Had my new SE SC not quite a week yet, pretty cool little truck. But I don't have a handle on the supercharger yet. Questions:

1. Does SC spin all the time or only on demand?
2. Is there a bypass?
3. When bypass & when SC? Vacuum demand? RPM?
4. Can I improve gas mileage?
5. Free-breather air cleaner/exhaust a good idea?
6. Any good tech articles out there?

Thanks!

- Tim

It is very simple:

The SC only kicks in when you press the gas petal to the floor due to a waste gate on the SC triggered by petal postion. This is why I did not buy one, it is crap. I waiting for an after market system that will take full advantage of a SC. I mean 5-7lbs boost only at wide open throtal??? Every other SC vehical I have ever seen uses the SC all the time and has a timed blow off valve for the shifts so you dont tear up the tranny.

The stupid thing is when I e-mailed Nissan their reson for this setup was to save gas and wear on the tranny. Ok lets think about this, in order to get the extra power from the SC you have to floor the truck..hmmm...

1-Wide open throtle=more gas (so much for millege)
2-Wide open thortle=Hard Down Shift with a boost
of 40 HP at the same time (so much for tranny
wear)

I love Nissan but they did not do their homework on their setup. I have a few friends with after market SC's on thier trucks (not Xterras) that run with the proper set up and have had no problems with their trucks...

When an after market SC does come out the truck will need an A.F.C. in it to get the air/fuel mix right.

Flowers have "petals".
Trucks have "pedals".

There isn't a real way to get better gas mileage with the SC. I guess if you just babied it you would get maybe better.

AN intake and exhaust will certainly help it breathe easier at the cost of your economy. We have an SC forum on our site that has some info in it even though most of it seems to be centered around intakes and exhausts since those are the most likely and cheap mods. There are also some smaller pulleys out there that bring your boost level up to about 10psi.

Xterra type-r I seem to have boost at different pedal levels and not when I mat it. My boost gauge shows me this. I think you are thinking of tubos that have blow off valves for shifting. SCs are different. They are alswys on and there is less lag. They also tend to be more reliable. I am sure too that the 40 HP isn't an instant on thing, it is gradual across the power band.

I think Nissan did do thier work. They went to Eaton, they boosed the injectors and strengthened things inside as well. Try to get 40HP another way right now and not spend the $1,500 that you would for the option from Nissan.

I know some have "answered" but here's specifics

The SC is always spinning, always compressing air (no clutch on the SC pulley or drive pulley). This is the main reason for poor fuel economy.

There is a bypass valve on the SC, it sees it's vacuum signal from a computer contoled solenoid.

Bypass is closed as engine vacuum drops. Typically it takes +/- 50% throttle to get any boost.

Don't we all wish The best way to improve mileage is to putt-putt, as the parasitic drag to run the blower all of the time will never allow the engine to reach fuel consumption rates of the NA engines. A combination boost/vacuum gauge is effective in showing when you are in boost (poor fuel mileage) and high vacuum (good fuel mileage)

Better for power, not necessarily better on fuel consumption, as the blower draws enough intake vacuum that a less restrictive intake will not help fuel mileage.

Haven't found any yet, however I have figured out how to bypass the computer solenoid - to the loss of some fuel economy though, but a slight gain in boost level and performance.

Actually, the SC doesn't have much drag when it's on bypass. Since it's not a positive displacement unit, it doesn't compress the air as it goes through the unit. It's nothing more than a fan really. It creates pressure by simply cramming air into the intake manifold. Most of the drag comes from pushing against the pressure in the manifold, the actual "work" it does, not from mechanical drag. I'll bet you could spin the lobes by hand with little effort. When it's running on bypass, it's like a fan running in a vacuum and not having to push against anything, therefore not sucking more than a negligible amount of power.

Brent

XterraType-R...what the hell are you ? Man is that some bullshit info!!! If you don't own it and don't know...shut up!!! The SC definately gives boost under mild acceleration (NOT FLOORED) hence the humming under the hood and being pressed back into the seat!

Actually, he's right. The supercharger only operates at full throttle according to a few things I've read. That noise is just the drive belt and the pulley, so of course you hear it all the time. It's always spinning.

This is from: NISSAN

Xterra’s supercharger is designed to operate under “boost” conditions (6 to 7 psi) under wide open throttle conditions (WOT) – which during typical driving is only five to ten percent of the time. Fuel pump flow rate has been increased and fuel injectors have been enlarged by 80 percent for supercharged models to handle the extra fuel needs under boost.

During normal driving, a bypass valve (a solenoid operated vacuum valve controlled by the Xterra’s electronic control module) diverts the excess air back into the supercharger inlet where it is recirculated, with the engine operating like a naturally aspirated Xterra V6. This helps maintain good overall fuel economy with power on demand.

