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VVT Solenoid- Red Bullet or Bull@*$% ?

Discussion in 'Gen 2 Prius Technical Discussion' started by mr_guy_mann, Sep 8, 2021.

  1. mr_guy_mann

    mr_guy_mann Senior Member

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    WARNING! Long winded post below with lots of technical content!
    Continue reading at your own peril.

    SO, for a while I have been intrigued by the claims made by Red Bullet about
    their VVT solenoid. Better, faster, MPGer, etc. Initially, I was skeptical, both
    because the website has lots of marketing hype with no data, and because as a
    mechanic I don't see how "shortening the response time" of the VVT system
    would have any significant gains - the system (at least on a Prius) usually isn't
    being commanded to make rapid changes to cam timing. I BELIEVE IN DATA. I
    don't want adjectives, or testimonials. I want tests that I can perform (or at least
    understand the procedure) and the results from those tests. Anything else in my
    eyes is here say, opinion, or placebo affect.

    First, what is VVT? ICE design is a series of compromises. Power vs. emissions vs.
    MPG vs. cost. The ICE is an air pump- the timing of the valve opening and closing
    (in relation to the crankshaft or piston position) directly affects how efficiently that
    pump works (which affects the other variables). Using a camshaft to mechanically
    control the valves is a cheap and reliable solution, BUT the "best" valve timing
    changes as RPM and load changes, while the cam lobes are "fixed". So a cam
    design that's good at low speeds doesn't work well at higher rpm and vice versa.
    Variable Valve Timing allows the camshaft to rotate with respect to the cam
    sprocket- altering when the valve timing occurs vs. crank position (at a decent cost).
    This allows the engine to operate more efficiently over a broader RPM range. It doesn't
    increase horsepower, but it can "flatten the torque curve".

    How does it work? The ECM controls a solenoid that has an electromagnet that
    moves a round piece of steel (called a pintle). The pintle pushes a round bit called the
    spool valve while a spring pushes back. The spool valve is in a housing that
    directs pressurized engine oil through passages in the cylinder head to the
    intake camshaft sprocket (VVT actuator). Controlling how much oil goes into two
    different sections of the actuator controls the camshaft timing. With the solenoid
    "off", the cam is fully retarded (timing is "late" vs. the crankshaft). With the
    solenoid fully "on", cam is fully advanced (timing is "earlier" vs. the crankshaft).
    Changing the voltage will change how much the spool valve moves- allowing the
    timing to be changed slower, or to "hold" cam timing steady by keeping equal
    pressure in the two sections of the actuator.

    I wondered about how well the Red Bullet would work, eventually I went and
    bought one to test it. Then to be thorough I bought a new OE unit from the
    Toyota dealer, as well as the cheapest one I could find on amazon.

    But how would I test them? Don't have a dyno to measure torque at the crank.
    Acceleration tests have way too many variables. MPG tests have even more
    variables. I know, why not measure what the website claims that the RB does?- ie,
    how fast it takes for the VVT system to respond to solenoid commands.
    Now I must say that while I generally like Toyota and how they design things,
    when it come to the VVT system and scantools- their engineers were schmucks.
    Most other makes have USEFUL VVT data and tests- desired and actual cam
    position, solenoid % commands, even position error. Great stuff. Not Toyota- the
    data is "turned off", even though the system is always "in use". Data IS there but
    only while performing a VVT bidirectional test. The "VVT CTRL percent" test is fairly
    useless as it takes a long time to change the solenoid command one click at a time
    (+1%, +1%, +1%....-1%, -1% etc). The "VVT CTRL on/off" test is better- it rapidly
    commands the system to full advance (73% DC) or full retard (12% DC), but both
    tests ONLY function at idle- don't really have lots of oil pressure then and Prius likes
    to shut off the ICE when it wants. Any throttle applied will cancel the test.
    The lack of VVT scan data made it difficult to determine what the ECM was
    commanding, and even if there was data, a scan tool is much too slow to
    evaluate VVT function and effect.

