Amazing, Chevy builds a 330 HP engine with 28mpg Options

[snflupigus]

QUOTE (bd1308 @ Sep 18 2005, 11:32 AM)

[/QUOTE] here, the lights are only suggestion.... red means stop if you want yellow means hello and green means go really fast through the light.

LOL - here too... we actually have signs that say special redlight reinforcement area. I couldnt believe my eyes when i saw those in phoenix. Those signs dont exist in nebraska or iowa... it blew my mind that signs have to be put up to try and keep people from running red lights... HAVE SOME GOD DAMN COMMON COURTESY people!!! Next there will be rifle towers with gaurds on every corner shoot out your tires for running reds. naziland usa

[anthony]

How is it that manufacturers cheat by such a large margin on the epa tests. I know they drive the cars like a granny - and of course nobody in real life does that.

My '94 VW has actually gotten better mileage than the 23/30 EPA certification. I get 26mpg on average and 32mpg on 75-80mph straight freeway trips.

[Pugbug]

And the fuel economy winner is........The Pac car at 5385 Kilometers per liter!

http://www.ethz.ch/news/ethupdate/2005/050...0625_2/index_EN

[snflupigus]

i used to get about 25mpg average on interstate trips from denver to omaha in my 305 throttle body injected 3600lb automatic 92 camaro. On the interstate i could go 360 miles to a tank. in the city i would get something like 230 miles out of a tank. roughly 14 gallon tank.

255lb ft, 170hp 5L v8.... the 70's technology designed ecm has a "lean mode" function where if the speed and throttle position stay at certain range over 60mph for so long it leans out the fuel to safe but very lean. Most new cars have that as well and they are much more aerodynamic.

I think i remember being taught while working for my families gm dealership that it only takes something like 8hp to keep the vette going at 60mph once it gets there. i might be off there though.

anyway, if they could get 25mpg out of a 92 camaro, 35-40mpg would seem more than feasible out of a v8 today tuning for something more like 300lb ft and 250hp. Make it a v6 and i think 50mpg with 200hp,200lb/ft should be the standard... but instead our cars have gotten heavier and more powerful. instead of lighter and more efficient.

the 914 starting to look pretty good again for a daily driver LOL

[bd1308]

on your 914 comment, I couldn't agree more.

The longer I own the 914, the more I enjoy driving it!

[dmenche914]

The 914 is light enough, so it does not need a ton of power to still be fun (heck it handles so well it be fun with a lawn mower engine).

What we need is better milage, a more effiecient type four motor, or a water cooled replacement that is light, super efficient, and not over powered (at expense of economy)

A lower ratio 5th gear would be helpful with the right engine to obtain incredeble highway MPG I would assume 50 mpg highway woudl be possible in a so modified 914.

Try to shave a few pounds off the stock 914, add a smaller but new effiecient engine, select a very low ratio overdrive top gear to match the new engine for best economy,a dn you could end up with a rear winner.

Lucky most of our 914's are smog exempt in Californazia so that we can make energy saving modifications legally at last (Sorry 1976 owners, Shwartznegger screwed you, you got to stay stock)

[groot]

The manufacturers don't cheat on the sticker numbers. The EPA does the testing and certification.... and I agree it's flawed. They have a very specific city loop and highway loop and it doesn't come close to real life.

There have been talks about revising this silly EPA standard, but what would the customers do if all of a sudden they went into a showroom and saw the fuel economy sticker to be 20-40% lower than it was on the same model than it was last year?

[roundboy914]

not for nothing, but i think the HP rating was 303, not 330. Still not bad at all.

[andys]

Though I've only put four tankfulls' since I bought it, my '05 Toyota Tacoma truck bested at 17.5 MPG combined. Rating is 18/22. I expect it will get slightly better as it loosens-up, but it still falls short for now. My previous old '83 Toyota SR5 truck with 279K miles did 24 MPG combined all day long.

Andys

[snflupigus]

at least comparitively they are useful... one truck/car at 18mpg epa rating will get better gas mileage as another truck/car w/ epa rating of 16mpg.

right?