That is "max" boost under WOT. The SC gives less boost under less aggresive acceleration. My Mom and several friends have non-SC 02's and one 03 all of which I have driven often. They have do not have the same torque feel (push in the small of your back) when accelerating 1/2 or 3/4 throttle. The boost is spread out across the rpm's with max boost only under WOT. If boost came on only under WOT then it would feel like a shot of NOS!!!! Trust me...you can feel the boost under less than WOT conditions. GO DRIVE ONE! Then come back and say..."err-ahh....SORRY"!!!

Can you post some proof? It sounds like you're making shit up in spite of the fact that I just posted something from Nissan to the contrary. And please explain this scientific method you used to compare an SC and a non SC at part throttle. Did you set up a ruler on the floor to measure exactly where 1/4 and 1/2 throttle are on both trucks? No, I didn't think so.

BTW, I have driven an SC, and if I had it to do over again I still wouldn't get one.

Here's why: Frontier Test

What is strange is just how urgently the supercharged Nissan leaps off the line with nothing more than a tap of the gas pedal, belying the mediocre drag-strip numbers. It turns out that an overly aggressive throttle linkage disproportionately opens the throttle plate when the pedal is depressed. Pure mechanical trickery, but the supercharged Frontier now easily merges into 80-mph freeway traffic.

Actually Brent you shouldhave consulted yourself before posting this.

It is a compressor, not a blower (A blower is only positive displacement). Look at the rotors (screw type)= compressor, (rotor type)= blower.

Yes you can turn it easily with your hand, but if you had a hand crank that was geared to allow you spin the SC up to compressor speed you would feel the drag of the compressing air. If you want even remove it and the manifold from the engine, and do it on the bench, it will still require force. It works the same with a turbo...you can spin it by hand...

I wasn't speaking of mechanical drag, but the force required to compress the air.

But don't take my word for it! If you get a chance to drive an SC with a boost/vacuum gauge you will see "0" vacuum at or about 1/2 throttle, whereas it takes full throttle on an NA engine to meet the same low vacuum. Cruising at 70 in an NA X should pull about 15" Hg, same in the SC is 0" Hg.

Poorer fuel consumption due to less intake vacuum, less intake vacuum due to higher engine load, higher engine load due to blower.

It does produce boost at less than full throttle. if you have a boost/vacuum gauge you can see this.

If you read that quote from Nissan, it is speaking of full boost at full throttle. And even at full throttle the boost level is not consistent - WOT at 2500 rpm only gets 5 psi.

As I stated in an earlier post, my boost gauge reads boost at throttle positions other thatn WOT. The article/literature you cited says that the boost of 6-7 psi (which is the peak) is reached at WOT which in reality isn't all the time. However even when I am not mashing the pedal to the floor but accelerating strongly (let's say 3/4 throttle) I still see boost on my guage at around 3-4psi. I guess I am full of shit...

OK, maybe I got my terms mixed up, it is positive displacement, but I was right about it's design. The SC on the Xterra does not compress the air on its own, it should not offer much resistance. At most it deals with the air drag as it rotates through it at lower RPM, but it's not having to fight pressure on the outlet side to get more air in until the bypass valve closes.

Brent

ILUVMYX......Who's your daddy? I got your scientific test right here. :p Take your ruler and measure how far you can stick it!!! BIG THANKS to Pacopico & AG Bullet, I knew some SC owners would wake up and get my back. Its not that hard to tell when the truck is getting extra push because of "part throttle" boost! Thank-you guys!!!

OK, let's try again. Another source... CLICK

The Eaton supercharger operates only under wide-open throttle conditions (WOT), providing 6 to 7 psi of boost. Fuel pump flow rate has been increased and fuel injectors have been enlarged by 80 percent for SC models to handle the extra fuel needs under boost.

Somehow that's exactly the proof I was expecting.

ILUVMYX....you look to a Canadian for proof? Get over it!!! YOU ARE WRONG!!! Ag Bullet's gauge shows boost at 3/4 throttle! How much more proof do you need? HOW ABOUT THIS...2003 Dealer Only Product Guide, page 13: "key benefits of the SC include immediate throttle response...across the complete engine operating range. The SC provides additional boost at all engine speeds." Maybe you should spend your time more wisely, say shouldn't you be checking your tire pressure or something? Oh shit I forgot, you drove one once...you're a friggin' SC expert!!!

Read it again. Where exactly does it mention throttle position? Immediate throttle response... complete operating range... all engine speeds... they're talking about the advantages of a supercharger over a turbo. Please, try again to post the part about throttle position. Good luck.

I have said all I need to say on this. The rest of my feelings are summed up in my sig file. Feel free to fly your ass here drive my truck and watch my boost gauge at different throttle positions...

As for the throttle position, what does immediate throttle response to you mean? To me (and maybe I am wrong here) it means that when you step on it that boost is beginning to be generated. At lower throttle positions (let's just say half way for the sake of this "argument") it is dumped or recirculated. After that, the bypass opens or does whatever it is it does and the boost begins to be used. On my gauge, the truck is no longer in a vacuum and the psi's begin to show on the SC side. It really is hard to dicern without a guage if you are going at it slow and steady. There is a whine but in the stock set up it is kind of muted until WOT. With an intake you can hear the SC turning (whining) at lower speeds/throttle positions. Go test drive one again with the windows down and the radio off and tell the salesman to shut up and listen. You will also notice a pep that by doing the same thing in a NA truck won't be there.

