Hey guys/gals. New one here. I'm considering trading in my 2001 Stratus R/T Coupe for a tC when they become available.

I'm wondering if anyone knows if the TRD Supercharger will have a rev-limiter much like the GM-Chevy Impala SS does, that limits rev's to 3K rpm's if the vehicle is sitting still (either in Park or Neutral.) Also, do we have any word as to whether the supercharger will come with a bypass or blow-off valve?

Thanks, and if this has been asked before I apologize - I just joined about 5 minutes ago and need a few nights to catch up. Thanks.

Jeff
www.jeffreystephen.com

superchargers don't use BOV... the reason is that you need a BOV for a turbocharger is that the momentum of the turbo keeps compressing intake air... think of it as units of air, the pump is supplying the perfect amount to make the desired pressure at 6000rpm, then you hit the clutch and shift to a lower gear and the engine is now turning 3000rpm which means it needs 1/2 the air supply, but the turbo has that momentum and it is still pumping the same amount of air... so now you would have twice the pressure... this would be bad... so the BOV relieves the pressure back down to a preset maximum so that you don't blow the engine up...

a supercharger on the other hand is "bolted" (really belted) to the engine... so as the engine drops in rpm during a shift, so does the amount of air the "pump" (supercharger) is perfectly matched to the needs of the engine...

make sense??

as far as a rev limiter, this is the first I have heard of a "park" rev limiter... I guess this is just a safety feature to keep you from dumping the clutch??

I know plenty of people with centrifugal-style stuperchargers who still use wastegates - especially in high-boost applications. I know a number of Stratus owners with the Ripp mods blower and a BOV on it.

It probably all depends on how much boost the blower puts out.

Yeah the GM motors have a rev-limiter on it, which greatly dumbs down the performance "feeling" of those cars. So I hope Toyota/TRD doesn't do the same. Guess I'll just have to wait and see.

why would u want to rev your engine up in park or neutral anyway? u have the need to destroy your pistons rings even faster?
there is good reason for that 3k rev limit...keeps stupid people from wrecking their motor.....

I know plenty of people with centrifugal-style stuperchargers who still use wastegates - especially in high-boost applications. I know a number of Stratus owners with the Ripp mods blower and a BOV on it.

It probably all depends on how much boost the blower puts out.

Yeah the GM motors have a rev-limiter on it, which greatly dumbs down the performance "feeling" of those cars. So I hope Toyota/TRD doesn't do the same. Guess I'll just have to wait and see.

okay, so your talking 35psi of boost... your also talking about a complete "do-it-yourself" setup... not a bolt on setup to any vehicle... we are talking about a street driven car, not a 1/4miler... you have to understand that it works like supply and demand - a supercharger is belted to the engine and pumps a corresponding amount of air based on the engine speed - a turbocharger, due to inertia, is always playing catch up, at first it isn't making much boost because exhaust pressures are low, as you rev your engine you get more turbo spool up and more pressure is being built, but then you shift and your demand for volume of air goes down, but the turbon is still pumping so the pressure will spike... on a supercharger it drops speed with the engine so the pumping is dialed into the demand...

I understand what you're saying. I just wasn't sure if it applied to all applications.

Scionxb04, I've been revving the motor of my 01 Strat at red lights and parking lots for 3 years now, and the thing hasn't seen a shop since the day I bought it.

A little tap on the accelerator every now and then isn't going to drastically affect the life/performance of an engine. Let's be realistic.

ask any mechanic and they will tell u free revving a motor is bad for rings..would u people learn something and read before posting stupid ____

I know plenty of people with centrifugal-style stuperchargers who still use wastegates - especially in high-boost applications. I know a number of Stratus owners with the Ripp mods blower and a BOV on it.

It probably all depends on how much boost the blower puts out.

Yeah the GM motors have a rev-limiter on it, which greatly dumbs down the performance "feeling" of those cars. So I hope Toyota/TRD doesn't do the same. Guess I'll just have to wait and see.

okay, so your talking 35psi of boost... your also talking about a complete "do-it-yourself" setup... not a bolt on setup to any vehicle... we are talking about a street driven car, not a 1/4miler... you have to understand that it works like supply and demand - a supercharger is belted to the engine and pumps a corresponding amount of air based on the engine speed - a turbocharger, due to inertia, is always playing catch up, at first it isn't making much boost because exhaust pressures are low, as you rev your engine you get more turbo spool up and more pressure is being built, but then you shift and your demand for volume of air goes down, but the turbon is still pumping so the pressure will spike... on a supercharger it drops speed with the engine so the pumping is dialed into the demand...

and u...look at any vortech supercharger kit and it will have a bov....even the cheap ones have a bosch bov....
http://www.vortechsuperchargers.com/products/yourcar/99-00civic.html here are the kits for my civic....notice the bov

I've been revving the motor of my 01 Strat at red lights and parking lots for 3 years now.

