: Pistons



Mike 09 V
01-14-10, 03:18 PM
I was reading an article in Wikipedia about the V and saw where the pistons are called Hypereutectic. The word was highlighted and led to another article linked at the bottom of this post. Basically what we have is a piston with a high amount of silicon which allows the fit to be of a much closer tolerance to the cylinder bore than a standard forged aluminum piston. This is better for emissions, less piston slap and doesn't expand as much with heat. The drawback seems to be that this process, while having all the attributes mentioned, ends up with a brittle piston that won't take detonation like the standard forged piston will. The piston crown will crack under too much spark knock. So we have to be careful in the tuning and CAI kits so that we don't end up with too much knock or we are in danger of busting our motors.

Here's the link http://en.wikipedia.org/wiki/Hypereutectic_piston
:bomb:

Prof
01-14-10, 04:23 PM
I made the same observation a few months back...but got shouted down...

IMO the lack of forged rods and pistons is a major short coming in the LSA engine. All we have to do is compare the rods and pistons with those of the LS9 and the difference is obvious.

"This is a very high risk build if the bottom end is not forged. The additional heat and pressure of that much boost requires forged pistons at a minimum, and I would add forged rods and main bearings and push rods in the process. The piston lands are the most at risk...if he starts to experience blow-by that is what is happening..."

Doct
01-14-10, 04:36 PM
Mike what you say is true. I think when it comes to any engine even more so forced induction engines a good tune is the most important part. There is no point to push the limits of a engine if fuel and spark isn't setup correctly.

I wouldn't be to worried about the fact that we have Hypereutectic pistons. I don't know who's car (maybe trevs?) is making great power with the zr-1 blower upgrade and I don't recall a piston swap. I believe jesse made 850 with nos. I am not saying that they will last forever but what will? I think this year will be good and more and more people will be pushing the limits of these motors. I know back when I had my 03 cobra people were worried about running 17lbs on a stock motor. As time went on and more companies produced more and more products supporting bigger hp boost numbers climbed well above 20lbs. on a stock motor. Turbo companies started popping up and hp numbers on stock engine were 680-740 rwhp if I recall. I won't deny reading that some engines were lost in the process lol but a lot was learned to.

Speaking of turbo's I would love to see a company design a tt kit for these cars to see what happens.

GMX322V S/C
01-14-10, 05:00 PM
Detonation will make short work of any piston, forged or not.

Luna.
01-14-10, 05:58 PM
I made the same observation a few months back...but got shouted down...

IMO the lack of forged rods and pistons is a major short coming in the LSA engine. All we have to do is compare the rods and pistons with those of the LS9 and the difference is obvious.



I guess I'm confused...is anyone really disputing this????

I would accept that comment as an axiom.


Detonation will make short work of any piston, forged or not.

Agree, but the fact that GM opted to NOT make the pistons and rods similar to the LS9 borders on egregious.

The Tony Show
01-14-10, 06:07 PM
The reason GM used Hypereutectic pistons instead of forged is simple- they're quieter (luxury car, remember) and they'll take stock boost levels all day. They'll even take greater than stock boost as long as the fuel maps and timing are adjusted accordingly, as evidenced by lots of people running Jesse's pulley rings. If you're dumb enough to run the car hard when it's knocking, even pistons made from Unobtanium aren't going to last long.

Manufacturers don't build cars for modders. Most people willing to spend $8k or more chasing higher boost levels will have no problem dropping new pistons in there anyway, so why would GM put more expensive pistons in the car when it doesn't need them?

4gear70
01-14-10, 06:51 PM
Detonation will make short work of any piston, forged or not.

Yes, but a hypereutectic piston usually shatters into a million pieces taking out every other part of the motor. A forged piston will usually sustain limited damage and may take out just a cylinder/sleeve. If there is any mild valve contact, you'll end up with a bent valve and easily fixed... not the case with the hypereutectic. Detonation is a killer and you better have a good tune.
I saw a video once of a bullet going through a forged piston like a slug. The hypereutectic one exploded everywhere.

4gear70
01-14-10, 07:27 PM
IMO the lack of forged rods and pistons is a major short coming in the LSA engine. All we have to do is compare the rods and pistons with those of the LS9 and the difference is obvious.



The LSA does have forged rods. They are forged powder metal connecting rods. The crank is forged steel. Valves are high-chromium steel.
The LS9 uses a Forged steel crank but Titanium rods and valves ($$$).