If none of this will convince you I say to heck with it beleive what you want the rest of us have tried to help...

I don't care what they say - I own one, and at least one owner has reported real world results via a boost guage - I didn't see your linked article backing up their statement with any kind of imperical measurements either, but rather the parroting of Nissan sales literature (and we know just how knowledgeable those marketing types can be - experts in every field, those guys!)

And after driving around an NA X for several weeks, and after having owned an SC X for several weeks - I can emphatically state you are full of it and should try driving one for more than 20 miles. You do not have to mash the petal to the floor to tell that there is an immediate and positive benifit to the SC.

Actually, I don't know why I am bothering responding to you - you have already stated your mind is closed, and I have already voted with my hard earned $$$ and bought the SC.

Oh that's right, someone new to the site might read this thread and think you know what you are talking about :rolleyes:

You are wrong. Immediate throttle response is mentioned because it's an advantage compared to turbocharged engines. It means the boost is instant the second you floor it. A turbo does not provide immediate throttle response--it requires time to "wind up" before it starts giving boost. There is no "wind up" with a supercharger because it is mechanically driven from the engine as opposed to exhaust gas driven in the case of a turbo. Also, a turbo is rather worthless at lower RPMs whereas a supercharger, again, because it's mechanically driven works across all engine RPMs.

Just because your boost gauge is giving you a reading doesn't mean the engine is seeing that boost. The supercharger may be generating pressure, but the bypass isn't sending that pressure to the engine. It only tells you that there is boost. It doesn't say where the pressure is going. The only way to know for sure is to have a way to monitor the bypass to see where the boost is going.

I bet you have a tornado in your X too don't you....

Okay ILUV, how about this. I am friends with Jeb (Ag Bullet), and have seen his truck run many times. I have witnessed the boost gauge. It is hooked into the vacuum system on the engine. If you don't know how that works, the engine vacuum is generated in the intake manifold, INBETWEEN the SC and the engine block. The gauge monitors EXACTLY what the engine "sees", to use your terminology.

Hey Jeb, this guy reminds me of another one over on TUNFS. You think they're related?

Coming from a guy who has a 3" lift, lockers, engine swap, revolvers, skid plates, and a "4x4 conversion" planned for his 2WD truck... well, it just doesn't bother me much. So how is that "4x4 conversion" going?

Great actually. I have the front-end coming in 3 weeks, the rear-end is in the mail, and the rest is one or two months down the road. Thanx for checking out my site!

Who is laughing now? By the way, do you laugh at all the SAS jobs too?

Really? So you have a front axle (solid, I'm sure), a transfer case, revolvers, a 3 inch lift, a new steering system, and, of course, let's not forget the engine swap? I'll believe it when I see it. Of course, if you really did it, I'd laugh even harder than I am now. Someone wanting to convert a 2WD truck into a 4x4 is funny. But someone who actually does throw away the money to do it is hysterical! Do you realize after spending the 50 grand for truck and mods, it's still only going to be an average rig. You could have spent 2 grand and bought a more capable Jeep. Of course, that's assuming you're not full of shit in the first place.

Actually, no, I took a dump earlier, so I know it's not BS.

Maybe one should stop to think. Hmm. It's my truck and I can do as I please.

And what does a 4x conversion have to do with a supercharger? I see how you are evading the topic altogether now instead of trying to deny the truth. It's okay to be wrong once in a while. I know I have been, I was wrong to think you just might have an open mind.

It has nothing to do with superchargers. It was a response to your attempt to insult me. I merely pointed out that insults from someone dumb enough to do that to a 2WD truck don't bother me. Now you make sure to post pics when you're done--I can't wait to see it!

I give up. This has just gotten down to nitpicking. Believe what you want many will know different. I don't doubt OnlyOneDR's ability to convert his truck to 4x4. Some folks like projects. Not everyone goes somewhere to have thier oil changed or have someone change thier wiper blades or light bulbs fot them either. He never claimed a SAS conversion. If he is getting all the parts pretty cheap for the conversion to 4x4, what is the harm in that? As for the motor swap, that might be a tougher nut to crack then again Calmini did it in thier X, so where there is a will (and a wallet) there is a way...

Well folks I think that sums it up here from the "show the world I'm an idiot" show. Tune in tomorrow night as ILUVMYX say's....."That humming is actually coming from your stereo speakers"! Some people just have to convince everyone that they are thick headed, can't admit defeat, never ever been wrong, ASSHOLE!!!! But just to show that I'm the bigger man, I would like to leave ILUVMYX with this final thought..... !!!!!!!

