As long as your bypassing intercooled air, then dumping back into the intake will be productive because the air will be cooler than ambient.


The reason it's colder is because first air gets compressed by the supercharger (gets hotter than ambient) and then it is cooled via the intercooler (becomes almost ambient temp.) and then it's decompressed via the bypass and becomes cold air.

However, if you're bypassing before the air goes through the intercooler, you might as well dump it out away from the intake.

--
Jeff

 

Damn Gary! You need to make it up to Northern VA for some of our Z meets so we can all scope your ATI install!!

Maybe Mike will have another gathering at his shop soon.. he told us he's all about Turbo.. but he's making himself quite a common name around here with this SC

 

I'd definitely like to come up for a meet. Especially after I get the ATI installed! There has been some talk about a meet in Richmond as well that I'd like to go to. Where do you all post info about NOVA meets, in the regional forum?

 

Yes.. keep an eye on the regional forum.. there tends to be gatherings about once at month or so.. some tied to events.. some tied to 'lets just meet up!'.

Last one we had about 15 Zs at when Jeff @ evolution sports had an 'open house' at their place. He's talking about putting together a z-only meet too in th near future.

 

When shut basically jsut make the SC compressor look very "leaky"
hence it cna't produce as much pressure. King of like drinking thru a straw and cutting a small hole in the side of the straw (ie. no more or less suction). Wha work for suction also works for positive pressure.

Whe I get a better look at the component and installation , could probalby determine if the bypass "dump" could remain were is , moved or vented externally.

Note that one reason an SC or Turbo is safer for a car like this is that the lower RPM TQ places less strin on the factroy drivtrain component (esp the IRS rear end).

The drivtrain is not designed for very low ET drag racing, were more instant TQ is beneficial.

 

Not quite sure what you're saying there G3PO.

Anyway, the "bypass valve" in the kit is plumbed back around to the inlet side of the supercharger. Since this bypass valve can't, and won't need to, flow a lot of air it can be plumbed this way. The kit operates at a fairly low boost level, so a huge bypass valve isn't needed.

If you are set up for higher boost you might need a larger bypass valve to achieve the desired effect. At some point, I'm not sure where, the bypass valve may have to be vented to atmosphere because the volume of air being vented back around to the supercharger inlet could cause problems. I think one problem is that the air would get heated more and more every time through the supercharger. The intercooler can't be 100% efficient, so even if it vents back around after the intercooler, it will still be warmer than ambient air. I believe this problem would get worse as the boost (and air volume) of the system is increase. Apparently, this recirculation doesn't really have a big effect at the kit's 7 psi.

The idea of running a smaller pulley for higher boost in conjuction with a bypass valve that can bleed off excess boost after a certain rpm is interesting. From what I understand though, the bypass valve, which works like a BOV on turbocharged applications, is not good for controlling boost. So I don't know that this idea is feasible, even if vented to atmoshpere.

 

Well aside from my crappy typeing, here is another take.

Granted at some pulley size , the provided bypass return hose (ie the size of the hole in the side of the straw) would be inadequate. Meaning that the Compressor's ablity to pump +psi
exceeds the ability for the bypass to leak that psi.

The reason an Intercooler gets "hot" is because it is "heat-sinking" air which has been "sqeezed above the ambient atmosphere". Less squeeze = less heat to be sunk". If the compressor is 100% pressure bypassed, the air passing thru the Intercooler is no longer "squeezed" hence all you are doing is "pulling" <0psi thru the intercooler.

If the Bypass is large enough to provide 100% bypass of normal atmospheric air, then the IC sees 100% "sucked-air" , rather than 100% "pressurized-air".


The main challenges are :

a) increasing the bypass volume to an adequate level. It only needs to be "sized to allow 100% NA intake volume" not boosted volume. Because as the "NA volume increases" the "boosted volume decreases" and approaches a zero (balanced state) when fully bypassed.

b) modualteing the bypass mechanism rapidly and smoothly to create a regulation of boost.

c) Fuel management which can take into account for the dynamic change.

The "waste-gateing" functionality applied to turbo systems can most definately also be applied to belt driven SCs.

It's just that it isn't a necessity. With a tubo system it is a "must" since Boost levels are not mechanically limited via crank RPM, and if left unchecked instablity due to postive feedback could destroy the engine.

