Hey Everyone!

Long time lurker, first time poster. Some of you guys may know me from the "other site", and some of you may not.

Anyways, I just bolted a whipple kit on my 04 5.4 3v screw 4x4 and I have some questions...

First off, I'm loving this blower!! I'm currently running a JDM base tune for my setup and I noticed that my VCT operation is at zero on my edge. I'm currently tuned with the SCT X3, but I am still using my edge CS for monitoring PID's. I have an AEM wide band and AEM Boost gauge installed and the tune thus far looks very good for a base tune.

Right now with the base tune I'm boosting around 8 psi with the 9# pulley. I have Hiflow Cats installed, y piped dual's, and a modified Volant CAI for the whipple. My blower specs are 47# injectors, air charge temps are being read from runner 5 on the intake, 95mm whipple MAF, and a 3.250-6 pulley. I'm in the process of data logging and tweaking the tune a bit with JDM, but I could sure use some advice from any of you guys with experience... For the record JDM's base tune has been solid and safe, so do you think he locked out the solenoids to maintain safety for my base tune?

What has everybody here been doing with the cam phasing anyways? lockouts?, Limiters? or leaving the phasers alone and tuning them?

What should I be looking for in my tune? What are some good questions to ask my tuner the next time we speak?

Thanks in advance guys!

 

So Jim jr told me VCT is likely disabled for safety reasons which does confirm my thoughts. But have any of you blown guys kept it operational with any success?

I'd like the milage benefits I can garner from it, but I also enjoy the feeling of the word safety. I've been running 5w-30 for over 65k miles and have had no phaser or timing issues to date.. I switched to 5w-30 to quiet things down a bit and to ensure the most protection, so I'm wondering if it would be worthwhile to go ahead and have it dialed into the tune... For now I'm in no hurry, because the truck runs like a top and hauls ***! But I'm still wondering what everybody's take is on it....

 

So my idle is at 688 in park, and taps 700 in gear.. I've got 22-24 vac at idle and on the brakes.. Is this a high idle for a blower?

Does everybody here have VCT enabled? If so, how's your gas milage when staying outta boost??

 

For the supercharger on your truck, how is the recirc/bypass valve controlled?

If it's electronically actuated, a tuner should be able to leave the VCT active and on-cal (or slightly reduced to combat higher MAT causing knock).

If it's vacuum controlled, the fuel economy gains of the VCT usually are decreased because the actuator ends up closing recirc/bypass valve sooner thereby increasing the energy consumed by the supercharger.

 

Wow this all sounds pretty good to me! Thanks for the great info!

I had another conversation with Jim and he said they always disable VCT for the 04 and 05 model year f150's as a precaution.. But I did ask for him to enable it, which he said he will..

Overall the truck runs supreme. The only thing I changed on the JDM tune were the 1-2 shift pressures. I'm not a huge fan of having such a firm shift at low speeds.. It feels perfect now..

I also just installed my frozen boost HE tonight and man did it make an improvement! I'm only seeing about a 4 degree drop in ACT's ranging from 20 - 16 degrees above ambient. But now it seems as though I can hit 8psi no problem where before it would only kiss 8psi and hold 7psi no problem.. Overall boosting feels much more powerful and the engine as a whole feels like its running as perfect as possible...

I also discovered tonight that my squealing belt in fact is a worn bearing in my whipple supplied manual tensioner. If anyone knows where I can get the bearing to fit this pulley I'd be happy to have it..

After taking a good look at that fluidyne unit and how restrictive to flow it is, I ended up scrapping my plan to daisy chain the 2 together.. The bars on the FB 3.5" thick HE are flowing much better then the fluidyne. I can even tell by just watching the movement of coolant in the degas reservoir.. It did not drop my temps drastically, but it did seen to offer up a vast improvement in the overall operation of the motor, plus it really helps me hold 8psi like never before! Boost temp recovery time is very quick, and I have yet to see my cruising temps break passed 20 degrees above ambient... Tonight was my first cool 58 degree night with the blower and wow! What a difference!

 

I'm talking about any simple spring loaded vacuum system where the available vacuum keeps the valve in the bypass position. Depending on the actual actuator assembly, it will start flowing through the SC as early as -40 kPa gauge will full flow around -20 kPa. With intake phasers calibrated to run the engine as close to -5 kpA gauge as it can handle, that means air will be flowing through the SC and the throttle will be fully controlling MAP thereby defeating the gains from the VCT.

I don't know what manufacturers use which system. I just know what I've had to work with.

 

The bypass is Vaccum controlled.
So your saying the bypass will close sooner with VCT? I kinda don't see how that's possible, do you care to elaborate?
Right now with VCT locked the bypass closes around 2,000 to 2,500 rpm's depending on how quick I pull Vaccum out of the manifold with the throttle.. To me it would seem like it should work the same, if not by just making the throttle a bit more touchy and responsive.. But I'm still learning here so please chime in..

A spring loaded bypass would basically be like wastegate on a turbo.. Picking your spring rate would effectively pick your boost time..

 

Here's a very very over simplified explanation of what happens with VCT controlling the cam timing. For a given airflow at a given engine speed, the MAP will be higher (less vacuum) with VCT active than VCT blocked so that pumping work (how hard the engine has to suck) is reduced, thereby making the engine more efficient. With less vacuum for a given airflow and engine speed that means the supercharger bypass valve will start to close sooner and allow air to flow through the supercharger. You are correct that adjusting the actuator and/or its spring will can change the exact vacuum at which the bypass valve will start to close, however that can be a can of worms if the actuator becomes unstable (opening and closing too rapidly) and fighting with the throttle.

