpm ranges. Perhaps the next NSX or S will have this.
07-30-2004, 08:47 AM
#54
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Originally Posted by SLO-S2000,Jul 29 2004, 09:57 AM
I think that the RSX-S feels the "VTEC kick" twice supposedly...once lower in the rpms and then up higher at around 6...it's similar to the Celica and VVTL-i
08-03-2004, 07:48 AM
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Originally Posted by SocratesDTC,Jul 30 2004, 08:47 AM
Nope! You cant hear/feel the vtec point in i-vtec engines...