ChevyCoonass

Forgive my ingnorance, but in the prochargers instance, what does the blowoff valve do? I know what it does in a turbo. I also am getting one with my FLP tranny because the line pressure is vacuum controlled. But what does it do in PC's case?

Also, oil??????spilling from where???? I clean my motor all the time. It gets everywhere or something?? Or is that what the blowoff valve is for? Oil? Explain about hearing it down road.

Appreciate all the comments because I need to tell Allen at FMS where to put all of this stuff like the blowoff valve, and if the intake relocation is going to be helpfull or not.

zippy

we recently installed a p1sc on a friends tahoe. first of all, the system sucks, but the head unit's top notch. with the vigilante 2800 boost is almost instant as it hits 2psi before it budges and 5-6 within a few feet peaking at 10-12 depending on the air. the blow off valve is made to keep the boost from spiking when you let off the throttle and the blower is still spinning (producing alot of boost) which can blow the tubes right off it. we eliminated the craptastic unit that came on it and vented it into the atmosphere. the new one is much louder, but seals tight not letting any air past at any time until it's supposed to. we also added a crankcase breather system to keep oil from getting into the blower as can happen with venting the breather system into the intake. if you get one with an fmu unit i'd recomend getting rid of that and putting larger injectors in then getting it programmed for it. we've also added an air intake temperature sensor onto the boosted side for street driving and run the sensor on the vacuum side for running race fuel at the track. programming was by ed wright due to the model of the vehicle. even on the old school L31 it put down 335 rwhp and has since been improved. next dyno run we're hoping for 350 rwhp. today playing around we ran over 400g/s on the maf readings.

Chevmann99

The blowoff valve diverts boost back to the inlet side of the blower when it's not needed (like at closed and partial open throttle positions) this keeps the blower from surging and causes less drag from the blower when cruising on the highway according to ATI. I tried dissconnecting it once and the blower would make fluttering whistly noises, which I assume is surging, anyway it didn't sound good.

The bypass noise comes from when you are cruising down the road and not on the throttle, the blower is spinning fast enough to make a little bit of boost, but the throttle plate is closed so the boost has no where to go, the bypass valve opens and the pressure in the system is relieved through a 1-1/2" tube. Problem is at highway speeds (especailly if you have low gearing) the blower is constantly bypassing. It's pretty noisy since this is happening literally just a couple feet in front of you.

When I changed the bypass to vent to atmosphere I started noticing oil mist all over the engine compartment (not much it took months to start being noticable) and it was about the same noise wise. I started measuring the old oil when I did oil changes and realized that only about 85% of the oil I put in the blower was coming back out at the 6,000 mile change. I called ATI and they said that the blower is sealed with a wet type seal and that it is normal for it to seep some oil and since I was venting to atmosphere the oil was getting all over the engine instead of just going through the inlet side of the blower and or into the engine, needless to say they recommended putting it back the way it is supposed to be.

My only real complaint with the ATI is the noisy bypass valve and intake, and is the main reason I want to re-route the intake, the noise might not bother some people but I don't like it. I figured the intercooler would take care of the heat issue from the intake being right on top of the exhaust manifold, my main concern is noise. FWIW my trucks gearing is relatively low 4.88 w/ 35" tires so my highway RPM's are pretty high 2500+ at 70mph (even with 4.10's they were over 2000 on the highway) so the blower is spinning pretty good and that makes the bypass louder.

I also deleted the FMU and put 43lb hr injectors in just this weekend, due to erratic air/fuel ratio issues, the PCM is on it's way to Ed Wright, as I type this for recal to the steeper gears and the injectors. I second that the head unit is nice, the rest of the stuff in the kit is so so.

zippy - What kind of after market valve did you replace the ATI one with?

Texas Terminator

nice pulley!

lm7

iTrader: (8)

the intake i made was totally useless it seemed like a good concept but i gained almost 2lb/min by taking it off to my current setup.
ive been working on relocating my battery but right now i think the best thing to do is throw a pvc 45 degree on the end of the rubber 45 off the blower to get the filter off the headers(current setup).
my iats barely went up but i flowed a lot more air than with that huge restrictive intake (look a black blown o2's setup his IMHO is best)......
seth from cmotorsports put it best......"you can blow through a straw in pretty much any position its bent in efficiently(boost), but you cant suck through a straw thats bent as well as u could through one that is short and straight (intake)"........ the blower can push boost through those hard angles no problem. but it struggles to suck in air through any real hard angles.
anything more than 11 degrees on the intake side becomes a restriction....so the shorter and less harsh the angle the better.

OOsilverado

I love my procharger. I believe their kit is crappy but their blower is the best out there by far. I have a atmospheric blow off valve as well, it does get annoying when im on the freeway, but Ive gotten used to it, it bothers some people though.

As far as an intake, I dont have one, my blower collapsed the filter in the first week and Ive never done anything about it. I dont drive it that much so im not worried.

I do have plans for my intake though, My plan is to do an Air/water intercooler and to turn the compressor housing either up and have the outlet go over the top of the blower and basically right into the intercooler, and I will have my intake go down under the blower like the old outlet pipe. Im trying to keep everything as short as possible. This should be happening soon so Ill post pics when I get to it.


Also I get oil everywhere because of my atmosperic blowoff valve as well. Im currently using a TurboXS type RFL but Im going to most likely change it out to their regular one and recirculate it when I do the intake.

Also the red accessory box is under my brake booster, I extended my alternator wire and it made for a much cleaner setup. This let me run all my wires under the blower and it made everything look much cleaner. Im also eventually going to move my battery to the firewall where they mount the second battery on the diesels. That will give you probably the best looking setup possible

black_yukon

I have a ProCharger in my 02' Yukon. I have a homemade intake that is relocated to the stock location. I used 4" brake duct.


After reading the responses here I might go with the 90 degree elbow idea. I had no idea that all the piping would create such a restriction.

One thing I don't understand about the stock ProCharger intake is that the supercharger's inlet is 4" but a reducer is used to drop it down to 3.5". I wonder if that was a well engineered plan or just a way of getting everything to fit.

BTW, What model # filter did you use Blown Black?

zippy

using the same blowoff on the tahoe, the turboXs type RFL. haven't had any oil issue's yet, but expect to soon.

black_yukon

I found that most of my oil was coming from the PCV line. I made a catch can with an air compressor filter and haven't had any oil problems.

lm7

iTrader: (8)

one thing i noticed with venting the bypass to atmosphere was it lowered the iats a bit vs. recirculating. i wanna know if it was just my eyes playing tricks on me or did u BOV guys notice the same thing? i think it has to do with the fact its not reciculating already compressed air thats been through the blower once....i havent noticed an oil problem with it, but with it being so far from the MAF i have plenty of room to relocate it without it throwing the MAF off... im gona try to face it down towards the ground and away from the engine bay and watch the oil level....closely.