Vtec
11-10-2006, 06:46 AM
#21
BMW do not make a camless production petrol engine!!!!!!!!!!
they make one with no throttle bodies but not no cam! they ARE working on one, as are several other companies, but nothing is in the show room.
thanks Chris.
they make one with no throttle bodies but not no cam! they ARE working on one, as are several other companies, but nothing is in the show room.
thanks Chris.
11-11-2006, 12:10 AM
#22
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BMW's vandos and double vandos system still definetly has cams. This is from memory so correct me if I'm wrong, but between the cam and the valve there is another "lobe" which can alter the effective lift and duration. By far the most innovative system available, but I dont think they have used it on the m5/m6 v10. Dont know the reason why but im pretty sure it isnt cost.
11-11-2006, 02:02 AM
#23
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Your right the I was misinformed on the camless beamer but I did some searching and there are articles on mercedes trying to manufacture a camless engine in '07
BMW does have a running car that is camless they said the biggest complaint was how noisey the valve train was.
BMW does have a running car that is camless they said the biggest complaint was how noisey the valve train was.
11-13-2006, 01:32 PM
#24
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Originally Posted by 02sierraz71_5.3
Having a physical camshaft is a big limitation.
The end all be all in my opinion is camless valve managments, valves are operated by electromagnets/pnuematics and a computer this means you have an unlimited number of "lobe profiles-duration" etc.... think about an engine that adapts completely to your driving habits and the more aggressive you are with the pedal the more lobe you get, add a CVT and it would feel like its pulling smoothly forever.
The day will come when all you do is tune the PCM to change valve events.
BMW currently has a camless motor in production
The end all be all in my opinion is camless valve managments, valves are operated by electromagnets/pnuematics and a computer this means you have an unlimited number of "lobe profiles-duration" etc.... think about an engine that adapts completely to your driving habits and the more aggressive you are with the pedal the more lobe you get, add a CVT and it would feel like its pulling smoothly forever.
The day will come when all you do is tune the PCM to change valve events.
BMW currently has a camless motor in production
11-13-2006, 04:26 PM
#26
VTEC makes sense in a small 4 thats trying to make big power. This way you can run large lift/long duration profiles, spin it to 8 or 9 grand, and make decent (maximum) power. But using such a cam in a daily driving situation is, well, less than ideal on an already torqueless wonder. So having a smaller profile for the low revs to keep up port velocity helps the low end torque, in addition to a liveable idle.
On something like an LS1, well even the most wild cams still don't negate the inherent torque of 5.7 liters and up of displacement. Figure you're still making ~300 ft*lbs off idle. So unless you have a need to tow or in love with deisels, thats pretty much plenty of grunt for moving around town. The only benefit of a VTEC-like setup would be a smoother idle. But most people running bigger cams kind of like the lumpy idle (like myself
)
On something like an LS1, well even the most wild cams still don't negate the inherent torque of 5.7 liters and up of displacement. Figure you're still making ~300 ft*lbs off idle. So unless you have a need to tow or in love with deisels, thats pretty much plenty of grunt for moving around town. The only benefit of a VTEC-like setup would be a smoother idle. But most people running bigger cams kind of like the lumpy idle (like myself
) 
11-13-2006, 05:02 PM
#28
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Vtec isnt the thing for gm for several reasons. Controllong valve timing on a pushrod motor is a waste of time might as well just get over head cams but people dont want that any one remember the ZR1 over head cam car that cost to much money its chepar to build a big motor that an intrical little one. Plus can you imagine The new vette 427 with 4 cams and varable valve timing the goventment would **** you cant give people 700bhp cars and say go have fun. On a side note i have heard about the bmw thing with no cams isnt that just for f1 cars right now though?
11-13-2006, 05:44 PM
#29
Originally Posted by treyZ28
300ft lbs off idle, sure. but its only 42hp. Just to keep things in prospective
11-14-2006, 06:50 AM
#30
Originally Posted by 98redorangeta
On a side note i have heard about the bmw thing with no cams isnt that just for f1 cars right now though?
thanks CHris.
11-14-2006, 11:05 AM
#31
Originally Posted by NHRATA01
VTEC makes sense in a small 4 thats trying to make big power. This way you can run large lift/long duration profiles, spin it to 8 or 9 grand, and make decent (maximum) power...
