Whipple Charged

The purpose for the bypass is really none of the above. Its to equalize pressure above and below the supercharger. Superchargers have a pressure differential when the throttle blades are closed, since the SC is "sucking" air when the blades are closed and the motor is also "sucking" air. This equalization does help some idles, as most are lean conditions and when they surge and vacuum gets less (motor almost stalls), the AF gets richer and motor runs, vacuum increases as idle surge goes up, motor gets lean. This is a revolving circle. A bypass would help reduce this, but you still have to jet and adjust properly to make it work, its not a cure.

Also, bypass lowers air charge temps at idle because there is less "vacuum" above the sc between sc and carbs/tb's as well as the fact that air is actually being diverted through the bypass to the motor instead of the SC, which means it does get beat or compressed during that stage. This reduces temp at idle, which also helps idle because you have a more consistent temp at idle and therefore the AF doesn't change as much.

So the bypass reduces parasitic losses during vacuum operation and lowers overall temps in vacuum conditions. It does not make more power, only helps during vacuum to boost transition, as the cooler air has less chance to detonate during transient conditions.

CcanDo

Thank's for your clarification !!!

While this question is fine line, to put your last paragraph into prospective, is it then possible to safely increase boost some measurable amount ? This question is based on finding % of time @ 100% of available power @ any RPM. Granted, the logical answer is subject to props,gears,load and etc. After that, the engine is constantly loading and unloading, thereby using 100 % available power some less than 100% of the time, at the given RPM.

In other words, the engine is on the dyno cruising at 4,500 RPM, (peak torque +/-) pulling 60% power. EGT's are ______? and # fuel is _____? Then, the dyno load is increased to 85%, EGT's become_______? and # fuel ______? (by pass valve is closed) Then after stabilization, the load is DROPPED to 50%, does the bypass open during the load reduction from 85 to 50% ? And, do the EGT's and # fuel, proportionately reflect the bypass opening vs. non bypass equipped. Relative to heat soak, is then possible the supercharger and other related components are less subjected to thermal shock?

CcanDo

Dustin, would you please offer a little more of your expertise ?

Subject to better understanding of how the system works, we will look at parts.

HTRDLNCN

they also help when throttling on and off when running hard in big water.

Whipple Charged

They ZERO to do with wide open throttle running, ZERO!. The valves are closed at wide open so its just like there not there.

I can't give you EGT's, I doubt you'll see much of a change. You have to measure the air charge temp below the SC, in the manifold to get a proper comparison. You could then measure fuel flow to see your BSFC are better. But a marine engine rarely runs in vacuum, mainly only idle so this is not much of an advantage.

Again, the only advantage for power that it has is on/off throttle, as the SC starves during decel because the SC is turning higher rpm, but has no air to compress when blades are closed. The bypass helps this so when you lift, the air charge temp doesn't sky rocket. If it goes high, then your next tip in will either not have as much power, or detonate because the charge temp is so high.

Dustin

MER Performance

Dustin, I talked with Mike@ Quest today about this today we know we us them on the screw blowers, but does it make sense to us it on a roots style! Mark

CcanDo

At any RPM, how does the bypass differentiate between screw type or roots, both are forced air/charge? Dustins' statement would indicate the system should serve both equally well. That is, if both screw and roots are producing equal pressure.

Perhaps, Dustin or someone else can tell us how the system should be installed on a roots style. The web was searched for bypass information. In addition to vacuum control, some use linkage between the throttle plate(s) and bypass valve. That would seem more like a waste gate to create positive action.

My biggest concern for fabricating a carb plate and opening in the roots case or below case adapter plate, DISTRIBUTION. For that matter, at off idle RPM, each time the valve opens or closes, is distribution not effected on any forced air system ?

Comparatively, is there any parallel between a bypass system and an oversized/ underdriven supercharger? As RPM increases boost pressure curves go flat. The flat curve has less suction available on the throttle plate. And, how would an underdrive interact with a bypass...better or worse ?

Whipple Charged

The bigger the supercharger, the more air it needs to equalize, requiring bigger valves. Yes it will help both and roots, although its more beneficial for screw's. The roots needs it and it was designed originally by Eaton for the Ford Thunderbird, a roots sc to lower the fuel consumption and help emissions.

CcanDo

.......................By pass system installation..................

Would it work to cut a hole in the rear half of the manifold "tent",plumb through the lifter valley, out manifold end or distributor hole, to bypass system, to throttle plate base? Or, would it be better to locate the hole subject to PSI and blower design ?

How critical would the "tent" hole location be?

RMPRam

iTrader: (1)

I ordered 2 complete 1.5" bypass valves on Thursday. I'm planning on installing the "valve" on the alum. plate that bolts to the top of the PSI's. There seems to be enough room in the front, see the picture, to mount the valve and vacuum cyl. I'm planning on discharging into an existing port below the blower, see picture, at the side of the intercooler. Comments?

Gary