Variable Valve Timing and tuning

[Meow]

Has anyone played around with variable intake valve timing to try to make some more power in areas. Our car stock have cam timing advance between 1k and 4k rpm stock, but this could be tweaked a bit to improve spool or improve high end flow for various different turbo setups. I did some searching and have yet to find someone doing any in depth research on what adjusting this might do to air flow and power curves. Anyone try tweaking it?

Stock valve timing advance:


If my thinking is correct, decreasing intake timing advance (aka retarding the intake timing) before the spool will increase boost pressure earlier and then increasing the intake timing at later rpm after spool will increase air flow up top and give a more broad power band (if your turbos can support the air flow, like k04's or bigger). This could really help the single turbo guys.


This is about the only thing that I can find with people tweaking it.
(not a b5, but its VVT)




Found another link to 034 motorsports doing some tuning with their A4 - http://blog.034motorsport.com/tuning...-cam-adjuster/

After receiving a fresh set of Cat Cams 3658 Billet Camshafts, we were able to do some dyno testing and determine the viability of utilizing the factory 1.8T VVT cam tensioner to improve the powerband of our Time Attack B5 Audi A4.

We verified clearance for up to 30 degrees of advance on the intake camshaft (the VVT tensioner itself only provides about 22 degrees of advance) on our 2.2L stroker motor with the 3658s, plugged in the VVT tensioner to our 034EFI Stage IIc Standalone ECU, and got to work.

Turning on the VVT tensioner resulted in about ~400 RPM quicker spool, and solid power gains up to ~6200 RPM. We netted gains of over 60 foot-pounds of torque at the wheels at ~4000 RPM.

Take a look at the dyno chart below, which compares one pull with the VVT tensioner turned off for the entire pull, and one pull with the VVT tensioner turned on for the entire pull.

By calibrating our ECU to switch the VVT tensioner on at low RPM, and off at ~6200RPM, we were able to combine the best of both worlds. This results in a much broader powerband, with a substantial pickup in low-end torque without sacrificing the impressive top-end power that the 3658s allow.

We strongly recommend checking clearances on your 1.8T build before attempting to utilize the VVT tensioner. Depending on the specifics of your motor, there may not be enough clearance to turn the VVT tensioner on without piston to valve contact.

Obviously, the potential gains and optimal switchover point will vary from build to build depending on the cams you’re using. For example, on stock AEB cams, there was only a ~5WHP gain at extremely low RPM.

This sounds wicked awesome, good low end torque and picking up lots of top end potential. I would love to see more info out there for the 2.7t engine and using its VVT to broaden the power band as well.

[julex]

Has anyone played around with variable intake valve timing to try to make some more power in areas. Our car stock have cam timing advance between 1k and 4k rpm stock, but this could be tweaked a bit to improve spool or improve high end flow for various different turbo setups. I did some searching and have yet to find someone doing any in depth research on what adjusting this might do to air flow and power curves. Anyone try tweaking it?

Stock valve timing advance:


If my thinking is correct, decreasing intake timing advance (aka retarding the intake timing) before the spool will increase boost pressure earlier and then increasing the intake timing at later rpm after spool will increase air flow up top and give a more broad power band (if your turbos can support the air flow, like k04's or bigger). This could really help the single turbo guys.


This is about the only thing that I can find with people tweaking it.
(not a b5, but its VVT)




Found another link to 034 motorsports doing some tuning with their A4 - http://blog.034motorsport.com/tuning...-cam-adjuster/




This sounds wicked awesome, good low end torque and picking up lots of top end potential. I would love to see more info out there for the 2.7t engine and using its VVT to broaden the power band as well.

This is a good post for nefmoto.com. Not to offend anybody here but truth is 99% of people here have zero idea about tuning and the ones that do... are also on nefmoto.com and that's where we discuss these things.

Cheers.

[034Motorsport]

This isn't something that can just be "played with" using Motronic. While it is possible to change crossover points, its not like Lemmiwinks where you can just point and click.

In general we consider VVT to be worth over 50whp and similar torque at various points in the point band, and sometimes even more in the lowend.

However, the reason why we saw so many gains was because we are comparing "no VVT" to "VVT". The gains in messing around with the CCT on a Motronic tuned car versus a stock crossover point isn't going to be anywhere near as dramatic.

We currently are not using VVT on our GTi-RS 3.0L APB project car because there is serious risk of the valves contacting the pistons, depending on how much base timing there is on the cams. Very large valve reliefs are required for this application and our 3.0L pistons just didn't have enough relief to safely use VVT.

Most normal cars or regular builds on pump gas won't be able to take advantage of the increased timing anyways as they are already limited by octane, etc. A full out build with race gas or E85 or lots of meth would benefit more for increasing the range of the VVT.

[jibberjive]

This is a good post for nefmoto.com. Not to offend anybody here but truth is 99% of people here have zero idea about tuning and the ones that do... are also on nefmoto.com and that's where we discuss these things.

Cheers.

Took the words out of my mouth. This is really technical, and is probably best discussed on that technical forum.

Here's a thread that is somewhat relevant to playing with the cam switchover on the ME7:

http://nefariousmotorsports.com/foru...p?topic=1848.0

And, as Max said, if you play around with this, be very aware that playing with cam timing could lead to interference contact with valves/pistons if done wrong.