[jniemeier]

I'm new to the group, but you're on a topic I know something about.
Warning: long boring post to follow: Read only if you want to know more than absoutely necessary about cylinder deactivation.

(I was the Engineering Supervisor for the Delphi Valve Train group when we developed the cylinder deactivation system used by GM.)
The old Cadillac system used an electric rotary actuator on top of the rocker arms. We found a '82 Seville with a V8-6-4 when we started working on the new system in '99, and it was still working fine. Must have been the only one left. Putting electrical connections under the valve covers is generally a bad idea. Someone mentioned the Mercedes. Their V8 and V12 were the first of the 'modern' systems (I think in '99), and was very complicated. Big surprise. It's very tough to switch off the valves in an overhead cam engine. It has a very expensive, high pressure valve asm. You've only got the rockers to do it in, and it's hard to get the right oil circuits to your hydraulic actuators (inside the rockers!). Honda have also done it this way. You need a pivot shaft running down the length of the head so the rockers stay in perfect alignment and for the oil to run in. ($)
The new systems from GM (Displacement on Demand) and Chrysler (Multiple Displacement System) are almost identical. They (we) are doing the switching in the Roller Hydraulic Valve Lifters of pushrod engines. Much cheaper. There's enough space there to add locking pins and when hydraulically unlocked to absorb the cam lift without moving the pushrod. Ford would be doing the same, but they seem to have forgotten how to make pushrod engines, so they are out of the party for now. Chrysler's are made by INA (Germany); GM's by Delphi and Eaton. (Yes, legal wrangling has ensued, but let's not talk about that)
Operationally, it switches off the exhaust first, then the intake of every other cylinder as you go throught the firing order. The lifter has to be on the cam's "base circle" to allow the locking pins to move. That means inside cylinders on one bank and outsides on the other. Hence, the motor stays even firing. The engine mounts are bi-state (!), and are electrically switched to a different natural frequency in sync with the motor switching. It is all done within two engine cycles, and no, you can't feel it. GM's calibrators can't even feel it. They wire up an LED on the dash for reference. There is an electrically actuated hydraulic control valve for each cylinder that fire in sequence driven by the ECM and the cam position sensor. Think high speed: elec signal, solenoid movement, oil pressure buildup, locking pin movement... all in 10 milliseconds, and repeatable over the full range of oil temps. Hint: changing your oil regularly is a good idea.
As to economy, as always, it depends. I'm talking full size trucks and TrailBlazers here. The overall real world average they figure to be 8%. Might not sound too huge, but to a car company, that's a big number. In suburban driving, ~45ish and lot's of light loads, it could be over 20%. On the other hand, I heard the calibration guys say once that about 75mph is where the "road load" power required prevents it from going into deac. So, I doubt the heavier versions of the trucks are deac'g much on the highway. I guess running a 6 or 7 thousand pound truck on 4 cylinders isn't too easy. Our job was to just get them turned off and on, not make it more powerful in 4cyl mode. As mentioned, not it's also in the Impala SS. I didn't think they were doing the Corvette, but maybe so. It's also possible to do a V6, although the useable range of loads is a bit narrower. To even-fire a V6 in 3 cylinder mode, you need to deac one whole bank. And, yes, it's been done on a 4 cylinder by a research firm, but... well, let's see how the V8's are accepted.
Concerns? Oil puddling on top of the valve guides, and then getting sucked in when the cylinder suddenly "re-acts". GM's trucks periodically switch back to 8 cyl even if not required to prevent this. The fuel injectors are off of course, but the spark is still on. No need to add the complexity of switching it on and off.
Sorry for the long post, but engineers never know when to shut up.
(IMG:http://www.914world.com/bbs2/html/emoticons/driving.gif) Jim N.
'73 2.0

[jd74914]

very interesting. thanks

[groot]

Great post, Jim!!!

I hadn't read how the cylinders are being deactivated.

So, you still have pumping loses, correct? ... which would explain the 8% improvement.

[914efi]

What happened to Saab's variable compression engine?

[BIGKAT_83]

Great post Jim..............