    It was time to bust out the oscilloscope and get crafty. A scope displays electrical
    signals along with a time base- so you can "see" things the same as what goes in
    and out of the ECM. Voltage is displayed on the up & down axis of the graph while
    time is shown from left to right. (it's a fancy voltmeter that uses piles of colored
    string instead of numbers).

    The ECM controls the VVT solenoid by switching the positive power supply to it
    on-and-off really fast (300 times a second). The solenoid can't open and close
    anywhere near that quickly- but by changing the percentage of time that the
    voltage is high (14.0V) or low (0V) [during each of the 300 cycles per second], the
    average voltage is changed- which controls how far the pintle and spool move.
    This is known as Pulse Width Modulation (PMW), and the percentage is called
    "uty cycle" (DC). 100% positive duty cycle for this system would be 14V, 90% = about
    12.6v, 50% = 7V, 10% = 1.4V, 0% = 0V, etc. After driving the car for weeks while
    scoping the VVT, it appears that 12% DC is "full off" - retard. 37 to 42% is "hold the
    timing steady". 45% and up is "advance" but I seldom saw anything much above
    50%. Here and there I briefly had 55-60%. 50% and 60% DC were the "advance" target
    I used for manual testing while 15% DC is "retard" (effectively the same as 0%) .

    The ECM has sensors that it uses to monitor the crankshaft and camshaft position
    (and how they relate to each other). Each sensor generates a pulse of AC voltage
    when a spoke from the trigger wheel (on the crank or camshaft) passes by. The
    crankshaft has 34 teeth spaced 10 degrees apart with 2 teeth missing to create a
    signature pulse that the ECM can recognize (aka 36-2 pattern.) The cam has 2
    pulses during one crankshaft revolution then 1 pulse for the next - again to allow the
    ECM to ID where in the 4-stroke cycle the engine is. Here is the waveform for my Gen2.
    SYNC.jpg
    The test subject in use is my 2006, with 175K (and apparently decent maintenance
    by the previous owner). I performed several tests on each solenoid- attempting to
    minimize variables and create repeatable results. I installed the solenoid and
    drove it a few days (can't say that I noticed any particular "seat of the pants"
    difference for ANY solenoid). Engine oil is generic synthetic with a couple
    thousand on it- level is full. Then for the tests I warmed the engine up until the
    radiator fan cycled several times.
    VVT SCREEN.JPG
    First test was to unplug the solenoid and manually apply full power and ground
    ("ready" at 14V but ICE off) while using an amp clamp to scope the current used
    by the solenoid- I wanted to see the electrical characteristics. All three (OE, RB, AND AM)
    use about the same amount of current, but the amperage patterns indicates that each
    pintle moves differently. Likely different return springs, but could also be
    changes in pintle design.
    amps view.jpg OE amps.jpg RB amps.jpg AM amps.jpg
    Next was the scantool VVT control test (not a great test but the ECM is consistent,
    so I figured I could compare each solenoid- apples to apples). I used the scantool
    test to drive the solenoid from "OFF" (12% DC or full retard) to "ON" (73% DC or
    slam it fully advanced). "Maintenance mode" is nice to keep the ICE running but
    it stops when you exit to go to the VVT tests-I hit the throttle to start the ICE and
    shifted to neutral to keep it running . I capture the cam and crank sensor signals
    as well as the VVT solenoid control. The scope software converts the solenoid
    control into a duty cycle graph. When that graph changes state, I zoom in and start
    comparing the two sensors until I see that the cam is fully advanced or retarded
    and count how many engine revolutions it took to accomplish that. Each entry
    resulted from at least 3 samples that were averaged together and rounded up
    RETARD.jpg ADVANCED.jpg SCOPE.jpg
    After that I wanted to try things at higher RPM. So I used my function generator
    (electronic test widget that produces different electrical signals: sine wave,
    square waves, etc- doesn't everyone have one of these?) to output a 0-12V
    adjustable pulsewidth signal at 300Hz to drive a mosfet and added a couple
    diodes to clean up the signal. (So the PWM is inverted once at the FET, but I only
    had a N type FET so I am controlling the NEGATIVE side of the solenoid - PWM is
    effectively inverted twice, but have to keep that in mind when looking at the
    scope- ie, 60% on the function generator is 40% on the scope but it's on the
    negative side so it equals 60% on the positive side- which is how the ECM would
    have controlled it- bleh!). This setup drives the solenoid directly- no ECM, so I can
    rapidly switch duty cycle to whatever I want (within limits). I propped the throttle
    down to bring the revs to 2400-2500 in park and ran several 15-50% and 15-60%
    (advance) tests and back again (retard). Results were measured and averaged as
    before.