You know that if a cop hears you rev the engin you can get in big trouble because its basicly saying you want to race. And we all know thats illegal. You dont want your car taken away for revving do you? I dunno, IMO, it's kinda ___ to sit there and rev anyways.

I've been revving the motor of my 01 Strat at red lights and parking lots for 3 years now.

You know that if a cop hears you rev the engin you can get in big trouble because its basicly saying you want to race. And we all know thats illegal. You dont want your car taken away for revving do you? I dunno, IMO, it's kinda ___ to sit there and rev anyways.

i would also bet any amount of money if i compression tested his motor it wouldnt even be close to where it should be....not that any normal driver would ever notice a slow decrease in compression unless it was a sharp dropoff in compression....

and u...look at any vortech supercharger kit and it will have a wastegate....even the cheap ones have a bosch wastegate....
http://www.vortechsuperchargers.com/products/yourcar/99-00civic.html here is the kit for my civic....notice the wastegate

this is an antisurge valve, that is its technical name and it isn't in place to prevent damage, it is there to stop noise... I understand your desire to understand the S/C setup, but you need to research first... here's the technical scoop... based on the downstream location of most throttle plates, the supercharger is still producing the boost when you let off the throttle, because the engine is still spinning at the high rpm - (the "gas pedal" controls the air throttle plate) - but say you are still in gear and the engine is spinning at 6000rpm... well the s/c is still pumping based on the desired pressure at 6000, but the throttle plate is constricting what can get by, the throttle plate sees high pressures on the upstream side and negative (vacuum) pressure on the downstream side, but the s/c keeps packing the air until it reaches its pumping maximum and literally the air starts popping back out the intake - this is quite noisy, but it isn't hurting anything... we're talking low pressures... and the pistons will never see this pressure, even if you floor it again after letting off, because you have a few inches at high pressure and a few more inches of intake at low pressure, not to mention a evacuated cylinder just trying to suck more air in... we are also talking about a very small amount of air to be "blown off"... so you will not hear this device doing its job, everybody loves the turbo BOV, but that isn't gonna happen here...

when a t/c is releasing the pressure it is because of the momentum of the impeller continuing to pump enough air to make desired boost at peak rpm, but when you shift down the next gear the engine is gonna need only half the air that the impeller is pushing, so until the impeller slows down it needs to dump quite a bit of air... so the BOV on a t/c is extremely audible, and definitely on high boost applications, but only when it is vented to atmosphere... (otherwise it might be into the exhaust) an alternative bypass valve might allow exhaust air to bypass the exhaust side impeller, which will help the impeller get down to the proper speed MUCH faster...

if you'd like to read a really good source on this info, I recommend picking up a copy of either BOOST (http://www.amazon.com/exec/obidos/tg/detail/-/0837601606/qid=1086748466/sr=8-1/ref=sr_8_xs_ap_i1_xgl14/104-4969350-5855922?v=glance&s=books&n=507846)
or SUPERCHARGED (http://www.amazon.com/exec/obidos/tg/detail/-/0837601606/qid=1086748466/sr=8-1/ref=sr_8_xs_ap_i1_xgl14/104-4969350-5855922?v=glance&s=books&n=507846)

sometimes I oversimplify... but my comprehension is there, feel free to ask questions, but more imporantly - walk away with understanding of what I am talking about... I have a degree in mechanical engineering and I have been working on engines and electronics for as long as I can remember... but I am not an expert, I'll be the first to say that... but I am extremely well read... I've spent a whole lot more time tinkering with aircooled engines, but watercooled engines are okay... :lol:

the real issue is here, now with quotes of 55 hp, I would put this at 5psi of boost... 215hp needs a limited slip differential... anyone fitted one for the Camry transmissions...

