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Thread: Interesting Info on Boost By-Passes for all to digest

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    Interesting Info on Boost By-Passes for all to digest

    ok... here we go... everyone strap on your seat belts I am guessing this post will generate some creative "dialog"...

    To elminate or keep the OEM Eaton Boost Bypass.... THAT my fellow brothers & Sisters in Harley Davidson Truck land, IS the question.... along with the bigger question why do we build street trucks with Race only mods on them?

    Let's take a quick look at the premis of the by-pass on a Roots style S/C like our little Eaton (or Heaton as some call it). What does it do exactly? Well, according to the various sources I have found the priniciple is quite simple. Upon letting off the throttle, there-by slamming the throttle body blade(s) closed, the S/C is still spinning & making boost. While making such boost, it is further heating the air & still trying to pump boost into the cylinders. Further raising temps, grossly leaning the engine out, because the EEC-V is pulling out Fuel & slightly increasing timing to burn off hydrocarbons & other emmisions no-no's all at the same time. The Boost Bypass is simply a vacuum operated dump, that vents the extra boost back through bypassing the engine itself or "reciculating" is another way to look at it.

    99.999% of the turbo & S/C kits on the market have a bypass provided in the kit. Turbos, Powerdyne, Procharger Vortech/Paxton, Magnuson, Whipple, Kennep-Bell Weind, B&M, etc doesn't matter the type, the construction, or boost level. THEY ALL have them included with the engineered kits sold.

    A quote from the current Race Pages, a large format monthly publication geared toward the NMRA (National Mustang Racers Association). Page 36, June 2004 VOlume06 Issue6:

    "Imagine what happens when you're hard on the gass, & the supercharger is making 10psi of boost, cramming copious amounts of presserized air into the intake manifold. All of the sudden you jump off the gas pedal & the throttle closes, but the blower is still moving the air. Creating surge & tremendous amounts of heat. IN EXTREME CASES, IT WILL BREAK THE BLOWER. That's why most supercharger kits include a by-pass valve. When the throttle is closed, the bypass valve vents the pressurized air into the discharge side fo the supercharger and recirculates it into the inlet tube, between the mass air meeter and the supercharger inlet. You can't just vent it to the atmosphere, since the mass air {meter} {sic} already told the engine what to expect in terms of airflow, & you'll run into a tuning nightmare. The higher the boost level, the bigger you have to go on the bypass valve. For example Vortech's standard S-trim kit has a little plastic bypass valve that works great under 10psi, but mire aggressive applications require a bigger bypass, even their new racing bypass, as shown"

    In a couple months there is going to be a full issue devoted to Lightning (& thus HD's by default) performance.

    So what's the point. As I refered to in the following link:

    http://www.nhtoc.com/vbforum/showthr...threadid=10708

    its about time we all got together & started really looking at the mods we are doing, really looking at WHY, & WHAT the consequences are. A full on drag-race machine is one thing. But Since we don't have any supporting vendors over here talking with us, just wanting our cash, we have to be more educated than the Lightning guys.

    Mods I truly question their effectiveness & have been vocal about:

    Bypassing the boost-bypass
    Throttle body on a non-built engine
    Long tubes on a street truck
    Oil Seperator (snake oil creator??)
    Any air system that pulls air from under the hood
    Tuning a chip/programmer via mail order

    just to name a few of the most popular mods.

    Yeah, yeah, yeah, I know Part xxx made me 15 rwhp or item yyz did so much etc... at what expense or at what cost to driveability or long term durablity? How many times did it have to be redone before it was right?

    We have a bunch of new members looking for answers that are being shunned by the Lightning boards or ignored. I would venture a gentleman's wager that over 90% of our HD's are street trucks that MIGHT see a drag strip 3-4 times in its career. So why are we building them like a JLP, JDM, PSP, or other tuner's drag race only truck??

    I am currently trying to compile a chart of the known trucks that puked guts & what the common threads among their mods are, if any. There are some interesting consistencies.

    Just stirring up some thoughts & conversation....

    Rob W.

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    Oil Seperator (snake oil creator??) Explain.

    I am runnng a stock performance machine.

    Mostly just bling.

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    Well the oil seperator is another of those things that the hard core drag racers sent up a 5-alarm fire about a while back in the Lightning community.

    I have talked with several (6 to be exact) people who have taken their L or HD's apart to inspect & clean the "dreaded oil build up" our of their lower intake/intercooler & have found a light coating of oil, not the puddles & layers of oil that the while hype tends to make people thing is happening inside the engine.

    Do I think it is a lame design, that the PCV & blow-y dumps some oil vapor into the S/c & intercooler at all? Heck yeah its a bad design. But for the AVERAGE joe who cares?

