I'm not talking about AFM/DOD, as that technology doesn't interest me in the slightest.

But I am very curious as to how everyone is tuning their vvt phasing tables.

What sort of results are people achieving with the aftermarket vvt cams? Post your results and engine/vehicle stats, please.

Can the vvt be tuned to help with spool/boost? I almost want to ask this question twice.

Does anyone besides TSP offer dyno tuned phaser tables?

Are the TSP tables available for reference/reverse-engineering?

Seems it would be useful to at least compare the changes they have made in their tuned vvt table versus a stock vvt table to see what they are changing, and by how much.

Any insight into this matter would be greatly appreciated. Thanks in advance.

 

I sure don't know what they offer but maybe these guys can help, or not.
Ad says something about VVT. hope it helps

http://mastmotorsports.myshopify.com...ant=1317709251

 

Thanks for the response. As for mast motorsports vvt products, I believe it all orbits around their m90 standalone computer. I don't know if they provide dyno tuned phaser tables separate from their ecm.

I was hoping to see what people are doing with the vvt programming using hptuners/efilive software and factory ecm's.

I would really like to see if the vvt programming can be used to influence boost, and either reduce spool lag or build boost on the line.

A lot of people add timing to spool the turbo(s) and start pulling timing back out once boost reaches a desired point. I would imagine that the vvt could also advance the cam in a very similar fashion to achieve a very similar result, and retard the cam once in boost to carry power further.

I am actually surprised by the lack of information available on this subject.

 

simply put.... VVT is just advancing or retarding a cam .......just like doing a cam install.,.. except controlled by the ECU instead of by you physically placing it in at one specified angle

so teh same things occur...
advancing the cam will shift the powerband lower, retarding the cam will move the power band higher...

in general...you can advance the cam at lower rpm's to get a little more torque and retard it some at higher rpm's to make it carry out further..

but you have to remember...its not huge amounts...
4* or 8* one way or the other might only shift the curve by a few hundred rpm...

its more of a help with fuel economy than it is with power
but there is power to be made by playing with it...especially in high rpms with an aftermarket cam.

it can help with turbo spool by advancing it down low...but there is a point where you go too far and it starts hurting it again...
same goes for up top... you can retard it to make it carry further...but again..you can go too far..


you have to have a dyno to play with it to really see what your combo likes.

 

Many turbocharged engines from Japan, like the sr20det, offer an intake valve advancement of 20* from 1200rpm to 5400rpm, as the above posted mentioned for more VE at low rpms and better economy. The device is solenoid/oil activated and simply turns off at 5400rpm allowing the cam to fall back 20* to where it was originally (there is no gradual movement but rather a sudden on/off operation, which seems to work just fine for these engines made in 1995-2002, all of which offer maintenance free timing chains/valvetrains for 200,000+ miles of service).

I would certainly expect to see some better engine vacuum taking any camshaft and electronically adjusting it to be 5-15* advanced for the low rpm.

 

the good thing about GM VVT..is that if it fails...you dont have to worry about Piston to Valve issues....it maximum mechanical position is safe in full advance and full retard with a stock cam...
so you can really push it anywhere and not have to worry about tagging parts together mechanically
with an aftermarket cam you have to be much more cautious about how far you push it since you have more duration on the lobes

If I remember correctly...(I might be remembering wrong)
GM has 7* max advance and 45* max retard


but really... I've never seen any benefit once you get the ICL of a cam more than 10*-12* retarded
some cams I didnt see any benefits going more than just a few degrees retarded on the top end..

 

What I read was ~50° total adjustment, with 6-8° total advance and the rest is retard... For the factory gm stuff. And the system remains non-interference at both extremes of the phaser limits.

The aftermarket vvt cams are coupled with a phaser limiter, making only +10/-10 max cam timing adjustments, but that seems to be all that is useful, anyways.

I was just thinking that you could tune the cam to mechanically retard in situations where you would normally pull ignition timing. Maybe alternate between advancing/retarding one degree of ignition timing and one degree of cam timing in places where you previously could only adjust ignition timing.

I love the thought of using it to advance everything to reach boost, then retard it once in boost to carry power further. And it seems like you could do it with fluid smoothness, rather than on/off like the jdm systems mentioned.

 

All theory aside, the proper way to set this up would be at the dyno. Simply put, if the system allows for on-the-fly adjustment of camshaft setting, I believe that I would first run the car with many degrees of retard, then run it nearly full advanced, and looking at the two graphs, determine the point at which one begins to defeat the other; knowing these two extreme situations, then, I would choose an advancement RPM that gave me the best looking graph (torque).

Boost is a completely different thing; you can have a fast onset of boost pressure without the onset of power, if your engine is not using the given compressor flow efficiently then it is just air pressure in the intake manifold. If the engine is a turbo model, then it can desire either a retard OR an advancement, as pressure within the exhaust manifold is driving the turbine AND seeking to re-enter the combustion chamber when the exhaust valve presents the opportunity; and this will be directly affected by your camshaft timing. There are other forces at work, such as EGT, a lean running engine typically results with a higher EGT and this will typically result with a higher turbine RPM (better response from the turbo), the idea here being only that these systems need to work together, and that there is no one size definite fits all solution (retarding a cam does not ALWAYS result with slower boost or less power; you must test the engine in question).

Last, I want to point out why i brought up the so called "JDM mechanism". That is, if they are suddenly changing cam timing by 20* all of the sudden, well, it must not be harmful or undesirable to do so. That is to say, you would expect that they have tested their system with some engineering platform and found that this was optimal given constraints for it's construction. We would not see such a device if there were no major benefit without any enormous drawback. It is something to keep in mind as we wander the fields of engine VE improvement technology.

 

I would like to revisit this discussion.

Hopefully we can get some first-hand experience with taking advantage of VVT tuning in here.

I am still very curious about VVT being used as a way to maybe not control, but influence, boost.

 

It's better to just tune for power. If you're optimizing for boost, you could "succeed" by restricting the flow of air into the combustion chambers. In other words, more pressure in the manifold, but less power.

I'm surprised nobody has come in to say "boost is just a measure of restriction." I hate that phrase with a passion, but this is one context in which it is actually informative.

 

What is it then?

 

It HAS been said in these forums somewhere, but not this thread.
But yeah, boost IS a measure of restriction, as pressure always needs something to "push" against. A non-restrictive passageway can never show boost pressure.

 

It's not the "is" that annoys me about that phrase, it's the "just."

You can change the boost without changing the restriction, so there's obviously more to it than just restriction.

 

I currently have an LMG 5.3 being built by Central Florida Machine and Speed

Stock Crank
Wiseco Forged 3.903 pistons with valve reliefs -11cc
Callies Compstar Forged H Beam Rods
Texas Speed VVT .600 216/220 112 LSA Cam

just trying to get it running well NA for now, not looking for max NA power. Will at some point, hopefully soon, experiment with some boost. I’ll let you guys know the results as I know this is a topic that doesn’t have much info out there.