Wanna Go Fast Day 1

[LancePearson]

Hog, seems like if you spend around $20,000 one way or another today you can take a 5.7 litre v8 and crank it up to 500-600 hp with the engineering knowledge around. It sure would make me think twice to leave the dohc architecture though. A dohc with twin turbos has to be a beast that will really crank. The little 3.5 l. v6 Sebastian Loeb ran in a Peugot and Rhys Millen ran a 4.0 twin turbo v6 4.0 liter that each put up published approx 900 hp and were probably tuned higher than that. Loeb won the Pike's Peak Hill climb race in his by obliterating the prior year record of 9'46" at 8'13" and change. Millen ran 9'02" but finished second. Take our engines and spin turbos on them and you'd have to see 1,000 hp. Way more than I could manage. The Loeb car on a flat track did 0-62 mph in 1.8 seconds, 0-124 mph in 7 seconds and to 149 in 10 seconds I believe. I love my lt5 and I love my 2008 LS2 with the 4:10 rear end but after seeing what people are doing with turbos it is hard not to think I might do something like that rather than the traditional re sleeve, port and relieve, solely if I were to do something more to the engine.

Lance

[Paul Workman]

Ah...the ol PEAK HORSEPOWER argument again... In an upcoming edition of the HOTB, the subject of torque and acceleration will be touched on, and for those that can "read between the lines", something will become clear when comparing contemporary pushrod architecture to DOHC. Lance's opinion on FI is correct, far as achieving really big HP numbers go (in anything that is street driven, BTW). But, the top speeds at the 1/2 mile shootout in Chicago were (exclusively?) DOHC platforms as well.

It is a never ending argument, I suppose. And, the venue has as much as anything to do with which engine architecture has an advantage; auto-cross and road courses favor low-end torque, the reason (in part) why the Challenge cars did so well. And, I believe, the reason the 1/2 mile smiled so favorably on the ZR-1s is due to the "long legs" of their DOHCs.

I tell ya what is going to end the argument tho...electric motors! A motor at each wheel is the future sports car; I'm talking hybrid. Bet on it. The question is how best to feed them? That will depend on the application. (Personally, I think it would be sexy to spin the generator(s) with a gas turbine. I suppose that might be fine for a LeMans type race, but not so much for a grocery getting in the "Family Truckster".)

Arguing about the virtues of various internal combustion architectures has been fun for a long time, though the sand is running out of the hourglass on that one, I believe.

We live in interesting times... But, my "antique" Corvette still has more capability than I'm capable of wringing out of it, tho I try to push the envelope when I can. I'm tellin ya that 5-2 down shift at around 50 and standing on that LT5 to mid 7000s has wiped the smirk off the faces of many would-be "bad azzez!" I'm just sayin!

P.

[XfireZ51]

Paul,

It's pretty amazing that you can do a 5-2 downshift on an LT5 without blowing up the motor.

[LancePearson]

Paul, I agree with you. Fact is, to me, torque and when and where you get it is really a better measure of pushing a car than HP. HP just sounded sexier to marketing types. The DOHC architecture is terrific for that it seems to me. With regard to electric motors some of the very best new hyper cars coming out now have not only gas engines, dohc, that are hugely powerful but they add a 160 to 200 hp dc drive motor to the rear transaxle and coordinate it to run WITH the gas engine...we are talking expensive cars but the experimenting is going on along with turbos spun by electricity rather than exhaust gas...no lag.

I saw a few days ago the auction of the 1954 famous Mercedes W196 race car that Juan Fangio campaigned in Formula 1. It was a 2.5 liter 8 cylinder, direct fuel injection car that generated about 290 hp on that small chassis and won 9 of 12 races it raced. It sold for $29.7 million to set an auction record as it is the original the famous Fangio drove, one of three. It also had something else unique...probably won't spell this correctly: desdemondic valve cam operation. Instead of a spring pressure closing the valve at the right time it uses a cam lobe to both open the valve for injection and another to close the valve. I'm told some Ducati motorcycles have used it as well. Looks more complex to me but there's no spring weakening with it either. I'll attach a photo or drawing in a second. There are so many technologies around that have been known for years....and our cars have a good mix of them especially considering they are 22 years old in my car's case. I could not find out how fast the W196 car ran but I'd guess it was in Ferrari Testarosa territory a few years later for top end (that's less than our cars can do btw!). Didn't hurt that the famous Argentine driver, Fangio, drove it. BTW, he won F1 for four different teams in four different cars, the only one ever to do it. Shumacher finally won four F1 crowns but not for four different teams and cars. Fangio became the honorary president of Mercedes of Argentina and died at age 84.