    An oil sperator like most use for our trucks will filter 4-10 MICRONS out of the air stream... HEck yeah the little trap is gonna fill up. Duh 4-10 microns is like mega spray gun filter levels to protect microscopic paint systems... its gonna pull oil out of the air. Common sense.

    All I am saying is until I take my S/C & intercooler apart in a few weeks, I am reserving judgement, but for now I am calling it a snake oil creator until I see standing oil in my intercooler, I am not buying. If I have standing oil in my IC then I will post a public appology.

    Rob W.

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    Cool. Keep us updated. No use spending $ on a non-problem.

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    I've seen what it does and for a few buck its worth it. Sinvce buying my truck I think I've dumped close to a quart from the seperator. Thats worth catching IMO. I agree with the SB throttle body and the under the hood air element. Its my guess thatthe stock air box flows more effectively on any motor at or under 450 HP the onlything it gives you is looks. At a dyno your not moving so you may get a false sense of added dyno HP but the cold air your stock box with a K&N will flow colder and more dense air. The Predator used with this K&N arrangement and a 6lber will be perfect in the pully tune of a Predator. My A/F's were dead on as well as many others. I like your thinking though. You cannot just do things because others do them

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    MBO your veiw of the seperator is the ONLY valid one I ahve heard... Yes I agree if we can keep the oil out of the IC area & it is not designed to be there as an OEM parameter, then catching it is a good thing...

    I will take pics of mine so we have a definitve look at what's goin' on... My truck will be @ 50K about the time I do it so it will be interesting to see what is in there.

    Rob W.

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    about the boost bypass.....when the boost is released ..do you have to turn the truck off to reset the valve...Just asking cause some people have said this to me.....

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    *edit* the OEM/Eaton bypass is vacuum & electrically controled thanks Chet....

    the example/excuse the vendors give is after a burn-out, the valve is slow to close & can cause a no boost situation @ launch if you stage quickly. Totally valid arguement for unhooking the by-pass for a DRAG RACE vehicle. But on a street truck it doesn't hold up. Supposedly people find 1-2lbs of boost with the by-pass disconected.. this its the lure to the dark side... that claim of a 1-2lb boost increase for a mere $5 in parts for your local harware store.

    Its just marketing a race piece to the street crowd. You risk much more on a street truck without it then you gain with it.

    Rob W.

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    Maximus Horsepowerus
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    Originally posted by 2002GreyHD150
    Well the oil seperator is another of those things that the hard core drag racers sent up a 5-alarm fire about a while back in the Lightning community.

    I have talked with several (6 to be exact) people who have taken their L or HD's apart to inspect & clean the "dreaded oil build up" our of their lower intake/intercooler & have found a light coating of oil, not the puddles & layers of oil that the while hype tends to make people thing is happening inside the engine.

    Do I think it is a lame design, that the PCV & blow-y dumps some oil vapor into the S/c & intercooler at all? Heck yeah its a bad design. But for the AVERAGE joe who cares?

    An oil sperator like most use for our trucks will filter 4-10 MICRONS out of the air stream... HEck yeah the little trap is gonna fill up. Duh 4-10 microns is like mega spray gun filter levels to protect microscopic paint systems... its gonna pull oil out of the air. Common sense.

    All I am saying is until I take my S/C & intercooler apart in a few weeks, I am reserving judgement, but for now I am calling it a snake oil creator until I see standing oil in my intercooler, I am not buying. If I have standing oil in my IC then I will post a public appology.

    Rob W.
    granted, my truck is seriously built -- KB, etc., but I had so much oil in my intake that it literally ran down the intake tube and saturated the bottom side of my filter element...

    on the underhood air filter issue, i tend to agree with the exception of the JLP and PSP ram air kits. They aren't true ram air, but they do work well. I tested my JLP unit against a stock setup quite thoroughly and it does work as advertised. There is a thread title intake temps or something along those lines if you would like to read them.

    as far as the "why would we build a street truck into a race truck" ... that is a great point. I now realize how much of a headache it is to maintain a fully built system. There is a reason oems spend millions of dollars making a complete "system". You start changing things and the system begins to break down and require constant maintenance and worry.... If the HP is worth the maintenance to you, sobeit.... but for a lot of folks, I bet it isn't.

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    Great thread guys! I too will be taking pictures of my intercooler in a few weeks when the KB gets here and I get some spare time to do the install. I put about 3000 miles on my truck before installing an oil sep. with a .01 micron oil filter. The truck now is closing in on 11000 miles, so I'm also curious to see what I find.