I've been wrong many many times. And I will be the first to admit that I'm wrong this time as soon as someone posts something better than "I feel it in the seat of my pants". Especially since I've found two sources--one being Nissan themselves--that say different. Funny how I'm catching all the grief from the SC owners. Defending your purchase perhaps? Hey, I too would be interested in an SC Xterra. There are times when it would be nice, but not if it only works at WOT. And so far I haven't seen any reliable evidence to the contrary. Show me some.

I've driven both, and own an SC model. I can unequivocably guarantee there is a difference at part-throttle. There is no question about it. I'm not defending MY purchase, because I'm happy with the SC and I'd do it again...but it most definitely has 'power on tap' with immediate response.

Sorry guy, your info is dead wrong.

Not mine; Nissan's and Canadian Driver's info.

And yet more. This road test from FreshAlloy . I guess they're nuts too.

The fact that the supercharger operates only at wide-open-throttle can confuse the transmission at times. Place your foot somewhat aggressively on the gas pedal and then back off and you'll find that the automatic transmission handles your fickle input quite abruptly as it tries to cope with a quick boost on/boost off situation. Thinking about calling the wedding off because of this herky jerky behavior? Just be considerate about not sending too many mixed messages and the relationship will flourish.

Nuts has nothing to do with it - the power is there, and it doesn't need to be floored to perform. It kicks in fine with a shot of juice, even part way. Obviously, if the 'test' of the supercharger means 'pedal-to-the-metal', then that's their experience.

I'll eventually install a boost guage and quantify it myself, but until then, I can only share my own experience.

To quote your FreshAlloy test: "place foot somewhat aggressively on the gas pedal (THIS MEANS PART THROTTLE - NOT FLOORED)....cope with quick boost on"-------so what the hell does that mean? Hmmm....seems to be boost at less than WOT!!! Not max boost, but some boost! Well thank you ILUVMYX for providing us the info to prove what we already knew....you're SO smart!!! I guess if I shit in a jar you'd swear its peanut butter because you friggin' read it on the label!!!

this thread was funny as hell

Amen.

Did you actually think about this before you wrote it?

Call me crazy, but every diagram I have seen for boost guagues shows the guage tapped into the intake manafold. Not between the SC and the bypass valve.

Are you for real? There either is boost inside the intake, or their isn't. There isn't "post supercharger but pre intake manifold no boost zone" where people magically connect their boost guages - give me a break!

By your own statement, if the bypass valve was open, it would be dumping all the boost and at the most there would be just a little pressure in the intake manifold on the positive side, maybe even a little on the negative if the bypass was doing what you are hinting at.

Guess what - that's not what he is reporting seeing with his boost guage, and it isn't what I have seen on other supercharger systems (no boost guage on my X but it's sounding like an interesting project).

And it's not what I noticed as I drove both a non-SC and SC X. I don't need a boost guage to confirm what I am feeling - the X really is a slug without the supercharger. I didn't think so (and if you search my earlier posts, I was quite emphatic about not caring about the supercharger) until I (gasp!) actually drove one for an extended period of time.

Also, I made my comparisons on models with manual trannys. No automatic transmission to mask anything - I had total control and total feel of the truck, and especially with the 5 speed there is a night and day difference.

If you don't think so - fine! Live without it - your loss. Me, I love my SC and would do it again if given the chance.

The reaction you see in this thread is directed towards you as someone who doesn't own a supercharger, is relying on marketing statments (again, those marketing guys are steller engineers and never make technical mistakes or mistatements!) and thouroughly discounting the experiences of those who have actuall tools that show what is going on without providing anything but more hearsay and speculation. None of the "reviews" you pointed to did anything other than parrot the Nissan marketing line. I didn't see any of them actually hook up a boost guage or do other testing. Members on this board have, and have reported what they see in that thing I like to call the "real world". Pardon me if I don't take their word over yours.

That's why people are reacting so strongly to your "facts".



If your trolling, you succedded...

I really couldn't care less what you fools believe. You bought it; you have to justify it somehow. You don't even have to look any further than Eaton's web site to know that their superchargers aren't producing power very often at all. Though it doesn't mention throttle position, it does say this:

The Eaton supercharger system incorporates a specially designed bypass valve, which is actuated by a vacuum motor near the throttle body, and recirculates the supercharger air flow when boost is not required. During typical driving conditions, the engine is under boost around 5% of the time, which means the remaining 95% of the time the engine is under vacuum, allowing for better fuel economy and a quieter ride. In addition, the helix angled rotors, along with specially designed inlet and outlet port geometry, also reduce pressure variations resulting in a smooth discharge flow and a lower level of noise during operation. The associated ducting and mounting used in installing the supercharger can play a major role in reducing the noise emitted by the supercharger.

I think it's pretty safe to say that means WOT or somewhere damn close. I'm so happy for you guys. I really am. I'm so glad you feel like your truck is a rocket even at 1/2 throttle. I think the fact that it accelerates so much faster than a non-SC even at part throttle is the fact that your wallet is so much lighter.

