I have looked on these forums and alot of you guys are talking about boost levels you are seeing with your M62. I was running the 3.1 pulley and I was seeing 10-11PSI. I just installed the 3.0 Pulley and I am seeing 11-12. But reading further into the forums, people with the 3.0 pulley are getting 13-15??? WTF? I have my boost gauge on a TEE coming off the nipple on the intake, running into the tee and the other side of the vacuum tee is going to the FPR. Is this causing me to get a false boost reading?

Weather conditions, engine RPM, supporting modifications, etc.


2001 Olds Alero (LD9)
636 whp / 543 ft-lb
@turboalero

Im not sure about the boost levels for different pulleys on the m62, but for any roots style sc when you drop pulley sizes you are generating more heat. Cooling mods will help generate more boost and keep the iat's lower, just like you can see more boost in colder weather as opposed to hot weather. Keep whatever vacume source your fpr line is supposed to run to, and just tee off the boost gauge there, dont run it anywhere else.

Im in Michigan, Its cold right now. I have a Tsudo 4-2-1 Header, Cobra HE, 2.25 exhaust with no cat. My engine has about 7000 miles on it from GM. I just dont understand how everyone is seeing these high boost levels and im down in little kid land at 10-11 :-(

Im running the GM Reflash, and 6500 RPMs

Yeah you only need to T off one spot. Usually the FPR line

I have it Tee'd from the FPR line. The hose comes up from the intake and I have it going into the bottom part of the Tee. Then on one side is the boost gauge and the other side is the FPR. Do you think that is why I am only seeing like 11 PSI? How do you guys have your boost gauge hooked up?

Douglas Collins wrote:Im in Michigan, Its cold right now. I have a Tsudo 4-2-1 Header, Cobra HE, 2.25 exhaust with no cat. My engine has about 7000 miles on it from GM. I just dont understand how everyone is seeing these high boost levels and im down in little kid land at 10-11 :-(

You have a full exhaust. PSI measures RESISTANCE. Exhaust heightens flow, lowering the resistance of the air going through your engine.

Everyone always bases their power off PSI, it's comical. It's flow that's important.


2001 Olds Alero (LD9)
636 whp / 543 ft-lb
@turboalero

Take your fpr line where it is supposed to go with m62 from the fpr, and just put a tee in line and run your boost gauge line. Thats it, dont run the line from the fpr to anywhere else, just whatever vacume its supposed to go with the sc.

icemike89 wrote:Take your fpr line where it is supposed to go with m62 from the fpr, and just put a tee in line and run your boost gauge line. Thats it, dont run the line from the fpr to anywhere else, just whatever vacume its supposed to go with the sc.

If you read his post, that's what he has.


2001 Olds Alero (LD9)
636 whp / 543 ft-lb
@turboalero

[ion wrote: C2]

Douglas Collins wrote:Im in Michigan, Its cold right now. I have a Tsudo 4-2-1 Header, Cobra HE, 2.25 exhaust with no cat. My engine has about 7000 miles on it from GM. I just dont understand how everyone is seeing these high boost levels and im down in little kid land at 10-11 :-(

You have a full exhaust. PSI measures RESISTANCE. Exhaust heightens flow, lowering the resistance of the air going through your engine.

Everyone always bases their power off PSI, it's comical. It's flow that's important.

Thats also a factor. You could be comparing boost levels to someone with a stock exhaust, whereas you have a full catless header back. Just like if you were to port your head and sc, you may not see as high boost levels but youll be flowing more air and making more power.

Im comparing to people like 03supercharged who was running the 3.0 with full exhaust, I believe he had a cat and he was seeing 15 on a cold night. He was one of the original people I was asking questions before I even boosted my eco. I seen in another thread some people were running the 2.9 pulley on there stock eco but they didnt say what there boost levels were.

Like I said.... flow resistance is not the best way to measure or compare power.


2001 Olds Alero (LD9)
636 whp / 543 ft-lb
@turboalero

Well does it seem like my boost gauge is installed properly? As far as I know it should be hooked up properly because its pressure and its going to be the same, its not flow where it could change.

Yes it is. If you want the best accuracy in boost measurement, use HPTuners to scan and check your MAP reading minus barometric pressure.


2001 Olds Alero (LD9)
636 whp / 543 ft-lb
@turboalero

Well it seems to make sense. My car might just be a freak of nature. I understand what you mean about the resistance though because the day my cat got plugged my boost spiked like crazy and threw me in limp mode.

every car is different, I'm on the stock pulley and only see about 7.5 psi or so.

icemike89 wrote:

[ion wrote: C2]

Douglas Collins wrote:Im in Michigan, Its cold right now. I have a Tsudo 4-2-1 Header, Cobra HE, 2.25 exhaust with no cat. My engine has about 7000 miles on it from GM. I just dont understand how everyone is seeing these high boost levels and im down in little kid land at 10-11 :-(

You have a full exhaust. PSI measures RESISTANCE. Exhaust heightens flow, lowering the resistance of the air going through your engine.

Everyone always bases their power off PSI, it's comical. It's flow that's important.

Thats also a factor. You could be comparing boost levels to someone with a stock exhaust, whereas you have a full catless header back. Just like if you were to port your head and sc, you may not see as high boost levels but youll be flowing more air and making more power.

Being that this is a positive displacement s/c, doesn't it flow the SAME CFM for a given pulley diameter/rpm? The pressure drop when porting the head is a result of less resistance to the mass of air that's being forced in. Turbochargers (with the help of your preferred form of boost control) generate a CFM @ a certain psi, and it varies by psi, and you want to operate at the flow where the turbo is efficient. Based on the efficiency map, a certain PSI should equal a certain CFM. This just isn't the case with positive displacement s/c's. Outside of maintenance issues or boost leaks, you boost can vary greatly with the s/c...

I'm seeing anywhere from 7.5 -9 depend on how cold it is and I have header back 2 1/4" exhaust. Back pressure definitely plays a role with these kit. But really if you can make the same power on 7 that another guy is making on 9 your better off.

What size pulley are you running?

Stock

Well I took the car out last night @ 2 am and it was like 40 degrees, beat on it hard like always and started to see about 12-13. But I started to flash a check engine light after a little while, code was mulitple cylinder misfire. Probably do to the fact that I still have stock spark plugs with stock gap.

Are you trying to pre-ignite the motor?

13 psi with stock heat range plugs???

Dude go change those out immediately. That's a TON of cylinder pressure and heat you're forcing into the motor, simple things like timing retard (in the reflash), higher octane gas and proper heat range plugs will save you from coming back to us in 3 days and saying "Help my motor is spewing oil and is down on power" followed 3 weeks later by "well I ripped the motor down and I blew the #3 ringland... sh!t I wish I spent the 10 minutes and $10 to change out those spark plugs..."

... seriously.

-Chris-



-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...