I need alittle help here guys .

Im kinda confused on what ive been reading and what ive been experiencing with my truck .
From what ive read is that this whipple makes boost in relation to throttle position and or RPM .

I want to know at what throttle position or RPM does a whipple on a 5.3L start making boost ?

Because the only time ive been experiencing boost is when im pretty much at WOT , it just doesnt sound right to me .

So does the only time this SC makes power is when it is in + boost levels or does it make power through out the RPM range?

For example tonight i went driving around to see how this thing would act , cruzing in 2nd and @ 3000rpm im still seeing 10hg of vacuum , is that right ?
I mean everybody ive talked to said , "Oh yeh the Whipple make tons of low end power !!!" HUH ??? where is it ??? At part throttle this thing really feels flat to me , doesnt have any real grunt to it , only time its really fun is when you hit the kickdown and it downshifts then it starts to roll , other than that its pretty unimpressive . My truck was tuned for 6psi but its only pushing 4psi so i know its probably running alittle on the rich side .

My truck @ WOT makes 4psi with the stock 4 3/8'' pulley , ive done the whipple bypass , checked for leaks of any boost bleeding off , belt is tight and still dont see 6 psi . Ive read that with cam and free flowing exhaust you might loose some , but 2psi ?

With everything ive done to my truck thats in my sig , to me it still feels like a big

maybee i need to throw that YankTT in there , but who knows if that would even help

save me before i light a match to this MF !

 

I had the whipple installed on my truck and it feels great at part throttle, and thats with a small leak.... and on only 8* of timing..

I would check your tuning...

 

his tuning wouldnt be the reason its not making boost...

 

Well if not the tuning, then I would check agian and make sure you have no hidden leaks.....

 

cammin03, where was your leak?

 

Where the 90* throttle body adapter met the supercharger!!

 

OK I think we are talking about two separate issues here. First, the Whipple kit has a bypass valve, which opens when engine is not under load, allowing the motor to breathe like it was N/A, which is better for long-term durability and also for emissions. That is why when you're cruising along you see 10 hg vacuum.

When you're on it is the only time you should really be worried about "missing" boost. I'm not real familiar with the effects of a cam on boost, I know it can drop but I don't know what is normal. That could be it, your bypass valve might not be adjusted correctly, you might have a leak somewhere....or maybe it's normal. Hopefully someone else can chime in soon with their experience. Boost is a measure of airflow restriction, so the less restrictive you make your motor, the less boost you will make with a given pulley size.

As far as making boost in relation to throttle position and RPM....there are two types of superchargers. Some, like the roots type, blow the air into the intake manifold and you get positive pressure because the amount of air blown into the manifold is greater then the amount used by the motor. Others, like the twin screw and centrifugal, actually compress the air internally and release compressed air charges. So the Whipple is always compressing air, but the bypass valve releases the compressed air when you're light on the throttle. The Radix, on the other hand, never compresses anything when the bypass valve is open because all the air that is blown into the intake is released before it builds positive pressure.

Hope this helps, I know it doesn't really answer all your questions, but hopefully it will help make a little more sense....

 

For the most part you really wont see any boost with any blower unless you are either heavy into the throttle OR moderately into the throttle but really loading the truck.. IE going up a hill, towing etc.

Always remember that PSI is just a measurement of restriction. By adding a cam and free flowing exhaust you will see less boost but you are still flowing the same amount of CFM but you are using it more efficiently so there will be less restriction thus less PSI on the guage but you'll be making more HP than if you had a corked up exhaust, stock cam and more PSI on the guage. Make sense?

Your truck probably feels like a turd because 4psi really isn't squat, especially if your timing it retarded too much and you're running rich.

Case in point. A guy came into Synergy Motorsports with an STS kit on his 4x4 and with a "custom" tune he was only making 285rwhp on like 8psi according to the test run on Rick's dyno. After a few hours of tuning he left with 380+. He didn't add any new parts. Just simply tuned what he had. Tuning can go a LONG way.

 

You need a smaller pulley. I am using a 3.75 pulley to make 6psi. As your pulley gets smaller your boost should come on earlier.

Are you using the whipple electronics?

Is you bypass valve manual or electronic?

 

Pretty much what's been posted above. I run a KB twin-screw which is similar to the Whipple. I can go 5000 rpms in a gear if I want and not show boost, unless my foot is on the floor or the engine is loaded like climbing a hill, passing a car, etc. This is normal. And I have the bypass valve shut off in my tune.

If you're only running 4 psi you won't get a huge boost in power/torque, though you should be able to feel the difference. Timing and tune are critical as far as how the truck will run, so a very conservative safe tune can feel lazy.

Jody