And besides, the only reason I would consider buying one is for the extra power when going over hills. Not because there isn't enough power now, but there isn't enough power to make it on some hills without the auto trans downshifting. If the supercharger only produces power when your foot is really on the gas, then it's going to downshift before the supercharger starts supplying power anyway. It's a non-issue with a manual trans, but not with an auto.

I will try to make the next SCCX run - So you can take a ride and check it out first hand.

BTW: Relax Coconut!

Tomorrow ILUVMYX will tell all the SC owners where the wingnuts are to remove the supercharger so we can change the filter. K&N part #oi8-JIZ!

More insults. Still no proof. No surprise.

Let me drive it over Vail and Loveland pass with it loaded up. If it doesn't downshift to make it up the pass, I'll be a believer. By the way, I've already driven two of them. One supercharged X, and my good friend has a supercharged Frontier.

It holds the same morbid compulsiveness as a bug zapper. Ya know they're gonna fry, but ya can't quit watching.

ZZzzt!

Zap.

FZzzZzt....

I meant just to see the boost -vs- throttle position.

But sure I'll let you drive it to vail, it will only cost you $20K . Just think - you can keep it afterward (or sell it) too!

You have to read between the lines with Eaton's explanation of their products. Boost conditions are predicated on the fact that the absolute pressure in the intake manifold is above ambient atmospheric pressure. The supercharger is indeed increasing the pressure in the manifold even before it crosses over 0psi gauge. I have an intake vacuum gauge installed in my truck, and I have to push the accelerator pedal to WOT before the gauge will read 0psi gauge (ambient atmospheric pressure). The fact that the supercharged motors can attain 0psi before WOT is testament to the fact the supercharger is "boosting" the pressure inside the manifold. Being that this pressure may still show as vacuum (below 0psi gauge) it is not considered "boost" by Eaton, and possibly you, ILUVMYX. Part semantics, part fact. The end result is the supercharged engine is producing more power than a naturally aspirated engine at less than WOT. Why? Because the supercharger is pushing the air into the intake manifold faster than the atmosphere can. That's the point. And to give you a better idea of the man behind the now laughed-at 2WD truck, I have a Mechanical Engineering degree from NC State. Thanks for listening.

So you're converting your 2WD truck to a 4x4 and you're an Engineer. What's your point? That you don't have to have common sense to get an Engineering degree?

It's funny how I present to you two logical responses to your issue at hand and you skirt them entirely and continue to focus on my truck.

Did it ever occur to you that I was attempting to lend some credibility to my response with a little bit of personal background?

And about the power-robbing issue. I cannot verify one way or the other that the SC engine produces more/less net power at a given RPM than the NA engine, but Nissan does supply the SC engine with larger injectors, and the ECM may be programmed such that they inject enough fuel to compensate for the parasitic effect of the SC itself. This is just speculation.

How about this. How much common sense does it take to cut a complete front drivetrain out of a truck and replace it with another, after having paid for the first one already? I thought so. What I am doing is about the same thing, only I'm not replacing things I already paid for, merely adding on. Were you aware that if I use factory components that the work is purely bolt-in? And that since I am going to keep the truck for a long time that it will only serve to increase it's value (over staying a 2wd) in the long run? Why do I have to justify my actions like this?

Can we stay on-topic here? Thanks.

The horse is dead, and there's nothing left to beat. And actually, I would have commented much nicer to your post had you not pulled the "I'm an Engineer" BS at the end. There is nothing more annoying than an Engineer who tries to make his argument solid by telling everyone he's an Engineer. Last month I argued for two straight hours with a Ford Engineer who tried to convince me that the independent suspension on the new Explorer made it superior off road to solid axles even in spite of the lack of articulation. Supposedly the clearance down the middle due to the raised diff. is more important than articulation. I tried to suggest he simply look at an off road magazine to see what they were using on the best rock-crawlers. But to him it didn't matter--he was an Engineer. Having an Engineering degree only means you're good at taking tests.

You sir are right, the horse was dead a long time ago. You are the one that kept kicking it along.

Somebody PLEEEASE shoot the fucking horse!!!

I'll re-design the horse! (It takes no sense to get an Engineering Degree...!)

I had to get in on this one.

If you want great gas mileage, buy a 4 banger. Gas where I live in CA is hovering around 1.73 gal for super. I'm unemployed but not in the poor house yet. If you don't want to pay for super unleaded don't buy an X-SC.

I had a 2000 X 4x4 before buying my 2002 4x4 SE/SC manual. Mods to date are Stillen cold-air intake, SC bypass mod, aftermarket SC pulley (9lbs boost +/- 1, M62 can handle up to 12lbs), boost gauge and dual exhaust. Without technical data but my own experience, the SC has significantly better acceleration over the non-SC from low to high end (this was before the mods). With the mods, all I can say is “What a Difference”. Even with the Nissan brush guard, the front-end lifts quit a bit during acceleration (in the process of suspension mods to correct this). I enjoy tinkering with my vehicles and have always done so but you need to be willing to pay the fiddler if something goes wrong and I accept that. I've owned a Cam Z28 350 LT1 so it's not just a speed thing. It's FUN!!!

