GT350 vs. Z/28

[thePill]

@Track



I still think a 1:36 at Barber is just a tad too slow for a 500hp car there. I know why the GT-R and 911 were slow, the wet track and cold weather was not helping. If the track was dry and temperatures were like the z28's 62 degree runs, I can see them in the 1:35 range easy. If the conditions were the same, the article would have been different as well as the vibe. Another thing I didn't like, they took 6psi out of the tires to produce a faster time. Initially, the z28 ran a 1:37.28... That is scary for an $80,000 car. There will be a violent recoil the first time another magazine doesn't take air out of the tires and then it can't manage what it just did.


I confirmed with MT in their forum that all 3 cars where run again during the optimal conditions. Yes, the slow time of the Z28 was due to the poor conditions with limited RWD grip while the tires weren't exactly meant for those conditions.

I don't mean to take anything away from your argument, but this appears to be the facts, according to the MT staff, specifically from Scott Evans.

Thanks for the intel, it was reported differently in the test. Once you draw inconsistencies to their attention, they will surely tell you they did test all three. They also said it was 20's and 30's for their entire trip but now...

Thanks anyway, nice to have a Q&A guy at MT.

The test wouldn't have ended until the z28 beat the two other cars.

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[on d bit]

I confirmed with MT in their forum that all 3 cars where run again during the optimal conditions. Yes, the slow time of the Z28 was due to the poor conditions with limited RWD grip while the tires weren't exactly meant for those conditions.

I don't mean to take anything away from your argument, but this appears to be the facts, according to the MT staff, specifically from Scott Evans.

Why did the both the Porsche and Nissan destroy the Z28 on the Ring? All three had multiple days on closed tracks and yet the Z28 is a distant third. Hell Porsche does not even market their times and they put a 10 spot on GM. :shocked::lol:

 

[Norm Peterson]

Your correct Stuntman, the LS7 weighs 460-470lbs. The old Aluminium 5.4 weighed about 560lbs.

I'm assuming that includes something like 80 lbs for the supercharger.


Norm

 

[Gman11Gt]

Thanks for the intel, it was reported differently in the test. Once you draw inconsistencies to their attention, they will surely tell you they did test all three. They also said it was 20's and 30's for their entire trip but now...

Thanks anyway, nice to have a Q&A guy at MT.

The test wouldn't have ended until the z28 beat the two other cars.

That is probably true, all the hype and selling magazines is part of the sales process and takes away from reality. If they published the Z28 as a big looser or 3rd place, it wouldn't have been much of an article. As most where surprised and building all the hoopla.

I am not sure if they ran them just one more time with all 3 while taking out tire pressure only the Z28 since it was the dog on the first run. I find it hard to believe it picked up so much more time and the times of the other 2 weren't given on the first run. Anyways, when track times are involved with so many variables, it will always be open to discussion as far as if they cheated, or based on conditions, tires, cage or no cage, etc.

I really think the new Z06 will break some track records or at least will be the "production king" for those stock bang for your buck car.

The GT350 should take care of the cartoon cow (Z28)

 

[thePill]

In light of the GM criminal investigation for negligence, I hope, if they survive this, they will start being an honest company. It's a shame it had to come to safety equipment that finally drew attention to them. I can't even predict how damaging this is to the Corvette, Camaro, GM Performace and Motorsports. All headed to the back burner for a few seasons. The 6th Gen could even see delays depending on the fines and compensation.

I watched both of the Daily Show's Jon Stewarts comments... When it's laid out like that, the company just truly makes me sick.

I demonstrate sustain for Chevy for a similar reason, but not nearly as serious as this... My beef was with performance claims and marketing of such when no real world evidence can prove them right. It's a moral issue at GM, cutting corners... and still marketing the product as such.

It's sad that this practice spawned almost 15 years ago, through a bailout and now caught cutting corners. They never intended on fixing any of this until they got caught... If safety is being skimpped on, so is everything else. There was just recently a GM recall on vehicles that were sold to the public but failed crash testing... They STILL sold the cars, the new Caddy XTS is on the list... Pathetic...

Engineering defects are one thing, engineering cars with parts not meeting specifications (Even after Delphi waned them) is criminal.

Quite frankly, I don't feel General Motors needs to be in business... It will take a decade for them to prove otherwise. I didn't trust the Camaro testing control measures and hoped, and speculated it was just a Team Camaro thing. Appearently, I was wrong.

Anyway, Team Camaro cut corners, not saying the z28 is a corner carver, just that I don't trust them enough to provide stock cars for testing. They wanted all the Boss 302 glory and did none of the hard work and R&D. It was the easy way out... They took it then, they are taking it now. It's low class...