    Now let's meet the contestants. First up is the OE replacement from Toyota, $87
    from the local dealer. Fits like the original because it's made like the original. Should
    outlast the car. GO team OEM!!
    OE SOLENOID.JPG

    Next is the REEEEEEEDDDDD Bullet!!! Faster is the master, redder is better,- (err
    wait I minute- it's NOT red). What?- but it's called the RED bullet. (Sorry- must have
    run out out of red coloring). Well, it USED to be red. Seen it on the website. In
    fact, it looked very very similar to the much pricier "Quantum Solenoid". Eh-
    whatever. $113 + shipping gets you this performance MONSTER (that arrived in a
    "Chiayi Racing" box). go rb- yippee. (ps- fits just fine)
    RB SOLENOID.JPG RB vs QS.jpg
    Last is the bottom of the barrel, cheaper is a keeper. amazon's "most thrifty"
    AfterMarket offering that goes for the princely sum of just $10.52 plus tax! (free
    shipping with prime!) No brand name on it anywhere! It looks like you might
    expect for the price. The mounting tab had to be bent out then shimmed with a
    washer, and I had to be careful getting the connector JUST right to plug it in.
    Who knows how long it will last, but "hey it's a part!". Let's give it up for team
    miser!
    AM SOLENOID.JPG

    NOW, here's the test results. - that I measured on MY car using the parts that I
    received. YMMV

    RESULTS.jpg

    Well....Ummm. Yeah. SOoooo, the Red Bullet was slower on all tests when
    advancing cam timing when compared to the OE solenoid, and only slightly
    faster than the cheap AM unit at 50% DC. All units were able to retard about
    the same.
    The world has been enlightened. Do what you will with this- now live long and
    prosper.

    Edit: forgot to add that total range for VVT adjustment is about 38 degrees.

    Maybe we can call it "the Bullet formerly known as RED"?
     

    Attached Files:

    #1 mr_guy_mann, Sep 8, 2021
    Last edited: Sep 8, 2021
  2. PriusCamper

    PriusCamper Senior Member

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    Thanks for taking the time to write this up... Your testing work is very advanced and you taught me lots of stuff because you took the time to explain some basics, but not sure how a bench test of the circuits relates to real life driving? You did say that when you were driving there wasn't much difference?

    I put a red bullet in my Prius in March and most obvious difference is a slightly less sluggish throttle response when I pull into traffic in the 3mph to 5mph range, which is a time frame and rpm range that's not yet been covered by your testing.

    I look forward to what others have to say about all these details. Excellent write up. I'm always aiming to learn more!
     
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  3. TMR-JWAP

    TMR-JWAP Senior Member

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    So, years back, when the 87-93 fox body 5.0 mustangs were super popular, there was a kit available that hyped a ~10-15hp increase when installed. This kit had a module that installed between the A9L engine ecu and the cars harness and it came with a small plastic rod that installed in the distributor. The rod that installed in the distributor essentially just advanced the base timing a few degrees, so the engine's timing curve was moved up from start to finish, but now required higher octane fuel (89 or better instead of 87). Most likely, the 5 cent rod accounted for any improvements and the module was mostly hype.