Prof
01-14-10, 09:32 PM
The LSA does have forged rods. They are forged powder metal connecting rods. The crank is forged steel. Valves are high-chromium steel.
The LS9 uses a Forged steel crank but Titanium rods and valves ($$$).

Yup, I stand corrected!

I knew that...it just takes a long time to get past all the age fog...

Zexnos
01-14-10, 09:50 PM
Mike what you say is true. I think when it comes to any engine even more so forced induction engines a good tune is the most important part. There is no point to push the limits of a engine if fuel and spark isn't setup correctly.

I wouldn't be to worried about the fact that we have Hypereutectic pistons. I don't know who's car (maybe trevs?) is making great power with the zr-1 blower upgrade and I don't recall a piston swap. I believe jesse made 850 with nos. I am not saying that they will last forever but what will? I think this year will be good and more and more people will be pushing the limits of these motors. I know back when I had my 03 cobra people were worried about running 17lbs on a stock motor. As time went on and more companies produced more and more products supporting bigger hp boost numbers climbed well above 20lbs. on a stock motor. Turbo companies started popping up and hp numbers on stock engine were 680-740 rwhp if I recall. I won't deny reading that some engines were lost in the process lol but a lot was learned to.

Speaking of turbo's I would love to see a company design a tt kit for these cars to see what happens.

Found these on another site but I have no more info...

http://www.vettesandperformance.com/images/09ctsv/4.jpg
http://www.vettesandperformance.com/images/09ctsv/5.jpg
http://www.vettesandperformance.com/images/09ctsv/6.jpg
http://www.vettesandperformance.com/images/09ctsv/7.jpg
http://www.vettesandperformance.com/images/09ctsv/8.jpg
http://www.vettesandperformance.com/images/09ctsv/10.jpg
http://www.vettesandperformance.com/images/09ctsv/11.jpg
http://www.vettesandperformance.com/images/09ctsv/12.jpg
http://www.vettesandperformance.com/images/09ctsv/13.jpg
http://www.vettesandperformance.com/images/09ctsv/14.jpg

Prof
01-14-10, 09:54 PM
Ohhhhh, yum!!!!!!!

Vrocks
01-14-10, 11:25 PM
I read it's pre-ignition that blows a hole in a piston, not detonation. The piston can withstand detonation for varying lengths of time - depends on how much power it's making at the time. That's why you can have detonation while at a low power level all the time but at a high power level the ring land will fail quickly (and the top of the piston will have a sand blasted look - or like it's cover with aluminum foil).

Doct
01-15-10, 12:24 AM
Zexnos, now thats what I am talking about man. Good find, going to look into it.

M-1028
01-15-10, 12:32 AM
Titanium rods (HATE) detonation. There very brittle and don't take shock too well. They were all the craze in drag racing years back.

I've seen non forged pistons hold up to alot of abuse.

M-1028
01-15-10, 12:37 AM
I read it's pre-ignition that blows a hole in a piston, not detonation. The piston can withstand detonation for varying lengths of time - depends on how much power it's making at the time. That's why you can have detonation while at a low power level all the time but at a high power level the ring land will fail quickly (and the top of the piston will have a sand blasted look - or like it's cover with aluminum foil).

If I'm not mistaken detonation is pre-ignition.

richeic77
01-15-10, 01:00 AM
If I'm not mistaken detonation is pre-ignition.

No. It's a misnomer. Pre-ignition is ignition prior to spark inducing ignition. There's is NO detonation in an engine unless you are using nitromethane...but that's a totally different story.

When builder's design engine's or Pistons to match with the chamber in the head, they are looking to create as close to a sphere as possible to have the most even distrubition of burn rate over a balanced area. Detonation is never counted/factored into the design. BURN RATE IS!! An engine does not detonate, it burns at a fast rate.

Hyperutectic pistons are a ticking time bomb. 1 Tank of bad gas and Pop, there goes a cynlinder and/sleeve. Usually it's the #7 Cynlinder on LSx platforms due to the folded hand intake design and the inherent lean condition it creates at the back cynlinder. I'm not sure on the LSA/LS9 design though due to the different shape of the intake. Might not have the same issue. But either way, 1 lean burn and the Piston will pre-ignite along the ring lands. A Hypereutectic piston is done for.

And, you can't just run it Uber rich or you'll overload the cylinder with fuel. If it doesn't wash the plug, it'll burn with a force much greater than normal and that causes major issues too.