MAXFLOW AIR BYPASS VALVES Flows 320 CFM @ 8 PSI
...their superchargers are centrifugal.....please go read...stop wasting my time
MAXFLOW AIR BYPASS VALVES Flows 320 CFM @ 8 PSI
Compact design is ideal for import applications and tight engine compartments
Includes gasket for installation (steel and aluminum mounting flanges available separately from Vortech)
Two bolt mounting pattern will retrofit to standard HKS/Greddy style mounting pads
u can also use these with turbo's which ive seen many people do
u can also use one from hks or greddy in its place which ive also seen done on the vortech kits...this gave them the ability to adjust boost....

non-centrifugal like the one on my 1,800hp alcohol injected drag boat....doesnt require any type of boost controll because its directly belt driven and runs at the exact same rpm as the motor...unlike the vortech ones which takes time to slow down...this is how vortech keeps the boost up between shifts....the non-centrifugal jackson racing one which is roots type spins with the motor has drop in psi between swifts when the rpm's drop...
ive driven civic's with both centrifugal and non-centrifugal...dont need no degree...have real world building experience
<img src=http://www.nipponpower.com/images/vortech04.jpg> <blow off valve

i thought u are here to ask questions. then u refuse to accept the answer/truth???
if u already know the answer, why would u ask people here???

I've been revving the motor of my 01 Strat at red lights and parking lots for 3 years now, and the thing hasn't seen a shop since the day I bought it.
why would u want to do that kind of stuff? whats your point?



A little tap on the accelerator every now and then isn't going to drastically affect the life/performance of an engine. Let's be realistic.
are you trying to be a street racer? since u always revving the motor at red lights?

Let's be realistic.

unlike the vortech ones which takes time to slow down...this is how vortech keeps the boost up between shifts....

you do realize that this is COMPLETELY FALSE... there is not a single supercharger that runs on a clutch type system that I have ever run across, it is impossible to function the way you are talking about.... superchargers of all kinds spin in perfect sync with the engine, there might be small amounts of belt slippage on a super high boost application, but you are completely 100% incorrect on this one... sorry

it kinda messes up the point of your post... not sure what the flowrate of a anti-surge valve has to do with the amount of air that will need to be dumped... I'm not saying that I'm not sure about the facts, I am saying that I am not sure what your point is...

Wow what a FLAMING. guys new to the board, you could be a little nicer dont you think?

Wow what a FLAMING. guys new to the board, you could be a little nicer dont you think?

some of the guys arent really new, but what a crazy disagreement.

Ok, i'm gonna have to stick up for this guy in the thread. Reving your engine doesn't do ____. If you sit their and bounce it off the rev limiter, then yeah, but thats obviously not what hes doing. A simple rev isnt going to effect your piston rings :roll: . Why do u think people would rev it up and then drop the clutch when racing if it really effected the motor. Seriously guys...

unlike the vortech ones which takes time to slow down...this is how vortech keeps the boost up between shifts....

you do realize that this is COMPLETELY FALSE... there is not a single supercharger that runs on a clutch type system that I have ever run across, it is impossible to function the way you are talking about.... superchargers of all kinds spin in perfect sync with the engine, there might be small amounts of belt slippage on a super high boost application, but you are completely 100% incorrect on this one... sorry

it kinda messes up the point of your post... not sure what the flowrate of a anti-surge valve has to do with the amount of air that will need to be dumped... I'm not saying that I'm not sure about the facts, I am saying that I am not sure what your point is...

good to see someone put one of the "i know everything" brats to shame. :)

unlike the vortech ones which takes time to slow down...this is how vortech keeps the boost up between shifts....

you do realize that this is COMPLETELY FALSE... there is not a single supercharger that runs on a clutch type system that I have ever run across, it is impossible to function the way you are talking about.... superchargers of all kinds spin in perfect sync with the engine, there might be small amounts of belt slippage on a super high boost application, but you are completely 100% incorrect on this one... sorry

it kinda messes up the point of your post... not sure what the flowrate of a anti-surge valve has to do with the amount of air that will need to be dumped... I'm not saying that I'm not sure about the facts, I am saying that I am not sure what your point is...
i used to run one....you have no idea what your talking about.....after i shut my car off i could hear it wind down....and i could adjust boost from within the car....something u cant do with normal supercharger without changing the pulley...
read this... http://www.sandsautomotive.com/whipple/superchargers/supercharger-comparison-chart.html notice how it says Centrifugal superchargers have lag....cause they spool up like a turbo....quit wasting my time educating u people...

when i drove my neigbors civic with jackson racing supercharger it wouldnt hit full boost till redline...the boost would rise with rpm....the vortech supercharger i had would hit full boost around 3,000rpm and hold that boost till redline...nothing like a normal supercharger.....more like a turbo...even sounded like a turbo spooling and i got the whooosh between shifts.....