My 2 cents, which matches my bank account.

Gee, glad you showed up. Now that's some relevant information. NOBODY's arguing that the SC doesn't make power from bottom to top. Of course it does. You may need to actually read this thread. And tell me you're joking about the "light" front end under acceleration. Even with those mods a stock Civic is still faster. Maybe if you put some Turbo Blue in there, you'll have to put some wheelie-bars on to keep from flipping over!

Well, considering a stock Honda Civic goes 0-60 in 9.3 seconds (that's with the manual tranny), you're wrong. Stock Xterra S/Cs go 0-60 in the 9 second range, and with more boost and all those other bolt-ons, I know it doesn't SLOW DOWN.

According to Motor Trend, a SC Frontier does 0-60 in 10.3 seconds. But it doesn't matter; I was exaggerating anyway. You'd have to add about 500 more horses and some drag slicks to an Xterra before a "light" front end would require suspension modifications. Something tells me that his mods didn't add 500 hp.

Hmm.. I see a trend here with the S/C Xterra owners... Boost is in direct comparison to their I.Q.'s... Showing us that the S/C has low boost (only 5-7psi: That is according to Eaton So,Fuck your boost gauge) and the driver has a low I.Q. to match it...

Damn and I thought only Ford owners were low I.Q. schmucks...

Yeah, I was comparing manual-to-manual. I really don't want to get involved in this (I don't even own an S/C), but I just don't like exaggeration! Oh well, no big deal.

If that "F the gauge" comment was directed at the 9psi info above, you are wrong. He has a smaller diameter aftermarket pulley that spins the SC faster than stock. Stuff more air in during the same amount of time and you create a higher pressure in the manifold. A few guys have tried smaller pulleys that increased the maximum boost to 11psi, but not without other adverse side effects. Go read some of the threads over on the Supercharged Forum on TUNFS.

Hey, Iluvmyx

I forgot this wasn't a free country. So why don't you shut your trap and quit talking out your ass! I see since you can cut and paste articles it makes you the authority. Get a clue!

XterraType-R, you just showed us your IQ.

I don't blame you for being angry. You've done all you can, yet every rice-rocket in California is still faster than your truck. But don't be angry with me. And if you seriously are having a problem with the front end being light under acceleration, I suggest you take the fat chick out of the back because it certainly isn't your engine that's causing it.

i am really curious about the answer to this...

can anyone find anything IN PRINT the contradicts ILUVMYX's posts... anything at all.

i only ask because since the frontier came out with the S/C it has been common knowledge that it only applies boost at WOT, I'm just curious if nissan changed this or if the boost you guys "feel" is psychosomatic... you think you feel it because you expect too and also because you hear the S/C, but not because it's there...

I'd really like to see it in writing that nissan changed the design of the S/C from the fronty to the X

anyone,
anyone,
Bueler

Well one of the ways would be for a SC to strap themselves on a dyno machine.

If the SC generates more HP than the non-SC V6 I gotta believe that's some "proof" that the SC is delivering boost (here more HP) over the entire powerband.

Notwithstanding the nonsense in this thread, I do believe that if my SC is only delivering boost at WOT, I've been mislead - and so have a lot of other owners.

I guess I should try to drive a non-SC V6 and see how it accelerates.

Oh well.

I think the best question is "What is WOT?"
If Nissan advanced the throttle to make the Xterra feel faster then you will be getting boost at less than full pedal travel - it will still be "WOT" though.
I don't think anyone is saying that the Xterra S/C doesn't get boost across the whole RPM range - it's just that the boost occurs at WOT.
There are modifications to the bypass (that are documented on this site) that will make the boost "always on". Check them out, but expect a drop in MPG.

You're talking about two different things. Nobody is arguing that it doesn't produce power accross the entire RPM range. YES IT DOES. That has nothing to do with the question of what the supercharger is doing at part throttle. Putting the truck on the dyno would tell you nothing--the dyno test would be done at WOT.

that was a good point about the advanced throttle... if thats the case an S/C owner could have the pedal halfway to the floor and be at WOT, so these anecdotal stories don't mean anything... thats why i was asking for written proof../. nissan saying "the supercharger is always on, always applying boost"

hell even if it says "the supercharger applies boost proportionally to the throttle position" that would mean something, but so far the only thing they have ever said is the S/C only applies boost at WOT... that does not mean at pedal to the floor, it means at WOT

Hehe - beat you to it, ILUVMYX :p

Here is an NA set of chassis dyno curves from my truck, and a set from Jeb's truck.

NA 3.3 V6 (5 speed 2wd)
SC 3.3 V6 (Automatic 2wd)

Jeb, can you get a better scan of that thing? I realized that the quality is pretty crappy.

I saw that. So you're a faster typer! Big deal!

