weird sound at WOT

[18psiWhiteMS3]

i was doing a few WOT runs today and when i hit about 6750 to 7000 rpm it sounds like very low sounding metalic pinging sounds from under the shifter im thinkign in the exhaust it might be coming from. what can that be and is that normal?? only around the 6700to7000 rpm range. car still pulls good tho just made them sounds. Fuel pressure is 1700 around there.

 

[Darth Vader]

Probably chunks of valves bouncing down the exhaust ;^)

Seriously, what makes you think this engine makes power at 7000 rpm? Stock the thing's flat on its face at 6. Unless you have some serious internal mods to make it work up there, I'd wonder why you're twisting its tail that hard.

 

[Circle9]

Why do you keep coming up with all these "problems" with your car? Perhaps you are a little paranoid?

 

[18psiWhiteMS3]

Why do you keep coming up with all these "problems" with your car? Perhaps you are a little paranoid?

this is the second thing i have ever noiced with my car and not having a warranty can make someone a little bit paranoid. the tranny was clear i took a video of that but thats has never been a problem since. now the sound i hurd today i am unsure of and i have never hurd it before. with the cobb ap it makes power up till 7. at least on my car it does witch is why i end up that high in the rev cause it pulles so hard and by the time i realize im at 6500 im at 7 already. but when i hurd that sound i did several more pulls trying to pinpoint what i hurd. could be nothing at all but still would like insight for peace of mind. i just gave my oppinion of were it sounded. it sounded like it was coming from under me. my shift ligth is for 6500 but i always end up over it so ill put it at 6000 so i shift by at least 6500

 

[schmitty]

Probably chunks of valves bouncing down the exhaust ;^)

Seriously, what makes you think this engine makes power at 7000 rpm? Stock the thing's flat on its face at 6. Unless you have some serious internal mods to make it work up there, I'd wonder why you're twisting its tail that hard.

Yeah man, unless you are in top gear, why would you rev it past 5500-5800? There is no power left after that.

 

[18psiWhiteMS3]

Yeah man, unless you are in top gear, why would you rev it past 5500-5800? There is no power left after that.

with the cobb ap it makes power and full boost up til 6700

 

[Darth Vader]

What is it, 6500, 6700, 7000? You're throwing numbers around like they don't mean anything. Ever 100 rpm you raise roughly squares the stress on engine components.

There's more to power than making "full boost", that's just a measure of the restriction in the intake and cylinder head not power production. If you rev the car too far past it's power peak, you'll be past the torque peak for the next gear and going slower, that's a fact.

 

[Circle9]

Perhaps the pinging sounds are unburnt gases igniting in your cat.

 

[Reyan]

Perhaps the pinging sounds are unburnt gases igniting in your cat.[/QUOTE

your probably right, maybe he got bad gas at the gas station.

 

[18psiWhiteMS3]

what rpm should i shift at then?? between 6000- and 6500?

 

[18psiWhiteMS3]

What is it, 6500, 6700, 7000? You're throwing numbers around like they don't mean anything. Ever 100 rpm you raise roughly squares the stress on engine components.

There's more to power than making "full boost", that's just a measure of the restriction in the intake and cylinder head not power production. If you rev the car too far past it's power peak, you'll be past the torque peak for the next gear and going slower, that's a fact.

and Thanks for that.... Thats interesting

 

[schmitty]

After running my car on the dyno with the AP (Stage1+mscai 93) I can confirm that the demo chart they show on the AP page is accurate. Power starts to die at 5600-5700.

 

[Circle9]

To my knowledge, no matter how much your throw at your car, the simple fact remains that our turbo runs out of breath at 5500-5600 rpms. You can prolong the peak power i little further with AP, but it still falls flat after or around 6000 rpms.

Example: I ran a 9.2 constantly in the 1/8 when stock, I was shifting at 5800 - 6000 everytime. After looking at dynos for our cars, I decided to shift at 5600, and the very next time I ran, I pulled off a 9.0.

 

[18psiWhiteMS3]

To my knowledge, no matter how much your throw at your car, the simple fact remains that our turbo runs out of breath at 5500-5600 rpms. You can prolong the peak power i little further with AP, but it still falls flat after or around 6000 rpms.

Example: I ran a 9.2 constantly in the 1/8 when stock, I was shifting at 5800 - 6000 everytime. After looking at dynos for our cars, I decided to shift at 5600, and the very next time I ran, I pulled off a 9.0.

I appreaciate that, thanks. ill def shift much sooner.

 

[18psiWhiteMS3]

i just checked cobbs dynoe sheet for my stage2 tune and also the power drops off the same. I will be shifting as soon as i see it hit 6.

 

[Circle9]

Just do some practice at the track to see what rpm works best for your mods. When I had my SU TMIC on, the sweet spot was 5800 rpm's.

 

[18psiWhiteMS3]

i just went out and did a few runs shifting at 6000 and the car felt great and strong the hole time. "and no sounds LOL" thanks guys for your help.
im getting dynoed soon so i can see my tq and power curve and further determine the sweet spot to shift

 

[AutoEuphoria]

with the cobb ap it makes power and full boost up til 6700

Um...no it doesn't.

 

[meicalnissyen]

Perhaps the pinging sounds are unburnt gases igniting in your cat.[/QUOTE

your probably right, maybe he got bad gas at the gas station.

I have bad gas, and it makes funny sounds under my shitter too!