type of supercharger your talking about looks like this..roots type.. <img src=http://www.jacksonracing.com/Graphics/Products/Large/989-300_1.jpg>
vortech's look like this..Centrifugal type... <img src=http://www.vortechsuperchargers.com/images/s-trim_cw_cvd_sat.gif>

roots type spin 2-3 revolutions to one revolution of the crank.....means at 8,000rpm the jackson racing would spin 16,000 to 24,000rpm(depending on pulley used)
vortech superchargers spin over 50,000rpm
they work nothing alike....and i have 0 boost when idling...the jackson racing supercharger roots type always made boost...even idling...he had the internal bypass valve removed....and his car was still slow....roots type suck....we both had the same car...2k civic si with b16a2....reason why i smoked him...roots type have a adiabatic efficiency of 40-60%...centrifugal superchargers have a 60-78% adiabatic efficiency

seriously, read a book... I understand what you are saying, but I think you are missing the point... a roots type blower is most efficient at lower rpms, sure it makes boost right off the line, it loses its efficiency as the rpms climb... centrifugals are a completely different beast, they have an efficiency range which is in the 10s of thousands, so most people set them up to make approximate the most boost where torque and hp are peaking... but you will see a basically linear increase in boost as you climb the rpm range... this is the simplicity of a centrifugal...

BUT you can easily put a different pulley on it and get the same setup to make peak boost much lower in the rpm range and then you MUST use a BOV to release this pressure... then you'll have a flat boost level above the point where you have designed it to do so... most people don't set it up this way, because it takes energy to compress that air and the BOV is just letting that pressurized air go away for free... I don't have my books with me, but later on today I will calculate what the energy losses are, but I would venture to guess that the losses will exceed the hp gain... if not, it will be close enough to not justify the extra plumbing... pumping that air up to high pressure would be the same as towing a parachute, but if you engine is using the air you have "paid" to compress then you are more efficient...

a BOV is not a necessary part of a correctly designed supercharger, with a turbo charger that makes any significant pressure it is a necessary evil... UNLESS you are dealing with a constant rpm application - like water pumps, gas compressors, etc...

as far as what you were hearing wind down, I'm not sure what to tell you... the centrifugal is a direct drive system... I would like to see the clutch mechanism that you are saying this setup would require, it would wear out, so there will be replacement items available... it is new to me...

http://www.sandsautomotive.com/whipple/superchargers/superchargers-compared.html
on this page, from your same site, it explains that centrifugals are fixed ratio, call them and ask if they have some clutch system it theirs, but I'm at a loss to tell you what that noise you were hearing was, but I am saying that it was NOT the supercharger "winding down" like a turbo... of course this is based on their not being a clutch installed on the unit...

do you know what adiabatic efficiency means?? just curious... I have a thermodynamics book that takes about a chapter to explain it... I didn't learn from Car&Driver...

and if all roots blowers suck, then I guess this is why the only type of supercharger you see on Top Fuel Dragsters...??? 6000hp isn't testament to their abilities??

Looks like the core market of the Scion knows about as much about moddding and car and engines as my sister does and that ain't much.

Yes, mix in a book every so often you might actually learn something.

Today's mechianics are part replacers not problem solvers like in the olden days....

Too much RPM is a bad for any engine, but that's why the bean counters make the engineers keep the revs well-below what the actual engine peak limit is. Bouncing it off the rev-limit a few hundred times isn't going to hurt anything, as long as you don't try and do it all in one day.

Minor changes to the valvetrain will allow you to spin the Camry engine to at least 7,000rpm. But spinning it that high might but extra pressure on the cylinder side walls and therefore putting more pressure on the rings. Not a good thing...

Real Time Racing's Nissan Sentra SE-R has a rather large 2.5L engine and to make it usable in SCCA World Challenge competition, had to totally change the geometry of the engine since another team tried to race the car at stock bore and stroke and blew it up in its first testing at racing speed.

So you might have to destroke the Camry engine to get any high RPM power. Not hard, just expensive and I highly doubt any Scion owner has the nads to even try it. Plus unless the car is totally embraced by the hardcore drag racing/road racing community, you won't see any hardcore parts for this car. I hope that isn't the case and a bunch of powder puff/HIN types and people affaid to make any changes on the car for fear of theif or considers it a waste of money (and those packet of cigs you buy for $2.25 a pack, several packs a week, hundred of packs a year isn't??) end up buying the car.