And that's why I posted this which can be found in Car & Driver:

What is strange is just how urgently the supercharged Nissan leaps off the line with nothing more than a tap of the gas pedal, belying the mediocre drag-strip numbers. It turns out that an overly aggressive throttle linkage disproportionately opens the throttle plate when the pedal is depressed. Pure mechanical trickery, but the supercharged Frontier now easily merges into 80-mph freeway traffic.

Y'all really need to go compare the two with the hoods up side by side. The cam that the throttle cable hooks to on the NA engine is circular. The cam on the SC engine is more "egg" shaped. It is setup so that the beginning part of the movement is quicker, but the last 1/2 of the curve is basically the same as the NA cam.

So you're agreeing that the relationship between the gas pedal and throttle plate is different for an SC than an NA.

oops.

damn must suck to make a post that basicly says

"hey, i'm wrong"

so problem solved... the S/C only applies boost at WOT which comes quicker in the pedal travel than on an N/A engine due to a modified throttle cable linkage.

Well, that still doesn't necessarily mean that the supercharger ONLY comes into play at WOT, but that IS the reason everyone is so SURE that the truck is so much faster at part throttle. I posted that thing from C & D way back on page one. Nissan isn't the first to do it. It used to be a common trick that GM did to make people think their cars were more powerful than they actually were. The car magazines used to joke about it. My guess is that Nissan did it so that uninformed people who test drove an SC and a non SC felt like there was a huge difference right off the line. Nissan could have made the SC to operate at all throttle positions, but then the gas mileage would have been horrible. This way, it "feels" faster all the time, and they get to put a sticker in the window that only shows a 1 MPG hit on fuel economy. I'd say given the defensiveness of certain posters, Nissan was successful in their ploy.

Hey, guys, I got this from a site called 'fc3spro':
"WOT "Wide Open Throttle" - term used to describe the throttle (plates) being fully open or the gas pedal being fully depressed"

Sounds to me like the definition of the term itself indicates 'pedal to the metal'.

The supercharger kicks in well before that.

Sorry guys....you lose.

I agree that the linkages are different. I also agree that there will be a difference between pedal position and trottle position between the SC and NA engines. Hello I've known this all along, and I wasn't arguing about that issue.

I guess until someone with money to blow on dyno runs comes along there really isn't going to be a happy party in this debate. Someone will have to strap onto a dyno and monitor the TPS voltage at part-throttle, then do another dyno run with a truck with the other engine and the same drivetrain, set the TPS to output the same voltage, and see what comes up.

I'm bored of this topic. Hell I'm arguing the SC side of things and I don't even own one. I'm sorry I can look at the diagrams for the SC and "see" how it (and the bypass) works without having to put my hands on it or run it on a dyno. I noticed that ILUVMYX worked for Roush (finally checked your site). I cannot understand why he cannot understand this.

Over and out.

It's simple, iluvmyx is an idiot. He's trying to sound educated about something he knows nothing about. Darwin award candidate.

Why I can't understand what? Look, I don't own a supercharged Xterra. So the only evidence I have to form an opinion is what I've read in magazines and web site reviews and what owners have to say. Given that I've found three sources that all say the SC only works at WOT and that Eaton themselves imply that by saying the supercharger only works 5% of the time and that Car & Driver pointed out what you just did about the throttle linkage... well, let's just say I'm pretty convinced of what the story really is. Yes, the only way to test for sure would be to do as you said: measure the voltage at the TPS while comparing the output on the dyno. But that's not going to happen. Since that's not going to happen, and since everyone else's "proof" amounts to "it feels faster at all throttle positions", I've come to my conclusion as best I can given the information I have.

Based on Eaton's claim that the supercharger is operating 5% of the time, I'll concede that there's a possibility that the SC begins to supply power just shy of WOT. But the evidence is quite overwhelming that the people who think the supercharger is operational accross all throttle positions were nicely taken by Nissan's throttle linkage trick.

As a side note since you mentioned Roush: My comment about Engineers comes largely from my engine development experience at Roush. I knew a lot of Dyno Techs whose knowlege and understanding of engines was far greater than some of the engineers. Not to say we didn't have some great Engineers--we did--but we also had some very shitty ones. So when I hear "but I'm an Engineer" it brings back some bad memories.

Are you 14 years old? Do you know what a Darwin Award is? Do I jump from tall buildings without a parachute? Do I strap rockets to my car? Do I play Russian Roulette? Do I juggle grenades? Do I smoke in an oxygen tent? No, I don't. And even if I did, you wouldn't know it from this thread. So you saying I'm a Darwin Award Candidate just shows what a moron you are.

Wow, what a thread! Lots of 'knots' along the way.
I installed(meaning with my own hands) an Eaton SC from a kit provided by the Downing-Atlanta race shop in my car. After nine years and 50,000 miles I'm still happy.
Too much of this thread is based on (mis)information, speculation, opinion and bullshit. So I'll provide some links that may help.

