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Evo8.com installed my cams

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Old May 10, 2004 | 11:52 AM
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From: FQ Story, Phoenix
Originally Posted by xstang
so basically the more lope, the better the top end right? I like the lope, just wouldn't want much more ...
it is called overlap and yes the higher valve lift improves top end...

winston
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Old May 10, 2004 | 01:02 PM
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Originally Posted by ImportPePe
xstang, do you have a black Evo w/ the "Evolution VIII" badge by any chance?

I happen to saw a black Evo that was very mean-sounding on US 377 in Keller on Saturday on my way to work, and wondering if it was you by any chance. The reason I'm curious is because you mentioned that you got your cams done at evo8.com, which is next door to Gotham Racing, and the one I saw on 377 sounded like it was "cammin'", so I figured with the direction it was heading, I may have thought it was yours. Correct me if I'm wrong. Thanks

I have a blue Evo... (-:
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Old May 10, 2004 | 01:17 PM
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From: Home of USGP!
Originally Posted by WINSTON
it is called overlap and yes the higher valve lift improves top end...

winston
Higher valve lift creates more horsepower but ends up with diminishing returns due to increased valve velocity (think about it, the ramp is steeper) and makes for far more potential to float the valves. Duration creates more power on top end, because there is more time for air/fuel to fill the cylinder. Increased duration eventually causes a problem with idle however, because the timing that works so well at high RPM provides too much time at low rpm which lowers vacuum and smoothness of the intake velocity. Increase the duration enough and you will eventually get to the point that there is a large "overlap" between the exhaust and intake, where both are open for a split second. This overlap doesn't affect the engine at high RPM, as the time period is so short. At idle though, the time period is much longer relative to intake velocity and the intake charge actually has enough time to travel into and out of the engine without burning. Hence, a "loping" idle.
Last edited by OnlineAlias; May 10, 2004 at 01:25 PM.
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Old May 10, 2004 | 02:05 PM
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From: San Antonio, TX
xstang - I have the time slot after you for the dallas dynoflash day. Would you mind letting me hear what it sounds like and possibly taking me for a spin?
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Old May 10, 2004 | 02:13 PM
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Originally Posted by Monkey
xstang - I have the time slot after you for the dallas dynoflash day. Would you mind letting me hear what it sounds like and possibly taking me for a spin?
Sure.... Should be a blast!!!! I know a great stretch of road... (-:

Monkey, are you located near Bedford tx?
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Old May 10, 2004 | 02:40 PM
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From: CA
Originally Posted by OnlineAlias
Higher valve lift creates more horsepower but ends up with diminishing returns due to increased valve velocity (think about it, the ramp is steeper) and makes for far more potential to float the valves. Duration creates more power on top end, because there is more time for air/fuel to fill the cylinder. Increased duration eventually causes a problem with idle however, because the timing that works so well at high RPM provides too much time at low rpm which lowers vacuum and smoothness of the intake velocity. Increase the duration enough and you will eventually get to the point that there is a large "overlap" between the exhaust and intake, where both are open for a split second. This overlap doesn't affect the engine at high RPM, as the time period is so short. At idle though, the time period is much longer relative to intake velocity and the intake charge actually has enough time to travel into and out of the engine without burning. Hence, a "loping" idle.
I dont quite understand how the returns would be diminishing. The rest of the data makes perfect sense and is why I dont think going 272 is nessesary unless you plan to rev really high (over8k). Also the large overlap creates unfriendly driveablility in the first few thousand RPMs.
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Old May 10, 2004 | 03:05 PM
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From: American Canyon C.a.
How about Tomei cams compare to Jun & HKS
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Old May 10, 2004 | 08:22 PM
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From: San Antonio, TX
Originally Posted by xstang
Sure.... Should be a blast!!!! I know a great stretch of road... (-:

Monkey, are you located near Bedford tx?
I'm actually in Waco right now finishing up school, but I am moving to Arlington this weekend after graduation. So I won't be too far from Bedford.
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Old Jun 10, 2004 | 12:43 AM
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From: Texas
Originally Posted by ImportPePe
xstang, do you have a black Evo w/ the "Evolution VIII" badge by any chance?

I happen to saw a black Evo that was very mean-sounding on US 377 in Keller on Saturday on my way to work, and wondering if it was you by any chance. The reason I'm curious is because you mentioned that you got your cams done at evo8.com, which is next door to Gotham Racing, and the one I saw on 377 sounded like it was "cammin'", so I figured with the direction it was heading, I may have thought it was yours. Correct me if I'm wrong. Thanks
Nope, that was me I'm pretty sure. I'm out that way alot doing my community service.....don't ask, long story. I have hks 272/272 with no cam gears. My car has a custom dynoflash and the idle is still rough, but not so bad that it stalls.

I just bought a Utec so it'll be interesting to see if it will smooth out a little more with some experimenting.
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