To sum it all up, Utectic pistons are so-so, tune is UBER important.

Prof
01-15-10, 05:04 AM
I read it's pre-ignition that blows a hole in a piston, not detonation. The piston can withstand detonation for varying lengths of time - depends on how much power it's making at the time. That's why you can have detonation while at a low power level all the time but at a high power level the ring land will fail quickly (and the top of the piston will have a sand blasted look - or like it's cover with aluminum foil).

Detonation and pre-ignition are the same thing. Heat creates an environment in which the air/fuel mixture is ignited at the wrong time...the dreaded "pinging" that we used to hear with bad gas. When the fuel/air mixture is correct at all rpm levels (sufficient fuel with a corresponding intake air temperature) ignition occurs when the piston has created the maximum compression of the air/fuel mixture with a little timing variation induced by the tuner...if there is too much fuel (rich) hp and tq are not optimized...if there is too much air (or air that is too hot) pre-ignition (detonation or ping) occurs...

Imagine the crank and rod thrusting the piston towards top dead center and all of a sudden while moving in that direction an explosion occurs because the air/fuel got too hot too soon...you have the old adage of an immovable object against an irresistible force...and the energy has to go somewhere...the result is a bent rod, maybe a nice new window in the cylinder, or a compression ring pushed in the wrong direction...

The best defense is a great tune by an expert. I bring a tuner from Florida to tune my SRT 10...Sean Roe...he dyno tunes the engine and then when it is machine perfect...he rides and listens...and literally hears minute detonation at certain RPM...and he adjusts the air/fuel mixture at that rpm to compensate. There are lots of safe guards, water/meth injection, intercoolers, always having a sufficient fuel supply (the fuel cools the intake charge as it is atomized in the intake manifold)...

We do need a wide band air/fuel gauge in our V's...it should be part of the package on any supercharged vehicle IMO. While they are not a good tuning tool, like oil pressure and transmission temperature gauges they are a great disaster avoidance/early warning tool.

Vrocks
01-15-10, 08:28 AM
If I'm not mistaken detonation is pre-ignition.

That's what I thought too but according to an engineer that developed the N*, detonation occurs after TDC. If I remember correctly, he said pre-ignition occurs after fuel and air are added - pre-spark. So detonation is after TDC on the power stroke and pre-ignition is when fuel and air are added and before the plug fires.

Ross L
01-15-10, 09:22 AM
All this talk about crappy hyperucrackedit pistons makes me scared to drive my wifes car:rolleyes: Come on now, W4M made 850 to the tires:eek:As far as I know His pistons are still going strong. ANY piston will fail with a lean condition under boost. Plenty of people have burned forged pistons too. I'm not saying forged are not better but there seems to be scare tactics going on when there is no current reason. Wait until pistons in the LSA actually start failing(probably up around 20psi),if then.
Ross (24psi/24degrees of timing with cast pistons in my GN):bouncy:

Gotham CTS-V
01-15-10, 09:59 AM
Wow, finally a turbo setup on the V! Awesome.

BTW, I don't have much experience or knowledge on this subject but all I know is that on my modded Z06, the titanium connecting rods bent after a few repeated high-speed highway runs.

Prof
01-15-10, 10:14 AM
Just to be clear in my opinion on pistons...stock V's are fine. The pistons should be there at the end and that should be way down the road.

It's just my approach to building machines for performance. My concept starts at the bottom end...build for performance and do what needs to be done to avoid problems. That says to me, if the pan is dropped...it is such a small step to be sure that the rods and pistons are not the weak point. The same with the push rods and main bearings...while the engine is out why not be sure that the oil pump and fuel pump will support whatever you decide to do?

We are not talking about building a $400 VW here...most of us would not worry about four or five thousand dollars for a set of forged pistons...(I am a Diamond advocate by the way). The same goes for the heads...once they are off, why would one not be sure that the valve train can take any abuse and facilitate induction and extraction???

The ideal would be the LS9 with better pistons in our V's...there I've said it...but its just a daily driver to me...and I have never ever stayed at a Holiday Inn Express (ugh!).

4gear70
01-15-10, 02:04 PM
Detonation and pre-ignition are the same thing. Heat creates an environment in which the air/fuel mixture is ignited at the wrong time...the dreaded "pinging" that we used to hear with bad gas. When the fuel/air mixture is correct at all rpm levels (sufficient fuel with a corresponding intake air temperature) ignition occurs when the piston has created the maximum compression of the air/fuel mixture with a little timing variation induced by the tuner...if there is too much fuel (rich) hp and tq are not optimized...if there is too much air (or air that is too hot) pre-ignition (detonation or ping) occurs...

