Bwright

IÂ’ve been thinking about how GM can get 600hp or thereabouts for the Blue Devil. Here are the only likely ways:

1. Supercharging. A cheap and easy way to make big horsepower numbers. It has one big drawback for a car like the Corvette. It cannot be raced. Superchargers lose power when exposed to prolonged heat. This Faustian bargain will paradoxically keep FordÂ’s GT from returning to its Le Mans roots. The likelihood of GM going with a supercharger when it could not form the basis for an endurance racing car is small. Maybe for a Cadillac sedan they did not plan to race (STS perhaps) but not the Corvette. Superchargers also sound remarkably like a shop vac. Not something you want in a Vette.

2. Turbocharging. There are heat and durability issues here but the biggest one is the immediacy of the power delivery. In a turbocharged engine this delivery is non-linear. Again, not something a Corvette driver is used to. Turbocharging does allow big power from a relatively small engine and is far less affected by heat than a supercharger but still. Corvettes have always been about big and immediate power. Turbocharging just doesnÂ’t seem right.

3. Increased power from the V8. Possible but I do not see them getting much beyond 500hp and staying within gas guzzler requirements. Given that Bob Lutz disregarded this requirement with the Pontiac GTO GM could do the same with the Blue Devil but I think there is a much better way.

4. A V12. It is well known that GM has an experimental XV12 kicking around. They have been trying to decide where to put it and a super Vette would be the perfect place. With Displacement on Demand it could go to an 8 or even 6-cylinder under light load to conserve fuel. It should be able to accommodate this with no untoward effect on the exhaust note (light load conditions). A V12 Super Vette would provide a devastating platform to launch an attack on Le Mans. It would have none of the issues of a super or torbocharger. They would also not have to strain the development limits of the V8. Costs could be amortized through a Cadillac super sedan (or SUV) which could share the engine. It would certainly be the only thing which could blow away the competition (Viper, Ford GT) as Lutz has said an upcoming Corvette variant would.

What say you all?


[Modified by Bwright, 11:27 AM 6/9/2004]

Z06 Mike

I'll take one of each...

98pace#870

A twin-turbo setup is the perfect complement to an already muscular V8. I had the chance to drive an '87 Callaway twin-turbo ("only" ~350HP) and it was amazing. The V8 has plenty of low-end torque already, and when the turbos kick in, the car just keeps pulling harder and harder... I would love a ride in a Lingenfelter twin-turbo C5, those have got to be awesome.

Runge_Kutta

I put my money on a 7.0L V8. To get 600hp from this, you need 86hp/L. To get
625hp, you need 89hp/L and for 650hp, you need 93hp/L. The LS6 puts out
71hp/L. The 3V engine has the potential to beat a 2V set up by 10%-15%.
That takes you to 78-82hp/L. So, I don't think a 7.0L, GenIV small-block,
that uses 3V heads can do the job. How does one take this engine from
82hp/L to 86-93hp/L?. I can only think of 2 reasonable ways: forced induction
or GDI.

Painrace

Bwright, I agree with your analysis. Turbocharging or Supercharging adds weight and complexity for a street car and I question enging/Turbo/Supercharger life. A V12 would be SWEET, especially if it was mid-engine!

Bwright

Your analysis of engine outputs and requirements is spot on. As regards GDI, GM pulled the Cadillac teams from Le Mans in 2002 citing the advantage of Audi's GDI technology in the LMP class. Since the Blue Devil will supposedly debut in two years that gives them a total of four years to get on the horse. Since I have not heard anything about them making any commercial breakthroughs in this department I am a bit skeptical.

Forced induction? For fifty years the factory has avoided it for the same reason that Gordon Murray cited as the reason he would not countenance it for the McLaren F1. Turbochargers have non-linear power curves. This is geneally anathema to serious road cars. Not to say that the Blue Devil could not go there, just that I seriously doubt it.

Superchargers cannot be used in endurance racing and so any manufacturer with aspirations thereof cannot seriously consider that for the road car to begin with.

Let's see what the future holds.

texel

Just bump the red line to 7500 rpm for the 3V 7 liter engine
and you got well in excess of 600 HP. No forced induction needed.

Gary

ivan111

Turbocharging is an attractive alternative, the masters in turbocharging is Porsche.......

Look at the 911 Twin Turbo and the GT2....

Many years ago Porsches 935 Turbos won many races for Porsche........


