3.4 pulley question

[Homie_Telefrag]

Just did a few monitored pulls in the SSEI, and I noticed something. At WOT, the most boost I see is between 4-5PSI with the 3.4 pulley. I was told that the stock pulley generates about 6? Im sure theres no way to adjust boost like on our GN's either.... Could something be wrong or is this correct? -Ben

 

[SHADOWII]

No expert here, but that was my understanding as well-6# w/ stock.

 

[murphinator]

sounds like an issue with the boost bypass valve or boost control solenoid. I forget if you can unplug the vac line/block off the vac line or unplug power to the solenoid I recall one of those procedures will allow full boost and help narrow down which is the problem. Its been a few years since I swapped from 3800 cars to ls1 cars.

as far as boost readings on a given pulley it depends on the density of the incoming air being compressed and how well downstream flow is after combustion chamber ( exhaust system , cam/high ratio rockers to hold valves open longer , ported heads etc...) stock pulley here (Maine) at sea level I have seen in the 6's & 7's on a stock car with stock pulley in hot summer temps and 9/10 psi when it gets real cold in the winter on the same stock pulley. On a 3.4 pulley I have seen 9psi on a car with good flow (headers/rockers/3" catback) and nearly 14psi when the mods weren't in place to stop a common issue with sc3800's that drop pulleys without proper supporting mods - boost stacking....

 

[Homie_Telefrag]

Murphinator, I have the following mods:
ZZPerformance VS cam
Mild Head Porting
105# Valve springs
LS7 Lifters
1.7 Yella Terra Aluminum Roller Rockers
3.4 Pulley
Hi volume oil pump
4IN Cold Air Intake
Power Log
ZZPerformance 1.0 PCM with HPTuners
MSD Coils
160* Thermostat
NGK TR8 plugs
ZZPerformance Downpipe to a custom 2.5in Dynomax Super Turbo muffler with twin LT1 tips
All new sensors, connectors, fuel pump, etc.

So from what you're saying I should basically be double the PSI from where Im at now... Is there an adjustment to the bypass valve? ::SHRUGS:: I put a new one on when I put the car together... I'll try to take a look at the solenoid though as I havent messed with that at all yet... unplug it and see what happens huh? Thanks for the info! -Ben

 

[Homie_Telefrag]

Ok so I unplugged the solenoid and no change. So I decided frak it and unplugged the accuator vacuum line just to see what would happen. As I removed it, PLINK! little plastic hose broke clean in half. So I plugged it up (along with a randum open hole on the bottom side of the solenoid) and went for a drive. Car 'feels' more responsive, but only 3PSI now.....great.... X_X

 

[machinegun]

Typically this is caused by one of 3 items.

Leak some where post Blower.

Blower being worn or rotor seals worn.

Bypass valve malfunction.

Start with Bypass valve.

 

[Homie_Telefrag]

Bypass valve is new, motor has all new gaskets/seals.... The S/C has a rebuilt snout, but also has 250+K on it...

 

[SHADOWII]

Bypass valve is new, motor has all new gaskets/seals.... The S/C has a rebuilt snout, but also has 250+K on it...

ouch that hurts. Maybe the rotors are shot? the good news is, they're fairly cheap on e-bay.(The s/c, that is)
I managed to purchase an entire assembly, rebuilt s/c, wiring harness, intake, inj.'s, heads, fuel lines, pistons and rods, pcm, air filter, and gaskets for $500.00 I'm not sure if it was a god deal or not, but it looked good to me!

 

[Homie_Telefrag]

Ive got 2 other S/Cers sitting on the shelf, just need to clean them out and go through them. I know the one has 97K on it, so thats probably the one thats goin back onto the car. That sounds like a pretty good deal to me! Heh

 

[SHADOWII]

Have you figured out your boost problem yet?
I forgot to mention the cam and lifters came w/the kit also.

 

[Homie_Telefrag]

I posted about it in the bonneville forum, and according to them, 3-4psi sounds right for my combo? They're saying ignore the low boost readout and just jack up the timing. Ive tried every trick I can think of to try and make it run more boost, but no joy. Ive got a 97K S/Cer just sitting, but its gonna need the snout replaced. Im thinkin about transplanting the good snout from my current S/C to that one and seeing if the lower used S/C will help?

 

[SHADOWII]

I think the swap would be the way to go. I can't see the boost being that poor w/o some kind of problem being present. I don't see justifying such a big expense on such a small increase in boost. It wouldn't even reach advertised HP.

 

[Homie_Telefrag]

I think the swap would be the way to go. I can't see the boost being that poor w/o some kind of problem being present. I don't see justifying such a big expense on such a small increase in boost. It wouldn't even reach advertised HP.

Yeah, Im gonna be putting the car down for repairs coming up next week. Soon as the funds are there, Im gonna get all the gaskets and swap out the S/Cers and snouts with eachother. If at that point Im STILL not making boost... I guess Im gonna have a use for one of the stock GN turbos I have laying around after all.

 

[FuryLS1]

Honestly 4-5 psi sounds about right with your mods and that pulley. Boost is low mostly because of your heads and cam. Boost is a measure of restriction. Your engine flows a lot more air now, and is no where near as restrictive as it was when it was stock. I'd say you just need a smaller pulley on the blower. I'd try a 3.2" pulley and see what it reads.

 

[SITHV6]

Honestly 4-5 psi sounds about right with your mods and that pulley. Boost is low mostly because of your heads and cam. Boost is a measure of restriction. Your engine flows a lot more air now, and is no where near as restrictive as it was when it was stock. I'd say you just need a smaller pulley on the blower. I'd try a 3.2" pulley and see what it reads.

With my common combo in the 03 regal GS....my 3.2 pulley does 13.5 PSI on cold days 13.0's on hot. I Too had a low 3 PSI boost problem not too long ago and posted on this forums under "gawd diddly dammit....low boost!" Hope it helps! =P

 

[Homie_Telefrag]

Ended up having a free day yesterday to play with the car a bit. Purchased a new boost solenoid and wouldnt ya know it? As I was taking the old one off, I notice the 90* connector going from the left side of it to the intake was completely blown open on the back side of it Replaced the connector and threw on the new solenoid. 8ishPSI on the 70* days we've been having here no sweat! Biiiiig difference in the 'feels' dept now. Thanks for all the help/info guys - mystery solved! -Ben