The V is getting more grunt

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exdeath

Lifer
Jan 29, 2004
13,679
10
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Right.

I would think that forged pistons would most likely add to, not reduce, piston slap since forged pistons tend to be used in hotter (more powerful) applications, which necessitates more gap for the piston's expansion.

That's what hes saying. Go forged, or if you don't like piston slap, really good hypers made for forced induction (thicker ring lands, etc).

Forged pistons require more clearance due to being more dense and having a higher coefficient of expansion at the same temperature, regardless of application.
 
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Howard

Lifer
Oct 14, 1999
47,982
11
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That's what hes saying. Go forged, or if you don't like piston slap, really good hypers made for forced induction (thicker ring lands, etc).
Reading it again, yes, that does seem like what he meant. But for the same power rating, it seems as though you would need the same amount of gap.
Forged pistons require more clearance due to being more dense and having a higher coefficient of expansion at the same temperature, regardless of application.
I don't think it's the density that matters.

http://www.ergaerospace.com/Aluminum-properties.htm
http://www.matweb.com/search/DataSheet.aspx?MatGUID=4303c5b908ff4cbd91a02fed7d4e8202

Exactly the same, though one is 8% the density of the other
 

alkemyst

No Lifer
Feb 13, 2001
83,769
19
81
There is a big difference with a forged piston and a cast one as far as how it sounds cold. There are things you can do sometimes to minimize that noise.

It's unappealing to many, much like putting a race exhaust on a luxury car.
 

exdeath

Lifer
Jan 29, 2004
13,679
10
81
Reading it again, yes, that does seem like what he meant. But for the same power rating, it seems as though you would need the same amount of gap.

The clearance is the same once the engine is warmed up, that is the whole point of allowing more cold clearance with forged parts.
 

Howard

Lifer
Oct 14, 1999
47,982
11
81
The clearance is the same once the engine is warmed up, that is the whole point of allowing more cold clearance with forged parts.
I concede. I recently became aware of the fact that hypereutectic Al alloys have significantly lower thermal expansion coefficients (thanks wikipedia), which corroborates what you and alkemyst said.
 
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JCH13

Diamond Member
Sep 14, 2010
4,981
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Reading it again, yes, that does seem like what he meant. But for the same power rating, it seems as though you would need the same amount of gap.

I don't think it's the density that matters.

http://www.ergaerospace.com/Aluminum-properties.htm
http://www.matweb.com/search/DataSheet.aspx?MatGUID=4303c5b908ff4cbd91a02fed7d4e8202

Exactly the same, though one is 8% the density of the other

I think you're right. It's the alloy that matters, aluminum casting alloys are different from normal forging alloys. A354, a common casting alloy, has a CTE around 10% lower than 6061, a common forging alloy. I don't know what exact alloys are used in pistons though, this is just an example from my knowledge of common automotive alloys.

FWIW forgings typically have higher densities than castings, so the CTE and densities are correlated, but there is not causation.
 
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Apex

Diamond Member
Oct 11, 1999
6,511
1
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www.gotapex.com
Why would you buy a CTS-V, spend money to upgrade it, and include a K&N filter that lets in an absurb amount of dust into your engine?

I'm guessing because with forced induction, intakes make a noticable difference in power and most owners would do normal oil changes anyway, negating any possible ill effect from the negligable increase in dust ingested by an on-road driven car.

Though I could be wrong. Perhaps the plan is to drive the car offroad and never do oil changes.
 

alkemyst

No Lifer
Feb 13, 2001
83,769
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Most that argue about K&N filters don't understand the real argument nor really do much to their cars anyway.
 

exdeath

Lifer
Jan 29, 2004
13,679
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81
so you're saying OP needed to worry about 1000HP from day one? :awe:

Nope, Im saying that anyone who doesn't even have close to 500 HP should worry about getting to 500 HP themselves before telling someone else "1000 HP or GTFO" :D
 

exar333

Diamond Member
Feb 7, 2004
8,518
8
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Nope, Im saying that anyone who doesn't even have close to 500 HP should worry about getting to 500 HP themselves before telling someone else "1000 HP or GTFO" :D

It's tough to hook that kind of power up anyways with a car like this. I read the review of a nice 700hp upgrade for the CTS-V and it was the same 0-60 but a little faster in the 1/4mile and 0-100 (as expected). It's fun to mess with the car for sure, but at some point these cars have issues getting it to the ground.

That said, I would be pretty happy with 500hp myself. :)
 

KentState

Diamond Member
Oct 19, 2001
8,397
393
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It's tough to hook that kind of power up anyways with a car like this. I read the review of a nice 700hp upgrade for the CTS-V and it was the same 0-60 but a little faster in the 1/4mile and 0-100 (as expected). It's fun to mess with the car for sure, but at some point these cars have issues getting it to the ground.

That said, I would be pretty happy with 500hp myself. :)

Even stock, the car has enough power to spin the tires in 1st gear when the rpms top 4k from an easy launch. As it nears red line, I can feel them starting to spin.
 

exar333

Diamond Member
Feb 7, 2004
8,518
8
91
Even stock, the car has enough power to spin the tires in 1st gear when the rpms top 4k from an easy launch. As it nears red line, I can feel them starting to spin.

What is your current tire size? Curious how large the CTS-V can comfortably accomodate.
 

punjabiplaya

Diamond Member
Nov 12, 2006
3,495
1
71
haha, just saw a guy taking off in his gen2 CTS-V while coming back from the bank and some MAF calibration logging. Sounded so gooooood - he def didn't have a stock exhaust.
 

TakeNoPrisoners

Platinum Member
Jun 3, 2011
2,599
1
81
It's an SUV manufactured by General Motors. It seats 20 and gets 6.3MPG with a 9L V8. Fat republicans from mostly poor backgrounds with little financial sense purchase them. They drive them while eating giant greasy hambugers. They have blue collar jobs. The vehicle cannot be operated while wearing penny loafers.

LOL Sounds like the car for me.