[Modified by ivan111, 11:37 PM 6/9/2004]

Runge_Kutta

If you take the LS2 as having a 101.6mm bore and assume that
they may be able to eke out another 3mm (104.6mm) via
http://www.uspto.gov/web/patents/pat...-20040518.html

then that leaves a stroke of about 101.8mm for a 7.0L V8. That is going
to be one very large and heavy piston travelling a very long ways. Even
with titanium connecting rods to drop the reciprocating mass, 7500 rpm is
very tough sell. Dropping the reciprocating mass doesn't mitigate the
tremendous loads that the piston would experience.

I don't think a 7500 rpm redline on such a big engine is realistic. Of
course AlBeMet162 could change that ...
http://www.reade.com/Products/Alloys...loy_al_be.html

It's just a tad pricey and watch out for berylliosis:
http://www.healthatoz.com/healthatoz...rylliosis.html

LittleBoyBlu99

EngPilot

I think the V12 is a distinct possibility for several reasons.

First, GM is developing a V12 for Cadillac, so utilizing this engine for the Blue Devil reduces development costs.

Second, the 7.5 liter V12 can produce the 625 +/- HP that has been discussed.

Third, I see this V12 as a growth of the 4.2 liter truck engine. My wife has a 2002 GMC Envoy, and that 4.2 engine is SWEET! It idles so smooth you can barely detect that it is running, yet at high rpms this thing screams. GM is also making 4 cyl and 5 cyl variations for other vehicles, so the V12 is just another way to use existing parts inventory, and utilize the development engineering that has already gone into the 4.2 engine.

The 4.2 has a 92 mm bore (3.62") and a 102 mm stroke (4.02"), but shorten the stroke to 92 mm, and add 6 cyls, and you have a 7.5 liter V12 that will be world class - low emissions, 4 valves/cyl, VVT, and DOD probably for fuel economy, and silky smooth yet powerful and responsive.

From a manufacturing and development perspective, this is what makes the most sense to me, IMHO.

Bill

Dave Schotz

The car will be Twin Turbo... I don't know Cubic Inches yet... but the 'strongest' rumor I have heard... is the car needs to be Turbocharged, due to the 2007 Viper being Super Charged!

Only time will tell... but I think the WAR HAS BEGUN!

WhiteDiamond

The XV12 could be a possibility. I have heard that the redesign for the SUVs is to happen very soon and a bunch of 12 cylinder Escalades are all ready running around. The XV12 supposably fits very easily in the space of the current V8, so there should be little issue in packaging. My wife really likes the big vehicles and I have told her to wait until more info is available on the supposed Escalade V series with this motor.

I don't believe GM has to go to a power adder for the "Blue Devil." I agree with Runge's comments to a point, but there are many proven 427ci LSx based engines running around. If 3-valve technology is giving the effeciency improvements mentioned in other threads, I think GM could hit numbers with larger displacement that would make the "blue devil" a world beater. Instead of focusing on 600hp, I think the "blue devil" would showcase a bunch of other technologies and end up having a low curb weight and 550hp or more engine. I believe GM could do a 2600lb super Vette easily...Aluminum frame, purposeful interior, carbon fiber body(or parts), ceramic or CF brakes, composite shafts, and composite windows. A low curb weight would go a long way in taking even a 500hp Vette into super-car territory. It just takes money

Todd

Runge_Kutta

Let's talk weight.

Northstar (1992) - 210kg
LS1 (1997) - 208kg (auto), 228kg (manual)
LS2(2004) - LS1-7kg = 201Kg
XV16 (2003) - 315kg

So, what would an analog of the XV12 weigh? If you loosely say that the
XV16 is essentially 2 LS2's stuck together then a geometric scaling
suggests that rather than an exponent of 1.0, it's 0.65. Hence, taking
1.5 Northstars to get an XV12, the weight increase will be 1.5^(0.65) =
1.30. So, with this, the XV12 is approximately 30% heavier than a
Northstar. That's 273kg. That's 72kg = 158 pounds more than the LS2.
Add some titanium valves and connecting rods to a 7.0L, 3V, GDI engine
and I bet you're near 210-215kg. Moving to a V12 adds back all the weight
lost by moving to an aluminum frame except that it all goes on top
of the front wheels.

I vote against a V12.