    I've never been one to believe in the latest gimmick, but there's a million suckers born every day, so my question about the "Red Bullet" is whether the shape or ports/slots in the spool are machined differently to initiate flow slightly sooner or anything like that. Wouldn't that effectively be similar to 'the rod' mentioned above? It would seem, that to make it successful, the timing change would need to be initiated faster. maybe you just happened to get a 'bum' bullet that was machined backwards?

    Any chance you can now perform a real test on a super whamma-dyne pulstar plasma phase proton emitting sparkplug?
     
  4. burrito

    burrito Active Member

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    Sooo.... have you considered becoming an engineer?
     
  5. edthefox5

    edthefox5 Senior Member

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    The engineering made perfect sense to me.

    I put a Red Bullet in my car last year on my bought new in 07 G2. Works great. The car has much quicker response at passing speed from say 50 to 65. Where before it was pretty poor. Its got something now it did not have before. I would imagine on the much more powerful G3 platform it would be alot of fun. I recommend it.

    Its just rolling in more timing when you really need it but no pinging at all. Really easy to install 2 bolts.

    It is no gas saver because your foot will be in it more as it's pretty fun.

    Let the flaming begin.
     
    #5 edthefox5, Sep 8, 2021
    Last edited: Sep 8, 2021
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  6. mr_guy_mann

    mr_guy_mann Senior Member

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    If you like the product, then it's good for you.
    I just want to see some proof that it does what it says (more oomph) the way it says it does it (by faster VVT).

    Posted via the PriusChat mobile app.
     
  7. mr_guy_mann

    mr_guy_mann Senior Member

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    Well, trying to process the data from real "on the road" driving is a PIA. I don't know of a way to force consistent operation of the VVT system. Drive several times in what seems to be identical manner and get different results- or perhaps very minor timing adjustments. Short form is I can't beat the programming- it'll do what it's gonna do.

    My thought was perform tests with more variables under direct control in order to get repeatable results.

    I just want see how the RB is "faster".

    Posted via the PriusChat mobile app.
     
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  8. burrito

    burrito Active Member

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    Isn't it great when no one can prove you wrong?
     
  9. PriusCamper

    PriusCamper Senior Member

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    As I was reading your whole post last night, I thought how if Toyota open-sourced their code, you could probably create the same results simply by optimizing how fast the software operates... That would probably make many more systems in the vehicle than just throttle response run better. But of course, Toyota isn't gonna open source anything... :-(
     
  10. ChapmanF

    ChapmanF Senior Member

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    Thank you very much for doing this. I've been hoping for more than two years now that somebody would. :D

    Spot on. Claims about whatever wonderful effects result from it doing the thing it allegedly does are all downstream of whether it even does the thing it allegedly does.

    Very good info here. For a while I assumed the valve might be driven by an H bridge (bidirectionally) and that its undriven position would be "hold the timing steady". Later I noticed there was enough info in the manual to make me probably wrong about that, but you've pinned down the details. Having it go full retard when not being driven probably makes for easier engine starting than my way would, in case of some problem in the circuit.

    Yes. I was pretty sure two years ago that would be the only adequately sensitive way to test it, and that was what told me I just didn't feel motivated enough to invest the time that would require myself. Thank you for taking it on; nice work.

    :D :D :D

    Golden. Now, TMR-JWAP does raise the valid point that one Bullet could have been a bad sample. A more powerful experiment design would have had at least one or two more of each type of valve. More money, of course. Mathematically, you can't compute a p value for the test if there was only one sample of each type. (And even with two or three, pretty stark results would be needed for the p to come out low. On the other hand, if you consistently got RB needing ~ 3✕ the revs of OE over a sample of a couple of each valve, that would be a pretty stark result!)