Thanks for the info (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

[Rotary'14]

IIRC the EPA accepts data provided from the manufacturer to "vouch" for the fuel economy. It's up to the manufacturers to be ready for an audit if it ever comes.
All fuel economy tests regardless of vehicle type are done under standard conditions. The test (FTP75) is a modified version of the original test that was put together in 1975. The test was generated by data logging the driving habits of a "typical" driver in the Los Angeles area during 1970s rush hour street driving. All test are done with the A/C off, and the heater in full cool position.

In the 8+ years of performing this test for manufacturers, I can tell you that small displacement engines will have a larger discrepency between EPA and real world fuel economy figures. Most people drive in the real world with the A/C on, or the windows down. The FTP75 test has a max speed that is less than 55 MPH, and on the highway version of the test the max speed is ~62 MPH. Most people nowadays don't drive this slow. I'm sure some of these factors explain the mileage discrepancy.

-Rob

[jniemeier]

This followup will be short, I promise.
Reduction in "pumping losses" is why Deac improves economy. By pumping losses I mean the work required to pull down on intake against the restriction of the throttle blade. When in 4 cyl mode, a deac engine has it's throttle blade further open than it would in 8 cyl mode at the same speed-load point. Think: working harder on the remaining four cylinders. Further open means air flows in easier, i.e. less losses.
If you mean the frictional losses of the piston going up and down with both valves closed all the time, yes of course that is an unavoidable loss of efficiency, but it's not that bad, cuz the work required to compress the air is recovered when it expands. You only lose the friction, which isn't terrible with a warm engine and the low tension rings they use now-a-days.
Saab's Variable Compression engine is no doubt still around, and still in development. (Did you hear about the one that sparked from the plug to the top of the piston? Those Swedes!) These things take years. I've also seen one from FEV, a Euro engine design company in their Detroit office. It's a steep uphill challenge: added complexity means lower reliability, and more variables means tougher to meet emissions reg's, which is the hardest aspect of designing an engine. And when a new engine line costs many hundreds of millions, they tend to be a conservative bunch. Believe me. Very conservative. On the other hand, engines are now extremely reliable when you think about it.
OK, not short, but let's call this one medium. See you around. Good questions.
(IMG:http://www.914world.com/bbs2/html/emoticons/driving.gif) Jim N
'73 2.0

[Mueller]

thanks Jim (IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif)

[phantom914]

Jim N,

I have a dumb question which I ask because I don't feel like thinking right now and because, well, I'm dumb. What would be the problem of just shutting off the injectors for particular cylinders and leaving the valvetrain operating normally? Wouldn't there still be a gain in economy?


Oh, and isn't part of the increased efficiency due to the fact that the remaining cylinders are operating with a greater charge density? I was under the impression that a denser charge burns more efficiently.


Andrew

[ewdysar]

As long as we're on a rant topic... OK we're not but (IMG:http://www.914world.com/bbs2/html/emoticons/hijacked.gif)

Toyota says they've got 9 (wow 9!) models that get 30+MPG. So what! And those are EPA figures!

In real life, my '58 bug (with the ragtop and windows usually open) got 30 MPG all the time. 47 years later, technology has done what? For a closer example, my 1990 Geo Metro, which cost $7k (it was the luxury model), got 50+MPG on all but 2 tanks of gas over 130K miles (when the mileage dropped to 44 MPG, I knew there was something terribly wrong) The Metro fit 4 adults and could cruise over the Grapevine at 65 with the airconditioning on. That car actually got better mileage with the AC running than AC off with the windows down. Under any reasonable analysis, high MPG versions of any cars offered today will not cover their premium price while gas is under $6 a gallon.

We're being screwed by Big Oil, Big Auto, Big Government (IMG:http://www.914world.com/bbs2/html/emoticons/finger.gif) and we're collectively letting them. (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) Even if everyone that I come in contact with understands and agrees, we are completely overwhelmed by the rest of the populace. (IMG:http://www.914world.com/bbs2/html/emoticons/slap.gif) We are sinking in a sea of mediocrity, I see more lemmings than sheep from where I sit.

Man I hate this, I feel better when I don't think about these things. But I've got a plan... (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/beer3.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/beer3.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif)

Don't worry, be happy! (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif)

End of rant...

Eric