On something like an LS1, well even the most wild cams still don't negate the inherent torque of 5.7 liters and up of displacement...The only benefit of a VTEC-like setup would be a smoother idle. But most people running bigger cams kind of like the lumpy idle (like myself )
On something like an LS1, well even the most wild cams still don't negate the inherent torque of 5.7 liters and up of displacement...The only benefit of a VTEC-like setup would be a smoother idle. But most people running bigger cams kind of like the lumpy idle (like myself
) Another problem GM would have with a VTEC is mating an A4 to it. GM's automatics don't seem to like 7500 rpm operation. So now you need a new tranny to go with the VTEC motor.
11-16-2006, 09:24 PM
#33
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GM dose use vairable cam timing. They refer to it as Cam phasing, i belive it will give you up to 40* of timing change. Caddys have been using it for a while. V6 with single cam phasing, now they use dual cam phasing on the V6 and it's also been incorperated into the Northstars now as well.
11-25-2006, 04:46 PM
#35
Originally Posted by Ragtop 99
Well it still makes sense because you can run less displacement and enjoy the benefits of better gas mileage and lower emissions. You may not care individually, but from a societal standpoint, have a 12 second corvette runing a 4.6l V8 rather than a 6.0l would be benefical. This is especially true in the SUV market where a fleetwide improvement of 2 mpg in this country over the last 8 years would have made a dent in the gasoline supplies and influenced pump prices. So much for the political statement,
Another problem GM would have with a VTEC is mating an A4 to it. GM's automatics don't seem to like 7500 rpm operation. So now you need a new tranny to go with the VTEC motor.
Another problem GM would have with a VTEC is mating an A4 to it. GM's automatics don't seem to like 7500 rpm operation. So now you need a new tranny to go with the VTEC motor.
No. I completely argee. The extra work and development pays off big time in the long run. Especially considering that adults are the ones buying new autos and in this day and age we don't care how fast you really are. Even if we did the streets are so crowded you couldn't do it safely. Anywho, if the average person can't run it WOT why make all cars gas hogs??? Resource conservation aside...
Anything to make us more independent and reverse global involvement and internationalism is a tactical plus in my mind.
12-19-2006, 06:58 PM
#37
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Vtech only adds 7% horsepower to the average honda motor. This was something I learned many years ago back from one of the honda boards when I was stupid enough to want to make my v6 accord faster. Some of the other previous posts explained that it is mostly to give the little gerbil a flatter torque curve. There are quite a number of automakers using the variable valve timing now to make more power out of smaller motors...I'm not sure if the cost justifies the means though...unless fuel mileage is a big concern.
12-20-2006, 07:20 PM
#38
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Originally Posted by v8hunter
Vtech only adds 7% horsepower to the average honda motor. This was something I learned many years ago back from one of the honda boards when I was stupid enough to want to make my v6 accord faster. Some of the other previous posts explained that it is mostly to give the little gerbil a flatter torque curve. There are quite a number of automakers using the variable valve timing now to make more power out of smaller motors...I'm not sure if the cost justifies the means though...unless fuel mileage is a big concern.
Honda fanboys act like VTEC allows them to have the efficiency of a 4 banger with the power of a V8, its funny really. They act like VTEC is the best thing since internal combustion, when in reality its similar to having a mild cam at higher RPM's, and thats in a performance application. Most Hondas are tuned for efficiency, so VTEC does little more than optimize valve lift and timing for best driveability and fuel economy.
12-20-2006, 08:48 PM
#39
I guess GM Engineers figure that we [the average consumer] operate the motors in such a tight RPM band, being V8's and all, that a mod which improves overall torque isn't worth it unless they changed to small displacement motors. I know that I drive in a very tight band and it is obvious that I could build a motor optimised for that easily. That 7% gain mod would be dead weight compared to really tuning the motor for the conditions in the first place.
In a future age where extreme small displacement due to limited natural resources, the camless motor might might its debut. Ok, maybe I played Wasteland the computer game too many times back in the 1980s
In a future age where extreme small displacement due to limited natural resources, the camless motor might might its debut. Ok, maybe I played Wasteland the computer game too many times back in the 1980s
12-20-2006, 09:09 PM
#40
Originally Posted by carzman5678
Only motor I know of without a cam is a.....Wankel engine.
Funny that you should have of previously mentioned that.
The military is working on a next generation Wankel that is addressing some of the issues of the old gen motor. It is called the RadMax Direct Charge Engine and the company claims 3 times the power with half the weight. I don't know if that version will be released to the public though. The military is working on it with some Canadian company.