Stock C6 ZR1 - 9psi boost - tune issue ?

[marcoturbo]

Hi,

I've just done some logs with my C6 ZR1 and I'm wondering about the boost and therefore the power of the car.

At WOT, the boost is only 9psi (see the autobahn log).

I remember reading on corvetteforum that the 10.5 psi announced by GM was not often reached (we don't know where it's measured). And clearly, the advertised 647 hp aren't there.

My question: can the tune be modified to improve boost?

The car is stock, apart from a Tony Mamo Throttle body and a Corsa X-pipe (instead of the 2 extra cats added from 2012).

The tune is original: I've only calibrated the MAF in CL mode (no WB yet) and lowered the PE table by 3%. I haven't touched the torque management table or the boost control values.

A priori, there's no boost leak. I checked and slightly modified the blower bypass valve to make sure it was closed at WOT, and no change. No DTC nor CEL.

After all, maybe everything is normal and I'm a little too paranoid ?

C6 ZR1 10 SEPTEMBRE 2023 BIS.hpl

[edcmat-l1]

First question is, what is your altitude?

[SiriusC1024]

Barometric pressure reads 14.5psi. Pretty close to sea level.

[marcoturbo]

Maximum 300 ft above sea level.

Temperature isn’t optimal.

[JayRolla]

Could be the xpipe and no cats. If no boost leak I would not worry about it. Its just a measurement of restriction and if you opened up the exhaust you can lose some boost.

[marcoturbo]

I still have the stock front cats. I’ve only removed the two rear cats.

[Guy With A Chevy]

Probably needs a bigger fan I have yet to touch boost enjoy the 9.5lbs of juice. Remember with wear they build up less pressure what's the mileage?

[marcoturbo]

19000 miles.

[sgod1100]

check for supercharger belt slip

[Alvin]

It could be belt slip. It is likely the exhaust modifications and the less boost doesn't mean its going to make less power.

[marcoturbo]

No evidence of belt slip. Belt has been changed less than 3000 miles ago (when bricks and sc coupler have been upgraded). No belt dust. Boost remains stable once it hits 9psi, it doesn’t collapse after a peak.

Any value to modify in the tune to get more spool (boost ramp, torque management…) ?

[JayRolla]

No evidence of belt slip. Belt has been changed less than 3000 miles ago (when bricks and sc coupler have been upgraded). No belt dust. Boost remains stable once it hits 9psi, it doesn’t collapse after a peak.

Any value to modify in the tune to get more spool (boost ramp, torque management…) ?

Its not like a turbo where you can just add boost. Nothing in the tune will add boost that I know of other than ramping it in quicker. Quick google search and I found a few people saying they only see 9psi at sea-level.

[sgod1100]

No evidence of belt slip. Belt has been changed less than 3000 miles ago (when bricks and sc coupler have been upgraded). No belt dust. Boost remains stable once it hits 9psi, it doesn’t collapse after a peak.

Any value to modify in the tune to get more spool (boost ramp, torque management…) ?

Yeah, you can ramp boost in quicker, but you can't create anymore boost in the tune...all dependent on what your pulley ratio is

[Guy With A Chevy]

Its not like a turbo where you can just add boost. Nothing in the tune will add boost that I know of other than ramping it in quicker. Quick google search and I found a few people saying they only see 9psi at sea-level.

Does a turboed setup control boost by controlling cylinder airmass?

[JayRolla]

Does a turboed setup control boost by controlling cylinder airmass?

Boost controller, wastegate.