Engaging VTEC Earlier
03-11-2009, 04:20 AM
#13
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[QUOTE=Nine1Sickness,Mar 11 2009, 12:29 AM] I am not giving engineers too much credit; they are forced to comply with emission standards too. A very good example is the new US model
03-11-2009, 04:26 AM
#14
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Originally Posted by LostMotion,Mar 10 2009, 11:56 PM
There's no question that even on a dead stock car the VTEC can be lowered about 500 RPMs with very favorable results. I have no idea why Honda put it where they did, but that's the reality of the situation. I think sometimes people give "Honda Engineers" a little too much credit. Sometimes things are done as a business decision and sometimes things are just skipped over for expediency. For example the TSX cam profiles (not the cams themselves just the lobe profiles) were directly copied from the AP1. There's no way you can tell me that they just happened to have the exact same profile to optimize performance and MPG for two motors that are quite a bit different. It was expediency. I'm sure they put thought into where VTEC was set, but it may not have been 100% about peak performance.
Not all gas is the same across the world
Decent MPG
Altitude
Climate
Pollution Control
Noise Control
I want you to build a car that will satisfy all conditions for everyone across the world... It's not easy so they build in "safety zones"
I've read about one car suffereing majorly from a vtec reduction while another was able to do it 300-400 rpms lower.
There are ALOT of variables, but if you want to zone in on your car, location, conditions you can optimize YOUR car and maximize HP.
03-11-2009, 05:16 AM
#15
i sure do know with bolt-ons the civic si's gain a TON of midrange power with vtec engagement at 4500 instead of 5800. (note: Hondata reflash also advances cam angles before and during vtec to gain this midrange)
The same can be said of the s2000, (look at hondata reflash dyno curves) to see. There are lots of factors why they pick the stock vtec engagement. Almost none of them are from a performance standpoint.
The guy above me pegged some of the reasons.
But another is fun factor. It feels fun to have a violent engagement like the stock setup is (you can REALLY feel it). If you tune to have it engage lower, you will be faster, but you won't feel it. Just a smooth pull to redline.
People say this of the si reflash. It's DEFINITELY faster, but it doesn't feel as fun hehe. I will say i'm looking forward to getting my reflash on my si, but i love driving my girlfriend's s2000.
The same can be said of the s2000, (look at hondata reflash dyno curves) to see. There are lots of factors why they pick the stock vtec engagement. Almost none of them are from a performance standpoint.
The guy above me pegged some of the reasons.
But another is fun factor. It feels fun to have a violent engagement like the stock setup is (you can REALLY feel it). If you tune to have it engage lower, you will be faster, but you won't feel it. Just a smooth pull to redline.
People say this of the si reflash. It's DEFINITELY faster, but it doesn't feel as fun hehe. I will say i'm looking forward to getting my reflash on my si, but i love driving my girlfriend's s2000.
03-11-2009, 07:20 AM
#16
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Originally Posted by ChefJ,Mar 10 2009, 11:01 PM
rpm isn't the only factor. you can drive at 6500 rpms and not be in vtec. There are load parameters that need to be met aswell, and throttle position requirements.
03-11-2009, 08:25 AM
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toda. But other dynos have been done without the header with basically the same results. Showing there are great gains with a lower VTEC if done right. Ie. Hondata reflash
03-11-2009, 09:47 AM
#19
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Sweet gains there witht he Hondata. I have mine set at 5500 and with the 4.77 gears make a nice combo. Doesn't feel like it pulls as hard in vtec since you don't feel it kick in but definitely made more power than when set at 6k.
