JRSC and partial throttle

[Kodeen]

So I'm under the impression that if you are keeping at part throttle with the JRSC then you are not seeing any boost due to a bypass valve (where that is I'm not exactly sure). So does that mean that at part throttle it feels like you are driving a stock a3, assuming you haven't done anything else?

[4angrybadgers]

To a point, yes. The bypass valve starts closing around 1/3-1/2 throttle, and it closes progressively all the way to WOT. I've found that at roughly 30-35% throttle (near 6mmHg vacuum), I can hear the bypass valve start whistling a bit, and the ECU starts dumping fuel (A/F drops to 11.5-13:1). Past that, boost is dependent on the amount of throttle.

The bypass valve is underneath the front part of the blower casing. It's really only visible from the bottom.

edit: The above info is from watching my vacuum/boost gauge, and the Brockway R920's A/F reading (straight off the OBD2 bus).

[Mikebuen]

I would believe so! Since Jackson Racing built the supercharger to only boost under load (WOT wide open throttle). So this is a good thing since it wont kill your mpg unless you have a heavy foot and boost all day long.

[Kodeen]

Ok, so the boost doesn't have a discrete engagement point, it kinda fades in. Does if feel like that, or do you only really notice it after the bypass valve is fully closed?

[4angrybadgers]

I would believe so! Since Jackson Racing built the supercharger to only boost under load (WOT wide open throttle). So this is a good thing since it wont kill your mpg unless you have a heavy foot and boost all day long.

Wrong. See above. You can go part throttle all day without hitting WOT and still kill your gas mileage, because the bypass valve progressively closes as the throttle opens up. The key is to learn where the bypass valve starts closing and stay below that. A vacuum/boost gauge is insanely helplful at figuring this out.

Ok, so the boost doesn't have a discrete engagement point, it kinda fades in. Does if feel like that, or do you only really notice it after the bypass valve is fully closed?

Part throttle (somewhere above 50%) feels like it pulls harder than the stock a3 at WOT. Of course, the "butt dyno" is far from accurate, but there is a definite increase in power before WOT.

[fatdong]

more throttle = more power from SC, less throttle = less power from SC.

light throttle isnt going to have it going fast enough to build very much boost. it took me about a third of the way down to get that little whistle (WOO WOO) and feel a little kick in the ass.

dont dick around though, cause $4.50 premium gas is not cool to pay for scooting around in a boosted civic. be gentle.

[Iluvcars]

part throttle can be improved for gas mileage via kpro. It has to be tuned by a professional in a certain way to improve all parts of part throttle

[4angrybadgers]

more throttle = more power from SC, less throttle = less power from SC.

light throttle isnt going to have it going fast enough to build very much boost. it took me about a third of the way down to get that little whistle (WOO WOO) and feel a little kick in the ass.

dont dick around though, cause $4.50 premium gas is not cool to pay for scooting around in a boosted civic. be gentle.

Yeah, I've been tracking my gas mileage for several months now and I've noticed a definite drop when I get even halfway boost-happy on a tank of gas. After 7 months with the blower I've learned to stay out of boost without watching the gauges, and it definitely helps stretch out a tank of gas.

[jimmyjames]

Yeah, I've been tracking my gas mileage for several months now and I've noticed a definite drop when I get even halfway boost-happy on a tank of gas. After 7 months with the blower I've learned to stay out of boost without watching the gauges, and it definitely helps stretch out a tank of gas.

Word, highway cruising is at 30-32 mpg. Driving like a retard = 22-23 mpg.

[superchargedk20]

Ok, so the boost doesn't have a discrete engagement point, it kinda fades in. Does if feel like that, or do you only really notice it after the bypass valve is fully closed?

is ur avatar from "stop or my mom will shoot"

[fEPst3r]

Partial Throttle Daily i hit 26-28 MPG

Happy Feet i hit 23-25 MPG

Track i hit 10 MPG

i def. say you save alot of gas stayin out of boost.

[Kodeen]

Thanks for the replies, everybody!

is ur avatar from "stop or my mom will shoot"

Yes.

[JohnyBlaze]

I've also found that how *fast* you change throttle also affects the bypass valve closing. E.g., if I go from 0 throttle to 40% open throttle very quickly, I can hear the bypass squeal a bit, but then it stabalizes and stays open. It's the engine load and difference in vacuum that opens / closes the bypass valve.

Anyways, with normal driving, I get about 26 mpg (JRSC-R)