Took The Gxp To The Track

[ender]

Originally Posted by RobL I'm going to assume that you want them in the correct context since I can find sooooo many sites that are incorrectly calling them the same but going on to explain them both as CBVs. Here you go, near the end of the article: http://bankspower.com/Tech_SecrettoMakingPower.cfm

Excellent article! I prefer the wastegate method to the pop-off and floating match methods... gives one the ability to control and enhance boost more easily.

Thanks,
Russ

[IBDRINKEN]

[brentil]

Ok, well I was getting concerned since everyone was going on about how silent the car is but I hear what sounds like a whistling/whine sound as air is sucked in quickly as boost increases. I thought it was the turbo doing its job, but was getting confused by people's posts of how silent theirs is. If I let off the gas or shift lightly I'll get the whoosh sound people describe, but if I shift while under WoT or let off the gas after a very hard run I hear what I thought was a chirping noise but listening to it more closely I think it's more of a pffft sound and not the woosh everyone keeps describing?

I usually see 14~15 psi while driving hard to redline working through the gears. If i'm in a higher gear and blip then down shift I've gotten into the 18~19 range, but it's for a very short time. I've never owned a turbo car so this is all new to me still.

[Silverplate]

Originally Posted by sidewayz2 I took our GXP to the track last night. I wanted to see if it could get the 14 sec qtr like GM says. Well here it is.... It was a mild sticky night in Donaldsonville, LA. very high humidity about 68-70 degrees. The car has exactly 505 miles on it when I arrived there. I let the turbo cool down for about an hour and then I lined up. I left very soft because the car is so new. I just punched it from a dead ,no boost no rev. The car was so smooth and well behaved no wheel spin or any problems. She ran a 14.60 at 93 miles per hour. I only did 1 run cause it's my wife ALPHA 1's car and she said she would seriously divorce me if I muffed it up. Next time I am going to spool it up with a little power breaking and see if it can achieve the GM numbers. The only thing that I found wierd is that the turbo under boost squeals like a banshee. I know it is probably the blow off valve but man is it loud. It happens about 14psi and doesn't quit until you lift the pedal. Is it supposed to be that loud. It sounds like a constant bleed not a shoosh sound. At the track everyone was like we could see the car and about half track all you could hear was the wheeeeee..... sound. I said it was because the car was having fun but then I explained it was a turbo 4 cyl and it was the blow off valve. I guess what I am asking is if the VERY loud blow off valve is normal or do I have an issue.WILL SOME OF YOU OTHER GXP OWNERS RESPOND??

and what is really ironic about your track experience, I have 2007 Muscle Car calendar on my wall and January 2007 is a orange 1969 Pontiac GTO Judge. It reads Ram Air III, 366 HP and 14.45 sec and 97.8MPH in quarter mile. We have come a long ways.

[mena661]

Originally Posted by Silverplate and what is really ironic about your track experience, I have 2007 Muscle Car calendar on my wall and January 2007 is a orange 1969 Pontiac GTO Judge. It reads Ram Air III, 366 HP and 14.45 sec and 97.8MPH in quarter mile. We have come a long ways.

Better tires and suspension design plus lighter weight.

[SolsticeMan]

Originally Posted by brentil Ok, well I was getting concerned since everyone was going on about how silent the car is but I hear what sounds like a whistling/whine sound as air is sucked in quickly as boost increases. I thought it was the turbo doing its job, but was getting confused by people's posts of how silent theirs is. If I let off the gas or shift lightly I'll get the whoosh sound people describe, but if I shift while under WoT or let off the gas after a very hard run I hear what I thought was a chirping noise but listening to it more closely I think it's more of a pffft sound and not the woosh everyone keeps describing? I usually see 14~15 psi while driving hard to redline working through the gears. If i'm in a higher gear and blip then down shift I've gotten into the 18~19 range, but it's for a very short time. I've never owned a turbo car so this is all new to me still.

Sounds to me like your car is working fine, brentil. What I've heard and was told was normal was a light "whirrrr" while under boost, gets slightly louder but in line with the louder engine noise as you build in RPM.

If you are tracking along, like on the highway in 4th gear, and you have your DIC on the BOOST [_ ] selection, and go wide open throttle, this noise starts to come on just before it registers boost. If you build to about 3 or 4 psi and quickly let off, you hear it release the pressure with a hi-pitched "fwhewwww".

(I know this sounds like a stupid way to describe it, but bear with me).


I also drove a RedLine with a loose hose/pipe connection between the turbo and the cooler inlet, and a GXP with a loose intake hose connection to the intake. In fact, the GXP eventually popped the hose off the intake one of the times.

In both cases, differing in volume of noise and location of origin, under boost there was a definite noise (a "FWEEEEEE!") that sounded either like you were blowing on a blade of grass between your thumbs, or that annoying noise your nephew makes with the neck of a balloon, or a high note on a harmonica. THAT is the "loose pipe/hose" noise.


Very few people can hear the normal turbo noises from outside the car. If you have a leaky joint, tho, everyone will turn and look in your direction and wonder WTF is wrong with your car...

[brentil]

Ok yeah, "whirrrr" is a good description of what I'm hearing as I build boost.

It's gotten warmer here (it's in the freakin high 80's...) and I'm starting to see more 15~16 psi on average with bumps into 17psi. The 14~15 psi with bumps into 16 psi were when the temp was more under 80 degrees. It's getting pretty humid for this time of year too, it sucks...