Imagine the crank and rod thrusting the piston towards top dead center and all of a sudden while moving in that direction an explosion occurs because the air/fuel got too hot too soon...you have the old adage of an immovable object against an irresistible force...and the energy has to go somewhere...the result is a bent rod, maybe a nice new window in the cylinder, or a compression ring pushed in the wrong direction...

The best defense is a great tune by an expert. I bring a tuner from Florida to tune my SRT 10...Sean Roe...he dyno tunes the engine and then when it is machine perfect...he rides and listens...and literally hears minute detonation at certain RPM...and he adjusts the air/fuel mixture at that rpm to compensate. There are lots of safe guards, water/meth injection, intercoolers, always having a sufficient fuel supply (the fuel cools the intake charge as it is atomized in the intake manifold)...

We do need a wide band air/fuel gauge in our V's...it should be part of the package on any supercharged vehicle IMO. While they are not a good tuning tool, like oil pressure and transmission temperature gauges they are a great disaster avoidance/early warning tool.

Good Post! :thumbsup:

4gear70
01-15-10, 02:06 PM
Just to be clear in my opinion on pistons...stock V's are fine. The pistons should be there at the end and that should be way down the road.

It's just my approach to building machines for performance. My concept starts at the bottom end...build for performance and do what needs to be done to avoid problems. That says to me, if the pan is dropped...it is such a small step to be sure that the rods and pistons are not the weak point. The same with the push rods and main bearings...while the engine is out why not be sure that the oil pump and fuel pump will support whatever you decide to do?

We are not talking about building a $400 VW here...most of us would not worry about four or five thousand dollars for a set of forged pistons...(I am a Diamond advocate by the way). The same goes for the heads...once they are off, why would one not be sure that the valve train can take any abuse and facilitate induction and extraction???

The ideal would be the LS9 with better pistons in our V's...there I've said it...but its just a daily driver to me...and I have never ever stayed at a Holiday Inn Express (ugh!).

I too subscribe to the same engine building philosophy. :)

Vrocks
01-15-10, 02:17 PM
Good Post! :thumbsup:

Except for the fact that they are two different things...

4gear70
01-15-10, 02:25 PM
Except for the fact that they are two different things...

Really? Kindly explain what exactly 'detonates' AFTER TDC on the power stroke?

GMX322V S/C
01-15-10, 02:40 PM
So pre-ignition means ignition of the combustible mixture before you expect it--before the spark plug fires. It's my understanding that the semantical difference between detonation and combustion is with combustion, we get a nice, relatively smooth pressure wave from one ignition point. Detonation occurs when there is more than one ignition source (such as a pre-ignition source and the spark plug firing later) and the pressure waves collide, greatly increasing the pressure at those points (like along the piston crown).

Luna.
01-15-10, 02:43 PM
The reason GM used Hypereutectic pistons instead of forged is simple- they're quieter (luxury car, remember)

Definitely don't argue that this might be part of the reason GM decided to do that (I was also told COST as well), but I WOULD argue that the LOGIC is simply pathetic from either perspective.

In a normal CTS? Heck yeah I'd be considering noise; that's 10x the grocery getter the CTS-V is.

In a 556hp monster? Give me a break. This is one of the leading 4-door performance cars in the world and they think that the average customer is going to be worried about a little more sound?!?!? In THIS car? Heck, can you even tell the difference at WOT?

I've yet to have anyone make that comment when I've specifically talked to people about it, but okay...

If you (not you Tony, that's an in-general "you") are one of these people, then I'm sorry, but shame on you. The increase in sound isn't that bad---the ZR1 gets away with it JUST FINE...

I was told that cost was a significant reason as well (which I believe). This is such a dubious, if not completely B.S. idea, I can't even see straight...



Manufacturers don't build cars for modders. Most people willing to spend $8k or more chasing higher boost levels will have no problem dropping new pistons in there anyway, so why would GM put more expensive pistons in the car when it doesn't need them?

I'm not sure I would agree with this, especially since I'm one of these dorks that would spend (cough--have spent) $10k chasing higher performance levels.

Is there a more challenging job to do on a motor than change the pistons? I mean, that's dead center in the entire motor... & I'm still not aware of any forged replacement yet (probably has come out by now, but there weren't a ton of answers last year when asked...)