I think it's either GDI or a twin-turbo to get 625+hp

Bwright

The concept Dodge Viper SRT-10 Carbon makes 625hp through traditional engine upgrades, not any form of forced induction. Where have you heard that the 2007 Viper will be supercharged? It is extremely unlikely that Dodge would go to a supercharger as such an engine would not be capable of serving as a platform for endurance racing of any kind. The Viper program is severely cash strapped so the likelihood of them having two different engine programs is vanishingly small.

Bwright

The weight of the all aluminum XV12 engine is not the primary issue. According to Steve Kowalk, GM Powertrain project manager for the Northstar XV12, "The packaging was probably the biggest challenge we faced, because from the outset we wanted to fit the V12 inside the package of a V8. We focused on keeping the size down to fit as many different types of vehicles as possible, while maximizing displacement, and then using Displacement on Demand to deliver the required power at all times. We also minimized cylinder bore wall thickness to 7 millimeters and used a rear cam drive to create a more compact package and enable a lower hoodline."

The Northstar XV12 is the same length as GM's Vortec 8100 V8, and it has the approximate width and height as the Northstar 4.6-liter and Vortec 6000 V8s.

If you want to talk weight then here's where the discussion should go. The C5 Z06 saved approximately 100 lbs. of weight over the regular C6 Coupe for a cost increase of approximately $10K. The current weight of the C5 Z06 stands 107 lbs. behind the staggering 660hp V12 Ferrari Enzo. Now, even given the bells, whistles and accoutrements which would necessarily attend the Blue Devil, and the finagling of the weight of the 750hp XV 12 (all aluminum so it should not be a great difficulty) if GM cannot reduce the weight of the car by approximately 100 lbs. for an additional $50K in projected cost then they should not be in the car business.

Period.

WhiteDiamond

You guys are thinking small!!! There is really no reason why the current C6 coupe weight(~3180lbs) cannot be dropped 400 to 500lbs with technology that can accompany the 50K (rumored) price over the C6 base models. From GMs own patents, there is a 30% or greater benefit in the aluminum frame, I don't know the benefit of the composite glass or CF body panels, and I believe I read that Porsche was able to knock something around 7lbs per wheel(sprung weight, much more critical in weight reduction) with the composite brake system. I believe the "blue devil" would be built in line with current offerings from other makers, so the interior dress would be dramatically reduced, taking a lot of weight with it. I don't know the weight of the XV12, but it isn't necessary to make the power they need if the weight is reduced greatly. Gas guzzler tax is out the window on the "blue devil", IMO, so a nice 400+ci small block can deliver the power without the weight penalty of a power adder.

Todd

Runge_Kutta

You're all over the map here.

Yes, the XV12 has been optimized for packaging. In spite of this, beyond
the weight increases that make it's viability in the Blue Devil rather
marginal, it still may not fit. It has been said by someone at GM that
the V12 doesn't fit in the XLR without stretching the nose. [Jury's still
out on that one from my perspective.]

The original debate was on how to get 600+hp into the Blue Devil. Implicitly,
you don't want to ruin the package while striving for 600+hp. I would contend
that adding 125-150 pounds over the front wheels by moving to some variation
on the XV12 comes really close to ruining matters. For a $40K surcharge, I
have no doubt that the Blue Devil will have lots of weight saving changes
like carbon-fiber body panels, titanium half-shafts, and the like. However,
the lighter the car gets, the more a 125-150 pound addition to the front of
the car upsets the weight distribution and moment of inertia. Further, compensating
for a 125-150 pound weight gain is going to be a seriously expensive endeavor.
Why bother? Sticking with a much lighter 7.0L V8 makes tremendous sense.

The C5 Z06 achieved it's weight savings by going after the low lying fruit
like dropping the run flat tires, the spare, and a bolt on exhaust system
that killed 18 pounds. The C6 Z06 will have no low lying fruit. To drop the
weight of a Z06 and create the Blue Devil will take some serious measures.

Weight will be a serious consideration in the Blue Devil, I think. That
comes real close to ruling out a V12. Packaging my make a supercharger
less desirable.

My money is on a twin-turbo or a GDI, 7.0L, 3V, V-8.

Addendum:
http://forums.corvetteforum.com/zerothread?id=413319


[Modified by Runge_Kutta, 1:35 PM 6/10/2004]

Ryan Bell

Of these options, I would prefer a turbo or two.

krwman007

ill wait and pray and hope for a 12, but it would still surprise me if GM went with it after half a century of no v12 in any corvettes.