They get what they deserve...

 

[PowerUp]

2013: BOSS with 57mm restriction: 1:36.227
Mustang (4th, 5th, 7th)
Camaro (2nd, 6th)

2012: BOSS (restrictor size unknown) 1:36.805
Mustang (5th, 8th, 9th)
Camaro (1st, 7th)

2011: BOSS no restrictor 1:36.844
Mustang (16th, 17th)
Camaro (1st, 4th, 6th, 8th, 12th)

2010: FR500C 1:37.588
Mustang (1st, 4th, 5th)
Camaro (Did not exist)

There you go, Stuntman, trying to inject confirmed FACT into a FANCIFUL thread. Sheesh!

Dismissing out of hand what you consider to be only amateur knowledge might really be a case of trying to fool yourself. I'll stay out of the crap that's been flying around (it's why I went MIA here for a bit). But I did get paid pretty good money to do various forms of structural analysis for most of my career, and I've got some idea how to relate that knowledge to vehicle dynamics. There's a Clemson.edu / SAE paper on improving chassis torsional stiffness that's useful for grasping the concept, if nothing else.

Anyway . . .

20 seconds in about 8 minutes is about a 4% improvement in average speed. That's an 8% increase in lateral acceleration assuming that that 4% is distributed evenly around the entire distance (V-squared/R). But that's an unreasonably low estimate, since forward acceleration isn't going to be grip limited in the upper gears and max straight-line braking deceleration is not heavily dependent on chassis torsional stiffness. So now you're asking people to believe that a cage is going to cause tire grip somewhere in excess of a 15% increase with no other changes and no attempt to optimize the no-cage tuning that would be your basis. You're trying to convince us that there is that much tire grip sensitivity to camber as a function only of chassis torsional stiffness.

Frankly, I just don't see enough chassis torsional deflection happening to support that kind of gain, unless you started with a wet-noodle for a chassis and truly questionable roll stiffness distribution (to exaggerate the amount of torsion carried to the stiff end and hence exaggerate the actual torsional deflection at one end relative to the other). Camber change due to load transfer and differential tire vertical deformation is a bigger effect, probably much bigger.

Bushings have already been mentioned, so why don't we carry that a step further. Let's say the bushings are 15000 lb/in and at the front struts there is 20" difference in the lateral link and strut top pickups. 1g @ 4000# x 50/50 weight distribution is 2000 lbs, so the lateral link bushing sees over 2000# load (I'm not going to do all the math). That would be >0.13" deflection, but since we know that OE suspension bushings aren't linear maybe it's closer to 0.08" (bear with me for my WAG here). 0.13"/20" → 0.4° if we assume zero lateral displacement at the strut top (which isn't quite true). Brackets deflect, too, so let's make that 0.6° total. Are we to believe that a fraction of that 0.6° from chassis deformation is worth 15%?

Welcome back, Norm. Just in the nick of time, too.

... the performance in the cars today we will always see some sort of cage in the for the protection of the driver/engineers.

Finally, some reason.

Therefore, given that the Zeta platform is a beefy one, I'd suspect that a roll bar would not do much to improve the ring times of the Z/28.

There IS a reason the Zeta weighs more than the S197. Platform (and therefore strength) would be a major contributor.

Of the roughly-200 changes made for the Z/28 conversion, how many were performed on the basic platform? NONE.

How many structure-related changes were made to the BOSS LS?

I think it makes a great performance target for some version of the Mustang, hopefully at a significantly reduced price.

From BOTH sides of the fence, we ALL hope this is true for BOTH Gen-6s.

Your correct Stuntman, the LS7 weighs 460-470lbs. The old Aluminium 5.4 weighed about 560lbs.

The cast iron 5.4 weighed 665lbs... Not sure about the 5.8 though.

The Coyote weighed 429lbs in 2011, lost a tiny bit between '12-'13, about 428lvs now.

The LS3 weighs 418lbs and the new LT1 weigh 450lbs (heavier than a DOHC now).

Why is an LS7 so much heavier than a 3?

Because the listed weight of the LS7 includes the obligatory dry-sump system. LS3 and LS7 engines, alone, are virtually the same weight. The blocks are similar in weight as are the bare heads, while the rotating mass is, as well, which contributes to the LS7's greater displacement at a higher redline. Ti rods are the "secret", here, in both instances.

You were saying the GT500 was heavy and I was just commenting that the [Base] 13 GT500 and the 14 Z28 are about the same weight give or take 20lbs.