How about Eaton, the company that makes the SC:
http://automotive.eaton.com/product/engine_controls/supercharger.html

Magnuson is the offical aftermarket supplier. Spend some time at their site - lots of information.
http://www.magnusonproducts.com/

From a typical aftermarket kit vendor(there are many):
http://www.jacksonracing.com/pages/sprchrgrhnd.html#

A TC and SC article in an industry mag:
http://www.autofieldguide.com/articles/050103.html (SC in the shaded section)

I'll let you guys spin things however you like.

dave and xtoy and miatank(with the SC)

Is this definition of the bypass the same as that applied to the Eaton SC used on the Xterra?

From Magnuson:

The best kept secret in forced induction is the little known bypass valve. This small valve, when properly installed between the supercharger and the air throttle body, allows the supercharger to become extremely efficient in terms of economy and parasitic power loss. Our M90 supercharger uses less than 1/3 of 1 HP at 60 MPH cruising. The bypass is operated by a vacuum actuator control unit that is normally closed. When vacuum is high (idle-cruising) the actuator opens the bypass valve, equalizing the vacuum pressure throughout the system. When boost is required (accelerating) the vacuum is decreased and the bypass valve instantly closes, causing pressure to increase into the cylinders. This equalized vacuum condition virtually eliminates the normal parasitic power loss of a forced induction system.

If so, it would seem that the SC supplies pressure during acceleration regardless of throttle position. The bypass then dumps during idle or crusing (maintaining steady throttle).

Yes, the Nissan application uses a bypass valve. There is one difference between the X and the install in my car. The X has an on-off solenoid valve that controls the action of the bypass valve. The ECU controls the solenoid. Kind of a way to idiot-proof the system. For example; low octane gas is added to the tank. The knock sensor will signal the ECU and boost can be 'shut off' by activating the solenoid which will block the vacuum line that activates the bypass valve. For those that don't know, sustained detonation will turn a forced induction engine into a boat anchor in no time. There are also other emissions related conditions when the ECU is programed to prevent boost. Of course bypassing the solenoid has been documented and doing so is up to the owner.

dave and xtoy - mistakes are expensive

Man, I wish you would, Darwin. You don't own an SC so why don't you move along and show your intellect on another thread or better yet another forum. For your information, Darwin, I have an AS and BS degree. Done with you Darwin.

Wow, you've just proven yourself to be even dumber than I thought. Calling someone Darwin isn't an insult. He was the one with the theory, remember? He was a brilliant man. Thanks for the compliment, dumb ass. And you're just more proof that getting a degree doesn't mean you're smart.

Thanks DatsunDave, for providing some real information, with absolutely no childish insults! I love learning, and you have helped me do that. And what a pleasure to get facts from an adult.

Looks like there is boost all the time, except when the bypass is activated at low vacuum (idle & cruising). I'm still not sure why the talk/literature about WOT needed. That doesn't jive with Dave's references:

From Eaton:
"The Eaton supercharger increases torque across the entire operating range without compromising driveability or emissions. ... Additionally, the supercharger incorporates a bypass system to reduce air handling losses when boost is not required, resulting in better fuel economy."

From Jackson Racing:
"The Jackson Racing Supercharger gives you a 40% boost in power. Instantly. From off-idle to max rpm, with no spiking and no hesitation."

I'm convinced there is always boost unless bypassed.

Now for the next lesson, how does the Engine Mgmt System interface vacuum demand of the SC and of the auto tranny? Does the EMS have a specific action at WOT? What besides low vacuum (and possibly low octane) opens the bypass valve? How low is low - at what vacuum pressure?

I really think that you will get a better understanding if you install a boost gauge in your truck. Granted, it won't exact in helping you determine your throttle postiion, but, you will get a better understanding at what is going on by watching the needle in vacuum and under boost.

The ECU (EMS if you prefer) uses a computer controlled solenoid that is plumbed in series from the vacuum signal port on the intake to the vacuum supply port of the bypass valve. The computer controls the opening and closing of this solenoid - controlling how much vacuum the supercharger bypass valve sees.

Someone else may answer this better but the only thing I have seen at WOT is lowering boost when low octane fuel is used, or lowering boost when under high loads at high ambient temperatures. Both are indicitave of being triggered by the knock sensor.

Presumably any other knock condition. High load and high ambient temperature...

I have no clue what you are asking here.

. For your information, Darwin, I have an AS and BS degree. Done with you Darwin.

So you have a degree. What was your GPA? How long did it take you? I went to college got my AS I also got my BS and I got my Mr. My wife has her AS her BS and her Mrs. People now refer to us as Mr. and Mrs. brings a smile to my face every time Since I own my own business I've used my degree 0 (zero) times but I use my common sense everyday. The only people that care about your degree are those that paid for it.

I almost died laughing when I saw that! SWEET!

I'm no engineer, but I feel my SC kick in at a certain speed/RPM and NOT when I have it floored. It gives me a little extra boost to pass on the road or splash through a bog. Nothing "super" about it other than a shot in the arm but I like it.