Boost Question

[FordNut]

I know from my previous work with the ProCharger that centrifugal blowers are setup to measure boost at the intake manifold and that there is usually 2-4 psi boost loss thru the intercooler. I've been studying the manuals from FoMoCo, Kenne Bell, and Trilogy in prep for a new setup. It appears that they measure boost at the discharge plate, before the intercooler. Is that accurate? Why wouldn't it be measured after the intercooler core?

Also, I was looking at the PCV tube which connects to the bottom of the lower intake manifold, to a tee then to the plenum and PCV valve. Is the tee really a check valve? If not, it looks like it would be bypassing boost from the bottom of the manifold to the inlet of the blower at the plenum. Help, I don't understand.

[Zack]

I know from my previous work with the ProCharger that centrifugal blowers are setup to measure boost at the intake manifold and that there is usually 2-4 psi boost loss thru the intercooler. I've been studying the manuals from FoMoCo, Kenne Bell, and Trilogy in prep for a new setup. It appears that they measure boost at the discharge plate, before the intercooler. Is that accurate? Why wouldn't it be measured after the intercooler core?

Also, I was looking at the PCV tube which connects to the bottom of the lower intake manifold, to a tee then to the plenum and PCV valve. Is the tee really a check valve? If not, it looks like it would be bypassing boost from the bottom of the manifold to the inlet of the blower at the plenum. Help, I don't understand.

Brian, the plate adapts the compressor to the lower intake. The exiting air of the KB goes stright through the intercooler, then out to the lower intake. The IAT sensor is in fact in the discharge plate, but is between the actual intercooler and lower intake (after the cooler)

Good question on the PCV. Trilogy has it and 03-04 Cobas. KB does NOT.

[Zack]

Damn you Brian, I can sense a Whipple 3.4 in your future

[Zack]

You got me thinkin now Brian. On a Trilogy, that line from under the blower hooks up to the passenger side PCV valve. It is definitely not a PCV valve suited for boost. So are trilogy cars boosting the crankcase at WOT?

[FordNut]

Brian, the plate adapts the compressor to the lower intake. The exiting air of the KB goes stright through the intercooler, then out to the lower intake. The IAT sensor is in fact in the discharge plate, but is between the actual intercooler and lower intake (after the cooler)

Good question on the PCV. Trilogy has it and 03-04 Cobas. KB does NOT.

OK, so the fitting for boost gauge connection is off to the side and measures boost after the intercooler then...

The PCV hookup probably wouldn't pressurize the crankcase, but it would leak boost back to the blower inlet if it's a simple tee fitting. I'm pretty sure that's the same fitting as the OEM '03-'04 Cobra uses, just wondering how it works.

[TooManyFords]

I know from my previous work with the ProCharger that centrifugal blowers are setup to measure boost at the intake manifold and that there is usually 2-4 psi boost loss thru the intercooler. I've been studying the manuals from FoMoCo, Kenne Bell, and Trilogy in prep for a new setup. It appears that they measure boost at the discharge plate, before the intercooler. Is that accurate? Why wouldn't it be measured after the intercooler core?

If I wanted to impress a ricer, I would measure the boost pre-intercooler. Regardless of where you measure from, boost is a meaningless number that measures the inefficiency of your motor, and I suspect you already know that. If you increase the efficience of the breathing of the motor, (bigger intercooler, bigger headers, bigger cams and valves but the supercharger and pulleys do not change, the boost goes DOWN but the power goes UP. I suspect you knew this too but included it for those reading that are just learning about boost and what it really means.

Cheers!

[FordNut]

If I wanted to impress a ricer, I would measure the boost pre-intercooler. Regardless of where you measure from, boost is a meaningless number that measures the inefficiency of your motor, and I suspect you already know that. If you increase the efficience of the breathing of the motor, (bigger intercooler, bigger headers, bigger cams and valves but the supercharger and pulleys do not change, the boost goes DOWN but the power goes UP. I suspect you knew this too but included it for those reading that are just learning about boost and what it really means.

Cheers!

Yes, as per your comments I already knew the answer to some of the queries, just wanted to be concise in my description. What I was really working up to was not boost measurement, but where is the best place for tapping into boost/vacuum for things like FRPS, boost bypass valve control diaphragm, boost-a-pump sensor switch...

As well as figuring out how the PCV thing works without being a boost bypass valve in iteslf.

[Dennis Reinhart]

If you have a the CDS or the analog Dyno jet set up as I do, you can measure before and after the IC on the centrifugal set up, this will actually show you IC efficiency and any boost loss it also can map IAT before and after, on pro charger set up they bypass the PCV and T in on the inlet of the Blower, I showed Rich how to fix this using the EV111 that I have used for the last 2 years and Vortech even has it in all there new kits.

[Marauderjack]

If you have a the CDS or the analog Dyno jet set up as I do, you can measure before and after the IC on the centrifugal set up, this will actually show you IC efficiency and any boost loss it also can map IAT before and after, on pro charger set up they bypass the PCV and T in on the inlet of the Blower, I showed Rich how to fix this using the EV111 that I have used for the last 2 years and Vortech even has it in all there new kits.

How much loss of boost do you see across the IC Dennis??

Seems to me that any boost pressure in the system shows the engine's inability to consume all the air produced by the blower (static pressure) therefore the pressure should be about the same throughout the system?? I guess there is some flow lost in the IC and maybe a pressure buildup on the blower side but at 8-9 PSI couldn't be too much??

Marauderjack

[magindat]

I showed Rich how to fix this using the EV111 that I have used for the last 2 years and Vortech even has it in all there new kits.

I made a post on that with the pictures of my catch can. Thanx, Dennis!

Brian knows all about it!

BTW, EV153 is an upgrade from EV111.

[magindat]

If you have a the CDS or the analog Dyno jet set up as I do, you can measure before and after the IC on the centrifugal set up, this will actually show you IC efficiency and any boost loss it also can map IAT before and after, on pro charger set up they bypass the PCV and T in on the inlet of the Blower, I showed Rich how to fix this using the EV111 that I have used for the last 2 years and Vortech even has it in all there new kits.

I bet Brian would benefit from knowing how you did the PCV system on that whipple!

[TooManyFords]

What I was really working up to was not boost measurement, but where is the best place for tapping into boost/vacuum for things like FRPS, boost bypass valve control diaphragm, boost-a-pump sensor switch...

Boost/Vacuum should be measured in the same volume of air that is entering the cylinders. That's what the motor is seeing so that's what the computer needs to calculate against.

John