The significant difference from a handling point of view, weight-wise: Weight Distribution!

GT 500 = 57/43, fr/rr

Z/28 = 50/50

 

[thePill]

Powerup, first, the z28's balance was 57/43 in all test... It was only advertised to be 50/50, another missed mark.

Second, we were both wrong about the LS7. The LS7 weighs 497.2lbs ready to run, it is 64lbs lighter than the LSA. That would bring the LSA up to. 561lbs, 143lbs heavier than the 418lbs LS3.

Norm,

That extra weight is from supercharger support systems and the unit. The old Iron 5.4 weighed 670lbs. Ford removed 102lbs from the engine in 2010 using Aluminum. That brings the 5.4 down to 568lbs... The 5.8 lost an additional 8lbs... pretty close to the LSA.

Norm, please give me a minute to recheck the FE 5.4's weight. That is all I have to work from until we pull a new. 5.4 or 5.8. Be right back...

Norm, the Iron blocked DOHC 5.4 weighed 540lbs NA. If I apply the 143lbs weight gain the LS3 experienced to the LSA since the systems are almost identical, that brings the FE 5.4 to 683lbs (13lbs heavier than I heard).

The Aluminum 5.4 lost 102lbs so, it would bring the weight down to 581lbs which is close/right on the money and what we heard. The new 5.8 could be lighter, depends on how much was gained in the support systems.

Keep in mind Norm, adding 143lbs to the 540lbs is not accurate. Nor was a simple minus 102lbs from the old 670lbs. What we see here is some loose data than gets us between 568lbs and 581lbs, a 13lbs spread for the Aluminium 5.4.

I can't give you a more accurate guess than that.

 

[5.0GT]

In light of the GM criminal investigation for negligence, I hope, if they survive this, they will start being an honest company. It's a shame it had to come to safety equipment that finally drew attention to them. I can't even predict how damaging this is to the Corvette, Camaro, GM Performace and Motorsports. All headed to the back burner for a few seasons. The 6th Gen could even see delays depending on the fines and compensation.

I watched both of the Daily Show's Jon Stewarts comments... When it's laid out like that, the company just truly makes me sick.

I demonstrate sustain for Chevy for a similar reason, but not nearly as serious as this... My beef was with performance claims and marketing of such when no real world evidence can prove them right. It's a moral issue at GM, cutting corners... and still marketing the product as such.

It's sad that this practice spawned almost 15 years ago, through a bailout and now caught cutting corners. They never intended on fixing any of this until they got caught... If safety is being skimpped on, so is everything else. There was just recently a GM recall on vehicles that were sold to the public but failed crash testing... They STILL sold the cars, the new Caddy XTS is on the list... Pathetic...

Engineering defects are one thing, engineering cars with parts not meeting specifications (Even after Delphi waned them) is criminal.

Quite frankly, I don't feel General Motors needs to be in business... It will take a decade for them to prove otherwise. I didn't trust the Camaro testing control measures and hoped, and speculated it was just a Team Camaro thing. Appearently, I was wrong.

Anyway, Team Camaro cut corners, not saying the z28 is a corner carver, just that I don't trust them enough to provide stock cars for testing. They wanted all the Boss 302 glory and did none of the hard work and R&D. It was the easy way out... They took it then, they are taking it now. It's low class...

They get what they deserve...

GM is pure scum from top to bottom. NO gm autos for me ever again until that corp is purged.

 

[PowerUp]

Powerup, first, the z28's balance was 57/43 in all test... It was only advertised to be 50/50, another missed mark.

Second, we were both wrong about the LS7. The LS7 weighs 497.2lbs ready to run, it is 64lbs lighter than the LSA. That would bring the LSA up to. 561lbs, 143lbs heavier than the 418lbs LS3.

ONE test shows 53/47, and that was an A/C car. And THAT'S the only w/d shown.

LS3, as per Chev PerfParts = 415 UNDRESSED (no clutch-flywheel or flexplate, no accessory drive). The 497 lb LS7 weight is with a Vette flywheel and drive. No one (not even GM) lists a weight for the LS7, "officially", but without the above-mentioned add-ons, it within pounds of an LS3, equally dressed/undressed.

The weight difference from LS7 to LSA is 63.7 lb, similarly dressed/undressed.

 

[thePill]

No, it's not, that would make the LSA much heavier than the Condor/Trinity. The GT500's 5.4 was 20lbs heavier than the LSA so, minus that 64lbs (per GM) makes the 497lbs of the LS7.