 

My guess on the squealing problem would be that the serpentine belt is slipping momentarily until the SC is being brought up to speed from a dead start. It being a centrifugal SC tells me that it is not "geared" for low rpms, or, for that matter, startups. Therefore, since it has no clutch(A/C), or is not variable speed(ie. power steering), there probably is a moment of resistance until the SC begins spinning...hence, a momentary squeal.

Just think of it as the momentary squeal your g/f gives at the beginning (fill in the blank). The pleasure afterwards is well worth a little squeal.

My two cents worth anyway.

 

This will be very difficult to do, and kind of pointless.

S/c'ers run off of RPM speed. So if your daily driving you will never see that much boost. If you redline your car that's when you will see maximum boost...and in NORMAL daily driving you don't redline your RPMS...unless your unnormal like me.

 

Something else to not is that like all belt driven SCs the
ATI unit has a "transmission". Under cold start condition the lube in the SC's crank case (though synthetic) still has some viscosity thickening when cold. On other setups I've seen the "cold SC" produce noise such as :

a) louder whine which quiets down somewhat once the SC grease and gears heat up.

b) Belt squeel due to the SC's initial tranmission drag. Usually this to, quiets down after warm up.

For clarification , Max,etc., this squeel you have heard...

a) is it only at cold engine start up or every startup?
b) is it when the engine is rev'd (mild, WOT)?
c) is it only upon acceleration (mild, WOT...?

One thing to note about belts, once they start squeeling regularly the rubber compound on the surface of the belt becomes "polished" and hence prone to future slipping.

Often this can be minimized by either replaceing the belt(s) or softening the contact surfaces (as mentioned , this can be done with laquer thinner cleaning). If the problem persists then yes there may be a mechanical flaw in the systems design and belt loading.

Personally I find belt squeeling akin "nails on a chalkboard".
So I'm pretty interested in it's resolution, before I commit to the system as is.

 

In the Procharger installation manual it states that the belts should all be re-tensioned after driving for 100 miles.

 

Good point. That *should* hold true with almost anything being installed which requires tightening.

 

I can see were the ATI provided "additional" belt system may require manual tensioning, but most factory serpentine systems employ a "spring tenshioned Idler pulley" which requires no manual adjusment. I assume that the majority of the factory serpentine system and tensioner remains intact after ATI installation.

So ,adjusting the ATI belt tension "may or may not" solve the issue depending which belt (s) is the root of the squeel.

 

I see EJ has been reading, good show dude.

The Belts are made by Gates not ATI.
My squeel stopped I think, or at least got better with time.

 

But still......the factory systems spring-tensioner will only have so much travel to it......if it's close to the end of it's travel when the install is done, then a shorter belt may be required

keep in mind we're introducing 3 new pulleys into the stock system.

i've gotta say that i've found the manual to be tip-top.......it addresses issues such as belt tracking, and how to correct it.......it suggests that the C-2 has it's oil changed after the first 500 miles, and every 6000 miles thereafter......the C-2 has it's own dipstick and a magnetic drain plug, BTW

 

But why worry about belt sizes if I want a 9 lb pulley BWHAHAHAHAHAHAHA
HA

HA
err Ha?

 

EJ, so do one or more of the three ATI supplied pulleys (placed into the factory serpentine system) provide an "off-centric" hub for adjustment.

If one of you early ATI adopter guys could scan the
the manual into a .pdf format , I'd certainly be will to pay for your efforts. Unless ATI offers a soft version. Having the manual in advance would be really helpful.

Thanx

 

okay.....i'm just going by memory at this point, since i'm at work, and don't have the manual in front of me........but i do remember it mentioning a patented "eccentric" adjustment.......i'm drawing a blank as to which pulley it was talking about, but i can clarify later if need be.......i don't have access to a scanner at this time

 

EJ Thanx, no hurry, just curious.

 

MadMax, do you mind giving us a break down of the parts that were required to complete your SC install and their prices? I'm planning on getting the ATI SC as well but wanted to know an estimate of the total cost of everything. You know the SC, ingectors, ECU, extra hoses or whatever extra you had to get.
Also if you don't mind sharing the installation and tunning costs that would be awesome. If anyone else could share their "shopping list" that would be awesome too.

Thanks,

zaway