RoDan

Guys, check out the latest MT. The cover article is basically this same subject, but with a twist. How many cylinders does it take to go 200. HP/liter comes up more than once.

GSXRofDFW

They nearly already do now. It is just not 5 liters. A 5.0 liter that makes 500hp for sure will not make 500tq. That would be something to brag about.

As others have stated. It is cooler to pack 7.0 liters in the space that most V6's take up than get 100hp/liter out of some monster the size of a BB Chevy.

My Brother-in-law who is a huge NASCAR fan but not a car guy really looked under the hood of a NASCAR and said "damn dude the engine is soooo freaking small"

Stang's Bane

iTrader: (22)

I just sent MT a letter. Had to vent about the Hp/l issues. I am sure that they will just disregard it, but it felt good to get it off of my chest.

Quick Double Nickel

iTrader: (5)

Well, in the same M/T issue that is being referred to above, the new Masarati is highlighted with its 4.2L V8 that makes 400 horsepower and 400 ft/lb of torque. That is something to brag about.

3.4camaro

iTrader: (1)

Yeah, but it's supercharged. This thread is about NA.

Quick Double Nickel

iTrader: (5)

Nope, it's NA. It's just too bad it's in a 4,150lb cruiser instead of 3,000lb runner.

3.4camaro

iTrader: (1)

ok. But it doesn't make 400 ft/lb. Their website says 339 ft/lbs.

http://www.emotionmeetsbusiness.com/...e.html?lang=na

Still a badass engine, but making 100 ft/lbs per liter is simply out of reach as it stands right now.

Quick Double Nickel

iTrader: (5)

I stand corrected. It says 400 lb/ft not ft/lb. Anyway, I think you could still get 100 hp/l and 100 tq/l if you used things like variable length intake runners and VVT and lift. If we had infidently variable valve timing (ie. electronically controlled valves) then I think it would be no problem.

3.4camaro

iTrader: (1)

Those things would help, I agree. VL Intake runners would help the most I imagine. However, I don't think they are cool enough, as it stands now, to make it to the 100 ft/lb/L mark. Example:

The new M5 engine from BMW. Makes 500 hp from a 5L. Badass. But it only makes ~380 ft/lb. This is because hp and torque are typically inverses of each other when one sets out to build an engine. It's like setting up suspension on a car to launch at a dragstrip and turn in autocross at the same time, it's not gonna happen.

A high hp car will normally be a short stroke engine that revs to the moon. They normally won't make any usable power until a high rpm, and not have lots of torque. On the other side of the coin, a torque monster engine might redline at 4500 rpm. This kind of engine would destroy any other car in a 60 foot race, but at the end of the track, it'll be out of breath. Both of these engines are awesome, but you can't really compare them to each other, because they have different goals in mind.

But how do we get the best of both world? Technology.

What needs to come on the market are pneumatic or solenoid operated valves, no more camshafts. This way, you can go into the computer, and say:

"at low rpm, I want my valves to have XXX lift and XXX duration, and at high rpm I want XXX lift and XXX duration. At cruise I want the valve events of a Honda Civic, but when I push my race button, the car starts loping more than any street car ever should."

^This is my vision for the best of both worlds. The fuel economy of a Civic, with the lope of a top fuel dragster when you decide it's time.

Quick Double Nickel

iTrader: (5)

The pneumatic or solenoid operated valves were exactly what I was thinking. I believe I remember Mercedes working on just such a system, but they need a much higher voltage system (somewhere near 40 volts?) to run the solenoids. It would be awesome, though, to do just what you described. Have a tiny lift on the valves with short duration to maximize pumping loads at low rpms, then have it turn into a beast up top. Because of the overall size (length and width) of the LSx cylinder head I wouldn't see it being a problem making it work with the traditional valve layout of the LSx engine. The large bore spacing, I would think, would actually make it a more ideal candidate due to the extra room for the solenoids as compared to an engine with a much smaller bore spacing.

Of course, all the purist would cry foul because the engine would no longer be as compact as the traditional pushrod engine, but I think the benefits would far outweight the extra height and width of the engine. With infinite adjustment on valve events I think the traditional notions of either max hp and little torque, or max torque and little horsepower are shifted quite a bit. Only time will tell. I can't wait to see what happens when we get that system perfected.

3.4camaro

iTrader: (1)

Thing is, this would be a bad thing for tuners, because once and for all there will actually be a BEST tune, because there will be no trade-off of low end torque for high end power, it'll all be on the table, and it'll all be tuned to the max.

engineermike

Don't confuse solenoid and pneumatics. The pneumatic stuff just replaces the valvespring with a pressurized air cylinder. It just gets rid of the spring, not the camshaft.

Also, peak torque and peak horsepower are not mutually exclusive. Peak torque is a function of bmep and displacement, whereas peak hp is a function of bmep, displacement, and rpm.

Mike

3.4camaro

iTrader: (1)

My fault on the pneumatic stuff. I've been DEEP into paintball guns and assumed they used a solenoid to operate a ram of some sort to move the valves.

Peak HP and peak tq are quite mutually exclusive in my opinion. Cam profiles geared towards pushing one or the other to the extreme are quite different.

engineermike

Okay, lets look at 2 examples. . .

350 TPI is an engine designed for torque, right? Stock, those motors made 245 hp and 345 ft-lb of torque.

Late Model SUPR engines are built specifically to maximize top end hp using 350 cid, 11/1 compression, and standard 23 deg heads. They use single plane intakes and camshafts over 260 at .050. These motors commonly make 570 - 640 hp and none make less than 500 ft-lb of torque.

At the same cid, the SUPR motor simply has a significantly higher bmep than the TPI motor.

Keep in mind that low-end torque and peak torque are two different things also. I'm sure at 2000 rpm, the TPI 350 is all over the SUPR 350.

Also note that stock LS1's make around 320 ft-lb at the rear wheels, while cam-only LS1's have been known to break 400 ft-lb with pretty lumpy cams.

Mike

3.4camaro

iTrader: (1)

What is bmep?

EDIT- Yeah see I'm thinking low-end torque(like drivability), not peak torque. My apologies for not being clear.

engineermike

brake mean effective pressure - "The definition of BMEP is: the average (mean) pressure which, if imposed on the pistons uniformly from the top to the bottom of each power stroke, would produce the measured (brake) power output."

When considered by itself, it does not tell you how much hp or torque an engine will make, nor how fast it will be at the racetrack. However, it does tell you a combination of how well the cylinder is filled and how much compression you have. Much like hp/liter, it's simply an effective comparison tool.

Mike

3.4camaro

iTrader: (1)

so its a ratio of cranking pressure to BHP?

engineermike

No, it's:

BMEP = 150.8 x TORQUE (lb-ft) / DISPLACEMENT (ci)

and

Torque = hp * 5252 / rpm

so

BMEP also = 150.8 x hp x 5252 / rpm / displacement

Its simply the average pressure that's in the cylinder during the power stroke.

Mike

3.4camaro

iTrader: (1)

that's a cool concept.

But my idea of the solenoid valves is just that you can have all the low end torque you can manage, along with all of the top end hp you can dream of, and optimal valve events at every rpm in between, kinda like the spark tables we have nowadays.

hammertime

iTrader: (1)

If the technology ever finds its way into production, I'm almost certain that is the way it would work. Essentially, four new maps for IVO/IVC/EVO/EVC. With continuously variable timing, you could have all of it controlled by TPS, MAP and MAF, and have the perfect cam profile for every possible operating parameter.