Keep in mind, the Coyote is 429lbs, 11lbs heavier than the LS3. What your proposing makes the LS3 heavier, it's not heavier than the Coyote. That would also mean the new LT1 wouldn't be 36lbs heavier than the LS3, the LT1 weighs 454lbs right? That isn't adding up...

 

[PowerUp]

LS7 is 497, dressed and ready for install...WITH DRY-SUMP...which the LS3 @ 415 lb undressed does NOT have.

An LS3 with DRY-SUMP set-up (Vette GS-stick), dressed, weighs more than the (new) wet-sump LT1, before accessories. FACT.

It's very difficult, if not impossible, to say ANY specific engine weighs a static amount. It depends on version, and state of dress.

THIS hair-splitting is consistent with YOUR posts...all 1200 of them. Own it. For once.

Just like the Coyote-based 5.0 has various weights, depending on how IT'S dressed (see the CJ version, for instance). It is 429 in it's LIGHTEST form. FACT.

 

[thePill]

Okay, so all the weights I posted were correct. I have no idea why you came in and said they were wrong.

I originally said the LS7 weighed 460-470lbs. I was unaware the engine weighed 497lbs. You told me the LS3 and LS7 weighed the same, they do not in anyway, shape or form. They list, ready to run, 418 vs 497. I'm not making that up, that's just the way it is. Yeah, no AC would probably bring an LS7 down to 470lbs... A dry sump LS3 may weigh more, it shouldn't be much.

And, there is 2 versions of the stock OEM versions of the Mustangs 5.0. The 2011 had piston oil squirters and was rated at 412hp. The '13 deleted the squirters and was rated at 420hp. Both engines were 428.8 and 429.9lbs, the new version is lighter.

It appears that pushrod engines are no longer lighter than DOHC's.

Anyway, I'm not sure why you had an issue with my initial 460-470lbs claim for an LS7. If it's 497lbs now, minus AC, it should be around what I claimed it was.

The LS3 in the Camaro IS 418lbs... I just don't see an LS3 being 460-470lbs... That is too heavy.

 

[thePill]

Wait a minute, you said a dry sump LS3 weighs more than a LT1. The LT1 weighs 465lbs, does the LS3 weigh over that? and holy sh!t the LT1 is a boat anchor. That is seriously heavy.

It says the LS3 crate engine is equipped, flex plate too...

The LS3 6.2L is the 430-hp standard engine in the Chevrolet Corvette and is a fantastic combination of high technology and uncompromising performance. Our LS3 crate engine comes complete, from the Corvette-specific oil pan to the ignition system. It also includes the EFI intake manifold assembly with injectors and throttle body, exhaust manifolds, water pump, balancer, 58X reluctor wheel, and 14-inch automatic-transmission flexplate.

I'd say it doesn't get much heavier, it does have a flex plate and not the flywheel. I'd say a flex plate LS3 weighs 415lbs like advertised and the LS3 manuals weighed 418lbs. Now, add in that 143lbs to the say, 418 and we get the LSA's 561lbs... Minus the 64lbs from the LSA's 561lbs you get 497lbs with AC. The said AC added 19lbs I think...

A dry sump system doesn't add 47lbs to the LS3... at least I hope not...

 

[thePill]

The weight of the LSA is 64lbs from the LS7's 497lbs. I has to be from the supercharger...

Coyote vs. LS3, Mustang vs. Camaro, it's 418 vs. 429 initially. A pushrod use to be lighter, the LS3 lacked technology. Once the LT1 adopted VCT, DI and a wide block casting, it took on some weight. From 6.2 to 6.2, it gained 47lbs. The Coyote was designed with DI engineered in and TiVCT too. It may get a tad heavier, but it looks like the 2nd Gen Coyote will be lighter than the LT1. Cheaper, lighter and more powerful.

Keep in mind, the Coyote has evolved to a Boss 302 with forged internals. It very well may have lost more weight, rotational mass, which is where SOME of the new power comes from and higher revs.

 

[thePill]

The only test that actually weighed the car was Car and Driver (see test sheet). I think they weigh all four corners. They got a 57/43 front rear weight distribution.

I know Team Camaro said 50/50 but, please refer back to my previous 1200 post. I doubt even 19lbs of AC in the front and a full tank of gas in the rear would even 3% out.

A supercharged 5.8 GT500 weighs a bloated 3850lbs and sits at a god awful 57/43. The 7 liter NA z28 is a slim 3865lbs at a very athletic 57/43 weight distribution.

Also, C&D weighed the car almost completely full of gas. Once that tank gets low, that 57/43 will turn into a 56/44... Maybe worse...

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