Variable Valve Timing
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Joined: Jun 2014
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From: Montana
Variable Valve Timing
Is it too soon to ask how everyone feels about the possibility of VVT on a (speculated) new version of the M8?
Please enlighten me on Variable Valve Timing, I'm just looking for a discussion.
Please enlighten me on Variable Valve Timing, I'm just looking for a discussion.
Grand HDF Member
Joined: Nov 2017
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From: Texas
Look at this Motorcycle.com dyno comparison of the VVT-equipped Sportster S vs the non-VVT Indian FTR. Same peak power from the same displacement, but the lower-RPM power is so much better from the VVT:
But, the speculation around the M8 VVT is suggesting it may have more to do with meeting tightening emissions control requirements, rather than optimizing power. Then again, they thought this system was more likely intended as a Sportster engine replacement rather than the M8, so take their speculation with a huge grain of salt.
Of course, we don't currently KNOW anything (and some folks will insist that it's all fake Photoshop anyway), so the speculation I'm talking about is from articles written about the VVT patent filings Harley made a few years ago.
Example:
https://www.google.com/amp/s/www.mot...vt.html/%3famp
Last edited by FatBob2018; Apr 1, 2023 at 12:38 PM.
Road Captain
Joined: Jun 2013
Posts: 671
Likes: 168
From: Ontario, Canada
The nice thing about VVT is that it can be used for both power and emissions improvements. It's a proven technology that I feel could have real benefits.
I trust VVT more than the BMW shift cam system and feel it can give a broader range of benefits
I trust VVT more than the BMW shift cam system and feel it can give a broader range of benefits
Seasoned HDF Member
Joined: Mar 2012
Posts: 100,455
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From: Centennial, CO
It will depend on the technology Harley decides to use and how they implement it.
Gratuitous bash: Knowing how the MoCo has implemented new tech in the past, I suspect this will be a **** show at first with lots of warranty claims as their weak (read: cheap) attempt and less than comprehensive testing will expose itself on the road.
Gratuitous bash: Knowing how the MoCo has implemented new tech in the past, I suspect this will be a **** show at first with lots of warranty claims as their weak (read: cheap) attempt and less than comprehensive testing will expose itself on the road.
Cruiser
Joined: Aug 2022
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From: South, TX
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Road Captain
Joined: Jun 2013
Posts: 671
Likes: 168
From: Ontario, Canada
It shouldn't have any impact on the lifters. They have no idea what they're doing, just following orders. The VVT will just make slight adjustments to the cam timing, it won't effect the load on them.
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Cruiser
Joined: Aug 2022
Posts: 151
Likes: 157
From: South, TX
The VVT system as a whole is what I was alluding to. VVT system failures, including cam actuators/phasers, oil control solenoids, provide for unlimited salty language around our shop.
Now AFM lifter failure and its associated system are not VVT but they also contribute, as well as two stage oil pump solenoid failures.
https://www.mightyautoparts.com/wp-c...ch-Tip-204.pdf
Now AFM lifter failure and its associated system are not VVT but they also contribute, as well as two stage oil pump solenoid failures.
https://www.mightyautoparts.com/wp-c...ch-Tip-204.pdf
Road Master
Joined: Mar 2013
Posts: 817
Likes: 380
From: Central Ohio
The only way to truly have vvt act like multiple cams is to have separate cams for intake / exhaust, then have an actuator for each. Can change centerline and lsa on the fly.
With a single cam all you control is the amount of advance. I'd venture to say most people will be doing a VVT delete (or limiter) when upgrading to a larger camshaft because of valve clearance issues
With a single cam all you control is the amount of advance. I'd venture to say most people will be doing a VVT delete (or limiter) when upgrading to a larger camshaft because of valve clearance issues
