derek14

Our Comptech and Vortech kits as we all know make peak boost and power at redline. We need more low-end power as we all know. Until A roots-type blower kit is available we are stuck with these kind of blowers unless we want to go turbo. I was thinking of a way to build higher boost, or peak boost at a lower RPM. I was thinking of using a high boost pulley (10, 12, 15 lbs) and a bleeder-type valve after making boost. This would be similar to how a wastegate works on the hotside of a turbo charged motor. Once the boost reaches a certain level (whatever PSI desired like a wastegate with a boost controller, or a set spring rate), the "wastegate"-type valve will open and bleed off the correct amount of air in order to regulate the boost. Using a high boost pulley, we make more boost down low, so why cant we bleed off what we dont want once it has been made and then hold it until redline? Remember, this is just an idea for thought and anyone with something to add, please do.

xviper

This gets asked every few months and surprisingly, no definitive answer has ever been given. Good luck with it this time.

bigpurp

This is why God invented (and Man bottled) nitrous oxide.

FF2Skip

And subsequently spawning the ever-popular phrase, "Too soon, Junior!"




On another note though, I have never seen this proposed. I'd be interested in the answer. Driveability might become an issue... certainly gas mileage would.

Sideways

Just crank up the boost and shift sooner. It works.

donjaime

I'm no mechanic or car genius, thus pardon my questions:
1. Is there a consistent relationship between the amount of boost produced at sub-redline RPM and the size of the pulley? Before anybody swears at me for my ignorant inquiry, what I'm asking is, when you compare a pulley that should make 10 PSI at redline to one that makes 5 PSI at redline, should you also see this 2:1 ratio at say 5k RPM, or is this same ratio not sustained throughout the powerband?
2. When you graph RPM vs. Boost on an FI setup such as Comptech, what is the shape of the curve--linear, asymptotic in the upper RPM range, etc?

I too am curious about Derek's question and apalled that with all the knowledgeable car folk in this forum, a clear-cut answer has not been provided. Is it not possible to test out such a thing?
Thanks
j

xviper

If you're so "appalled", be my guest. You go ahead and test it out.

You think that just because somebody asks something, that one of us should simply go out and put on a high boost supercharger with a relief valve and risk blowing the crap out of our car just so somebody can get an answer?

Slows2k

Sideways answered this question the best.

You guys are trying to make a Centrifugal SC act like a roots or screw type SC. It's a nice thought in theory, but when it come time to do it, Most people just turn up the boost.

Even with some type of pressure relief valve, you will need a AEM EMS running things. A FMU isn't going to cut it.

donjaime

I didn't mean to hurt feelings or imply that I expect people to damage their cars for the sake of one person's question. Please not that that is not what I had in mind...I'm apalled that an answer couldn't be reached empirically.
In any case, I hope somebody can refer me to the answer for my first two questions.
And I agree, roots is the way to go if you want a SC to behave as mentioned previously.

hackmac87

it would work but you would need to control the valve very precisely. you would need to have a valve that would release the max amount of air at full boost/redline etc.