[LancePearson]

Desdemondic valve operation...and what the W196 looked like...it was supercharged with technology of the day. 290 hp out of a 2.5 liter straight 8 cylinder engine then was a lot. Today more can be wrung out of it than that by far but usually with v6 or v8 architecture of something like 64 to 90 degree v's...puts them in smaller space or behind the driver and ahead of the rear wheels. The limit on power today seems to me that it is not knowledge but money to modify and install. You can get to huge horsepowers any of several ways. I'm looking forward to reading the torque/acceleration discussion. I can tell you the torque in my LS2 410 hp engine with a 4:10 rear end is nothing compared to that of my LT5. Not even close.

The Des. valve arrangement looks like you would go from four cams to six cams to do it which would seem to add complexity and cost...same arguments for sticking with the two valve pushrod engine architecture GM used. However, I wonder what the possible trade offs in benefits are? No one that I saw really said when referring to the Mercedes race car.

Lance

[XfireZ51]

Desmodromic valve train is a hallmark of Ducati bikes. That and birdcage chassis.

[Hog]

Originally Posted by Paul Workman

Ah...the ol PEAK HORSEPOWER argument again... In an upcoming edition of the HOTB, the subject of torque and acceleration will be touched on, and for those that can "read between the lines", something will become clear when comparing contemporary pushrod architecture to DOHC. Lance's opinion on FI is correct, far as achieving really big HP numbers go (in anything that is street driven, BTW). But, the top speeds at the 1/2 mile shootout in Chicago were (exclusively?) DOHC platforms as well.

It is a never ending argument, I suppose. And, the venue has as much as anything to do with which engine architecture has an advantage; auto-cross and road courses favor low-end torque, the reason (in part) why the Challenge cars did so well. And, I believe, the reason the 1/2 mile smiled so favorably on the ZR-1s is due to the "long legs" of their DHOCs.

I tell ya what is going to end the argument tho...electric motors! A motor at each wheel is the future sports car; I'm talking hybrid. Bet on it. The question is how best to feed them? That will depend on the application. (Personally, I think it would be sexy to spin the generator(s) with a gas turbine. I suppose that might be fine for a LeMans type race, but not so much for a grocery getting in the "Family Truckster".)

Arguing about the virtues of various internal combustion architectures has been fun for a long time, though the sand is running out of the hourglass on that one, I believe.

We live in interesting times... But, my "antique" Corvette still has more capability than I'm capable of wringing out of it, tho I try to push the envelope when I can. I'm tellin ya that 5-2 down shift at around 50 and standing on that LT5 to mid 7000s has wiped the smirk off the faces of many would-be "bad azzez!" I'm just sayin!

P.

I remember reading a car rag from the mid 90's that stated "By the time the ZR-1 driver performed a 5-2 downshift, that pesky twin turbo Porsche would be gone". (I thought to myself, wouldn't it take time for the tiny engine to spool its hairdryers???)

I wasn't arguing the merits of engine platforms, merely the spending of $20,000 on a Coyote engine vs spending $6000 for a 525hp engine. Pure economics.

I wont argue the power that will be made with a turbo or 2 on a DOHC engine like the LT5 or Coyote. It would be FUN to say the least.

I think throwing a turbo on an LT5 really takes away the need for larger cubes. Pressurized air from turbos entering hogged out runners and heads make for much more power.

Paul I await the article on torque vs acceleration. I read an article that touches on the GEN 1 L98 vs GEN 2 LT1 comparison. The L98 makes more peak torque than the GEN 2 LT1, but the LT1 makes 50 extra hp with an extra 1000rpm or useable revs.
The comparison of a 1991 L98 auto coupe and a 1992 LT1 auto coupe is a great one as there are very comparable in weight and aerodynamics. It really illustrates how torque, power and rpm can influence acceleration when all else is equal.
250hp@4000rpm/350 lb/ft torque@3200rpm
300hp@5000rpm/335lb/ft torque@3600rpm

Its all about physics: Force, Work, Time and the LT5 takes this a step further over the LT1.

[Paul Workman]

Originally Posted by XfireZ51

Paul,

It's pretty amazing that you can do a 5-2 downshift on an LT5 without blowing up the motor.

U R Kidding, right? I'm referring to shifting from 5 to 2 @ 50 mph.

7200 = approx. 90 mph in 2nd gear (stock ZR-1 config; diff, tires, wheels, etc), so proportionally speaking, 50 mph = approx. 4k rpm...right in the wheel house of the LT5. And, you know from first hand experience that tires can come loose going to 3rd gear at mid 5000s, leave alone 4000 in 2nd gear.

Oh, yeah, a 5-2 shift is something Pete put me onto, and it is a real stunner; something a DOHC can really appreciate. Try it sometime!

PS: Usually, I double-clutch into 2nd, or at least pop the revs with the clutch in so it comes out of the hole hard when the clutch comes out quick. YeeeHaw!

[Blue Flame Restorations]

Paul, music to my ears!!!!

[DennisC]

Amazing Video, WOW!