    In fairness, of course, it's not your job to show a low p value for the product not doing what's claimed; it's the promoter's job to show with a low p value that it does do what's claimed. Your results here (if consistent over a sample of more than one valve) go a fair way to proving it does the opposite of what's claimed, which is even funnier than any result I would have expected.

    In the end, though, the reason I was too jaded to dive into this myself comes from what I've seen in the past with such kinds of products. I can foresee one of a couple things happening. Most likely, the promoters will find some way of just dismissing what you've found. Alternatively, all the marketing copy will soon be updated to say that the product makes the car better, faster, MPGer, etc., by stabilizing the valve timing and making sure it doesn't change too fast, and will link to your test as support. ;)
     
    #10 ChapmanF, Sep 8, 2021
    Last edited: Sep 8, 2021
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  11. edthefox5

    edthefox5 Senior Member

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    Don't know what you bought there but its not a Red Bullet. Its the same size porting as a stock valve. Mine does not look like that pos. The fact that its not red should of been a tip off even for you. You wasted alot of time there for nothing lol.

    Products | Red Bullet

    .
     
    #11 edthefox5, Sep 8, 2021
    Last edited: Sep 8, 2021
  12. burrito

    burrito Active Member

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    When did you buy yours?
     
  13. edthefox5

    edthefox5 Senior Member

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    Its been 2 years I think. Its a pretty benign device really. A G2 does not have alot of power to begin with so
    in my car I only notice a big improvement when its up to speed. It will always be a mutt from a stop.

    Its only $125. If you put one on your 2015 you will really enjoy it. Really easy to install 2 bolts easy to get to.

    They have instructions on there site. And a quote from a priuschat guy on his G3.


    .
     
    #13 edthefox5, Sep 8, 2021
    Last edited: Sep 8, 2021
  14. burrito

    burrito Active Member

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    Not where, when?
    Edit: Now it shows up!
     
  15. ChapmanF

    ChapmanF Senior Member

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    m_g_m, where did you buy yours? From redbullet.net or some other vendor? Was there an invoice or receipt with it?

    If from another seller, I suppose it's not beyond possibility that there could be counterfeit Red Bullets.

    If from the same site, but two years later than Ed's ... are there any signs around the web site of changes of ownership or management? Could be an instance of "brand harvesting"....
     
  16. mr_guy_mann

    mr_guy_mann Senior Member

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    Well, I bought my Red Bullet from that site that you linked (redbullet.net), all correspondence was with Max Jen International.
    What's interesting is a few months ago I was considering doing all this but didn't buy then - here was a screenshot from the site in June.
    rb2.jpg
    When I did purchase the solenoid the site had changed to what is shows now.
    RB3.jpg
    If you scroll to the bottom of the pics in the prius section you see this.
    RB4.jpg
    That's the same brand as the box my part came in. So if there is more than just a color change then it is because Max Jen changed suppliers or designs- or ownership.
     
    #16 mr_guy_mann, Sep 8, 2021
    Last edited: Sep 8, 2021
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  17. burrito

    burrito Active Member

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    So it's entirely possible that the old Red Bullet works like magic, but the new one is just an illusion.
     
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  18. PriusCamper

    PriusCamper Senior Member

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    That'd be the most fun outcome.
     
  19. mr_guy_mann

    mr_guy_mann Senior Member

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    If anyone wants to loan me an "old" Red Bullet, I could run the same tests on it and see.

    Posted via the PriusChat mobile app.
     
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  20. TMR-JWAP

    TMR-JWAP Senior Member

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    I let it get the best of me and spent a few non-refundable life minutes looking at the site. Two things I'm curious about:

    1. why the HP graph only shows from 3600 rpm to 6150 rpm. Is that the normal Prius rpm range?
    2. why this is the only dyno graph I've ever seen where the HP and T do not cross (equal each other) at 5252 rpm. Kind of odd, since the math requires it to happen.........
     
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