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How many pounds of boost should I be running?

slow94formula

slow94formula

New member
I only get 7 PSI at the shift points and I feel like the number should be higher. Am I right?

Here are the mods that are on the car:
Speedbuilt FWI with 9" K&N cone filter
ZZP 1.0 PCM
Autolite 104 Sparkplugs
drilled 180* thermostat
TOG Headers
3" Downpipe to 2.5" exit
Stock midsection exhaust with 2.5" Y-Pipe with Flowmaster 40 series
3.4" Pulley
Caspers Fan Switch
 


r u scanning? i have everything listed below done 2 my car and i get 11 lbs of boost at the shift points. change the zzp tune, i hear they r no good.
 
that turbo car blew up because it was using an l36 UIM which is plastic. thats the only reason.

your boost level seems fine. i usually liked to keep stock timing (~16* WOT) and run as much boost as i could before the car knocked, then backed it off a little. these cars run the best around ~10 psi, but i have seen 13-14 psi when it was cold outside on a 3.4 pulley. i was running a 3.2 non-intercooled with methanol injection and saw around 12 during the spring.
 


Boost really depends on how well your motor flows. The more air you get in and out the less boost it will show but its actually pushing more air in there. Our super charger doesn't work like a typical roots style charger.
 
basically every motor is different and depending on mods w a 3.4 I have heard of anywhere between 6psi and 13psi @ WOT...boost means nothing other than how efficiently it is flowing...knock is way more important unless you are way out of range... does it feel strong?
 
i see 13psi on my 3.5, but its been cold as balls here lately. when i first ran i seen about 9psi on a 60* day.
 


dagger said:
I thought our superchargers don't compress the air inside the housing like normal, I thought that they just force more air in which why they produce so much heat?
Click to expand...

it is true that we dont have blowers that compress air, but it still works exactly the same as other roots blowers. our boost is made in the LIM instead of the blower casing itself.
 
twin screw blowers compress air in the housing ie kenne bell and whipples.

both roots style blower, just a twin screw is more advanced.
 
it is called a blower because of what it does. it blows air, any roots supercharger does it, it forces air out of itself faster than the engine can take it creating pressure within the intake manifold. a twin screw is not a blower, it compresses air within the housing via male and female rotors

pressure = heat. to prove how inefficient blowers are think about this. the crank transfers energy to the supercharger via mechanical force. mechanical force then pushes air but it gives off heat in the process. where is the added heat coming from? energy cannot be created. heat = wasted energy in this situation
 
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true a twin screw is not a blower.

but hey, boost is boost even if it is wasted energy :D

this is what whipple has to say on the topic


Whipple Charger
Centrifugal
Turbo
Roots

Response
Awesome idle-to-redline rpm power. No lag.
Poor low-speed response, similar to "turbo lag."
Poor low-speed response. Turbo lag.
Good low to mid range power.

Driveability
Increased lugging ability in higher gears. Increased power throughout rpm range.
Must downshift to maintain boost level.
Must downshift to maintain boost level.
Increased lugging ability in higher gears.

Engine Torque Curve
Virtually flat curve; ideal characteristic.
Often worse than uncharged engine at low speeds.
Often worse than uncharged engine at low speeds.
Wide range; fall-off can occur at high speeds.

Heat Buildup
Low; intercoolers are usually not needed.
Low; intercoolers are usually not needed.
High; may need intercooler
High; limits boost available.

Noise
Very low noise levels.
Typically very noisy.
Very low noise levels.
Typically very noisy.

Adiabatic Efficiency
70-80%
60-78%
60-75% Peak
40-55%
 


blowfishRus6 said:
true a twin screw is not a blower.

but hey, boost is boost even if it is wasted energy :D

this is what whipple has to say on the topic


Whipple Charger
Centrifugal
Turbo
Roots

Response
Awesome idle-to-redline rpm power. No lag.
Poor low-speed response, similar to "turbo lag."
Poor low-speed response. Turbo lag.
Good low to mid range power.

Driveability
Increased lugging ability in higher gears. Increased power throughout rpm range.
Must downshift to maintain boost level.
Must downshift to maintain boost level.
Increased lugging ability in higher gears.

Engine Torque Curve
Virtually flat curve; ideal characteristic.
Often worse than uncharged engine at low speeds.
Often worse than uncharged engine at low speeds.
Wide range; fall-off can occur at high speeds.

Heat Buildup
Low; intercoolers are usually not needed.
Low; intercoolers are usually not needed.
High; may need intercooler
High; limits boost available.

Noise
Very low noise levels.
Typically very noisy.
Very low noise levels.
Typically very noisy.

Adiabatic Efficiency
70-80%
60-78%
60-75% Peak
40-55%
Click to expand...

this really needed to even be posted? of course a turbo > CSC > roots. its common knowledge if you know how cars work.
 
Whipple. FAILS there...saying that you don't need an intercooler with a Twin Screw blower...proven, especially with the W140AX on a 3800 platform...that thing made SO MUCH heat...you couldn't run with with anything smaller than a 4.0" pulley without an IC, S3IC to be exact...and he ended up running a just a 3.75" or a 3.5" since anything smaller was brutal on knock.
 
whipples put out less heat than eatons. i wouldent say it does not need an intercooler tho. the funny thing is most all of there set ups do come with intercoolers.

bio it was posted to compare our eaton to a twin screw to show the diffrence. alot of people get confused and think there the same thing and work the same. i just wanted to post some faqs about it. sorry if its not up to your standerds :)
 
beyond my standards really. i dont really do actual comparative research. i just tell people what they need to know. therefore, good work.

the eaton is a heat pump, simply put. its efficiency is a joke.
 
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