Engine Swap Forum

I'll be trolling the megasquirt forums and doing some more research into the issue but I've come to the conclusion that a dumbed down version of megasquirt may be the best for controlling VTC's. Consider it a $250 investment for 100lb-ft of low end torque on a nat asp engine (the 100lb-ft is the common # I've heard from multiple sources). With the right tune (ign & fuel, in addition to cam timing), I suspect the gains could double on a turbo engine.

The option of using the Fast Idle (FIdle) circuit on the MS was presented as the most viable option for MS users (due the PWM triggering req'd by the VTC), but it was expected that MS would be controlling ignition and fuel. My application has a dedicated ecu and I was thinking of using the megasquirt's fuel injection drivers & maps to continuously vary the cam timing...

<insert curious minds here>

Controlling the VTC using the injector drivers (and maps) also allows the possibility of replacing what would be engine inputs, with more appropriate inputs as desired. The one most appealing to me is [IF: wheelspin = true & rpm = <4000; THEN: duty cycle = 100%] (You ECU nerds should be able to figure that out). It allows the use of MAP/ RPM/ Throttle position/Wheelspeed/ etc as inputs for cam timing (I'll call this the Speed Density VTC configuration). For those who don't want "ultimate adjustability", the Alpha N VTC version could be used... 

Of course it will require some reverse engineering to perfect the maps.
For e.g. since MS calculates PW using [REQ_FUEL * MAP/100 * VE/100 * GammaE/100 + Inj Open Time], either some of the built in calibrations or the engine-size-derived inputs will have to be zeroed or scaled to get the pulsewidth required for the VTC (which Fred had sourced in the FSM).

Another advantage that comes to mind is that it opens the door for the other potential ecu's (Haltech, SDS, Accel, F.A.S.T., modified VG30DETT ecu, etc) to jump back on the VQ bandwagon...

Needless to say this setup has it faults. Firstly, there's the process of reverse engineering the whole PWM thing. Now u have to spend another $250 on an extra ecu and then u have to spend time assembling it. Now u have to load the tuning software on the tuning laptop as well. Then there's the whole deal of getting it tuned properly (~5 dyno runs) and the whole "ultimate adjustability" thing. And this is just for the basic Alpha N type setup...

I get the feeling not many ppl will come along for the ride but I'm hoping some of the intelligent ppl will at least be up for a good discussion...

Post your thots!

Regards,

H. Kurt Betton

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Argh... guess I'll stick w/ the plan...

You need to talk to a few guys on maxima.org, a few of them have done alot of testing and have the inital stuff figured out.I'll see if I can dig up their names...

IMO I wouldn't use a whole MS, if its just the 2 or 4 outputs then I would think it wouldn't be too much harder to make a simple controller and just use simplified MS software.... Then you can sell to an entire standalone market and not just MS users.

How many people that use haltec and microtech want to use their honda or nissan or toyota VTC's (just keeping it general) with a standalone? Any way either way Im very interested, as my main goal with any engine buildup is a wide power band and VTC's would be very benificial NA or boosted...

~Alex

I'll check out maxima.org to see what ppl are doing nowadays. I know alotta guys there have fully functioning older gen VTC's so I wouldn't be surprised to see them doing work on the new PWM type.

To make sure we're on the same wavelength, I don't plan to sell whatever I plan to use. I'd do it MegaSquirt style (or Fred style if u may) and post my info online and whoever's willing to do the work can do it. (The more ppl that feed the community, the better the world will be...) Maybe it'd influence the tech heads at msefi or the guys at DIYAutotune to make some adjustments to the program and help us VQ35 guys some more

I see the logic for the simple controller but designing micro circuits is not my forte so somebody else would have to do that part. Also I figure once we get the MS setup running properly, we could start eliminating the unused circuits from it for future users (approaching the 'simple controller' idea).

Not to mention that the simple controller probably won't have the benefit of continuously variable cam timing (and the wide array of input options mentioned/ unmentioned in the first post). If I had to go thru the trouble of buying, wiring & tuning an additional ecu (or simple controller), even if I only wanted the "Alpha N VTC" control, I'd feel more comfortable knowing I could go "Speed Density VTC" if I eventually wanted to.

The 'tuner market' (I hate hearing those two words...) is flooded with marketing strategies claiming "the most horsepower per dollar" blah blah blah. How many can guarantee low end torque (100lb-ft of it) when properly tuned with absolutely no loss in top end power (possible gains!) for $350 (that includes any wiring & accesories req'd). I expect once we have this thing up and running the price will come down.

I only know of 2 VVT systems that use PWM activation (of course I don't know everything...) so the main target of the MS VTC controller would be the VQ35 market (HR included). I expect the floodgates to open for all those PWM controlled electronic throttle bodies that are also giving the aftermarket ecu manufacturers hell...

All that being said, if somebody wanted to start working on a simple controller, I'd definitely be reading their posts tho!

Regards,

H. Kurt Betton

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Argh... guess I'll stick w/ the plan...

An interesting conversation about this prospect going on on maxima.org thans to Alex_V

http://forums.maxima.org/showthread.php?t=506364

Regards,

H. Kurt Betton

 

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Argh... guess I'll stick w/ the plan...

Sup guys ,

i am glad to see members doing R&D for the Vtc

i must admit i am completely surpass in this subject , ill try to do some catchup...

Heres a very interesting post on maxima.org from Eng92 http://forums.maxima.org/showthread.php?t=476664&highlight=vtc

just in case u dinot see it , witch u probably not but still ..