And the increase in cost would almost assurdly be negligible. I was told that the accountants had a significant say in what went into the motor. I firmly believe they screwed the pooch on this one...


All this talk about crappy hyperucrackedit pistons makes me scared to drive my wifes car:rolleyes: Come on now, W4M made 850 to the tires:eek:As far as I know His pistons are still going strong.

As someone who popped a piston in an LS6 (with a SAFE tune), I remain very skeptical. Yeah, perhaps those pistons in W4M's car are still living (if they are even at that same power level), but how much longer will they last? I got, say, 20k boosted miles out of my pistons before they went caput. Fatigue? Hell, I don't know...



The ideal would be the LS9 with better pistons in our V's...there I've said it...but its just a daily driver to me...and I have never ever stayed at a Holiday Inn Express (ugh!).

Yup--I've said the same before and actually now wonder if I should have done that differently. Perhaps I should have dropped in an LS9 and yanked the near-new LSA and sell the sucker to help pay for the LS9...

Vrocks
01-15-10, 03:37 PM
Really? Kindly explain what exactly 'detonates' AFTER TDC on the power stroke?
This is where I got the info: http://www.contactmagazine.com/Issue54/EngineBasics.html


Detonation: Detonation is the spontaneous combustion of the end-gas (remaining fuel/air mixture) in the chamber. It always occurs after normal combustion is initiated by the spark plug. The initial combustion at the spark plug is followed by a normal combustion burn. For some reason, likely heat and pressure, the end gas in the chamber spontaneously combusts. The key point here is that detonation occurs after you have initiated the normal combustion with the spark plug.

Pre-ignition: Pre-ignition is defined as the ignition of the mixture prior to the spark plug firing. Anytime something causes the mixture in the chamber to ignite prior to the spark plug event it is classified as pre-ignition. The two are completely different and abnormal phenomenon.

Razorecko
01-15-10, 03:38 PM
The fact is that they wanted to create a larger performance difference between the V and ZR1. They needed the ZR1 to stand alone on the mountain top. Seriously it would probaly be only slightly more expensive for gm to dump zr1 motors into the cts-v. The additonal cost would be what ? 5k tops ?

Luna.
01-15-10, 03:49 PM
The fact is that they wanted to create a larger performance difference between the V and ZR1. They needed the ZR1 to stand alone on the mountain top. Seriously it would probaly be only slightly more expensive for gm to dump zr1 motors into the cts-v. The additonal cost would be what ? 5k tops ?

Putting forged pistons into the LSA would significantly increase its rwhp/rwtq?? :confused:

4gear70
01-15-10, 04:14 PM
This is where I got the info: http://www.contactmagazine.com/Issue54/EngineBasics.html


Detonation: Detonation is the spontaneous combustion of the end-gas (remaining fuel/air mixture) in the chamber. It always occurs after normal combustion is initiated by the spark plug. The initial combustion at the spark plug is followed by a normal combustion burn. For some reason, likely heat and pressure, the end gas in the chamber spontaneously combusts. The key point here is that detonation occurs after you have initiated the normal combustion with the spark plug.

Pre-ignition: Pre-ignition is defined as the ignition of the mixture prior to the spark plug firing. Anytime something causes the mixture in the chamber to ignite prior to the spark plug event it is classified as pre-ignition. The two are completely different and abnormal phenomenon.

Good article, thanks.. I was just looking at the same one on a different site.

http://www.streetrodstuff.com/Articles/Engine/Detonation/


I guess I've used the terms interchangebly.

Some sites differ on the timing of these events:

"Detonation and preignition often occur simultaneously and one may cause the other. Since either condition causes high engine temperature accompanied by a decrease in engine performance, it is often difficult to distinguish between the two."

Another site explaining the difference:

http://www.misterfixit.com/deton.htm

The key would be that Detonation is an uncontrolled, explosive ignition of the fuel/air mixture within the cylinder´s combustion chamber.

or

Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.

Another condition that is sometimes confused with detonation is "preignition." This occurs when a point within the combustion chamber becomes so hot that it becomes a source of ignition and causes the fuel to ignite before the spark plug fires. This, in turn, may contribute to or cause a detonation problem.

Vrocks
01-15-10, 04:46 PM
Good article, thanks.. I was just looking at the same one on a different site.

http://www.streetrodstuff.com/Articles/Engine/Detonation/


I guess I've used the terms interchangebly.