I see alot of potential in this car and like to see it exploted.

I might even get a tC if a SRT-4 still proves to hard to finance.

Welcome... I am new here too. Good question.

Well we now know that BOV are available for SC's too. :idea:

Interesting group of guys....

I find it most entertaining that everyone seems to say "Read a book" and then not two of you say the same thing. Just what books are you reading? I've seen a plethora of in-depth online articles about forced induction, and a number of them spoke of blow-off or bypass valves on a supercharger.

If you look at some of the pictures on the Scion boards (try clicking the tC link at top-right) you'll see that the supercharger in the Scion is a centrifugal. Centrifugal superchagers work almost identically to a turbo system, except that it's belt-driven instead of exhaust driven. But then again, you all know that.

Just to let you know, mgithens (not to put you down or nothin') but the most efficient supercharger at low-rpms is the twin-screw type, built almost exclusively by Whipple Superchargers and used in marine applications, because of the extreme heat build-up and the need for an air-to-water intercooler.

And finally, revving your motor to 4,000 rpm's is LESS damaging than driving down the highway at 80 miles per hour, maintaining a constant 4,000 rpm on the engine. And I love the guy who goes "If a police man sees you you're going to be in twubble...." Okay if you're dumb enough to rev an engine in front of a cop than you deserve to be pulled outta your car and beaten with a "dumbass" stick.

Oh yeah, and go read a book. <- my new line.

I made no reference to what type was most efficient... simplicity of design is the key to a bolt on kit...

the need for an intercooler has nothing to do with HOW the air is being compressed, the majority of the heat that is in the "charged" air is due to the fact that when you compress any gas there is heat... I like to compare the heat to a salty glass of water, imagine you have a "salt-o-meter" and you can measure the concentration in a glass of water... well for my example we can't compress water, but we can remove some... so we take away half the glass of water, not the salt, just the water... the concentration of salt goes up, this is how the heat is in the compressed gas... there is a portion of heat that does come from the process of compression, but the majority is just a higher "concentration" of the heat that was in the original gas... I'm avoiding all technical words and trying to maintain a layman's terminology, and I think this description works...

the need for an intercooler has to do with HOW MUCH you compress the air... and it has to do with the compression ratio of the engine... and it has to do with the stability of the fuel (octane) that you are burning...

the only similarity between a turbo and a centrifugal S/C is that they use similar type impellers... the belt driven part of the S/C removes the requirement for the BOV, read my previous posts or the books Boost or Supercharged both by Corky Bell, it takes power to compress air - period... and a BOV is a "leak" in the system, so you are spending the horsepower to compress more air than you need and then just blowing it off, this reduces efficiency in the design...

I'm wondering if anyone knows if the TRD Supercharger will have a rev-limiter much like the GM-Chevy Impala SS does, that limits rev's to 3K rpm's if the vehicle is sitting still (either in Park or Neutral.) Also, do we have any word as to whether the supercharger will come with a bypass or blow-off valve?
No idea. Rev limits are easy to get around though. Not sure about the BOV. That's probably the least important part in any turbo system, yet it's one of the most talked about part amongst the ricers. Concentrate on the core stuff first and you'll be ok. And no, it won't hurt your engine to free rev it. I've held various engines at 7k RPM w/o any problems. No drop in compression or leakdown #'s after dozens and dozens of times.

Lol - cheesefrog, best reply yet. Except that BOV's in a turbo application can be very VERY important when you start dealing with significant (i.e. above 9-11 psi) boost levels. Tell a guy with a 32psi system that he doesn't need a BOV! :)

mgithens, buddy you keep telling me stuff I know. I know why you need the intercooler - you're right - heat. I told ya that. I studied this sh!t for months! It's cool though man - I appreciate your knolwedge.

The reason the twin-screw is the most efficient at low-rpm is because of the design of the blades. A twin-screw actually produces boost at idle, whereas even a typical, production-type roots blowers won't produce boost until 300-500rpm above idle. The blades just don't have enough speed to built pressure. But with a twin screw, the air enters at one end of the blade (as opposed to the top of the blades) and is "squeezed" towards the other end of the blades, which have a tigther diameter. Therefore, you are always creating boost.

Anyhoo - this nice big thread isn't actually answering my question. I emailed the guy from AutoWeek magazine who wrote the review two weeks ago, but he didn't have any answer on the rev-limiter question. He did however say that there was no lag from the blower.