    I'm also hoping to put together a "How To" with photos for doing the Kenne Bell swap on a mostly stock engine. I'll be taking my interchangable lower setup off and putting the stock pulley back on because the KB is coming with a 2.75 upper which should put me near 14-15 psi in conjunction with the stock lower. BTW, anyone got a KB 3.00 they would like to trade for a 2.50?
    Justin

    NHTOC#157 / 03 2-tone #9101
    444 RWHP / 527 Ft-lbs TQ SAE

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    Ken, you, Aryton & I are amoung the few "stalwarts" as I see it who cast a discrening eye to everything put in front of us.

    I have your intake temp thread printed & at my disposal all the time. That's what made my decision concrete in my mind.

    Your comments on the "built" engine are my EXACT point. Almost every item people (espcially new people) flock to are the useless mods I am talking about. The True ram air that does make a difference will not make a tangible difference on a basically stock truck. A TB, long tubes, etc wont make squat useable difference on a street truck. but the hype around the mods ends up costing many people performance, driveability, & fun in the long run.

    The oil in the intake/IC is a case by case deal. More than less ahve little if any real issue. Guys who really push their trucks will obviously have a higher incidence than the average highway truck like mine. But I think mine will tell the truth for a typical HD on the street in a couple weeks.

    Ken, thanks for posting up.. I appreciate & value your commnets

    Rob W.

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    Bypassing the boost-bypass
    Throttle body on a non-built engine
    Long tubes on a street truck
    Oil Seperator (snake oil creator??)
    Any air system that pulls air from under the hood
    Tuning a chip/programmer via mail order

    hmm....
    havent touched the boost bypass deal.
    i ported the stock tb.
    i have long tubes.
    i have a homemade oil seperator.
    i have an airaid intake.
    jdm tuned my chip over the mail.
    oh, and im using kendall 20w-50 motor oil.

    i took my blower and intercooler out at 42K miles, and the whole setup was caked with oil, all the way down to the filter box on the intake. since adding the oil seperator, the blowby is minimal.

    with the long tubes, tune, and intake, i just drove my truck from tucson to charlotte, with close to an extra 1500 lbs worth of stuff in the bed and in the cab, and got 16+ mpg, no detonation, no issues whatsovever.

    i also have a billet lightning upper, a 2# lower (soon to be a 4#), phenolic spacer, and tr6s on top of all this. my truck is getting ready to hit 50K, and i still drive the piss out of it.

    i agree with your points on the boost bypass, which is why i havent installed it, but as far as other mods, most of us want to be able to run low 13s at the track if we take it, not 10s like jlp and jdm with the Ls. i think most of the members here have realistic expectations of what they want the truck to do, and also what it can do. think about it - honestly, i think only a handful of hd owners actually have a built motor in their truck, and compared the # of L guys that do, i think it shows that we want to drive our trucks everyday, not on weekends, take the fam out to dinner and a movie, and dust some young dumbass in a import or even a stang or camaro on the way home. thats it. we have more pride in our ownership than 95% of the other clubs that you can find online - a tight relationship with each other. hell, guys are even paying attention to my career and posting it on here.

    to cut to the chase, its up to each individual member to decide what they want to buy, how much they want to spend on their truck, and who to buy it from. and we get all this info through this forum. it just doesnt make sense to me to pick out the feew bad examples of things gone wrong, without pointing out the mulitudes that have gone very well. id rather see this board continue to be a support and encouraging place to come, rather than to come online and have posts that tell me that i shouldnt buy this, or have a certain thing on my truck just because a few individuals think its a bad idea, since they had problems with it.

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    I have the boost by pass right now but once I instale my L upper pulley and #6 lower with the FTVB i will be removing it.

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    Over the course of the last year I have spoken with more “experts” than I can remember and very few could back up their claims when questioned. Telling me I need something is not good enough, nor is trying to convince me with hype. I have blown off more than one well known tuner because he/she/they tried to BS me and I called them on it. The Lightning/HD/03 Cobra crowd is really small in the big world of built engines and race technology and when trying to get real answers to your questions, don’t be afraid to “think outside the box”….or something.

    *Disclaimer* the author of this post is high on cold medication.

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    Originally posted by 2002GreyHD150
    the OEM/Eaton bypass is simply a Vacuum Solenoid. It actuates at high vacuum (off throttle/decelleration) only. it is not electrically actuated or controled. Totally vacuum.
    Well, not exactly.........grasshopper...hehehe!

    There is a "Boost Dump" solenoid (electricaly controlled) in the vacuum circuit that does open the boost by-pass when commanded by the ECM, ie.....hitting the rev limiter, overheated engine, high reading at IAT2..........it is an engine protection feature.
    Probably pretty valuable when you do this

    after a few of these:drink:

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