Some sites differ on the timing of these events:

"Detonation and preignition often occur simultaneously and one may cause the other. Since either condition causes high engine temperature accompanied by a decrease in engine performance, it is often difficult to distinguish between the two."

Another site explaining the difference:

http://www.misterfixit.com/deton.htm

The key would be that Detonation is an uncontrolled, explosive ignition of the fuel/air mixture within the cylinder´s combustion chamber.

or

Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.

Another condition that is sometimes confused with detonation is "preignition." This occurs when a point within the combustion chamber becomes so hot that it becomes a source of ignition and causes the fuel to ignite before the spark plug fires. This, in turn, may contribute to or cause a detonation problem.
Definitely a good read, I found it back when I modded my V (9" crank pulley, stock tune). So I had it dynoed (for multiple reasons) and they said there was no evidence of detonation so I don't worry all that much about it (ECM call pull 4 degrees of timing and I only run 93+).

Anyway, the best I can understand it is: pre-ignition only occurs after new fuel and air have been added to the cylinder chamber, and it "detonates" before the spark plug ignites it. Detonation seems to be more of an "after shock" from remaining combustible fuel / oxxygen - I guess that it shouldn't occur after the exhaust stroke. To me, it sounds like pre-ignition is worse because there's more fuel and air to burn - sort of like comparing an M80 to a full stick of dynamite or worse.

TrevorD
01-16-10, 12:12 PM
There's no doubt that you can make some BIG power on hypereutectic pistons, but there's no longevity or forgiveness with them. I took out #7 on my '07 Z06 due to a bad tank of gas. When we drained the tank, it had a sour smell; there was also rust on the plugs. Such is life. A stock Z would've probably made it through fine with it's ultra-rich a/f and incredibly conservative low-octane table. My car was making 580 RWHP. Another 150 RWHP on a hypereutectic piston takes your safety margin close to zero. Tuning is certainly essential, but that's a given. Insult to injury is when it takes out the block, too! The LS7 has brittle sleeves, and I had to replace the block, too. It was a little bit of a bummer, but that block now has Darton sleeves and is going together as a 454. :D Cost and noise both go into GM's decision on the pistons. People that purchase a ZR1 are buying an "exotic" car that is built to do one thing. The CTS-V is definitely a performance sedan, but it's still a Caddy. I also agree that they needed to widen the gap between the LSA and LS9. You have to justify a $120,000 price tag!

I finished my pulley swap yesterday, and my car now makes 582 RWHP and 610 RWTQ. The tune is good, but if the engine eventually gives up it'll be my excuse to upgrade the pistons and rods. :)

Trevor

zr1vet
01-17-10, 12:00 AM
Wow. 582 is nice. What mods have you done to get it? Any problems getting traction on warm dry surfaces?

TrevorD
01-17-10, 12:11 AM
Wow. 582 is nice. What mods have you done to get it? Any problems getting traction on warm dry surfaces?

We installed a 9.55" crank pulley, upgraded heat exchanger, 160 t-stat, and metal intake tube. It's also a manual. The car put down 502 RWHP and 490 RWTQ bone-stock. The car is putting 600 lbs./ft. of TQ to the rear wheels at 3,000 RPM! Traction is virtually non-existent. I can get it to hook on concrete in second gear, but first gear is just about useless. It did try to hook, though, when I had two people in the back seat last night. It shows right at 13 psi on the factory boost gauge, but I'm not sure how accurate it is. I'll make a post on Monday after I have the graph scanned and video uploaded. She'll end up with a set of drag radials for some get-togethers this spring and summer. :)

Prof
01-17-10, 08:22 AM
I think what he meant was the the forged pistons are just a better choice in a higher rpm engine that has increased boost over the LSA.

I have heard from a GM tech that the forged pistons that the ZR1 has, have experienced some problems, and that they were not the best forged choice for the ZR1.

It never ends! But that is what some of us gear heads love...

neuronbob
01-17-10, 09:10 AM
Reading all this makes it less likely that I'm going to mod my engine or even add a tune....without calling in someone who works with these cars (V2s) all day long and knows the right tune to avoid pre-ignition issues. Seems like Jesse is the resident V2 geek around here and he's only a three-hour drive for me.

Prof
01-17-10, 09:20 AM
Your approach is wise...knowledgeable, experienced tuners are vital to the performance and longevity of any forced induction engine.

Good tune = Zoom!

Bad tune = Boom!


:yup::yup::yup: