I want to see dynos of the K04+ making 40-50 WHP over stock K04 with no additional modding.

 

Thats gonna be a toughy as most people that are going KO4+ already have other mods. But there are dyno #'s out there with before/after dyno's with the KO4+ bolt on. I know this upgrade is really popular on the Kappa's and a few cobalt ss/tc's have it. Only 1 person I know is having problems with there KO4+ and it was Hiltu on css.net, but he told me he is the only one experiencing problems, compressor surge at low rpm's. BTF was working with him on sorting the issue out. I haven't talked to him in awhile he might have it sorted out by now.

 

Thanks for all the info so far guys! Does any one have a schematic of the turbo setup?

 

Is there a link to those dyno's? I'm want to see if they are having the boost spike like the stock K04's do and what RPM's they do it at. Mine does it at 4K RPM's which I don't know if I should count it as top HP and TQ. I think alot of people are doing the same thing by counting boost spike. I don't know how to control that.

 

What boost spike are you talking about on the factory KO4? Is your car spiking to a higher psi then settling down to a lower? My HHR doesn't do this, it will boost to 22 psi (winter time) and stay there throughout the entire pull to red line, in the summer it goes to 24 psi and stays. Only time the boost comes down at WOT is if I let up off the gas.

Others having this issue with a peak boost, then drop off?

 

Mine will hit 28 PSI and settle at about 25 PSI.. I've heard it's the PCM controlling the stock BOV so was wondering is an after market BOV would be best to prevent that. 1st, 2nd gears are worthless now. More power = waste unless you can hook. Kinda disapointed a little because of it.... Im going to the track tomorrow night and I honestly don't know how the ET's will be.

 

Ahh, why didn't you get boost limited to like 7-10 psi in first? Maybe like 20 psi in second, then let it go the rest of the gears? I bet it would help your track times tremendously. Unless you roll with slicks I don't ever see getting traction in first with an after market tune and "street" tires.

 

I just found something on my way home an hour agao. In 4th gear, it will hold 26-27 PSI for more than 5 seconds then I let off anyways. this is getting more confusing to me LOL Well Ill hit the track tomorow and see how things go. Stay tuned. :)

 

BOV is a purely mechanical device with no electrical interface with the ECM. It is there to prevent compressor damage when the throttle abruptly closes. That's it. It does not "control boost." That's the job of the wastegate, which is electronically controlled. People who believe that replacing a non-defective BOV will improve performance need to step away from the crack pipe.

The ECM does not care about boost, and neither should we. "Boost" is the measure of air that didn't make it into the engine. The boost gauge is mostly there for your entertainment, although abnormal readings might indicate a leak or defective BOV. The real use of a boost gauge goes back to the Indy car days when wastegates were user adjustable from inside the cabin. The ECM monitors throttle position, engine load, RPM, knock, traction, and a host of other parameters. The value of manifold pressure at any particular moment is a peripheral result of other parameters that are far more important to the engine management system.

 

Great, bring science into it.

Yeah, it's not always what it appears. I remember a buddy explaining the intercooler in terms of being a cold storage device not a "cooler". It has a limit to the amount of "cold" it can store. It changes how you think about things.

I've had to stop looking at the freaking boost gauge and watch the tach, It's way too easy to hit the limiter.