From the factory with VCT active, the accelerator pedal position does not directly control the throttle body. It controls a combination of throttle position and cam phaser position. Even with the VCT blocked the accelerator pedal position doesn't correlate directly with the throttle position, aka YY% pedal does not equal XX% throttle position at all speeds, because it's all electronically programmed. That "touchiness" you may notice is someone having messed with the pedal calibration.

Turbo vs Supercharger control
For consumer vehicles, a wastegate on a turbo usually works in the opposite direction of a supercharger. Air is always flowing through the compressor side of the turbo charger. Also the turbo charger is upstream of the throttle body. Until boost is made on a turbo, the wastegate is forced closed by its actuator so all the exhaust flows through the the turbine. Once a certain threshold of boost is made, the wastegate starts to open so that exhaust gases can bypass the turbine to reduce the power used to drive the turbine and compressor and prevent excess boost.

The bypass on a supercharger is equivalent to bypassing airflow on the compressor side of a turbocharger. The supercharger bypass literally allows the air to go from the throttle body to the intake manifold completely. Near zero airflow goes through the screws of the supercharger.

 

In the end, because the SC is vacuum controlled, you'll see very little gain with the VCT active and as long as the tuner redoes the spark calibration having the VCT blocked will be fine.

 

Thanks for the excellent post corpsie!

I checked into what you said, and you are spot on.. I've decided to leave VCT off.. I may still turn it on in the future, but I am more concerned with getting my fuel trims dialed in at this point.
I've managed to get up to 21 mpg with my blower on a tank of gas and corresponding driving habits. So I'm not missing VCT at the moment. Of course with great milage like that I was not boosting a whole lot, but I was still boosting when the lay of the land necessitated it.
I've actually been on the fence quite a bit with regards to VCT. It does seem as though your argument makes a lot of sense. Now if I did put VCT back on, I'm wondering if it would clean up fuel trims a bit.. My trims are a little "jumpy" but nothing that the 02's can't easily correct. I'm wondering if I did turn VCT on if this would clean up my fuel trims a touch..

On another note..
I have had a long crank at cold start for sometime now. Somedays its longer then others, but still long.. The long crank sounds like the engine is starved for fuel at cold start.. With my 47# injectors, I'm wondering if they are scaled correctly. I get perfect starts on a warm engine, but a long, sluggish start on a cold engine. Anybody have any ideas why this is happening?..

 

Don't get me wrong, I wouldn't mind if VCT was functioning on my tune. I've been datalogging and watching the PID's carefully. I've noticed that boost can be "crept" into with the accel pedal position around 45 to 51% without dropping a gear (with a careful foot). I can usually see up to 3 lbs of boost before the Trans predictably drops a gear and boosts up to 9psi.. I'm wondering if I could even get the high gear boost creep I'm getting with VCT on. I can definitely tell when the bypass closes at zero Vaccum, and I can see the leaner burn on my wideband while in high gear when I'm creeping into boost in 4th gear.. But I'm still wondering what others are experiencing with VCT on or off...

Anybody have any idea whats up with the long crank, sluggish cold start issue I'm experiencing. Like I said, when the engines hot the truck turns over briskly in a few short cranks, but when cold it takes more cranks and kinda lags for a second before she fires up.. JDM says its normal, but I'm still wondering if it has something to do with how my 47# injectors are scaled in the tune. Could it be they just need a bit more refining on the scaling in general? I'm thinking it might also help clean up my fuel trims a bit too.

 

My VCT is on. I have a tune with it on and off. Truck is faster at the track with it on. My throttle settings allow me to make 2-4lbs of boost by just slightly touching the throttle even at 1200rpm. Love it. In fact in a high gear at low rpms it rocks because the blower starts whining and the truck accelerates fait quick without a change in the exhaust note. As for the start issue. Try this. Get in, turn the key to on but not to start, put your seat belt on, then start. That few seconds of delay while you put on your belt allows the fuel pressure to come up. Truck will start right away.

 

I've tried that trick a few times.. It does seem to make it slightly better, but I still get that cold start lag. I even gave it 5 Minutes once......
Now you got me wondering if I have an issue at the FRPS. I should note that on the 04's like mine, our fuel rail pressure sensor is smaller, and the fuel rail is even different, with different injector clips.. I wonder if this has anything to do with my issue.. Otherwise I keep thinking it's the injector scaling in the tune..

It's nice to hear the VCT is working out well for you. I think I might have it turned on. I have been kinda hestitant with this cold start lag I've never had when stock question still lacking an answer... I was even wondering if it could be a slight oil pressure or pressure sensor issue at cold starts. If this is the case, then I'm guessing I' possibly have a timing tensioner draining down when the engines at rest.. The motors whisper quiet, no ticking, or knocking. I do have a very slight passenger side exhaust manifold leak that seals up pretty good when hot...

Is this cold start lag common with supercharged engines?

 

The only time I have any type of lag, is right after I change the tune in the truck. It takes probably 5 seconds, after a reflash, then it always fires right up after that.

 

What happened to the rest of this thread? I noticed crash disappeared and his posts are missing, what gives?

Just curios to see what kind of VCT reading you guys are seeing on your datalogs and tuners. How much are you guys seeing at 3000 rpm's and higher?

Anybody here know exactly what parameters are monitored to regulate VCT function? I've read it's engine load and rpm.. Is it pulling from a look up table or on the fly? I'm guessing look up table, but would like some input from someone who knows for sure or anyone who has any ideas..